"""Read-only reporting over transactions and budgets (R11).

Queries only: nothing in this module mutates state.
"""

from __future__ import annotations

from ..money import Money
from ..models import EXPENSE, BudgetLine, CategoryTotal, Month, MonthSummary
from ..repository import Repository

__all__ = ["ReportingService"]


class ReportingService:
    """Monthly summaries, category breakdowns, and budget status."""

    def __init__(self, repo: Repository) -> None:
        self._repo = repo

    def monthly_summary(self, month: Month) -> MonthSummary:
        start, end = month.range
        income_cents, expense_cents = self._repo.income_expense_totals(start, end)
        return MonthSummary(
            month=month,
            income=Money(cents=income_cents),
            expenses=Money(cents=expense_cents),
        )

    def category_totals(self, month: Month) -> list[CategoryTotal]:
        start, end = month.range
        return [
            CategoryTotal(
                category=row["category"],
                kind=row["kind"],
                total=Money(cents=row["total_cents"]),
            )
            for row in self._repo.category_totals(start, end)
        ]

    def budget_status(self, month: Month) -> list[BudgetLine]:
        """Budgeted lines first, then unbudgeted spending (R11)."""
        start, end = month.range
        spent = {
            row["category"]: Money(cents=row["total_cents"])
            for row in self._repo.category_totals(start, end)
            if row["kind"] == EXPENSE
        }
        lines: list[BudgetLine] = []
        for row in self._repo.list_budgets():
            name = row["category"]
            lines.append(
                BudgetLine(
                    category=name,
                    budget=Money(cents=row["amount_cents"]),
                    spent=spent.get(name, Money.zero()),
                )
            )
        budgeted = {line.category for line in lines}
        for name, cost in sorted(spent.items()):
            if name not in budgeted and cost.is_positive:
                lines.append(BudgetLine(category=name, budget=Money.zero(), spent=cost))
        return lines