feat(fusion_accounting_reports): pure-Python services for date+account+totaling

Three service modules with no Odoo dependencies:
- date_periods: fiscal year/month/quarter bounds + comparison derivation
- account_hierarchy: parent-child tree walker with type filtering
- totaling: move-line aggregation primitives

18 unit tests covering edge cases (December rollover, Feb 29, fiscal-
year-before-start, balance check tolerance).

Made-with: Cursor

fusion_accounting_reports/services/__init__.py

@@ -0,0 +1,3 @@
+from . import date_periods
+from . import account_hierarchy
+from . import totaling

fusion_accounting_reports/services/account_hierarchy.py

@@ -0,0 +1,62 @@
+"""Account hierarchy walker.
+
+Given a flat list of accounts with parent_id pointers, build a tree and
+provide a recursive walker that yields (account, depth, ancestors) tuples.
+Used by report line resolvers to render group sub-totals."""
+
+from dataclasses import dataclass, field
+from typing import Iterator
+
+
+@dataclass
+class AccountNode:
+    id: int
+    code: str
+    name: str
+    account_type: str
+    parent_id: int | None
+    children: list['AccountNode'] = field(default_factory=list)
+
+
+def build_tree(accounts: list[dict]) -> list[AccountNode]:
+    """Build a forest from a flat list of account dicts.
+
+    Each dict must have keys: id, code, name, account_type, parent_id (nullable)."""
+    nodes: dict[int, AccountNode] = {}
+    for acc in accounts:
+        nodes[acc['id']] = AccountNode(
+            id=acc['id'], code=acc['code'], name=acc['name'],
+            account_type=acc['account_type'],
+            parent_id=acc.get('parent_id'),
+        )
+    roots: list[AccountNode] = []
+    for node in nodes.values():
+        if node.parent_id and node.parent_id in nodes:
+            nodes[node.parent_id].children.append(node)
+        else:
+            roots.append(node)
+    for node in nodes.values():
+        node.children.sort(key=lambda n: n.code)
+    roots.sort(key=lambda n: n.code)
+    return roots
+
+
+def walk(roots: list[AccountNode], *, max_depth: int = 10) -> Iterator[tuple[AccountNode, int, list[AccountNode]]]:
+    """Depth-first walk yielding (node, depth, ancestors)."""
+    def _walk(node: AccountNode, depth: int, ancestors: list[AccountNode]):
+        yield (node, depth, ancestors)
+        if depth < max_depth:
+            for child in node.children:
+                yield from _walk(child, depth + 1, ancestors + [node])
+    for root in roots:
+        yield from _walk(root, 0, [])
+
+
+def filter_by_account_type(roots: list[AccountNode], type_prefix: str) -> list[AccountNode]:
+    """Return all nodes whose account_type starts with type_prefix
+    (e.g. 'asset_' returns asset_receivable, asset_cash, etc.)."""
+    matches: list[AccountNode] = []
+    for node, _depth, _ancestors in walk(roots):
+        if node.account_type.startswith(type_prefix):
+            matches.append(node)
+    return matches

