from fastapi import APIRouter
from pydantic import BaseModel

router = APIRouter()


class ExchangeRateResponse(BaseModel):
    from_currency: str
    to_currency: str
    rate: float
    updated_at: str


EXCHANGE_RATES = {
    ("USD", "CNY"): 7.24,
    ("EUR", "CNY"): 7.85,
    ("GBP", "CNY"): 9.15,
    ("CNY", "USD"): 0.138,
    ("USD", "EUR"): 0.92,
    ("EUR", "USD"): 1.09,
    ("GBP", "USD"): 1.27,
    ("USD", "GBP"): 0.79,
}


@router.get("/convert")
async def convert_currency(
    from_currency: str = "USD",
    to_currency: str = "CNY",
    amount: float = 1.0,
):
    rate = EXCHANGE_RATES.get((from_currency, to_currency), 1.0)
    return {
        "from_currency": from_currency,
        "to_currency": to_currency,
        "amount": amount,
        "converted": round(amount * rate, 2),
        "rate": rate,
        "updated_at": "2026-05-08T00:00:00Z",
    }


@router.get("/rates")
async def get_rates(base: str = "USD"):
    rates = {}
    for (from_curr, to_curr), rate in EXCHANGE_RATES.items():
        if from_curr == base:
            rates[to_curr] = rate

    return {
        "base": base,
        "rates": rates,
        "updated_at": "2026-05-08T00:00:00Z",
    }