from odoo.tests.common import TransactionCase, tagged
from odoo.addons.fusion_accounting_bank_rec.services.exchange_diff import (
    compute_exchange_diff, ExchangeDiffResult,
)


@tagged('post_install', '-at_install')
class TestExchangeDiff(TransactionCase):

    def test_no_diff_when_currencies_match_and_rates_match(self):
        result = compute_exchange_diff(
            line_amount=100.00, line_currency_code='CAD',
            against_amount=100.00, against_currency_code='CAD',
            line_rate=1.0, against_rate=1.0,
        )
        self.assertFalse(result.needs_diff_move)
        self.assertEqual(result.diff_amount, 0.0)

    def test_diff_when_rates_differ_same_currency(self):
        """USD invoice posted at 1.35, USD bank line settled at 1.40 -> diff exists.
        100 USD at 1.40 = 140 CAD; same at 1.35 = 135 CAD; diff = 5 CAD gain."""
        result = compute_exchange_diff(
            line_amount=100.00, line_currency_code='USD',
            against_amount=100.00, against_currency_code='USD',
            line_rate=1.40, against_rate=1.35,
        )
        self.assertTrue(result.needs_diff_move)
        self.assertAlmostEqual(result.diff_amount, 5.00, places=2)

    def test_diff_negative_when_rate_dropped(self):
        """USD invoice at 1.40, settled at 1.35 -> loss"""
        result = compute_exchange_diff(
            line_amount=100.00, line_currency_code='USD',
            against_amount=100.00, against_currency_code='USD',
            line_rate=1.35, against_rate=1.40,
        )
        self.assertTrue(result.needs_diff_move)
        self.assertAlmostEqual(result.diff_amount, -5.00, places=2)

    def test_company_amounts_computed_correctly(self):
        result = compute_exchange_diff(
            line_amount=100.00, line_currency_code='USD',
            against_amount=100.00, against_currency_code='USD',
            line_rate=1.40, against_rate=1.35,
        )
        self.assertAlmostEqual(result.line_company_amount, 140.00, places=2)
        self.assertAlmostEqual(result.against_company_amount, 135.00, places=2)

    def test_tolerance_handles_rounding_noise(self):
        """Tiny FX rounding under 0.005 should NOT trigger a diff move."""
        result = compute_exchange_diff(
            line_amount=100.00, line_currency_code='USD',
            against_amount=100.00, against_currency_code='USD',
            line_rate=1.40000, against_rate=1.40003,  # 0.003 cent diff
        )
        self.assertFalse(result.needs_diff_move)