balance_sheet: Add cash flows report.

With this, the balance sheet report has all the reports from the audit.

conservancy_beancount/reports/balance_sheet.py

@@ -181,9 +181,11 @@ class Balances:
 
 
 class Report(core.BaseODS[Sequence[None], None]):
+    C_CASH = 'Cash'
     C_SATISFIED = 'Satisfaction of program restrictions'
-    EQUITY_ACCOUNTS = ['Equity', 'Income', 'Expenses']
+    EQUITY_ACCOUNTS = frozenset(['Equity', 'Income', 'Expenses'])
     NO_BALANCE = core.Balance()
+    SPACE = ' ' * 4
 
     def __init__(self,
                  balances: Balances,
@@ -219,6 +221,7 @@ class Report(core.BaseODS[Sequence[None], None]):
         self.write_financial_position()
         self.write_activities()
         self.write_functional_expenses()
+        self.write_cash_flows()
 
     def walk_classifications(self, cseq: Iterable[data.Account]) \
         -> Iterator[Tuple[str, Optional[data.Account]]]:
@@ -226,11 +229,11 @@ class Report(core.BaseODS[Sequence[None], None]):
         for classification in cseq:
             parts = classification.split(':')
             tail = parts.pop()
-            tabs = ' ' * 4 * len(parts)
+            space = self.SPACE * len(parts)
             if parts != last_prefix:
-                yield f'{tabs[4:]}{parts[-1]}', None
+                yield f'{space[len(self.SPACE):]}{parts[-1]}', None
                 last_prefix = parts
-            yield f'{tabs}{tail}', classification
+            yield f'{space}{tail}', classification
 
     def walk_classifications_by_account(
             self,
@@ -549,6 +552,7 @@ class Report(core.BaseODS[Sequence[None], None]):
         for text, classification in self.walk_classifications_by_account('Expenses'):
             text_cell = self.string_cell(text)
             if classification is None:
+                self.add_row(text_cell)
                 if not text[0].isspace():
                     self.add_row()
                 self.add_row(text_cell)
@@ -576,6 +580,109 @@ class Report(core.BaseODS[Sequence[None], None]):
               for tot_bal in totals),
         )
 
+    def write_cash_flows(self) -> None:
+        self.use_sheet("Cash Flows")
+        bal_kwargs: Sequence[Dict[str, Any]] = [
+            {'period': Period.PERIOD},
+            {'period': Period.PRIOR},
+        ]
+        col_count = len(bal_kwargs) + 1
+        for index in range(col_count):
+            col_style = self.column_style(1.5 if index else 3)
+            self.sheet.addElement(odf.table.TableColumn(stylename=col_style))
+        self.add_row(
+            self.multiline_cell([
+                "DRAFT Statement of Cash Flows",
+                self.period_name,
+            ], numbercolumnsspanned=col_count, stylename=self.style_header)
+        )
+        self.add_row()
+        self.add_row(
+            odf.table.TableCell(),
+            self.string_cell(self.period_name, stylename=self.style_huline),
+            self.string_cell(self.opening_name, stylename=self.style_huline),
+        )
+        self.add_row()
+        self.add_row(self.string_cell(
+            "Cash Flows from Operating Activities",
+            stylename=self.style_bold,
+        ))
+        self.add_row()
+
+        totals = [
+            -sum((self.balances.total(account=account, **kwargs)
+                  for account in self.EQUITY_ACCOUNTS), core.MutableBalance())
+            for kwargs in bal_kwargs
+        ]
+        self.add_row(
+            self.string_cell("Change in Net Assets"),
+            *(self.balance_cell(bal) for bal in totals),
+        )
+        self.add_row(self.string_cell(
+            "(Increase) decrease in operating assets:",
+        ))
+        for text, classification in self.walk_classifications_by_account('Assets'):
+            text_cell = self.string_cell(self.SPACE + text)
+            if classification is None:
+                self.add_row(text_cell)
+            elif classification == self.C_CASH:
+                continue
+            else:
+                balances = [
+                    -self.balances.total(classification=classification, **kwargs)
+                    for kwargs in bal_kwargs
+                ]
+                self.add_row(
+                    text_cell,
+                    *(self.balance_cell(bal) for bal in balances),
+                )
+                for total, bal in zip(totals, balances):
+                    total += bal
+        self.add_row(self.string_cell(
+            "Increase (decrease) in operating liabilities:",
+        ))
+        for text, classification in self.walk_classifications_by_account('Liabilities'):
+            text_cell = self.string_cell(self.SPACE + text)
+            if classification is None:
+                self.add_row(text_cell)
+            else:
+                balances = [
+                    -self.balances.total(classification=classification, **kwargs)
+                    for kwargs in bal_kwargs
+                ]
+                self.add_row(
+                    text_cell,
+                    *(self.balance_cell(bal) for bal in balances),
+                )
+                for total, bal in zip(totals, balances):
+                    total += bal
+        self.add_row(
+            self.string_cell("Net cash provided by operating activites"),
+            *(self.balance_cell(tot_bal, stylename=self.style_totline)
+              for tot_bal in totals),
+        )
+        self.add_row()
+
+        self.add_row(
+            self.string_cell("Net Increase in Cash"),
+            *(self.balance_cell(tot_bal) for tot_bal in totals),
+        )
+        self.add_row()
+        balances = [
+            self.balances.total(classification=self.C_CASH, period=period)
+            for period in [Period.BEFORE_PERIOD, Period.OPENING]
+        ]
+        self.add_row(
+            self.string_cell("Beginning Cash"),
+            *(self.balance_cell(bal) for bal in balances),
+        )
+        self.add_row()
+        self.add_row(
+            self.string_cell("Ending Cash"),
+            *(self.balance_cell(tot + bal, stylename=self.style_bottomline)
+              for tot, bal in zip(totals, balances)),
+        )
+
 
 def parse_arguments(arglist: Optional[Sequence[str]]=None) -> argparse.Namespace:
     parser = argparse.ArgumentParser(prog=PROGNAME)

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='1.7.4',
+    version='1.8.0',
     author='Software Freedom Conservancy',
     author_email='info@sfconservancy.org',
     license='GNU AGPLv3+',