Add Project History Page (#553)

Co-Authored-By: Glandos <bugs-github@antipoul.fr>

All project activity can be tracked, using SQLAlchemy-continuum.
IP addresses can optionally be recorded.

17 files changed, 1781 insertions, 10 deletions

diff --git a/ihatemoney/forms.py b/ihatemoney/forms.py
index 62c2144..495eefa 100644
--- a/ihatemoney/forms.py
+++ b/ihatemoney/forms.py
@@ -1,7 +1,7 @@
 from flask_wtf.form import FlaskForm
 from wtforms.fields.core import SelectField, SelectMultipleField
 from wtforms.fields.html5 import DateField, DecimalField, URLField
-from wtforms.fields.simple import PasswordField, SubmitField, StringField
+from wtforms.fields.simple import PasswordField, SubmitField, StringField, BooleanField
 from wtforms.validators import (
     Email,
     DataRequired,
@@ -14,7 +14,7 @@ from flask_wtf.file import FileField, FileAllowed, FileRequired
 
 from flask_babel import lazy_gettext as _
 from flask import request
-from werkzeug.security import generate_password_hash
+from werkzeug.security import generate_password_hash, check_password_hash
 
 from datetime import datetime
 from re import match
@@ -22,7 +22,7 @@ from jinja2 import Markup
 
 import email_validator
 
-from ihatemoney.models import Project, Person
+from ihatemoney.models import Project, Person, LoggingMode
 from ihatemoney.utils import slugify, eval_arithmetic_expression
 
 
@@ -89,6 +89,19 @@ class EditProjectForm(FlaskForm):
     name = StringField(_("Project name"), validators=[DataRequired()])
     password = StringField(_("Private code"), validators=[DataRequired()])
     contact_email = StringField(_("Email"), validators=[DataRequired(), Email()])
+    project_history = BooleanField(_("Enable project history"))
+    ip_recording = BooleanField(_("Use IP tracking for project history"))
+
+    @property
+    def logging_preference(self):
+        """Get the LoggingMode object corresponding to current form data."""
+        if not self.project_history.data:
+            return LoggingMode.DISABLED
+        else:
+            if self.ip_recording.data:
+                return LoggingMode.RECORD_IP
+            else:
+                return LoggingMode.ENABLED
 
     def save(self):
         """Create a new project with the information given by this form.
@@ -100,14 +113,20 @@ class EditProjectForm(FlaskForm):
             id=self.id.data,
             password=generate_password_hash(self.password.data),
             contact_email=self.contact_email.data,
+            logging_preference=self.logging_preference,
         )
         return project
 
     def update(self, project):
         """Update the project with the information from the form"""
         project.name = self.name.data
-        project.password = generate_password_hash(self.password.data)
+
+        # Only update password if changed to prevent spurious log entries
+        if not check_password_hash(project.password, self.password.data):
+            project.password = generate_password_hash(self.password.data)
+
         project.contact_email = self.contact_email.data
+        project.logging_preference = self.logging_preference
 
         return project
 
@@ -126,6 +145,14 @@ class ProjectForm(EditProjectForm):
     password = PasswordField(_("Private code"), validators=[DataRequired()])
     submit = SubmitField(_("Create the project"))
 
