import pytest

from cashflow_model import CurrencyConverter, CurrencyError, ExchangeRate


class TestExchangeRate:
    def test_to_dict_roundtrip(self):
        rate = ExchangeRate(from_currency="USD", to_currency="RUB", rate=80.0)
        d = rate.to_dict()
        r2 = ExchangeRate.from_dict(d)
        assert r2.from_currency == "USD"
        assert r2.to_currency == "RUB"
        assert r2.rate == 80.0

    def test_defaults(self):
        r = ExchangeRate()
        assert r.from_currency == "USD"
        assert r.to_currency == "RUB"
        assert r.rate == 80.0


class TestCurrencyConverter:
    def test_convert_usd_to_rub(self, sample_converter):
        result = sample_converter.convert(100, "USD", "RUB")
        assert result == 8000.0

    def test_convert_rub_to_usd(self, sample_converter):
        result = sample_converter.convert(8000, "RUB", "USD")
        assert result == 100.0

    def test_same_currency(self, sample_converter):
        result = sample_converter.convert(500, "USD", "USD")
        assert result == 500.0

    def test_unknown_pair(self):
        converter = CurrencyConverter()
        with pytest.raises(CurrencyError):
            converter.convert(100, "USD", "RUB")

    def test_negative_rate(self):
        converter = CurrencyConverter()
        with pytest.raises(CurrencyError):
            converter.set_rate("USD", "RUB", -1)

    def test_zero_rate(self):
        converter = CurrencyConverter()
        with pytest.raises(CurrencyError):
            converter.set_rate("USD", "RUB", 0)

    def test_inverse_auto(self):
        rate = ExchangeRate(from_currency="EUR", to_currency="RUB", rate=90.0)
        converter = CurrencyConverter([rate])
        assert converter.convert(900, "RUB", "EUR") == 10.0

    def test_get_symbol(self, sample_converter):
        assert sample_converter.get_symbol("USD") == "$"
        assert sample_converter.get_symbol("RUB") == "₽"
        assert sample_converter.get_symbol("XYZ") == "XYZ"

    def test_with_defaults(self):
        converter = CurrencyConverter.with_defaults()
        assert converter.convert(10, "USD", "RUB") == 800.0

    def test_multiple_rates(self):
        rates = [
            ExchangeRate(from_currency="USD", to_currency="RUB", rate=80.0),
            ExchangeRate(from_currency="EUR", to_currency="RUB", rate=90.0),
        ]
        converter = CurrencyConverter(rates)
        assert converter.convert(10, "USD", "RUB") == 800.0
        assert converter.convert(10, "EUR", "RUB") == 900.0
        assert converter.convert(900, "RUB", "EUR") == 10.0