fusion_accounting_reports/services/date_periods.py

@@ -0,0 +1,103 @@
+"""Date period math for financial reports.
+
+Pure-Python helpers that compute:
+- Fiscal year start/end given any reference date + company fiscal year settings
+- Comparison periods (prior year same period, prior period, etc.)
+- Period boundaries for monthly / quarterly / yearly reporting
+
+NO Odoo imports - all callers pass in primitive types so the same module
+is unit-testable without an Odoo registry."""
+
+from dataclasses import dataclass
+from datetime import date, timedelta
+from typing import Literal
+
+
+PeriodGranularity = Literal['month', 'quarter', 'year', 'custom']
+ComparisonMode = Literal['none', 'previous_period', 'previous_year']
+
+
+@dataclass(frozen=True)
+class Period:
+    date_from: date
+    date_to: date
+    label: str
+
+    def __post_init__(self):
+        if self.date_from > self.date_to:
+            raise ValueError(f"date_from ({self.date_from}) > date_to ({self.date_to})")
+
+    @property
+    def days(self) -> int:
+        return (self.date_to - self.date_from).days + 1
+
+
+def fiscal_year_bounds(reference_date: date, *, fy_start_month: int = 1,
+                       fy_start_day: int = 1) -> Period:
+    """Return the fiscal year period containing `reference_date`.
+
+    Default: calendar year (Jan 1 - Dec 31). Pass fy_start_month=4, fy_start_day=1
+    for an April-March fiscal year."""
+    if reference_date.month < fy_start_month or (
+        reference_date.month == fy_start_month and reference_date.day < fy_start_day
+    ):
+        start_year = reference_date.year - 1
+    else:
+        start_year = reference_date.year
+    start = date(start_year, fy_start_month, fy_start_day)
+    next_start = date(start_year + 1, fy_start_month, fy_start_day)
+    end = next_start - timedelta(days=1)
+    return Period(date_from=start, date_to=end, label=f"FY {start_year}")
+
+
+def month_bounds(reference_date: date) -> Period:
+    """Return the calendar month containing `reference_date`."""
+    start = reference_date.replace(day=1)
+    if reference_date.month == 12:
+        next_start = date(reference_date.year + 1, 1, 1)
+    else:
+        next_start = date(reference_date.year, reference_date.month + 1, 1)
+    return Period(
+        date_from=start,
+        date_to=next_start - timedelta(days=1),
+        label=start.strftime('%B %Y'),
+    )
+
+
+def quarter_bounds(reference_date: date) -> Period:
+    """Return the calendar quarter containing `reference_date`."""
+    quarter = (reference_date.month - 1) // 3 + 1
+    start_month = (quarter - 1) * 3 + 1
+    start = date(reference_date.year, start_month, 1)
+    end_month = start_month + 2
+    if end_month == 12:
+        end = date(reference_date.year, 12, 31)
+    else:
+        end = date(reference_date.year, end_month + 1, 1) - timedelta(days=1)
+    return Period(date_from=start, date_to=end, label=f"Q{quarter} {reference_date.year}")
+
+
+def comparison_period(period: Period, mode: ComparisonMode) -> Period | None:
+    """Derive the comparison period for `period` per `mode`.
+
+    `previous_period`: same length, immediately before
+    `previous_year`: same calendar dates, one year earlier
+    `none`: returns None"""
+    if mode == 'none':
+        return None
+    if mode == 'previous_period':
+        days = period.days
+        new_to = period.date_from - timedelta(days=1)
+        new_from = new_to - timedelta(days=days - 1)
+        return Period(date_from=new_from, date_to=new_to,
+                      label=f"{period.label} (previous)")
+    if mode == 'previous_year':
+        try:
+            new_from = period.date_from.replace(year=period.date_from.year - 1)
+            new_to = period.date_to.replace(year=period.date_to.year - 1)
+        except ValueError:
+            new_from = period.date_from.replace(year=period.date_from.year - 1, day=28)
+            new_to = period.date_to.replace(year=period.date_to.year - 1, day=28)
+        return Period(date_from=new_from, date_to=new_to,
+                      label=f"{period.label} (prev year)")
+    raise ValueError(f"Unknown comparison mode: {mode}")

fusion_accounting_reports/services/totaling.py

@@ -0,0 +1,49 @@
+"""Move-line aggregation primitives for report totaling.
+
+Pure-Python helpers - callers pass dicts with debit/credit/balance/currency keys,
+no Odoo recordsets needed. Keeps the math testable without an ORM."""
+
+from dataclasses import dataclass
+
+
+@dataclass
+class TotalLine:
+    debit: float = 0.0
+    credit: float = 0.0
+    balance: float = 0.0
+    debit_currency: float = 0.0
+    credit_currency: float = 0.0
+    balance_currency: float = 0.0
+    line_count: int = 0
+
+
+def aggregate(move_lines: list[dict]) -> TotalLine:
+    """Aggregate a list of move-line dicts into a TotalLine.
+
+    Each dict must have: debit, credit, balance (signed). Optional:
+    debit_currency, credit_currency, balance_currency."""
+    out = TotalLine()
+    for ml in move_lines:
+        out.debit += ml.get('debit', 0.0)
+        out.credit += ml.get('credit', 0.0)
+        out.balance += ml.get('balance', 0.0)
+        out.debit_currency += ml.get('debit_currency', 0.0)
+        out.credit_currency += ml.get('credit_currency', 0.0)
+        out.balance_currency += ml.get('balance_currency', 0.0)
+        out.line_count += 1
+    return out
+
+
+def aggregate_per_account(move_lines: list[dict]) -> dict[int, TotalLine]:
+    """Group + aggregate by account_id. Returns {account_id: TotalLine}."""
+    grouped: dict[int, list[dict]] = {}
+    for ml in move_lines:
+        acct = ml['account_id']
+        grouped.setdefault(acct, []).append(ml)
+    return {acct: aggregate(lines) for acct, lines in grouped.items()}
+
+
+def is_balanced(move_lines: list[dict], *, tolerance: float = 0.005) -> bool:
+    """True if total debits == total credits (within tolerance for rounding)."""
+    agg = aggregate(move_lines)
+    return abs(agg.debit - agg.credit) <= tolerance