+    def save(self):
+        # WTForms Boolean Fields don't insert the default value when the
+        # request doesn't include any value the way that other fields do,
+        # so we'll manually do it here
+        self.project_history.data = LoggingMode.default() != LoggingMode.DISABLED
+        self.ip_recording.data = LoggingMode.default() == LoggingMode.RECORD_IP
+        return super().save()
+
     def validate_id(form, field):
         form.id.data = slugify(field.data)
         if (form.id.data == "dashboard") or Project.query.get(form.id.data):
diff --git a/ihatemoney/history.py b/ihatemoney/history.py
new file mode 100644
index 0000000..cda141e
--- /dev/null
+++ b/ihatemoney/history.py
@@ -0,0 +1,139 @@
+from flask_babel import gettext as _
+from sqlalchemy_continuum import (
+    Operation,
+    parent_class,
+)
+
+from ihatemoney.models import (
+    PersonVersion,
+    ProjectVersion,
+    BillVersion,
+    Person,
+)
+
+
+def get_history_queries(project):
+    """Generate queries for each type of version object for a given project."""
+    person_changes = PersonVersion.query.filter_by(project_id=project.id)
+
+    project_changes = ProjectVersion.query.filter_by(id=project.id)
+
+    bill_changes = (
+        BillVersion.query.with_entities(BillVersion.id.label("bill_version_id"))
+        .join(Person, BillVersion.payer_id == Person.id)
+        .filter(Person.project_id == project.id)
+    )
+    sub_query = bill_changes.subquery()
+    bill_changes = BillVersion.query.filter(BillVersion.id.in_(sub_query))
+
+    return person_changes, project_changes, bill_changes
+
+
+def history_sort_key(history_item_dict):
+    """
+    Return the key necessary to sort history entries. First order sort is time
+    of modification, but for simultaneous modifications we make the re-name
+    modification occur last so that the simultaneous entries make sense using
+    the old name.
+    """
+    second_order = 0
+    if "prop_changed" in history_item_dict:
+        changed_property = history_item_dict["prop_changed"]
+        if changed_property == "name" or changed_property == "what":
+            second_order = 1
+
+    return history_item_dict["time"], second_order
+
+
+def describe_version(version_obj):
+    """Use the base model str() function to describe a version object"""
+    return parent_class(type(version_obj)).__str__(version_obj)
+
+
+def describe_owers_change(version, human_readable_names):
+    """Compute the set difference to get added/removed owers lists."""
+    before_owers = {version.id: version for version in version.previous.owers}
+    after_owers = {version.id: version for version in version.owers}
+
+    added_ids = set(after_owers).difference(set(before_owers))
+    removed_ids = set(before_owers).difference(set(after_owers))
+
+    if not human_readable_names:
+        return added_ids, removed_ids
+
+    added = [describe_version(after_owers[ower_id]) for ower_id in added_ids]
+    removed = [describe_version(before_owers[ower_id]) for ower_id in removed_ids]
+
+    return added, removed
+
+
+def get_history(project, human_readable_names=True):
+    """
+    Fetch history for all models associated with a given project.
+    :param human_readable_names Whether to replace id numbers with readable names
+    :return A sorted list of dicts with history information
+    """
+    person_query, project_query, bill_query = get_history_queries(project)
+    history = []
+    for version_list in [person_query.all(), project_query.all(), bill_query.all()]:
+        for version in version_list:
+            object_type = {
+                "Person": _("Person"),
+                "Bill": _("Bill"),
+                "Project": _("Project"),
+            }[parent_class(type(version)).__name__]
+
+            # Use the old name if applicable
+            if version.previous:
+                object_str = describe_version(version.previous)
+            else:
+                object_str = describe_version(version)
+
+            common_properties = {
+                "time": version.transaction.issued_at.strftime("%Y-%m-%dT%H:%M:%SZ"),
+                "operation_type": version.operation_type,
+                "object_type": object_type,
+                "object_desc": object_str,
+                "ip": version.transaction.remote_addr,
+            }
+
+            if version.operation_type == Operation.UPDATE:
+                # Only iterate the changeset if the previous version
+                # Was logged
+                if version.previous:
+                    changeset = version.changeset
+                    if isinstance(version, BillVersion):
+                        if version.owers != version.previous.owers:
+                            added, removed = describe_owers_change(
+                                version, human_readable_names
+                            )
+
+                            if added:
+                                changeset["owers_added"] = (None, added)
+                            if removed:
+                                changeset["owers_removed"] = (None, removed)
+
+                    for (prop, (val_before, val_after),) in changeset.items():
+                        if human_readable_names:
+                            if prop == "payer_id":
+                                prop = "payer"
+                                if val_after is not None:
+                                    val_after = describe_version(version.payer)
+                                if version.previous and val_before is not None:
+                                    val_before = describe_version(
+                                        version.previous.payer
+                                    )
+                                else:
+                                    val_after = None
+
+                        next_event = common_properties.copy()
+                        next_event["prop_changed"] = prop
+                        next_event["val_before"] = val_before
+                        next_event["val_after"] = val_after
+                        history.append(next_event)
+                else:
+                    history.append(common_properties)
+            else:
+                history.append(common_properties)
+
+    return sorted(history, key=history_sort_key, reverse=True)
diff --git a/ihatemoney/migrations/versions/2dcb0c0048dc_autologger.py b/ihatemoney/migrations/versions/2dcb0c0048dc_autologger.py
new file mode 100644
index 0000000..0800835
--- /dev/null
+++ b/ihatemoney/migrations/versions/2dcb0c0048dc_autologger.py
@@ -0,0 +1,214 @@
+"""autologger
+
+Revision ID: 2dcb0c0048dc
+Revises: 6c6fb2b7f229
+Create Date: 2020-04-10 18:12:41.285590
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = "2dcb0c0048dc"
+down_revision = "6c6fb2b7f229"
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table(
+        "bill_version",
+        sa.Column("id", sa.Integer(), autoincrement=False, nullable=False),
+        sa.Column("payer_id", sa.Integer(), autoincrement=False, nullable=True),
+        sa.Column("amount", sa.Float(), autoincrement=False, nullable=True),
+        sa.Column("date", sa.Date(), autoincrement=False, nullable=True),
+        sa.Column("creation_date", sa.Date(), autoincrement=False, nullable=True),
+        sa.Column("what", sa.UnicodeText(), autoincrement=False, nullable=True),
+        sa.Column(
+            "external_link", sa.UnicodeText(), autoincrement=False, nullable=True
+        ),
+        sa.Column("archive", sa.Integer(), autoincrement=False, nullable=True),
+        sa.Column(
+            "transaction_id", sa.BigInteger(), autoincrement=False, nullable=False
+        ),
+        sa.Column("end_transaction_id", sa.BigInteger(), nullable=True),
+        sa.Column("operation_type", sa.SmallInteger(), nullable=False),
+        sa.PrimaryKeyConstraint("id", "transaction_id"),
+    )
+    op.create_index(
+        op.f("ix_bill_version_end_transaction_id"),
+        "bill_version",
+        ["end_transaction_id"],
+        unique=False,
+    )
+    op.create_index(
+        op.f("ix_bill_version_operation_type"),
+        "bill_version",
+        ["operation_type"],
+        unique=False,
+    )
+    op.create_index(
+        op.f("ix_bill_version_transaction_id"),
+        "bill_version",
+        ["transaction_id"],
+        unique=False,
+    )
+    op.create_table(
+        "billowers_version",
+        sa.Column("bill_id", sa.Integer(), autoincrement=False, nullable=False),
+        sa.Column("person_id", sa.Integer(), autoincrement=False, nullable=False),
+        sa.Column(
+            "transaction_id", sa.BigInteger(), autoincrement=False, nullable=False
+        ),
+        sa.Column("end_transaction_id", sa.BigInteger(), nullable=True),
+        sa.Column("operation_type", sa.SmallInteger(), nullable=False),
+        sa.PrimaryKeyConstraint("bill_id", "person_id", "transaction_id"),
+    )
+    op.create_index(
+        op.f("ix_billowers_version_end_transaction_id"),
+        "billowers_version",
+        ["end_transaction_id"],
+        unique=False,
+    )
+    op.create_index(
+        op.f("ix_billowers_version_operation_type"),
+        "billowers_version",
+        ["operation_type"],
+        unique=False,
+    )
+    op.create_index(
+        op.f("ix_billowers_version_transaction_id"),
+        "billowers_version",
+        ["transaction_id"],
+        unique=False,
+    )
+    op.create_table(
+        "person_version",
+        sa.Column("id", sa.Integer(), autoincrement=False, nullable=False),
+        sa.Column(
+            "project_id", sa.String(length=64), autoincrement=False, nullable=True
+        ),
+        sa.Column("name", sa.UnicodeText(), autoincrement=False, nullable=True),
+        sa.Column("weight", sa.Float(), autoincrement=False, nullable=True),
+        sa.Column("activated", sa.Boolean(), autoincrement=False, nullable=True),
+        sa.Column(
+            "transaction_id", sa.BigInteger(), autoincrement=False, nullable=False
+        ),
+        sa.Column("end_transaction_id", sa.BigInteger(), nullable=True),
+        sa.Column("operation_type", sa.SmallInteger(), nullable=False),
+        sa.PrimaryKeyConstraint("id", "transaction_id"),
+    )
+    op.create_index(
+        op.f("ix_person_version_end_transaction_id"),
+        "person_version",
+        ["end_transaction_id"],
+        unique=False,
+    )
+    op.create_index(
+        op.f("ix_person_version_operation_type"),
+        "person_version",
+        ["operation_type"],
+        unique=False,
+    )
+    op.create_index(
+        op.f("ix_person_version_transaction_id"),
+        "person_version",
+        ["transaction_id"],
+        unique=False,
+    )
+    op.create_table(
+        "project_version",
+        sa.Column("id", sa.String(length=64), autoincrement=False, nullable=False),
+        sa.Column("name", sa.UnicodeText(), autoincrement=False, nullable=True),
+        sa.Column(
+            "password", sa.String(length=128), autoincrement=False, nullable=True
+        ),
+        sa.Column(
+            "contact_email", sa.String(length=128), autoincrement=False, nullable=True
+        ),
+        sa.Column(
+            "logging_preference",
+            sa.Enum("DISABLED", "ENABLED", "RECORD_IP", name="loggingmode"),
+            server_default="ENABLED",
+            autoincrement=False,
+            nullable=True,
+        ),
+        sa.Column(
+            "transaction_id", sa.BigInteger(), autoincrement=False, nullable=False
+        ),
+        sa.Column("end_transaction_id", sa.BigInteger(), nullable=True),
+        sa.Column("operation_type", sa.SmallInteger(), nullable=False),
+        sa.PrimaryKeyConstraint("id", "transaction_id"),
+    )
+    op.create_index(
+        op.f("ix_project_version_end_transaction_id"),
+        "project_version",
+        ["end_transaction_id"],
+        unique=False,
+    )
+    op.create_index(
+        op.f("ix_project_version_operation_type"),
+        "project_version",
+        ["operation_type"],
+        unique=False,
+    )
+    op.create_index(
+        op.f("ix_project_version_transaction_id"),
+        "project_version",
+        ["transaction_id"],
+        unique=False,
+    )
+    op.create_table(
+        "transaction",
+        sa.Column("issued_at", sa.DateTime(), nullable=True),
+        sa.Column("id", sa.BigInteger(), autoincrement=True, nullable=False),
+        sa.Column("remote_addr", sa.String(length=50), nullable=True),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.add_column(
+        "project",
+        sa.Column(
+            "logging_preference",
+            sa.Enum("DISABLED", "ENABLED", "RECORD_IP", name="loggingmode"),
+            server_default="ENABLED",
+            nullable=False,
+        ),
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_column("project", "logging_preference")
+    op.drop_table("transaction")
+    op.drop_index(
+        op.f("ix_project_version_transaction_id"), table_name="project_version"
+    )
+    op.drop_index(
+        op.f("ix_project_version_operation_type"), table_name="project_version"
+    )
+    op.drop_index(
+        op.f("ix_project_version_end_transaction_id"), table_name="project_version"
+    )
+    op.drop_table("project_version")
+    op.drop_index(op.f("ix_person_version_transaction_id"), table_name="person_version")
+    op.drop_index(op.f("ix_person_version_operation_type"), table_name="person_version")
+    op.drop_index(
+        op.f("ix_person_version_end_transaction_id"), table_name="person_version"
+    )
+    op.drop_table("person_version")
+    op.drop_index(
+        op.f("ix_billowers_version_transaction_id"), table_name="billowers_version"
+    )
+    op.drop_index(
+        op.f("ix_billowers_version_operation_type"), table_name="billowers_version"
+    )
+    op.drop_index(
+        op.f("ix_billowers_version_end_transaction_id"), table_name="billowers_version"
+    )
+    op.drop_table("billowers_version")
+    op.drop_index(op.f("ix_bill_version_transaction_id"), table_name="bill_version")
+    op.drop_index(op.f("ix_bill_version_operation_type"), table_name="bill_version")
+    op.drop_index(op.f("ix_bill_version_end_transaction_id"), table_name="bill_version")
+    op.drop_table("bill_version")
+    # ### end Alembic commands ###
diff --git a/ihatemoney/migrations/versions/cb038f79982e_sqlite_autoincrement.py b/ihatemoney/migrations/versions/cb038f79982e_sqlite_autoincrement.py
new file mode 100644
index 0000000..ae5ab32
--- /dev/null
+++ b/ihatemoney/migrations/versions/cb038f79982e_sqlite_autoincrement.py
@@ -0,0 +1,50 @@
+"""sqlite_autoincrement
+
+Revision ID: cb038f79982e
+Revises: 2dcb0c0048dc
+Create Date: 2020-04-13 17:40:02.426957
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = "cb038f79982e"
+down_revision = "2dcb0c0048dc"
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    alter_table_batches = [
+        op.batch_alter_table(
+            "person", recreate="always", table_kwargs={"sqlite_autoincrement": True}
+        ),
+        op.batch_alter_table(
+            "bill", recreate="always", table_kwargs={"sqlite_autoincrement": True}
+        ),
+        op.batch_alter_table(
+            "billowers", recreate="always", table_kwargs={"sqlite_autoincrement": True}
+        ),
+    ]
+
+    for batch_op in alter_table_batches:
+        with batch_op:
+            pass
+
+
+def downgrade():
+    alter_table_batches = [
+        op.batch_alter_table(
+            "person", recreate="always", table_kwargs={"sqlite_autoincrement": False}
+        ),
+        op.batch_alter_table(
+            "bill", recreate="always", table_kwargs={"sqlite_autoincrement": False}
+        ),
+        op.batch_alter_table(
+            "billowers", recreate="always", table_kwargs={"sqlite_autoincrement": False}
+        ),
+    ]
+
+    for batch_op in alter_table_batches:
+        with batch_op:
+            pass
diff --git a/ihatemoney/models.py b/ihatemoney/models.py
index 4d32fd9..d765c93 100644
--- a/ihatemoney/models.py
+++ b/ihatemoney/models.py
@@ -1,6 +1,8 @@
 from collections import defaultdict
 
 from datetime import datetime
+
+import sqlalchemy
 from flask_sqlalchemy import SQLAlchemy, BaseQuery
 from flask import g, current_app
 
@@ -13,6 +15,40 @@ from itsdangerous import (
     BadSignature,
     SignatureExpired,
 )
+from sqlalchemy_continuum import make_versioned
+from sqlalchemy_continuum.plugins import FlaskPlugin
+from sqlalchemy_continuum import version_class
+
+from ihatemoney.patch_sqlalchemy_continuum import PatchedBuilder
+from ihatemoney.versioning import (
+    LoggingMode,
+    ConditionalVersioningManager,
+    version_privacy_predicate,
+    get_ip_if_allowed,
+)
+
+
+make_versioned(
+    user_cls=None,
+    manager=ConditionalVersioningManager(
+        # Conditionally Disable the versioning based on each
+        # project's privacy preferences
+        tracking_predicate=version_privacy_predicate,
+        # Patch in a fix to a SQLAchemy-Continuum Bug.
+        # See patch_sqlalchemy_continuum.py
+        builder=PatchedBuilder(),
+    ),
+    plugins=[
+        FlaskPlugin(
+            # Redirect to our own function, which respects user preferences
+            # on IP address collection
+            remote_addr_factory=get_ip_if_allowed,
+            # Suppress the plugin's attempt to grab a user id,
+            # which imports the flask_login module (causing an error)
+            current_user_id_factory=lambda: None,
+        )
+    ],
+)
 
 db = SQLAlchemy()
 
