Display monthly statistics for the range of months where the project …

…was active

Currently, we display a hard-coded "one year" range of monthly statistics
starting from today.  This generally is not the intended behaviour: for
instance, on an archived project, the bills might all be older than one
year, so the table only displays months without any operation.

Instead, display all months between the first and last bills.  There might
be empty months in the middle, but that's intended, because we want all
months to be consecutive.

If there are no bills, simply display an empty table.

ihatemoney/models.py

@@ -262,6 +262,14 @@ def get_member_bills(self, member_id):
             .order_by(Bill.id.desc())
         )
 
+    def get_newest_bill(self):
+        """Returns the most recent bill (according to bill date) or None if there are no bills"""
+        return self.get_bills_unordered().order_by(Bill.date.desc()).first()
+
+    def get_oldest_bill(self):
+        """Returns the least recent bill (according to bill date) or None if there are no bills"""
+        return self.get_bills_unordered().order_by(Bill.date.asc()).first()
+
     def get_pretty_bills(self, export_format="json"):
         """Return a list of project's bills with pretty formatting"""
         bills = self.get_bills()

ihatemoney/tests/budget_test.py

@@ -917,6 +917,11 @@ def test_statistics(self):
         # Add a participant with a balance at 0 :
         self.client.post("/raclette/members/add", data={"name": "pépé"})
 
+        # Check that the "monthly expenses" table is empty
+        response = self.client.get("/raclette/statistics")
+        regex = r"<thead>\s*<tr>\s*<th>Period</th>\s*<th>Spent</th>\s*</tr>\s*</thead>\s*<tbody>\s*</tbody>"
+        self.assertRegex(response.data.decode("utf-8"), regex)
+
         # create bills
         self.client.post(
             "/raclette/add",
@@ -952,7 +957,7 @@ def test_statistics(self):
         )
 
         response = self.client.get("/raclette/statistics")
-        regex = r"<td class=\"d-md-none\">{}</td>\s+<td>{}</td>\s+<td>{}</td>"
+        regex = r"<td class=\"d-md-none\">{}</td>\s*<td>{}</td>\s*<td>{}</td>"
         self.assertRegex(
             response.data.decode("utf-8"),
             regex.format("zorglub", r"\$20\.00", r"\$31\.67"),
@@ -982,6 +987,85 @@ def test_statistics(self):
         self.assertRegex(response.data.decode("utf-8"), re.compile(regex1, re.DOTALL))
         self.assertRegex(response.data.decode("utf-8"), re.compile(regex2, re.DOTALL))
 
+        # Check that the "monthly expenses" table has a single month and the correct amount
+        regex = r"<tbody>\s*<tr>\s*<td>August 2011</td>\s*<td>\$40.00</td>\s*</tr>\s*</tbody>"
+        self.assertRegex(response.data.decode("utf-8"), regex)
+
+        # Add bills for other months and check monthly expenses again
+        self.client.post(
+            "/raclette/add",
+            data={
+                "date": "2011-12-31",
+                "what": "champomy",
+                "payer": 1,
+                "payed_for": [1, 2],
+                "amount": "10",
+            },
+        )
+        self.client.post(
+            "/raclette/add",
+            data={
+                "date": "2011-08-01",
+                "what": "ice cream",
+                "payer": 2,
+                "payed_for": [1, 2],
+                "amount": "10",
+            },
+        )
+        months = [
+            ("December 2011", r"\$10.00"),
+            ("November 2011", r"\$0.00"),
+            ("October 2011", r"\$0.00"),
+            ("September 2011", r"\$0.00"),
+            ("August 2011", r"\$50.00"),
+        ]
+        months_fmt = [
+            r"<tr>\s*<td>{}</td>\s*<td>{}</td>\s*</tr>".format(month, amount)
+            for month, amount in months
+        ]
+        regex = r"<tbody>\s*" + r"\s*".join(months_fmt) + r"\s*</tbody>"
+        response = self.client.get("/raclette/statistics")
+        self.assertRegex(response.data.decode("utf-8"), regex)
+
+        # Test more corner cases
+        self.client.post(
+            "/raclette/add",
+            data={
+                "date": "2011-07-31",
+                "what": "more ice cream",
+                "payer": 1,
+                "payed_for": [1, 2],
+                "amount": "20",
+            },
+        )
+        months.append(("July 2011", r"\$20.00"))
+        months_fmt = [
+            r"<tr>\s*<td>{}</td>\s*<td>{}</td>\s*</tr>".format(month, amount)
+            for month, amount in months
+        ]
+        regex = r"<tbody>\s*" + r"\s*".join(months_fmt) + r"\s*</tbody>"
+        response = self.client.get("/raclette/statistics")
+        self.assertRegex(response.data.decode("utf-8"), regex)
+
+        self.client.post(
+            "/raclette/add",
+            data={
+                "date": "2012-01-01",
+                "what": "more champomy",
+                "payer": 2,
+                "payed_for": [1, 2],
+                "amount": "30",
+            },
+        )
+        months.insert(0, ("January 2012", r"\$30.00"))
+        months_fmt = [
+            r"<tr>\s*<td>{}</td>\s*<td>{}</td>\s*</tr>".format(month, amount)
+            for month, amount in months
+        ]
+        regex = r"<tbody>\s*" + r"\s*".join(months_fmt) + r"\s*</tbody>"
+        response = self.client.get("/raclette/statistics")
+        self.assertRegex(response.data.decode("utf-8"), regex)
+
     def test_settle_page(self):
         self.post_project("raclette")
         response = self.client.get("/raclette/settle_bills")

ihatemoney/web.py

@@ -8,8 +8,9 @@
 some shortcuts to make your life better when coding (see `pull_project`
 and `add_project_id` for a quick overview)
 """
-from datetime import datetime
 from functools import wraps
+import datetime
+import itertools
 import json
 import os
 
@@ -893,12 +894,25 @@ def strip_ip_addresses():
 @main.route("/<project_id>/statistics")
 def statistics():
     """Compute what each participant has paid and spent and display it"""
-    today = datetime.now()
+    # Determine range of months between which there are bills
+    months = []
+    if g.project.has_bills():
+        oldest_date = g.project.get_oldest_bill().date
+        newest_date = g.project.get_newest_bill().date
+        # Infinite iterator towards the past
+        newest_month = datetime.date(
+            year=newest_date.year, month=newest_date.month, day=1
+        )
+        all_months = (newest_month - relativedelta(months=i) for i in itertools.count())
+        # Stop when reaching one month before the first date
+        months = itertools.takewhile(
+            lambda x: x > oldest_date - relativedelta(months=1), all_months
+        )
     return render_template(
         "statistics.html",
         members_stats=g.project.members_stats,
         monthly_stats=g.project.monthly_stats,
-        months=[today - relativedelta(months=i) for i in range(12)],
+        months=months,
         current_view="statistics",
     )