account-financial-tools/account_loan/model/account_invoice.py

# Copyright 2018 Creu Blanca
# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).

from odoo import api, fields, models


class AccountInvoice(models.Model):
    _inherit = "account.invoice"

    loan_line_id = fields.Many2one(
        "account.loan.line", readonly=True, ondelete="restrict",
    )
    loan_id = fields.Many2one(
        "account.loan", readonly=True, store=True, ondelete="restrict",
    )

    @api.multi
    def finalize_invoice_move_lines(self, move_lines):
        vals = super().finalize_invoice_move_lines(move_lines)
        if self.loan_line_id:
            ll = self.loan_line_id
            if ll.long_term_loan_account_id and ll.long_term_principal_amount != 0:
                vals.append(
                    (
                        0,
                        0,
                        {
                            "account_id": ll.loan_id.short_term_loan_account_id.id,
                            "credit": ll.long_term_principal_amount,
                            "debit": 0,
                        },
                    )
                )
                vals.append(
                    (
                        0,
                        0,
                        {
                            "account_id": ll.long_term_loan_account_id.id,
                            "credit": 0,
                            "debit": ll.long_term_principal_amount,
                        },
                    )
                )
        return vals