@@ -22,11 +58,20 @@ class Project(db.Model):
         def get_by_name(self, name):
             return Project.query.filter(Project.name == name).one()
 
+    # Direct SQLAlchemy-Continuum to track changes to this model
+    __versioned__ = {}
+
     id = db.Column(db.String(64), primary_key=True)
 
     name = db.Column(db.UnicodeText)
     password = db.Column(db.String(128))
     contact_email = db.Column(db.String(128))
+    logging_preference = db.Column(
+        db.Enum(LoggingMode),
+        default=LoggingMode.default(),
+        nullable=False,
+        server_default=LoggingMode.default().name,
+    )
     members = db.relationship("Person", backref="project")
 
     query_class = ProjectQuery
@@ -37,6 +82,7 @@ class Project(db.Model):
             "id": self.id,
             "name": self.name,
             "contact_email": self.contact_email,
+            "logging_preference": self.logging_preference.value,
             "members": [],
         }
 
@@ -277,6 +323,9 @@ class Project(db.Model):
             return None
         return data["project_id"]
 
+    def __str__(self):
+        return self.name
+
     def __repr__(self):
         return "<Project %s>" % self.name
 
@@ -301,6 +350,11 @@ class Person(db.Model):
 
     query_class = PersonQuery
 
+    # Direct SQLAlchemy-Continuum to track changes to this model
+    __versioned__ = {}
+
+    __table_args__ = {"sqlite_autoincrement": True}
+
     id = db.Column(db.Integer, primary_key=True)
     project_id = db.Column(db.String(64), db.ForeignKey("project.id"))
     bills = db.relationship("Bill", backref="payer")
@@ -337,8 +391,9 @@ class Person(db.Model):
 # We need to manually define a join table for m2m relations
 billowers = db.Table(
     "billowers",
-    db.Column("bill_id", db.Integer, db.ForeignKey("bill.id")),
-    db.Column("person_id", db.Integer, db.ForeignKey("person.id")),
+    db.Column("bill_id", db.Integer, db.ForeignKey("bill.id"), primary_key=True),
+    db.Column("person_id", db.Integer, db.ForeignKey("person.id"), primary_key=True),
+    sqlite_autoincrement=True,
 )
 
 
@@ -365,6 +420,11 @@ class Bill(db.Model):
 
     query_class = BillQuery
 
+    # Direct SQLAlchemy-Continuum to track changes to this model
+    __versioned__ = {}
+
+    __table_args__ = {"sqlite_autoincrement": True}
+
     id = db.Column(db.Integer, primary_key=True)
 
     payer_id = db.Column(db.Integer, db.ForeignKey("person.id"))
@@ -403,6 +463,9 @@ class Bill(db.Model):
         else:
             return 0
 
+    def __str__(self):
+        return "%s for %s" % (self.amount, self.what)
+
     def __repr__(self):
         return "<Bill of %s from %s for %s>" % (
             self.amount,
@@ -426,3 +489,10 @@ class Archive(db.Model):
 
     def __repr__(self):
         return "<Archive>"
+
+
+sqlalchemy.orm.configure_mappers()
+
+PersonVersion = version_class(Person)
+ProjectVersion = version_class(Project)
+BillVersion = version_class(Bill)
diff --git a/ihatemoney/patch_sqlalchemy_continuum.py b/ihatemoney/patch_sqlalchemy_continuum.py
new file mode 100644
index 0000000..e0680c6
--- /dev/null
+++ b/ihatemoney/patch_sqlalchemy_continuum.py
@@ -0,0 +1,138 @@
+"""
+A temporary work-around to patch SQLAlchemy-continuum per:
+https://github.com/kvesteri/sqlalchemy-continuum/pull/242
+
+Source code reproduced under their license:
+
+    Copyright (c) 2012, Konsta Vesterinen
+
+    All rights reserved.
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright notice, this
+      list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above copyright notice,
+      this list of conditions and the following disclaimer in the documentation
+      and/or other materials provided with the distribution.
+
+    * The names of the contributors may not be used to endorse or promote products
+      derived from this software without specific prior written permission.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+    ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+    DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY DIRECT,
+    INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+    LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+    OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+    ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+"""
+
+import sqlalchemy as sa
+from sqlalchemy_continuum import Operation
+from sqlalchemy_continuum.builder import Builder
+from sqlalchemy_continuum.expression_reflector import VersionExpressionReflector
+from sqlalchemy_continuum.relationship_builder import RelationshipBuilder
+from sqlalchemy_continuum.utils import option, adapt_columns
+
+
+class PatchedRelationShipBuilder(RelationshipBuilder):
+    def association_subquery(self, obj):
+        """
+        Returns an EXISTS clause that checks if an association exists for given
+        SQLAlchemy declarative object. This query is used by
+        many_to_many_criteria method.
+
+        Example query:
+
+        .. code-block:: sql
+
+        EXISTS (
+            SELECT 1
+            FROM article_tag_version
+            WHERE article_id = 3
+            AND tag_id = tags_version.id
+            AND operation_type != 2
+            AND EXISTS (
+                SELECT 1
+                FROM article_tag_version as article_tag_version2
+                WHERE article_tag_version2.tag_id = article_tag_version.tag_id
+                AND article_tag_version2.tx_id <=5
+                AND article_tag_version2.article_id = 3
+                GROUP BY article_tag_version2.tag_id
+                HAVING
+                    MAX(article_tag_version2.tx_id) =
+                    article_tag_version.tx_id
+            )
+        )
+
+        :param obj: SQLAlchemy declarative object
+        """
+
+        tx_column = option(obj, "transaction_column_name")
+        join_column = self.property.primaryjoin.right.name
+        object_join_column = self.property.primaryjoin.left.name
+        reflector = VersionExpressionReflector(obj, self.property)
+
+        association_table_alias = self.association_version_table.alias()
+        association_cols = [
+            association_table_alias.c[association_col.name]
+            for _, association_col in self.remote_to_association_column_pairs
+        ]
+
+        association_exists = sa.exists(
+            sa.select([1])
+            .where(
+                sa.and_(
+                    association_table_alias.c[tx_column] <= getattr(obj, tx_column),
+                    association_table_alias.c[join_column]
+                    == getattr(obj, object_join_column),
+                    *[
+                        association_col
+                        == self.association_version_table.c[association_col.name]
+                        for association_col in association_cols
+                    ]
+                )
+            )
+            .group_by(*association_cols)
+            .having(
+                sa.func.max(association_table_alias.c[tx_column])
+                == self.association_version_table.c[tx_column]
+            )
+            .correlate(self.association_version_table)
+        )
+        return sa.exists(
+            sa.select([1])
+            .where(
+                sa.and_(
+                    reflector(self.property.primaryjoin),
+                    association_exists,
+                    self.association_version_table.c.operation_type != Operation.DELETE,
+                    adapt_columns(self.property.secondaryjoin),
+                )
+            )
+            .correlate(self.local_cls, self.remote_cls)
+        )
+
+
+class PatchedBuilder(Builder):
+    def build_relationships(self, version_classes):
+        """
+        Builds relationships for all version classes.
+
+        :param version_classes: list of generated version classes
+        """
+        for cls in version_classes:
+            if not self.manager.option(cls, "versioning"):
+                continue
+
+            for prop in sa.inspect(cls).iterate_properties:
+                if prop.key == "versions":
+                    continue
+                builder = PatchedRelationShipBuilder(self.manager, cls, prop)
+                builder()
diff --git a/ihatemoney/static/css/main.css b/ihatemoney/static/css/main.css
index fe8eec2..7d91c38 100644
--- a/ihatemoney/static/css/main.css
+++ b/ihatemoney/static/css/main.css
@@ -326,7 +326,8 @@ footer .footer-left {
 }
 
 #bill_table,
-#monthly_stats {
+#monthly_stats,
+#history_table {
   margin-top: 30px;
   margin-bottom: 30px;
 }
@@ -363,6 +364,36 @@ footer .footer-left {
   background: url("../images/see.png") no-repeat right;
 }
 
+.history_icon > .delete,
+.history_icon > .add,
+.history_icon > .edit {
+  font-size: 0px;
+  display: block;
+  width: 16px;
+  height: 16px;
+  margin: 2px;
+  margin-right: 10px;
+  margin-top: 3px;
+  float: left;
+}
+
+.history_icon > .delete {
+  background: url("../images/delete.png") no-repeat right;
+}
+
+.history_icon > .edit {
+  background: url("../images/edit.png") no-repeat right;
+}
+
+.history_icon > .add {
+  background: url("../images/add.png") no-repeat right;
+}
+
+.history_text {
+  display: table-cell;
+}
+
+
 .balance .balance-value {
   text-align: right;
 }
@@ -518,12 +549,23 @@ footer .icon svg {
   fill: white;
 }
 
+.icon.icon-red {
+  fill: #dc3545;
+}
+.btn:hover .icon.icon-red  {
+  fill: white !important;
+}
+
 /* align the first column */
 #monthly_stats tr *:first-child {
   text-align: right;
   width: 200px;
 }
 
