"""The reports engine - orchestrator for all report computation.

5-method public API. All controllers, AI tools, wizards, exports must
go through these methods; no direct ORM aggregation queries from
anywhere else.

Internal pipeline (per report run):
1. Validate (period valid, company allowed, report exists)
2. Fetch account hierarchy (cached per (company, fiscal_year))
3. Aggregate move lines per account (the SQL workhorse)
4. Resolve line_specs into report rows
5. (Optional) Compute comparison-period rows
6. (Optional) Detect anomalies (deferred to later tasks)
"""

import logging
from datetime import date

from odoo import _, api, models
from odoo.exceptions import ValidationError

from ..services.account_hierarchy import build_tree
from ..services.date_periods import Period, comparison_period as _comp_period
from ..services.drill_down_resolver import fetch_drill_down
from ..services.line_resolver import resolve as _resolve_lines
from ..services.totaling import TotalLine

_logger = logging.getLogger(__name__)


class FusionReportEngine(models.AbstractModel):
    _name = "fusion.report.engine"
    _description = "Fusion Financial Reports Engine"

    # ============================================================
    # PUBLIC API (5 methods)
    # ============================================================

    @api.model
    def compute_pnl(
        self, period: Period, *, comparison: str = 'none',
        company_id: int | None = None,
    ) -> dict:
        """Income statement (P&L) for the given period."""
        report = self._get_report('pnl', company_id=company_id)
        return self._compute(
            report, period, comparison=comparison, company_id=company_id,
        )

    @api.model
    def compute_balance_sheet(
        self, date_to: date, *, comparison: str = 'none',
        company_id: int | None = None,
    ) -> dict:
        """Balance sheet AS OF date_to. Period.date_from is set to a
        far-past date so balances are cumulative-since-inception."""
        report = self._get_report('balance_sheet', company_id=company_id)
        period = Period(
            date_from=date(1970, 1, 1),
            date_to=date_to,
            label=f"As of {date_to}",
        )
        return self._compute(
            report, period, comparison=comparison, company_id=company_id,
        )

    @api.model
    def compute_trial_balance(
        self, period: Period, *, company_id: int | None = None,
    ) -> dict:
        """Trial balance for the given period - every account with
        non-zero balance."""
        report = self._get_report('trial_balance', company_id=company_id)
        return self._compute(
            report, period, comparison='none', company_id=company_id,
        )

    @api.model
    def compute_gl(
        self, period: Period, *, account_ids: list | None = None,
        company_id: int | None = None,
    ) -> dict:
        """General ledger for the given period.

        Returns per-account move-line listings rather than aggregated rows."""
        report = self._get_report('general_ledger', company_id=company_id)
        company_id = company_id or self.env.company.id
        result = self._compute(
            report, period, comparison='none', company_id=company_id,
        )
        gl_by_account = {}
        target_ids = account_ids or list(result.get('account_totals', {}).keys())
        for acct_id in target_ids:
            gl_by_account[acct_id] = fetch_drill_down(
                self.env,
                account_id=acct_id,
                date_from=period.date_from,
                date_to=period.date_to,
                company_id=company_id,
                limit=200,
            )
        result['gl_by_account'] = gl_by_account
        return result

    @api.model
    def drill_down(
        self, *, account_id: int, period: Period,
        company_id: int | None = None,
    ) -> list:
        """Drill into a report line: list the journal items behind it."""
        company_id = company_id or self.env.company.id
        return fetch_drill_down(
            self.env,
            account_id=account_id,
            date_from=period.date_from,
            date_to=period.date_to,
            company_id=company_id,
            limit=500,
        )

    # ============================================================
    # PRIVATE HELPERS
    # ============================================================

    def _get_report(self, report_type: str, *, company_id: int | None = None):
        """Look up the active fusion.report definition for a given
        type+company. If no per-company override, falls back to global
        (company_id=False)."""
        Report = self.env['fusion.report'].sudo()
        company_id = company_id or self.env.company.id
        report = Report.search(
            [
                ('report_type', '=', report_type),
                ('active', '=', True),
                '|',
                ('company_id', '=', company_id),
                ('company_id', '=', False),
            ],
            order='company_id desc nulls last',
            limit=1,
        )
        if not report:
            raise ValidationError(
                _("No active fusion.report definition for type '%s'") % report_type
            )
        return report

    def _fetch_accounts(self, company_id):
        """Fetch all accounts for a company, return flat dict + tree."""
        Account = self.env['account.account'].sudo()
        records = Account.search([('company_ids', 'in', company_id)])
        # account.account doesn't carry a parent_id in V19 - we use
        # account_type prefixes instead, so parent_id is always None here.
        flat = [
            {
                'id': a.id,
                'code': a.code,
                'name': a.name,
                'account_type': a.account_type or '',
                'parent_id': None,
            }
            for a in records
        ]
        accounts_by_id = {a['id']: a for a in flat}
        tree = build_tree(flat)
        return accounts_by_id, tree

    def _aggregate_period(self, period: Period, company_id: int) -> dict:
        """SQL aggregate per account_id for a period.

        Raw SQL for performance; this is the perf-critical step."""
        self.env.cr.execute(
            """
            SELECT account_id,
                   COALESCE(SUM(debit), 0) AS d,
                   COALESCE(SUM(credit), 0) AS c,
                   COALESCE(SUM(balance), 0) AS b
            FROM account_move_line
            WHERE parent_state = 'posted'
              AND company_id = %s
              AND date >= %s
              AND date <= %s
            GROUP BY account_id
            """,
            (company_id, period.date_from, period.date_to),
        )
        out = {}
        for row in self.env.cr.fetchall():
            out[row[0]] = TotalLine(
                debit=float(row[1] or 0),
                credit=float(row[2] or 0),
                balance=float(row[3] or 0),
            )
        return out

    def _compute(
        self, report, period: Period, *, comparison: str,
        company_id: int | None = None,
    ) -> dict:
        """Shared computation pipeline. Returns dict with rows, totals,
        metadata."""
        company_id = company_id or self.env.company.id

        accounts_by_id, _tree = self._fetch_accounts(company_id)

        account_totals = self._aggregate_period(period, company_id)

        comp_totals = None
        comp_period = None
        if comparison and comparison != 'none':
            comp_period = _comp_period(period, comparison)
            if comp_period:
                comp_totals = self._aggregate_period(comp_period, company_id)

        rows = _resolve_lines(
            report.line_specs or [],
            account_totals=account_totals,
            accounts_by_id=accounts_by_id,
            comparison_totals=comp_totals,
        )

        return {
            'report_id': report.id,
            'report_name': report.name,
            'report_type': report.report_type,
            'period': {
                'date_from': str(period.date_from),
                'date_to': str(period.date_to),
                'label': period.label,
            },
            'comparison_period': (
                {
                    'date_from': str(comp_period.date_from),
                    'date_to': str(comp_period.date_to),
                    'label': comp_period.label,
                }
                if comp_period
                else None
            ),
            'company_id': company_id,
            'rows': rows,
            'account_totals': {
                aid: tl.balance for aid, tl in account_totals.items()
            },
        }