Travel stats: distance and price by year and travel type

Closes: #155

web_view.py

@@ -526,6 +526,47 @@ def birthday_list() -> str:
     return flask.render_template("birthday_list.html", items=items, today=today)
 
 
+def calculate_yearly_stats(trips: list[Trip]) -> dict[int, StrDict]:
+    """Calculate total distance and distance by transport type grouped by year."""
+    yearly_stats: defaultdict[int, StrDict] = defaultdict(dict)
+    for trip in trips:
+        year = trip.start.year
+        dist = trip.total_distance()
+        yearly_stats[year].setdefault("count", 0)
+        yearly_stats[year]["count"] += 1
+        if dist:
+            yearly_stats[year]["total_distance"] = (
+                yearly_stats[year].get("total_distance", 0) + trip.total_distance()
+            )
+        for transport_type, distance in trip.distances_by_transport_type():
+            yearly_stats[year].setdefault("distances_by_transport_type", {})
+            yearly_stats[year]["distances_by_transport_type"][transport_type] = (
+                yearly_stats[year]["distances_by_transport_type"].get(transport_type, 0)
+                + distance
+            )
+    return dict(yearly_stats)
+
+
+@app.route("/trip/stats")
+def trip_stats() -> str:
+    """Travel stats: distance and price by year and travel type."""
+    route_distances = agenda.travel.load_route_distances(app.config["DATA_DIR"])
+    trip_list = get_trip_list(route_distances)
+    today = date.today()
+
+    past = [item for item in trip_list if (item.end or item.start) < today]
+
+    yearly_stats = calculate_yearly_stats(past)
+
+    return flask.render_template(
+        "trip/stats.html",
+        count=len(past),
+        total_distance=calc_total_distance(past),
+        distances_by_transport_type=sum_distances_by_transport_type(past),
+        yearly_stats=yearly_stats,
+    )
+
+
 @app.route("/callback")
 def auth_callback() -> tuple[str, int] | werkzeug.Response:
     """Process the authentication callback."""