+#history_warnings {
+  margin-top: 30px;
+}
+
 /* edit settings */
 
 .edit-project form {
diff --git a/ihatemoney/static/images/add.png b/ihatemoney/static/images/add.png
new file mode 100644
index 0000000..262891b
--- /dev/null
+++ b/ihatemoney/static/images/add.png
diff --git a/ihatemoney/static/images/x.svg b/ihatemoney/static/images/x.svg
new file mode 100644
index 0000000..3416d7a
--- /dev/null
+++ b/ihatemoney/static/images/x.svg
@@ -0,0 +1,8 @@
+<svg
+   xmlns="http://www.w3.org/2000/svg"
+   viewBox="0 0 807 807"><g
+     transform="translate(-20,-20)"
+     id="g8"><polygon
+       id="polygon6"
+       points="173,20 423,269 673,20 827,173 577,423 827,673 673,827 423,577 173,827 20,673 269,423 20,173 "
+       class="fil0" /></g></svg>
\ No newline at end of file
diff --git a/ihatemoney/static/js/ihatemoney.js b/ihatemoney/static/js/ihatemoney.js
index c240dc1..9ffc877 100644
--- a/ihatemoney/static/js/ihatemoney.js
+++ b/ihatemoney/static/js/ihatemoney.js
@@ -5,3 +5,7 @@ function selectCheckboxes(value){
     els[i].checked = value;
   }
 }
+
+function localizeTime(utcTimestamp) {
+    return new Date(utcTimestamp).toLocaleString()
+}
diff --git a/ihatemoney/templates/forms.html b/ihatemoney/templates/forms.html
index bec7018..33a283f 100644
--- a/ihatemoney/templates/forms.html
+++ b/ihatemoney/templates/forms.html
@@ -20,6 +20,16 @@
     </div>
 {% endmacro %}
 
+{% macro checkbox(field) %}
+    <div class="controls{% if inline %} col-9{% endif %}">
+        {{ field(id=field.name) }}
+        <label for="{{ field.name }}">{{ field.label() }}</label>
+    {% if field.description %}
+        <small id="{{field.name}}_description"" class="form-text text-muted">{{ field.description }}</small>
+    {% endif %}
+    </div>
+{% endmacro %}
+
 {% macro submit(field, cancel=False, home=False) -%}
     <div class="actions">
         <button type="submit" class="btn btn-primary">{{ field.name }}</button>
@@ -78,6 +88,14 @@
     {{ input(form.name) }}
     {{ input(form.password) }}
     {{ input(form.contact_email) }}
+    <div class="form-group">
+        <label for="privacy_checkboxes">{{ _("Privacy Settings") }}</label>
+        <div id="privacy_checkboxes" class="card card-body bg-light">
+        {{ checkbox(form.project_history) }}
+        {{ checkbox(form.ip_recording) }}
+        </div>
+    </div>
+
     <div class="actions">
         <button class="btn btn-primary">{{ _("Edit the project") }}</button>
         <a id="delete-project" style="color:red; margin-left:10px; cursor:pointer; ">{{ _("delete") }}</a>
diff --git a/ihatemoney/templates/history.html b/ihatemoney/templates/history.html
new file mode 100644
index 0000000..875040e
--- /dev/null
+++ b/ihatemoney/templates/history.html
@@ -0,0 +1,250 @@
+{% extends "sidebar_table_layout.html" %}
+
+{% macro change_to_logging_preference(event) %}
+{% if event.val_after == LoggingMode.DISABLED %}
+    {% if event.val_before == LoggingMode.ENABLED %}
+        {{ _("Disabled Project History") }}
+    {% else %}
+        {{ _("Disabled Project History & IP Address Recording") }}
+    {% endif %}
+{% elif event.val_after == LoggingMode.ENABLED %}
+    {% if event.val_before == LoggingMode.DISABLED %}
+        {{ _("Enabled Project History") }}
+    {% elif event.val_before == LoggingMode.RECORD_IP %}
+        {{ _("Disabled IP Address Recording") }}
+    {% else %}
+        {{ _("Enabled Project History") }}
+    {% endif %}
+{% elif event.val_after == LoggingMode.RECORD_IP %}
+    {% if event.val_before == LoggingMode.DISABLED %}
+        {{ _("Enabled Project History & IP Address Recording") }}
+    {% elif event.val_before == LoggingMode.ENABLED %}
+        {{ _("Enabled IP Address Recording") }}
+    {% else %}
+        {{ _("Enabled Project History & IP Address Recording") }}
+    {% endif %}
+{% else %}
+    {# Should be unreachable #}
+    {{ _("History Settings Changed") }}
+{% endif %}
+{% endmacro %}
+
+{% macro describe_object(event) %}{{ event.object_type }} <em class="font-italic">{{ event.object_desc }}</em>{% endmacro %}
+
+{% macro simple_property_change(event, localized_property_name, from=True) %}
+    {{ describe_object(event) }}:
+    {{ localized_property_name }} {{ _("changed") }}
+    {% if from %}{{ _("from") }} <em class="font-italic">{{ event.val_before }}</em>{% endif %}
+    {{ _("to") }} <em class="font-italic">{{ event.val_after }}</em>
+{% endmacro %}
+
+{% macro clear_history_modals() %}
+<!-- Modal -->
+<div id="confirm-ip-delete" class="modal fade show" role="dialog">
+    <div class="modal-dialog" role="document">
+        <div class="modal-content">
+            <div class="modal-header">
+                <h3 class="modal-title">{{ _('Confirm Remove IP Adresses') }}</h3>
+                <a href="#" class="close" data-dismiss="modal">&times;</a>
+            </div>
+            <div class="modal-body">
+                <p>{{ _("Are you sure you want to delete all recorded IP addresses from this project?
+                The rest of the project history will be unaffected. This action cannot be undone.") }}</p>
+            </div>
+            <div class="modal-footer">
+                <button type="button" class="btn btn-secondary" data-dismiss="modal">{{ _("Close") }}</button>
+                <form action="{{ url_for(".strip_ip_addresses") }}" method="post">
+                    <input type="submit" class="btn btn-danger" value="{{ _("Confirm Delete") }}" name="{{ _("Confirm Delete") }}"/>
+                </form>
+              </div>
+        </div>
+    </div>
+</div>
+<!-- Modal -->
+    <div id="confirm-erase" class="modal fade show" role="dialog">
+    <div class="modal-dialog" role="document">
+        <div class="modal-content">
+            <div class="modal-header">
+                <h3 class="modal-title">{{ _('Delete Confirmation') }}</h3>
+                <a href="#" class="close" data-dismiss="modal">&times;</a>
+            </div>
+            <div class="modal-body">
+                <p>{{ _("Are you sure you want to erase all history for this project? This action cannot be undone.") }}</p>
+            </div>
+            <div class="modal-footer">
+                <button type="button" class="btn btn-secondary" data-dismiss="modal">{{ _("Close") }}</button>
+                <form action="{{ url_for(".erase_history") }}" method="post">
+                    <input type="submit" class="btn btn-danger" value="{{ _("Confirm Delete") }}" name="{{ _("Confirm Delete") }}"/>
+                </form>
+              </div>
+        </div>
+    </div>
+</div>
+{% endmacro %}
+
+{% macro owers_changed(event, add) %}
+    {{ describe_object(event) }}: {% if add %}{{ _("Added") }}{% else %}{{ _("Removed") }}{% endif %}
+    {% if event.val_after|length > 1 %}
+        {% for name in event.val_after %}
+            <em class="font-italic">{{ name }}</em>{% if event.val_after|length > 2 and loop.index != event.val_after|length %},{% endif %}
+            {% if loop.index == event.val_after|length - 1 %} {{ _("and") }} {% endif %}
+        {% endfor %}
+    {% else %}
+        <em class="font-italic">{{ event.val_after[0] }}</em>
+    {% endif %}
+    {% if add %}{{ _("to") }}{% else %}{{ _("from") }}{% endif %}
+    {{ _("owers list") }}
+{% endmacro %}
+
+{% block sidebar %}
+    <div id="table_overflow">
+    <table class="balance table">
+    <thead>
+        <tr class="d-none d-md-table-row">
+            <th>{{ _("Who?") }}</th>
+            <th class="balance-value">{{ _("Balance") }}</th>
+        </tr>
+    </thead>
+    {% set balance = g.project.balance %}
+    {% for member in g.project.members | sort(attribute='name') if member.activated or balance[member.id]|round(2) != 0 %}
+    <tr id="bal-member-{{ member.id }}" action={% if member.activated %}delete{% else %}reactivate{% endif %}>
+        <td class="balance-name">{{ member.name }}</td>
+        <td class="balance-value {% if balance[member.id]|round(2) > 0 %}positive{% elif balance[member.id]|round(2) < 0 %}negative{% endif %}">
+            {% if balance[member.id]|round(2) > 0 %}+{% endif %}{{ "%.2f" | format(balance[member.id]) }}
+        </td>
+    </tr>
+    {% endfor %}
+    </table>
+    </div>
+{% endblock %}
+
+
+
+{% block content %}
+    {% if current_log_pref == LoggingMode.DISABLED  or (current_log_pref != LoggingMode.RECORD_IP and any_ip_addresses) %}
+    <div id="history_warnings" class="card card-body bg-light">
+    {% if current_log_pref == LoggingMode.DISABLED  %}
+        <p>
+            <i>{{ _("This project has history disabled. New actions won't appear below. You can enable history on the") }}</i>
+            <a href="{{ url_for(".edit_project") }}">{{ _("settings page") }}</a>
+        </p>
+        {% if history %}
+        <p><i>{{ _("The table below reflects actions recorded prior to disabling project history. You can ") }}
+            <a href="#" data-toggle="modal" data-keyboard="false" data-target="#confirm-erase">{{ _("clear project history") }}</a> {{ _("to remove them.") }}</i></p>
+        {% endif %}
+    {% endif %}
+    {% if current_log_pref != LoggingMode.RECORD_IP and any_ip_addresses %}
+        <p><i>{{  _("Some entries below contain IP addresses, even though this project has IP recording disabled. ") }}
+            <a href="#" data-toggle="modal" data-keyboard="false" data-target="#confirm-ip-delete">{{ _("Delete stored IP addresses") }}</a></i></p>
+    {% endif %}
+    </div>
+    {% endif %}
+    {{ clear_history_modals() }}
+    <span class="float-right mt-3" {% if not history %} data-toggle="tooltip" title="{{_('No history to erase')}}" {% endif %}>
+        <a href="#" class="btn btn-outline-danger float-right {% if not history %} disabled {% endif %}" data-toggle="modal" data-keyboard="false" data-target="#confirm-erase">
+            <i class="icon icon-red plus">{{ static_include("images/x.svg") | safe }}</i>
+            {{ _("Clear Project History") }}
+        </a>
+    </span>
+    <span class="float-right mt-3" {% if not any_ip_addresses %}data-placement="top" data-toggle="tooltip" title="{{_('No IP Addresses to erase')}}" {% endif %}>
+        <a href="#" class="btn btn-outline-danger float-right mr-2 {% if not any_ip_addresses %} disabled {% endif %}" data-toggle="modal" data-keyboard="false" data-target="#confirm-ip-delete">
+            <i class="icon icon-red plus">{{ static_include("images/x.svg") | safe }}</i>
+            {{ _("Delete Stored IP Addresses") }}
+        </a>
+    </span>
+
+    <div class="clearfix"></div>
+    {% if history %}
+    <table id="history_table" class="split_bills table table-striped">
+        <thead><tr>
+            <th style="width: 15%">{{ _("Time") }}</th>
+            <th style="width: 65%">{{ _("Event") }}</th>
+            <th style="width: 20%">
+                <span data-toggle="tooltip" title="{{_('IP address recording can be') }}
+                                                    {% if current_log_pref != LoggingMode.RECORD_IP %}
+                                                    {{ _("enabled") }}{% else %}{{ _("disabled") }}{% endif %}
+                                                    {{ _('on the Settings page') }}">
+                {{ _("From IP") }}</span></th>
+        </tr></thead>
+    <tbody>
+    {% for event in history %}
+    <tr>
+            <td><script>document.write(localizeTime("{{ event.time }}"));</script></td>
+            <td >
+                <div class="history_icon">
+                    <i {% if event.operation_type == OperationType.INSERT  %}
+                    class="add"
+                    {% elif event.operation_type == OperationType.UPDATE  %}
+                    class="edit"
+                    {% elif event.operation_type == OperationType.DELETE  %}
+                    class="delete"
+                    {% endif %}
+                    ></i>
+                </div>
+                <div class="history_text">
+                {% if event.operation_type == OperationType.INSERT %}
+                    {{ event.object_type }} <em class="font-italic">{{ event.object_desc }}</em> {{ _("added") }}
+                {% elif event.operation_type == OperationType.UPDATE  %}
+                    {% if event.object_type == _("Project") %}
+                        {% if event.prop_changed == "password" %}
+                           {{ _("Project private code changed") }}
+                        {% elif event.prop_changed == "logging_preference" %}
+                            {{ change_to_logging_preference(event) }}
+                        {% elif event.prop_changed == "name" %}
+                            {{ _("Project renamed to") }} <em class="font-italic">{{ event.val_after }}</em>
+                        {% elif event.prop_changed == "contact_email" %}
+                            {{ _("Project contact email changed to") }} <em class="font-italic">{{ event.val_after }}</em>
+                        {% else %}
+                            {{ _("Project settings modified") }}
+                        {% endif %}
+                    {% elif event.prop_changed == "activated" %}
+                        {{ event.object_type }} <em class="font-italic">{{ event.object_desc }}</em>
+                        {% if event.val_after == False %}{{ _("deactivated") }}{% else %}{{ _("reactivated") }}{% endif %}
+                    {% elif event.prop_changed == "name" or event.prop_changed == "what" %}
+                        {{ describe_object(event) }} {{ _("renamed") }} {{ _("to") }} <em class="font-italic">{{ event.val_after }}</em>
+                    {% elif event.prop_changed == "weight" %}
+                        {{ simple_property_change(event, _("Weight")) }}
+                    {% elif event.prop_changed == "external_link" %}
+                        {{ describe_object(event) }}: {{ _("External link changed to") }}
+                        <a href="{{ event.val_after }}" class="font-italic">{{ event.val_after }}</a>
+                    {% elif event.prop_changed == "owers_added" %}
+                        {{ owers_changed(event, True)}}
+                    {% elif event.prop_changed == "owers_removed" %}
+                        {{ owers_changed(event, False)}}
+                    {% elif event.prop_changed == "payer" %}
+                        {{ simple_property_change(event, _("Payer"))}}
+                    {% elif event.prop_changed == "amount" %}
+                        {{ simple_property_change(event, _("Amount")) }}
+                    {% elif event.prop_changed == "date" %}
+                        {{ simple_property_change(event, _("Date")) }}
+                    {% else %}
+                       {{ describe_object(event) }} {{ _("modified") }}
+                    {% endif %}
+                {% elif event.operation_type == OperationType.DELETE %}
+                    {{ event.object_type }} <em class="font-italic">{{ event.object_desc }}</em> {{ _("removed") }}
+                {% else %}
+                {# Should be unreachable #}
+                {{ describe_object(event) }} {{ _("changed in a unknown way") }}
+                {% endif %}
+                </div>
+            </td>
+            <td>{% if event.ip %}{{ event.ip }}{% else %} -- {% endif %}</td>
+    </tr>
+    {% endfor %}
+    </tbody>
+    </table>
+    {% else %}
+        <div class="py-3 d-flex justify-content-center empty-bill">
+        <div class="card d-inline-flex p-2">
+            <div class="card-body text-center text-muted">
+                <i class="icon icon-white hand-holding-heart">{{ static_include("images/hand-holding-heart.svg") | safe }}</i>
+                <h3>{{ _('Nothing to list')}}</h3>
+                <p>
+                    {{ _("Someone probably") }}<br />
+                    {{ _("cleared the project history.") }}
+                </p>
+            </div>
+        </div></div>
+    {% endif %}
+
+{% endblock %}
diff --git a/ihatemoney/templates/layout.html b/ihatemoney/templates/layout.html
index 8609779..eaf13a6 100644
--- a/ihatemoney/templates/layout.html
+++ b/ihatemoney/templates/layout.html
@@ -45,6 +45,7 @@
           <li class="nav-item{% if current_view == 'list_bills' %} active{% endif %}"><a class="nav-link" href="{{ url_for("main.list_bills") }}">{{ _("Bills") }}</a></li>
           <li class="nav-item{% if current_view == 'settle_bill' %} active{% endif %}"><a class="nav-link" href="{{ url_for("main.settle_bill") }}">{{ _("Settle") }}</a></li>
           <li class="nav-item{% if current_view == 'statistics' %} active{% endif %}"><a class="nav-link" href="{{ url_for("main.statistics") }}">{{ _("Statistics") }}</a></li>
+          <li class="nav-item{% if current_view == 'history' %} active{% endif %}"><a class="nav-link" href="{{ url_for("main.history") }}">{{ _("History") }}</a></li>
           <li class="nav-item{% if current_view == 'edit_project' %} active{% endif %}"><a class="nav-link" href="{{ url_for("main.edit_project") }}">{{ _("Settings") }}</a></li>
           {% endblock %}
         {% endif %}
diff --git a/ihatemoney/tests/tests.py b/ihatemoney/tests/tests.py
index c4b1585..5dff64d 100644
--- a/ihatemoney/tests/tests.py
+++ b/ihatemoney/tests/tests.py
@@ -17,7 +17,8 @@ from flask_testing import TestCase
 
