balance_sheet: Support arbitrary date ranges.

This lets you do year-over-year comparisons of smaller ranges of time, like
a quarter.

conservancy_beancount/reports/balance_sheet.py

@@ -71,9 +71,11 @@ class Fund(enum.IntFlag):
 class Period(enum.IntFlag):
     OPENING = enum.auto()
     PRIOR = enum.auto()
+    MIDDLE = enum.auto()
     PERIOD = enum.auto()
-    BEFORE_PERIOD = OPENING | PRIOR
+    THRU_PRIOR = OPENING | PRIOR
-    ANY = OPENING | PRIOR | PERIOD
+    THRU_MIDDLE = THRU_PRIOR | MIDDLE
+    ANY = THRU_MIDDLE | PERIOD
 
 
 class BalanceKey(NamedTuple):
@@ -92,24 +94,35 @@ class Balances:
                  fund_key: str='project',
                  unrestricted_fund_value: str='Conservancy',
     ) -> None:
-        self.prior_range = ranges.DateRange(
+        year_diff = (stop_date - start_date).days // 365
-            cliutil.diff_year(start_date, -1),
+        if year_diff == 0:
-            cliutil.diff_year(stop_date, -1),
+            self.prior_range = ranges.DateRange(
-        )
+                cliutil.diff_year(start_date, -1),
-        assert self.prior_range.stop <= start_date
+                cliutil.diff_year(stop_date, -1),
+            )
+            self.period_desc = "Period"
+        else:
+            self.prior_range = ranges.DateRange(
+                cliutil.diff_year(start_date, -year_diff),
+                start_date,
+            )
+            self.period_desc = f"Year{'s' if year_diff > 1 else ''}"
+        self.middle_range = ranges.DateRange(self.prior_range.stop, start_date)
         self.period_range = ranges.DateRange(start_date, stop_date)
         self.balances: Mapping[BalanceKey, core.MutableBalance] \
             = collections.defaultdict(core.MutableBalance)
         for post in postings:
             post_date = post.meta.date
-            if post_date in self.period_range:
+            if post_date >= stop_date:
+                continue
+            elif post_date in self.period_range:
                 period = Period.PERIOD
+            elif post_date in self.middle_range:
+                period = Period.MIDDLE
             elif post_date in self.prior_range:
                 period = Period.PRIOR
-            elif post_date < self.prior_range.start:
-                period = Period.OPENING
             else:
-                continue
+                period = Period.OPENING
             if post.account == 'Expenses:CurrencyConversion':
                 account = data.Account('Income:CurrencyConversion')
             else:
@@ -214,6 +227,7 @@ class Report(core.BaseODS[Sequence[None], None]):
     ) -> None:
         super().__init__()
         self.balances = balances
+        self.period_desc = balances.period_desc
         self.date_fmt = date_fmt
         one_day = datetime.timedelta(days=1)
         date = balances.period_range.stop - one_day
@@ -359,7 +373,7 @@ class Report(core.BaseODS[Sequence[None], None]):
         self.start_sheet("Financial Position")
         balance_kwargs: Sequence[KWArgs] = [
             {'period': Period.ANY},
-            {'period': Period.BEFORE_PERIOD},
+            {'period': Period.THRU_PRIOR},
         ]
 
         asset_totals = self.write_classifications_by_account('Assets', balance_kwargs)
@@ -400,7 +414,7 @@ class Report(core.BaseODS[Sequence[None], None]):
             "Activities",
             ["Without Donor", "Restrictions"],
             ["With Donor", "Restrictions"],
-            totals_prefix=["Total Year Ended"],
+            totals_prefix=[f"Total {self.period_desc} Ended"],
         )
         bal_kwargs: Sequence[Dict[str, Any]] = [
             {'period': Period.PERIOD, 'fund': Fund.UNRESTRICTED},
@@ -482,7 +496,7 @@ class Report(core.BaseODS[Sequence[None], None]):
 
         for kwargs in bal_kwargs:
             if kwargs['period'] is Period.PERIOD:
-                kwargs['period'] = Period.BEFORE_PERIOD
+                kwargs['period'] = Period.THRU_MIDDLE
             else:
                 kwargs['period'] = Period.OPENING
         equity_totals = [
@@ -502,7 +516,7 @@ class Report(core.BaseODS[Sequence[None], None]):
             ["Program", "Services"],
             ["Management and", "Administrative"],
             ["Fundraising"],
-            totals_prefix=["Total Year Ended"],
+            totals_prefix=[f"Total {self.period_desc} Ended"],
         )
         totals = self.write_classifications_by_account('Expenses', [
             {'period': Period.PERIOD, 'post_type': 'program'},
@@ -558,7 +572,7 @@ class Report(core.BaseODS[Sequence[None], None]):
         self.write_totals_row("Net Increase in Cash", period_totals)
         begin_totals = [
             self.balances.total(classification=self.C_CASH, period=period)
-            for period in [Period.BEFORE_PERIOD, Period.OPENING]
+            for period in [Period.THRU_MIDDLE, Period.OPENING]
         ]
         self.write_totals_row("Beginning Cash", begin_totals)
         self.write_totals_row(
@@ -572,8 +586,8 @@ class Report(core.BaseODS[Sequence[None], None]):
             "Trial Balances",
             ["Account Name"],
             ["Classification"],
-            ["Balance Ending", self.opening_name],
+            ["Balance Beginning", self.balances.period_range.start.strftime(self.date_fmt)],
-            totals_prefix=["Change During", "Year Ending"],
+            totals_prefix=["Change During", f"{self.period_desc} Ending"],
             title_fmt="Chart of Accounts with DRAFT {sheet_name}",
         )
         # Widen text columns

setup.py

@@ -5,7 +5,7 @@ from setuptools import setup
 setup(
     name='conservancy_beancount',
     description="Plugin, library, and reports for reading Conservancy's books",
-    version='1.8.3',
+    version='1.8.4',
     author='Software Freedom Conservancy',
     author_email='info@sfconservancy.org',
     license='GNU AGPLv3+',