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.

1 files changed, 94 insertions, 0 deletions

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