 from ihatemoney.run import create_app, db, load_configuration
 from ihatemoney.manage import GenerateConfig, GeneratePasswordHash, DeleteProject
-from ihatemoney import models
+from ihatemoney import models, history
+from ihatemoney.versioning import LoggingMode
 from ihatemoney import utils
 from sqlalchemy import orm
 
@@ -843,6 +844,7 @@ class BudgetTestCase(IhatemoneyTestCase):
             "name": "Super raclette party!",
             "contact_email": "alexis@notmyidea.org",
             "password": "didoudida",
+            "logging_preference": LoggingMode.ENABLED.value,
         }
 
         resp = self.client.post("/raclette/edit", data=new_data, follow_redirects=True)
@@ -1517,6 +1519,7 @@ class APITestCase(IhatemoneyTestCase):
             "name": "raclette",
             "contact_email": "raclette@notmyidea.org",
             "id": "raclette",
+            "logging_preference": 1,
         }
         decoded_resp = json.loads(resp.data.decode("utf-8"))
         self.assertDictEqual(decoded_resp, expected)
@@ -1528,6 +1531,7 @@ class APITestCase(IhatemoneyTestCase):
                 "contact_email": "yeah@notmyidea.org",
                 "password": "raclette",
                 "name": "The raclette party",
+                "project_history": "y",
             },
             headers=self.get_auth("raclette"),
         )
@@ -1544,6 +1548,7 @@ class APITestCase(IhatemoneyTestCase):
             "contact_email": "yeah@notmyidea.org",
             "members": [],
             "id": "raclette",
+            "logging_preference": 1,
         }
         decoded_resp = json.loads(resp.data.decode("utf-8"))
         self.assertDictEqual(decoded_resp, expected)
@@ -2104,12 +2109,32 @@ class APITestCase(IhatemoneyTestCase):
             "contact_email": "raclette@notmyidea.org",
             "id": "raclette",
             "name": "raclette",
+            "logging_preference": 1,
         }
 
         self.assertStatus(200, req)
         decoded_req = json.loads(req.data.decode("utf-8"))
         self.assertDictEqual(decoded_req, expected)
 
