"""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, timedelta

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, report_code: str | None = None,
    ) -> dict:
        """Income statement (P&L) for the given period.

        ``report_code`` selects between multiple PnL-typed report definitions
        (``pnl``, ``cash_flow``, ``executive_summary``, ``annual_statements``).
        When omitted, falls back to the canonical ``pnl`` definition.
        """
        report = self._get_report(
            'pnl', company_id=company_id, code=report_code,
        )
        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, report_code: str | 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, code=report_code,
        )
        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,
        report_code: str | None = None,
    ) -> dict:
        """Trial balance for the given period - every account with
        non-zero balance.

        ``report_code`` selects between multiple TB-typed reports (e.g.
        ``trial_balance``, ``tax_summary``).
        """
        report = self._get_report(
            'trial_balance', company_id=company_id, code=report_code,
        )
        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, report_code: str | 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, code=report_code,
        )
        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,
        )

    @api.model
    def compute_partner_grouped(
        self, period: Period, *, account_type: str = 'asset_receivable',
        comparison: str = 'none', company_id: int | None = None,
    ) -> dict:
        """Per-partner aggregation report (Aged Receivable, Aged Payable,
        Partner Ledger).

        Returns a dict with ``rows`` = list of partner-level aggregates.
        Each row has the partner_id, partner_name, total residual, and
        aging buckets: current / 1-30 / 31-60 / 61-90 / 90+ days past
        ``period.date_to``.

        SQL-direct for performance: a single GROUP BY query with conditional
        sum per bucket. Only un-reconciled, posted lines with non-zero
        residual at the as-of date are included.
        """
        company_id = company_id or self.env.company.id

        accounts = self.env['account.account'].sudo().search([
            ('account_type', '=', account_type),
            ('company_ids', 'in', company_id),
        ])
        if not accounts:
            return {
                'report_type': 'partner_grouped',
                'account_type': account_type,
                'period': {
                    'date_from': str(period.date_from),
                    'date_to': str(period.date_to),
                    'label': period.label,
                },
                'rows': [],
                'total': 0.0,
                'partner_count': 0,
            }

        as_of = period.date_to
        d30 = as_of - timedelta(days=30)
        d60 = as_of - timedelta(days=60)
        d90 = as_of - timedelta(days=90)

        self.env.cr.execute(
            """
            SELECT
                COALESCE(p.id, 0) AS partner_id,
                COALESCE(p.name, '(no partner)') AS partner_name,
                SUM(aml.amount_residual) AS total_residual,
                SUM(CASE
                        WHEN aml.date_maturity >= %s
                          OR aml.date_maturity IS NULL
                        THEN aml.amount_residual ELSE 0
                    END) AS bucket_current,
                SUM(CASE
                        WHEN aml.date_maturity < %s
                         AND aml.date_maturity >= %s
                        THEN aml.amount_residual ELSE 0
                    END) AS bucket_1_30,
                SUM(CASE
                        WHEN aml.date_maturity < %s
                         AND aml.date_maturity >= %s
                        THEN aml.amount_residual ELSE 0
                    END) AS bucket_31_60,
                SUM(CASE
                        WHEN aml.date_maturity < %s
                         AND aml.date_maturity >= %s
                        THEN aml.amount_residual ELSE 0
                    END) AS bucket_61_90,
                SUM(CASE
                        WHEN aml.date_maturity < %s
                        THEN aml.amount_residual ELSE 0
                    END) AS bucket_90_plus,
                COUNT(*) AS line_count
            FROM account_move_line aml
            LEFT JOIN res_partner p ON p.id = aml.partner_id
            WHERE aml.account_id = ANY(%s)
              AND aml.parent_state = 'posted'
              AND aml.reconciled = false
              AND aml.amount_residual != 0
              AND aml.company_id = %s
              AND aml.date <= %s
            GROUP BY p.id, p.name
            HAVING SUM(aml.amount_residual) != 0
            ORDER BY total_residual DESC
            """,
            (
                as_of,
                as_of, d30,
                d30, d60,
                d60, d90,
                d90,
                list(accounts.ids), company_id, as_of,
            ),
        )

        rows = []
        for r in self.env.cr.dictfetchall():
            rows.append({
                'partner_id': r['partner_id'] or False,
                'partner_name': r['partner_name'] or '(no partner)',
                'total': float(r['total_residual'] or 0),
                'bucket_current': float(r['bucket_current'] or 0),
                'bucket_1_30': float(r['bucket_1_30'] or 0),
                'bucket_31_60': float(r['bucket_31_60'] or 0),
                'bucket_61_90': float(r['bucket_61_90'] or 0),
                'bucket_90_plus': float(r['bucket_90_plus'] or 0),
                'line_count': r['line_count'],
            })

        total = sum(r['total'] for r in rows)
        return {
            'report_type': 'partner_grouped',
            'account_type': account_type,
            'period': {
                'date_from': str(period.date_from),
                'date_to': str(period.date_to),
                'label': period.label,
            },
            'company_id': company_id,
            'rows': rows,
            'total': total,
            'partner_count': len(rows),
        }

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

    def _get_report(
        self, report_type: str, *, company_id: int | None = None,
        code: str | None = None,
    ):
        """Look up the active fusion.report definition.

        When ``code`` is provided, prefer the report with that exact code
        (validating its ``report_type`` matches). Otherwise fall back to
        the canonical-by-type lookup: prefer code == report_type, then any
        report of that type. Per-company overrides win over global.
        """
        Report = self.env['fusion.report'].sudo()
        company_id = company_id or self.env.company.id
        company_domain = [
            ('active', '=', True),
            '|',
            ('company_id', '=', company_id),
            ('company_id', '=', False),
        ]
        if code:
            report = Report.search(
                [('code', '=', code)] + company_domain,
                order='company_id desc nulls last',
                limit=1,
            )
            if not report:
                raise ValidationError(
                    _("No active fusion.report definition with code '%s'") % code
                )
            if report.report_type != report_type:
                raise ValidationError(
                    _("Report '%(code)s' has type '%(actual)s' but '%(expected)s' was expected.")
                    % {
                        'code': code,
                        'actual': report.report_type,
                        'expected': report_type,
                    }
                )
            return report

        # No code: prefer the canonical (code == report_type), then any
        # other report of that type.
        report = Report.search(
            [('code', '=', report_type), ('report_type', '=', report_type)] + company_domain,
            order='company_id desc nulls last',
            limit=1,
        )
        if report:
            return report
        report = Report.search(
            [('report_type', '=', report_type)] + company_domain,
            order='company_id desc nulls last, sequence',
            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()
            },
        }