from odoo import api, fields, models
from datetime import timedelta

class HrExpenseSheet(models.Model):
    _inherit = 'hr.expense.sheet'

    @api.depends('account_move_ids.payment_state', 'account_move_ids.amount_residual')
    def _compute_state(self):
        # Store original states to detect transition to 'done'
        original_states = {sheet.id: sheet.state for sheet in self}
        
        super()._compute_state()
        
        for sheet in self:
            if original_states.get(sheet.id) != 'done' and sheet.state == 'done':
                # Transitioned to 'Paid'
                today = fields.Date.today()
                for expense in sheet.expense_line_ids:
                    if not expense.receipt_due_date:
                        due_days = expense.product_id.receipt_due_days or 0
                        expense.receipt_due_date = today + timedelta(days=due_days)