+    def test_log_created_from_api_call(self):
+        # create a project
+        self.api_create("raclette")
+        self.login("raclette")
+
+        # add members
+        self.api_add_member("raclette", "alexis")
+
+        resp = self.client.get("/raclette/history", follow_redirects=True)
+        self.assertEqual(resp.status_code, 200)
+        self.assertIn(
+            "Person %s added" % em_surround("alexis"), resp.data.decode("utf-8")
+        )
+        self.assertIn(
+            "Project %s added" % em_surround("raclette"), resp.data.decode("utf-8"),
+        )
+        self.assertEqual(resp.data.decode("utf-8").count("<td> -- </td>"), 2)
+        self.assertNotIn("127.0.0.1", resp.data.decode("utf-8"))
+
 
 class ServerTestCase(IhatemoneyTestCase):
     def test_homepage(self):
@@ -2224,5 +2249,626 @@ class ModelsTestCase(IhatemoneyTestCase):
                 self.assertEqual(bill.pay_each(), pay_each_expected)
 
 
+def em_surround(string, regex_escape=False):
+    if regex_escape:
+        return r'<em class="font-italic">%s<\/em>' % string
+    else:
+        return '<em class="font-italic">%s</em>' % string
+
+
+class HistoryTestCase(IhatemoneyTestCase):
+    def setUp(self):
+        super().setUp()
+        self.post_project("demo")
+        self.login("demo")
+
+    def test_simple_create_logentry_no_ip(self):
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertIn(
+            "Project %s added" % em_surround("demo"), resp.data.decode("utf-8"),
+        )
+        self.assertEqual(resp.data.decode("utf-8").count("<td> -- </td>"), 1)
+        self.assertNotIn("127.0.0.1", resp.data.decode("utf-8"))
+
+    def change_privacy_to(self, logging_preference):
+        # Change only logging_preferences
+        new_data = {
+            "name": "demo",
+            "contact_email": "demo@notmyidea.org",
+            "password": "demo",
+        }
+
+        if logging_preference != LoggingMode.DISABLED:
+            new_data["project_history"] = "y"
+            if logging_preference == LoggingMode.RECORD_IP:
+                new_data["ip_recording"] = "y"
+
+        # Disable History
+        resp = self.client.post("/demo/edit", data=new_data, follow_redirects=True)
+        self.assertEqual(resp.status_code, 200)
+        self.assertNotIn("danger", resp.data.decode("utf-8"))
+
+        resp = self.client.get("/demo/edit")
+        self.assertEqual(resp.status_code, 200)
+        if logging_preference == LoggingMode.DISABLED:
+            self.assertIn('<input id="project_history"', resp.data.decode("utf-8"))
+        else:
+            self.assertIn(
+                '<input checked id="project_history"', resp.data.decode("utf-8")
+            )
+
+        if logging_preference == LoggingMode.RECORD_IP:
+            self.assertIn('<input checked id="ip_recording"', resp.data.decode("utf-8"))
+        else:
+            self.assertIn('<input id="ip_recording"', resp.data.decode("utf-8"))
+
+    def assert_empty_history_logging_disabled(self):
+        resp = self.client.get("/demo/history")
+        self.assertIn(
+            "This project has history disabled. New actions won't appear below. ",
+            resp.data.decode("utf-8"),
+        )
+        self.assertIn(
+            "Nothing to list", resp.data.decode("utf-8"),
+        )
+        self.assertNotIn(
+            "The table below reflects actions recorded prior to disabling project history.",
+            resp.data.decode("utf-8"),
+        )
+        self.assertNotIn(
+            "Some entries below contain IP addresses,", resp.data.decode("utf-8"),
+        )
+        self.assertNotIn("127.0.0.1", resp.data.decode("utf-8"))
+        self.assertNotIn("<td> -- </td>", resp.data.decode("utf-8"))
+        self.assertNotIn(
+            "Project %s added" % em_surround("demo"), resp.data.decode("utf-8")
+        )
+
+    def test_project_edit(self):
+        new_data = {
+            "name": "demo2",
+            "contact_email": "demo2@notmyidea.org",
+            "password": "123456",
+            "project_history": "y",
+        }
+
+        resp = self.client.post("/demo/edit", data=new_data, follow_redirects=True)
+        self.assertEqual(resp.status_code, 200)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertIn(
+            "Project %s added" % em_surround("demo"), resp.data.decode("utf-8")
+        )
+        self.assertIn(
+            "Project contact email changed to %s" % em_surround("demo2@notmyidea.org"),
+            resp.data.decode("utf-8"),
+        )
+        self.assertIn(
+            "Project private code changed", resp.data.decode("utf-8"),
+        )
+        self.assertIn(
+            "Project renamed to %s" % em_surround("demo2"), resp.data.decode("utf-8"),
+        )
+        self.assertLess(
+            resp.data.decode("utf-8").index("Project renamed "),
+            resp.data.decode("utf-8").index("Project contact email changed to "),
+        )
+        self.assertLess(
+            resp.data.decode("utf-8").index("Project renamed "),
+            resp.data.decode("utf-8").index("Project private code changed"),
+        )
+        self.assertEqual(resp.data.decode("utf-8").count("<td> -- </td>"), 4)
+        self.assertNotIn("127.0.0.1", resp.data.decode("utf-8"))
+
+    def test_project_privacy_edit(self):
+        resp = self.client.get("/demo/edit")
+        self.assertEqual(resp.status_code, 200)
+        self.assertIn(
+            '<input checked id="project_history" name="project_history" type="checkbox" value="y">',
+            resp.data.decode("utf-8"),
+        )
+
+        self.change_privacy_to(LoggingMode.DISABLED)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertIn("Disabled Project History\n", resp.data.decode("utf-8"))
+        self.assertEqual(resp.data.decode("utf-8").count("<td> -- </td>"), 2)
+        self.assertNotIn("127.0.0.1", resp.data.decode("utf-8"))
+
+        self.change_privacy_to(LoggingMode.RECORD_IP)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertIn(
+            "Enabled Project History & IP Address Recording", resp.data.decode("utf-8")
+        )
+        self.assertEqual(resp.data.decode("utf-8").count("<td> -- </td>"), 2)
+        self.assertEqual(resp.data.decode("utf-8").count("127.0.0.1"), 1)
+
+        self.change_privacy_to(LoggingMode.ENABLED)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertIn("Disabled IP Address Recording\n", resp.data.decode("utf-8"))
+        self.assertEqual(resp.data.decode("utf-8").count("<td> -- </td>"), 2)
+        self.assertEqual(resp.data.decode("utf-8").count("127.0.0.1"), 2)
+
+    def test_project_privacy_edit2(self):
+        self.change_privacy_to(LoggingMode.RECORD_IP)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertIn("Enabled IP Address Recording\n", resp.data.decode("utf-8"))
+        self.assertEqual(resp.data.decode("utf-8").count("<td> -- </td>"), 1)
+        self.assertEqual(resp.data.decode("utf-8").count("127.0.0.1"), 1)
+
+        self.change_privacy_to(LoggingMode.DISABLED)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertIn(
+            "Disabled Project History & IP Address Recording", resp.data.decode("utf-8")
+        )
+        self.assertEqual(resp.data.decode("utf-8").count("<td> -- </td>"), 1)
+        self.assertEqual(resp.data.decode("utf-8").count("127.0.0.1"), 2)
+
+        self.change_privacy_to(LoggingMode.ENABLED)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertIn("Enabled Project History\n", resp.data.decode("utf-8"))
+        self.assertEqual(resp.data.decode("utf-8").count("<td> -- </td>"), 2)
+        self.assertEqual(resp.data.decode("utf-8").count("127.0.0.1"), 2)
+
+    def do_misc_database_operations(self, logging_mode):
+        new_data = {
+            "name": "demo2",
+            "contact_email": "demo2@notmyidea.org",
+            "password": "123456",
+        }
+
+        # Keep privacy settings where they were
+        if logging_mode != LoggingMode.DISABLED:
+            new_data["project_history"] = "y"
+            if logging_mode == LoggingMode.RECORD_IP:
+                new_data["ip_recording"] = "y"
+
+        resp = self.client.post("/demo/edit", data=new_data, follow_redirects=True)
+        self.assertEqual(resp.status_code, 200)
+
+        # adds a member to this project
+        resp = self.client.post(
+            "/demo/members/add", data={"name": "alexis"}, follow_redirects=True
+        )
+        self.assertEqual(resp.status_code, 200)
+
+        user_id = models.Person.query.one().id
+
+        # create a bill
+        resp = self.client.post(
+            "/demo/add",
+            data={
+                "date": "2011-08-10",
+                "what": "fromage à raclette",
+                "payer": user_id,
+                "payed_for": [user_id],
+                "amount": "25",
+            },
+            follow_redirects=True,
+        )
+        self.assertEqual(resp.status_code, 200)
+
+        bill_id = models.Bill.query.one().id
+
+        # edit the bill
+        resp = self.client.post(
+            "/demo/edit/%i" % bill_id,
+            data={
+                "date": "2011-08-10",
+                "what": "fromage à raclette",
+                "payer": user_id,
+                "payed_for": [user_id],
+                "amount": "10",
+            },
+            follow_redirects=True,
+        )
+        self.assertEqual(resp.status_code, 200)
+        # delete the bill
+        resp = self.client.get("/demo/delete/%i" % bill_id, follow_redirects=True)
+        self.assertEqual(resp.status_code, 200)
+
+        # delete user using POST method
+        resp = self.client.post(
+            "/demo/members/%i/delete" % user_id, follow_redirects=True
+        )
+        self.assertEqual(resp.status_code, 200)
+
+    def test_disable_clear_no_new_records(self):
+        # Disable logging
+        self.change_privacy_to(LoggingMode.DISABLED)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertIn(
+            "This project has history disabled. New actions won't appear below. ",
+            resp.data.decode("utf-8"),
+        )
+        self.assertIn(
+            "The table below reflects actions recorded prior to disabling project history.",
+            resp.data.decode("utf-8"),
+        )
+        self.assertNotIn(
+            "Nothing to list", resp.data.decode("utf-8"),
+        )
+        self.assertNotIn(
+            "Some entries below contain IP addresses,", resp.data.decode("utf-8"),
+        )
+
+        # Clear Existing Entries
+        resp = self.client.post("/demo/erase_history", follow_redirects=True)
+        self.assertEqual(resp.status_code, 200)
+        self.assert_empty_history_logging_disabled()
+
+        # Do lots of database operations & check that there's still no history
+        self.do_misc_database_operations(LoggingMode.DISABLED)
+
+        self.assert_empty_history_logging_disabled()
+
+    def test_clear_ip_records(self):
+        # Enable IP Recording
+        self.change_privacy_to(LoggingMode.RECORD_IP)
+
+        # Do lots of database operations to generate IP address entries
+        self.do_misc_database_operations(LoggingMode.RECORD_IP)
+
+        # Disable IP Recording
+        self.change_privacy_to(LoggingMode.ENABLED)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertNotIn(
+            "This project has history disabled. New actions won't appear below. ",
+            resp.data.decode("utf-8"),
+        )
+        self.assertNotIn(
+            "The table below reflects actions recorded prior to disabling project history.",
