from odoo import api, fields, models, _




class AccountPayment(models.Model):
    _inherit = 'account.payment'

    # Computed residual amount field
    payment_residual = fields.Monetary(
        string='Payment Residual',
        compute='_compute_payment_residual',
        currency_field='currency_id',
        help="Residual amount of this payment (amount not yet reconciled)",
        readonly=True
    )

    payment_residual_currency = fields.Monetary(
        string='Payment Residual Currency',
        compute='_compute_payment_residual',
        currency_field='currency_id',
        help="Residual amount in payment currency",
        readonly=True
    )

    @api.depends('move_id.line_ids.amount_residual',
                 'move_id.line_ids.amount_residual_currency',
                 'move_id.line_ids.account_id',
                 'move_id.line_ids.account_id.account_type',
                 'is_matched')
    def _compute_payment_residual(self):
        """Compute the residual amount for payments.

        Matched payments always display zero residual.
        For unmatched payments, we first look at residuals on reconcilable counterpart
        lines (receivable/payable/write-off). If those are fully cleared, we fall back
        to the liquidity lines to surface outstanding balances waiting for bank
        statement matching.
        """
        for pay in self:
            if pay.is_matched or not pay.move_id:
                pay.payment_residual = 0.0
                pay.payment_residual_currency = 0.0
                continue

            company_currency = pay.company_id.currency_id
            payment_currency = pay.currency_id or company_currency

            liquidity_lines, counterpart_lines, writeoff_lines = pay._seek_for_lines()
            reconcilable_lines = (counterpart_lines + writeoff_lines).filtered(lambda l: l.account_id.reconcile)

            residual = sum(reconcilable_lines.mapped('amount_residual'))
            residual_currency = sum(
                reconcilable_lines.mapped(
                    'amount_residual_currency' if payment_currency != company_currency else 'amount_residual'
                )
            )

            liquidity_residual = sum(liquidity_lines.mapped('amount_residual'))
            liquidity_residual_currency = sum(
                liquidity_lines.mapped(
                    'amount_residual_currency' if payment_currency != company_currency else 'amount_residual'
                )
            )

            if not company_currency.is_zero(liquidity_residual):
                residual = liquidity_residual
            if not payment_currency.is_zero(liquidity_residual_currency):
                residual_currency = liquidity_residual_currency

            pay.payment_residual = abs(residual)
            pay.payment_residual_currency = abs(residual_currency)