import logging
from typing import List

import httpx
from fastapi import APIRouter, HTTPException, Query, Request
from fastapi.responses import Response

from app.ratelimit import limiter

from app.config import settings
from app.schemas import Candle
from app.services.price_store import price_store

router = APIRouter()
logger = logging.getLogger(__name__)

VALID_ASSETS = {"BTC", "ETH"}
VALID_TIMEFRAMES = {"5m", "15m", "1H", "4H", "1D", "1W"}

BINANCE_INTERVAL = {
    "5m": "5m",
    "15m": "15m",
    "1H": "1h",
    "4H": "4h",
    "1D": "1d",
    "1W": "1w",
}

SYMBOL_MAP = {"BTC": "BTCUSDT", "ETH": "ETHUSDT"}


async def fetch_binance_candles(asset: str, tf: str, limit: int) -> List[Candle]:
    symbol = SYMBOL_MAP[asset]
    interval = BINANCE_INTERVAL[tf]
    url = f"{settings.binance_rest_url}/api/v3/klines?symbol={symbol}&interval={interval}&limit={limit}"
    async with httpx.AsyncClient(timeout=15) as client:
        resp = await client.get(url)
        resp.raise_for_status()
    rows = resp.json()
    return [
        Candle(
            time=row[0] // 1000,   # ms → seconds
            open=float(row[1]),
            high=float(row[2]),
            low=float(row[3]),
            close=float(row[4]),
            volume=float(row[5]),
        )
        for row in rows
    ]


@router.get("/prices/{asset}", response_model=List[Candle])
@limiter.limit("30/minute")
async def get_prices(
    request: Request,
    asset: str,
    tf: str = Query(default="4H"),
    limit: int = Query(default=200, ge=1, le=1000),
    response: Response = None,
):
    asset = asset.upper()
    if asset not in VALID_ASSETS:
        raise HTTPException(status_code=400, detail=f"Asset must be one of {VALID_ASSETS}")
    if tf not in VALID_TIMEFRAMES:
        raise HTTPException(status_code=400, detail=f"Timeframe must be one of {VALID_TIMEFRAMES}")

    # 1m: use in-memory store (updated in real-time) — don't cache at CDN level
    if tf == "1m":
        candles = price_store.get_candles(asset, "1m", limit)
        if response is not None:
            response.headers["Cache-Control"] = "public, max-age=5, stale-while-revalidate=10"
        return [Candle(**c) for c in candles]

    # Larger timeframes change infrequently — safe to cache longer
    if response is not None:
        ttl = 60 if tf in ("5m", "15m") else 300   # 1m for short TFs, 5m for 1H+
        response.headers["Cache-Control"] = f"public, max-age={ttl}, stale-while-revalidate={ttl * 2}"

    try:
        return await fetch_binance_candles(asset, tf, limit)
    except Exception as exc:
        logger.error("Binance REST fetch failed for %s %s: %s", asset, tf, exc)
        raise HTTPException(status_code=502, detail="Failed to fetch price data")