+            resp.data.decode("utf-8"),
+        )
+        self.assertNotIn(
+            "Nothing to list", resp.data.decode("utf-8"),
+        )
+        self.assertIn(
+            "Some entries below contain IP addresses,", resp.data.decode("utf-8"),
+        )
+        self.assertEqual(resp.data.decode("utf-8").count("127.0.0.1"), 10)
+        self.assertEqual(resp.data.decode("utf-8").count("<td> -- </td>"), 1)
+
+        # Generate more operations to confirm additional IP info isn't recorded
+        self.do_misc_database_operations(LoggingMode.ENABLED)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertEqual(resp.data.decode("utf-8").count("127.0.0.1"), 10)
+        self.assertEqual(resp.data.decode("utf-8").count("<td> -- </td>"), 6)
+
+        # Clear IP Data
+        resp = self.client.post("/demo/strip_ip_addresses", follow_redirects=True)
+        self.assertEqual(resp.status_code, 200)
+        self.assertNotIn(
+            "This project has history disabled. New actions won't appear below. ",
+            resp.data.decode("utf-8"),
+        )
+        self.assertNotIn(
+            "The table below reflects actions recorded prior to disabling project history.",
+            resp.data.decode("utf-8"),
+        )
+        self.assertNotIn(
+            "Nothing to list", resp.data.decode("utf-8"),
+        )
+        self.assertNotIn(
+            "Some entries below contain IP addresses,", resp.data.decode("utf-8"),
+        )
+        self.assertEqual(resp.data.decode("utf-8").count("127.0.0.1"), 0)
+        self.assertEqual(resp.data.decode("utf-8").count("<td> -- </td>"), 16)
+
+    def test_logs_for_common_actions(self):
+        # adds a member to this project
+        resp = self.client.post(
+            "/demo/members/add", data={"name": "alexis"}, follow_redirects=True
+        )
+        self.assertEqual(resp.status_code, 200)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertIn(
+            "Person %s added" % em_surround("alexis"), resp.data.decode("utf-8")
+        )
+
+        # create a bill
+        resp = self.client.post(
+            "/demo/add",
+            data={
+                "date": "2011-08-10",
+                "what": "fromage à raclette",
+                "payer": 1,
+                "payed_for": [1],
+                "amount": "25",
+            },
+            follow_redirects=True,
+        )
+        self.assertEqual(resp.status_code, 200)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertIn(
+            "Bill %s added" % em_surround("25.0 for fromage à raclette"),
+            resp.data.decode("utf-8"),
+        )
+
+        # edit the bill
+        resp = self.client.post(
+            "/demo/edit/1",
+            data={
+                "date": "2011-08-10",
+                "what": "new thing",
+                "payer": 1,
+                "payed_for": [1],
+                "amount": "10",
+            },
+            follow_redirects=True,
+        )
+        self.assertEqual(resp.status_code, 200)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertIn(
+            "Bill %s added" % em_surround("25.0 for fromage à raclette"),
+            resp.data.decode("utf-8"),
+        )
+        self.assertRegex(
+            resp.data.decode("utf-8"),
+            r"Bill %s:\s* Amount changed\s* from %s\s* to %s"
+            % (
+                em_surround("25.0 for fromage à raclette", regex_escape=True),
+                em_surround("25.0", regex_escape=True),
+                em_surround("10.0", regex_escape=True),
+            ),
+        )
+        self.assertIn(
+            "Bill %s renamed to %s"
+            % (em_surround("25.0 for fromage à raclette"), em_surround("new thing"),),
+            resp.data.decode("utf-8"),
+        )
+        self.assertLess(
+            resp.data.decode("utf-8").index(
+                "Bill %s renamed to" % em_surround("25.0 for fromage à raclette")
+            ),
+            resp.data.decode("utf-8").index("Amount changed"),
+        )
+
+        # delete the bill
+        resp = self.client.get("/demo/delete/1", follow_redirects=True)
+        self.assertEqual(resp.status_code, 200)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertIn(
+            "Bill %s removed" % em_surround("10.0 for new thing"),
+            resp.data.decode("utf-8"),
+        )
+
+        # edit user
+        resp = self.client.post(
+            "/demo/members/1/edit",
+            data={"weight": 2, "name": "new name"},
+            follow_redirects=True,
+        )
+        self.assertEqual(resp.status_code, 200)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertRegex(
+            resp.data.decode("utf-8"),
+            r"Person %s:\s* Weight changed\s* from %s\s* to %s"
+            % (
+                em_surround("alexis", regex_escape=True),
+                em_surround("1.0", regex_escape=True),
+                em_surround("2.0", regex_escape=True),
+            ),
+        )
+        self.assertIn(
+            "Person %s renamed to %s"
+            % (em_surround("alexis"), em_surround("new name"),),
+            resp.data.decode("utf-8"),
+        )
+        self.assertLess(
+            resp.data.decode("utf-8").index(
+                "Person %s renamed" % em_surround("alexis")
+            ),
+            resp.data.decode("utf-8").index("Weight changed"),
+        )
+
+        # delete user using POST method
+        resp = self.client.post("/demo/members/1/delete", follow_redirects=True)
+        self.assertEqual(resp.status_code, 200)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertIn(
+            "Person %s removed" % em_surround("new name"), resp.data.decode("utf-8")
+        )
+
+    def test_double_bill_double_person_edit_second(self):
+
+        # add two members
+        self.client.post("/demo/members/add", data={"name": "User 1"})
+        self.client.post("/demo/members/add", data={"name": "User 2"})
+
+        # add two bills
+        self.client.post(
+            "/demo/add",
+            data={
+                "date": "2020-04-13",
+                "what": "Bill 1",
+                "payer": 1,
+                "payed_for": [1, 2],
+                "amount": "25",
+            },
+        )
+        self.client.post(
+            "/demo/add",
+            data={
+                "date": "2020-04-13",
+                "what": "Bill 2",
+                "payer": 1,
+                "payed_for": [1, 2],
+                "amount": "20",
+            },
+        )
+
+        # Should be 5 history entries at this point
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertEqual(resp.data.decode("utf-8").count("<td> -- </td>"), 5)
+        self.assertNotIn("127.0.0.1", resp.data.decode("utf-8"))
+
+        # Edit ONLY the amount on the first bill
+        self.client.post(
+            "/demo/edit/1",
+            data={
+                "date": "2020-04-13",
+                "what": "Bill 1",
+                "payer": 1,
+                "payed_for": [1, 2],
+                "amount": "88",
+            },
+        )
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertRegex(
+            resp.data.decode("utf-8"),
+            r"Bill %s:\s* Amount changed\s* from %s\s* to %s"
+            % (
+                em_surround("25.0 for Bill 1", regex_escape=True),
+                em_surround("25.0", regex_escape=True),
+                em_surround("88.0", regex_escape=True),
+            ),
+        )
+
+        self.assertNotRegex(
+            resp.data.decode("utf-8"),
+            r"Removed\s* %s\s* and\s* %s\s* from\s* owers list"
+            % (
+                em_surround("User 1", regex_escape=True),
+                em_surround("User 2", regex_escape=True),
+            ),
+            resp.data.decode("utf-8"),
+        )
+
+        # Should be 6 history entries at this point
+        self.assertEqual(resp.data.decode("utf-8").count("<td> -- </td>"), 6)
+        self.assertNotIn("127.0.0.1", resp.data.decode("utf-8"))
+
+    def test_bill_add_remove_add(self):
+        # add two members
+        self.client.post("/demo/members/add", data={"name": "User 1"})
+        self.client.post("/demo/members/add", data={"name": "User 2"})
+
+        # add 1 bill
+        self.client.post(
+            "/demo/add",
+            data={
+                "date": "2020-04-13",
+                "what": "Bill 1",
+                "payer": 1,
+                "payed_for": [1, 2],
+                "amount": "25",
+            },
+        )
+
+        # delete the bill
+        self.client.get("/demo/delete/1", follow_redirects=True)
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertEqual(resp.data.decode("utf-8").count("<td> -- </td>"), 5)
+        self.assertNotIn("127.0.0.1", resp.data.decode("utf-8"))
+        self.assertIn(
+            "Bill %s added" % em_surround("25.0 for Bill 1"), resp.data.decode("utf-8")
+        )
+        self.assertIn(
+            "Bill %s removed" % em_surround("25.0 for Bill 1"),
+            resp.data.decode("utf-8"),
+        )
+
+        # Add a new bill
+        self.client.post(
+            "/demo/add",
+            data={
+                "date": "2020-04-13",
+                "what": "Bill 2",
+                "payer": 1,
+                "payed_for": [1, 2],
+                "amount": "20",
+            },
+        )
+
+        resp = self.client.get("/demo/history")
+        self.assertEqual(resp.status_code, 200)
+        self.assertEqual(resp.data.decode("utf-8").count("<td> -- </td>"), 6)
+        self.assertNotIn("127.0.0.1", resp.data.decode("utf-8"))
+        self.assertIn(
+            "Bill %s added" % em_surround("25.0 for Bill 1"), resp.data.decode("utf-8")
+        )
+        self.assertEqual(
+            resp.data.decode("utf-8").count(
+                "Bill %s added" % em_surround("25.0 for Bill 1")
+            ),
+            1,
+        )
+        self.assertIn(
+            "Bill %s added" % em_surround("20.0 for Bill 2"), resp.data.decode("utf-8")
+        )
+        self.assertIn(
+            "Bill %s removed" % em_surround("25.0 for Bill 1"),
+            resp.data.decode("utf-8"),
+        )
+
+    def test_double_bill_double_person_edit_second_no_web(self):
+        u1 = models.Person(project_id="demo", name="User 1")
+        u2 = models.Person(project_id="demo", name="User 1")
+
+        models.db.session.add(u1)
+        models.db.session.add(u2)
+        models.db.session.commit()
+
+        b1 = models.Bill(what="Bill 1", payer_id=u1.id, owers=[u2], amount=10,)
+        b2 = models.Bill(what="Bill 2", payer_id=u2.id, owers=[u2], amount=11,)
+
+        # This db commit exposes the "spurious owers edit" bug
+        models.db.session.add(b1)
+        models.db.session.commit()
+
+        models.db.session.add(b2)
+        models.db.session.commit()
+
+        history_list = history.get_history(models.Project.query.get("demo"))
+        self.assertEqual(len(history_list), 5)
+
+        # Change just the amount
+        b1.amount = 5
+        models.db.session.commit()
+
+        history_list = history.get_history(models.Project.query.get("demo"))
+        for entry in history_list:
+            if "prop_changed" in entry:
+                self.assertNotIn("owers", entry["prop_changed"])
+        self.assertEqual(len(history_list), 6)
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/ihatemoney/utils.py b/ihatemoney/utils.py
index 126b9de..0641d1c 100644
--- a/ihatemoney/utils.py
+++ b/ihatemoney/utils.py
@@ -2,6 +2,7 @@ import re
 import os
 import ast
 import operator
+from enum import Enum
 
