from odoo import api, fields, models


class ProductTemplate(models.Model):
    _inherit = 'product.template'

    lot_sequence_id = fields.Many2one(
        'ir.sequence',
        string='Serial/Lot Numbers Sequence',
        domain=[('code', '=', 'stock.lot.serial')],
        help='Technical Field: The Ir.Sequence record that is used to generate serial/lot numbers for this product'
    )
    serial_prefix_format = fields.Char(
        'Custom Lot/Serial',
        compute='_compute_serial_prefix_format',
        inverse='_inverse_serial_prefix_format',
        help='Set a prefix to generate serial/lot numbers automatically when receiving or producing this product. '
             'Use % codes like %(y)s for year, %(month)s for month, etc.'
    )
    next_serial = fields.Char(
        'Next Number',
        compute='_compute_next_serial',
        help='The next serial/lot number to be generated for this product'
    )

    @api.depends('lot_sequence_id', 'lot_sequence_id.prefix')
    def _compute_serial_prefix_format(self):
        for template in self:
            template.serial_prefix_format = template.lot_sequence_id.prefix or ""

    def _inverse_serial_prefix_format(self):
        valid_sequences = self.env['ir.sequence'].search([('prefix', 'in', self.mapped('serial_prefix_format'))])
        sequences_by_prefix = {seq.prefix: seq for seq in valid_sequences}
        for template in self:
            if template.serial_prefix_format:
                if template.serial_prefix_format in sequences_by_prefix:
                    template.lot_sequence_id = sequences_by_prefix[template.serial_prefix_format]
                else:
                    # Create a new sequence with the given prefix
                    new_sequence = self.env['ir.sequence'].create({
                        'name': f'{template.name} Serial Sequence',
                        'code': 'stock.lot.serial',
                        'prefix': template.serial_prefix_format,
                        'padding': 7,
                        'company_id': False,  # Global sequence to avoid cross-company conflicts
                    })
                    template.lot_sequence_id = new_sequence
                    sequences_by_prefix[template.serial_prefix_format] = new_sequence
            else:
                # Reset to default if no prefix
                template.lot_sequence_id = self.env.ref('stock.sequence_production_lots', raise_if_not_found=False)

    @api.depends('serial_prefix_format', 'lot_sequence_id')
    def _compute_next_serial(self):
        for template in self:
            if template.lot_sequence_id:
                template.next_serial = '{:0{}d}{}'.format(
                    template.lot_sequence_id.number_next_actual,
                    template.lot_sequence_id.padding,
                    template.lot_sequence_id.suffix or ""
                )
            else:
                template.next_serial = '00001'