"""Materialized view of per-account-per-month balances.

Created lazily by init() (called by Odoo on install/upgrade). Refresh
via the model's _refresh() method or via cron (Task 25)."""

import logging
import os

from odoo import api, fields, models

_logger = logging.getLogger(__name__)


class FusionAccountBalanceMV(models.Model):
    _name = "fusion.account.balance.mv"
    _description = "MV of per-account per-month aggregated balances"
    _auto = False
    _table = "fusion_account_balance_mv"
    _order = "period_month desc, account_id"

    account_id = fields.Many2one('account.account', readonly=True)
    company_id = fields.Many2one('res.company', readonly=True)
    period_month = fields.Date(readonly=True)
    debit = fields.Float(readonly=True)
    credit = fields.Float(readonly=True)
    balance = fields.Float(readonly=True)
    line_count = fields.Integer(readonly=True)

    def init(self):
        # If the MV exists but is missing the synthetic `id` column (e.g. from
        # an earlier dev install), drop it so the new schema applies cleanly.
        self.env.cr.execute(
            """
            SELECT 1
            FROM pg_matviews mv
            JOIN pg_attribute a
              ON a.attrelid = (mv.schemaname || '.' || mv.matviewname)::regclass
             AND a.attname = 'id'
            WHERE mv.matviewname = 'fusion_account_balance_mv'
            """
        )
        if not self.env.cr.fetchone():
            self.env.cr.execute(
                "DROP MATERIALIZED VIEW IF EXISTS fusion_account_balance_mv"
            )
        sql_path = os.path.join(
            os.path.dirname(__file__), '..', 'data', 'sql',
            'create_mv_account_balance.sql',
        )
        with open(sql_path, 'r') as f:
            self.env.cr.execute(f.read())
        _logger.info(
            "fusion_account_balance_mv: created/verified MV + indexes")

    @api.model
    def _refresh(self, *, concurrently=True):
        """Refresh the MV. Falls back to non-concurrent if CONCURRENTLY fails.

        REFRESH MATERIALIZED VIEW CONCURRENTLY requires the MV to be already
        populated and an autocommit-capable cursor; the cron path in Task 25
        opens a dedicated cursor for that. This helper keeps callers safe by
        retrying without CONCURRENTLY on failure."""
        keyword = "CONCURRENTLY" if concurrently else ""
        try:
            self.env.cr.execute(
                f"REFRESH MATERIALIZED VIEW {keyword} fusion_account_balance_mv"
            )
            _logger.debug(
                "fusion_account_balance_mv refreshed (%s)",
                'concurrent' if concurrently else 'blocking',
            )
        except Exception as e:
            if concurrently:
                _logger.warning(
                    "Concurrent MV refresh failed (%s); falling back", e)
                self.env.cr.execute(
                    "REFRESH MATERIALIZED VIEW fusion_account_balance_mv"
                )
            else:
                raise