 from io import BytesIO, StringIO
 
@@ -12,7 +13,6 @@ from babel import Locale
 from werkzeug.routing import HTTPException, RoutingException
 from datetime import datetime, timedelta
 
-
 import csv
 
 
@@ -257,3 +257,26 @@ def same_bill(bill1, bill2):
         if bill1[a] != bill2[a]:
             return False
     return True
+
+
+class FormEnum(Enum):
+    """Extend builtin Enum class to be seamlessly compatible with WTForms"""
+
+    @classmethod
+    def choices(cls):
+        return [(choice, choice.name) for choice in cls]
+
+    @classmethod
+    def coerce(cls, item):
+        """Coerce a str or int representation into an Enum object"""
+        if isinstance(item, cls):
+            return item
+
+        # If item is not already a Enum object then it must be
+        # a string or int corresponding to an ID (e.g. '0' or 1)
+        # Either int() or cls() will correctly throw a TypeError if this
+        # is not the case
+        return cls(int(item))
+
+    def __str__(self):
+        return str(self.value)
diff --git a/ihatemoney/versioning.py b/ihatemoney/versioning.py
new file mode 100644
index 0000000..50ad6ec
--- /dev/null
+++ b/ihatemoney/versioning.py
@@ -0,0 +1,94 @@
+from flask import g
+from sqlalchemy.orm.attributes import get_history
+from sqlalchemy_continuum import VersioningManager
+from sqlalchemy_continuum.plugins.flask import fetch_remote_addr
+
+from ihatemoney.utils import FormEnum
+
+
+class LoggingMode(FormEnum):
+    """Represents a project's history preferences."""
+
+    DISABLED = 0
+    ENABLED = 1
+    RECORD_IP = 2
+
+    @classmethod
+    def default(cls):
+        return cls.ENABLED
+
+
+class ConditionalVersioningManager(VersioningManager):
+    """Conditionally enable version tracking based on the given predicate."""
+
+    def __init__(self, tracking_predicate, *args, **kwargs):
+        """Create version entry iff tracking_predicate() returns True."""
+        super().__init__(*args, **kwargs)
+        self.tracking_predicate = tracking_predicate
+
+    def before_flush(self, session, flush_context, instances):
+        if self.tracking_predicate():
+            return super().before_flush(session, flush_context, instances)
+        else:
+            # At least one call to unit_of_work() needs to be made against the
+            # session object to prevent a KeyError later. This doesn't create
+            # a version or transaction entry
+            self.unit_of_work(session)
+
+    def after_flush(self, session, flush_context):
+        if self.tracking_predicate():
+            return super().after_flush(session, flush_context)
+        else:
+            # At least one call to unit_of_work() needs to be made against the
+            # session object to prevent a KeyError later. This doesn't create
+            # a version or transaction entry
+            self.unit_of_work(session)
+
+
+def version_privacy_predicate():
+    """Evaluate if the project of the current session has enabled logging."""
+    logging_enabled = False
+    try:
+        if g.project.logging_preference != LoggingMode.DISABLED:
+            logging_enabled = True
+
+        # If logging WAS enabled prior to this transaction,
+        # we log this one last transaction
+        old_logging_mode = get_history(g.project, "logging_preference")[2]
+        if old_logging_mode and old_logging_mode[0] != LoggingMode.DISABLED:
+            logging_enabled = True
+    except AttributeError:
+        # g.project doesn't exist, it's being created or this action is outside
+        # the scope of a project. Use the default logging mode to decide
+        if LoggingMode.default() != LoggingMode.DISABLED:
+            logging_enabled = True
+    return logging_enabled
+
+
+def get_ip_if_allowed():
+    """
+    Get the remote address (IP address) of the current Flask context, if the
+    project's privacy settings allow it. Behind the scenes, this calls back to
+    the FlaskPlugin from SQLAlchemy-Continuum in order to maintain forward
+    compatibility
+    """
+    ip_logging_allowed = False
+    try:
+        if g.project.logging_preference == LoggingMode.RECORD_IP:
+            ip_logging_allowed = True
+
+        # If ip recording WAS enabled prior to this transaction,
+        # we record the IP for this one last transaction
+        old_logging_mode = get_history(g.project, "logging_preference")[2]
+        if old_logging_mode and old_logging_mode[0] == LoggingMode.RECORD_IP:
+            ip_logging_allowed = True
+    except AttributeError:
+        # g.project doesn't exist, it's being created or this action is outside
+        # the scope of a project. Use the default logging mode to decide
+        if LoggingMode.default() == LoggingMode.RECORD_IP:
+            ip_logging_allowed = True
+
+    if ip_logging_allowed:
+        return fetch_remote_addr()
+    else:
+        return None
diff --git a/ihatemoney/web.py b/ihatemoney/web.py
index 8e0bca6..744d1bf 100644
--- a/ihatemoney/web.py
+++ b/ihatemoney/web.py
@@ -31,6 +31,7 @@ from flask import (
 from flask_babel import get_locale, gettext as _
 from flask_mail import Message
 from sqlalchemy import orm
+from sqlalchemy_continuum import Operation
 from werkzeug.exceptions import NotFound
 from werkzeug.security import check_password_hash, generate_password_hash
 
@@ -46,7 +47,8 @@ from ihatemoney.forms import (
     get_billform_for,
     UploadForm,
 )
-from ihatemoney.models import db, Project, Person, Bill
+from ihatemoney.history import get_history_queries, get_history
+from ihatemoney.models import db, Project, Person, Bill, LoggingMode
 from ihatemoney.utils import (
     Redirect303,
     list_of_dicts2json,
@@ -404,6 +406,12 @@ def edit_project():
         return redirect(url_for("main.list_bills"))
     else:
         edit_form.name.data = g.project.name
+
+        if g.project.logging_preference != LoggingMode.DISABLED:
+            edit_form.project_history.data = True
+            if g.project.logging_preference == LoggingMode.RECORD_IP:
+                edit_form.ip_recording.data = True
+
         edit_form.contact_email.data = g.project.contact_email
 
     return render_template(
@@ -742,6 +750,45 @@ def settle_bill():
     return render_template("settle_bills.html", bills=bills, current_view="settle_bill")
 
 
+@main.route("/<project_id>/history")
+def history():
+    """Query for the version entries associated with this project."""
+    history = get_history(g.project, human_readable_names=True)
+
+    any_ip_addresses = any(event["ip"] for event in history)
+
+    return render_template(
+        "history.html",
+        current_view="history",
+        history=history,
+        any_ip_addresses=any_ip_addresses,
+        LoggingMode=LoggingMode,
+        OperationType=Operation,
+        current_log_pref=g.project.logging_preference,
+    )
+
+
+@main.route("/<project_id>/erase_history", methods=["POST"])
+def erase_history():
+    """Erase all history entries associated with this project."""
+    for query in get_history_queries(g.project):
+        query.delete(synchronize_session="fetch")
+
+    db.session.commit()
+    return redirect(url_for(".history"))
+
+
+@main.route("/<project_id>/strip_ip_addresses", methods=["POST"])
+def strip_ip_addresses():
+    """Strip ip addresses from history entries associated with this project."""
+    for query in get_history_queries(g.project):
+        for version_object in query.all():
+            version_object.transaction.remote_addr = None
+
+    db.session.commit()
+    return redirect(url_for(".history"))
+
+
 @main.route("/<project_id>/statistics")
 def statistics():
     """Compute what each member has paid and spent and display it"""