# -*- coding: utf-8 -*-
# Copyright 2026 Nexa Systems Inc.
# License OPL-1 (Odoo Proprietary License v1.0)
#
# Phase 1 multi-serial — backfill the new M2M relations from the
# pre-existing single-M2O column on sale.order.line and account.move.line.
#
# x_fc_serial_id was historically a stored Many2one. Phase 1 made it a
# computed alias of `x_fc_serial_ids` (the new M2M). Existing rows have
# the old FK column populated but no rows in the M2M relation table.
# This migration walks the legacy column and inserts one M2M row per
# (line, serial) pair so smart buttons / reverse links continue to find
# the linked records.

import logging

_logger = logging.getLogger(__name__)


def migrate(cr, version):
    """Backfill fp_sale_order_line_serial_rel + fp_account_move_line_serial_rel."""
    backfill_table(cr, 'sale_order_line', 'fp_sale_order_line_serial_rel', 'line_id')
    backfill_table(cr, 'account_move_line', 'fp_account_move_line_serial_rel', 'line_id')


def backfill_table(cr, source_table, m2m_table, line_col):
    cr.execute(
        "SELECT 1 FROM information_schema.columns "
        "WHERE table_name = %s AND column_name = 'x_fc_serial_id'",
        (source_table,),
    )
    if not cr.fetchone():
        _logger.info("Phase 1 multi-serial: %s has no x_fc_serial_id column, skip", source_table)
        return

    # Make sure the M2M table exists (Odoo creates it on registry load,
    # but the migration runs BEFORE the registry comes up on upgrade —
    # use IF NOT EXISTS to be safe).
    cr.execute(
        f"""
        CREATE TABLE IF NOT EXISTS "{m2m_table}" (
            "{line_col}" integer NOT NULL REFERENCES "{source_table}"(id) ON DELETE CASCADE,
            "serial_id" integer NOT NULL REFERENCES "fp_serial"(id) ON DELETE CASCADE,
            PRIMARY KEY ("{line_col}", "serial_id")
        )
        """
    )

    cr.execute(
        f"""
        INSERT INTO "{m2m_table}" ("{line_col}", "serial_id")
        SELECT id, x_fc_serial_id FROM "{source_table}"
        WHERE x_fc_serial_id IS NOT NULL
        ON CONFLICT DO NOTHING
        """
    )
    _logger.info(
        "Phase 1 multi-serial: backfilled %s rows from %s.x_fc_serial_id into %s",
        cr.rowcount, source_table, m2m_table,
    )