from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select
from datetime import datetime, timedelta
import asyncio
import urllib.request
import urllib.parse
import urllib.error
import json

from app.database import get_db
from app.models.settings import Settings
from app.config import settings as app_settings
from app.routers.auth import get_current_session

router = APIRouter()

_cache: dict = {}


def _fetch_json(url: str) -> dict:
    with urllib.request.urlopen(url, timeout=10) as resp:
        return json.loads(resp.read().decode())


@router.get("/")
async def get_weather(
    db: AsyncSession = Depends(get_db),
    current_user: Settings = Depends(get_current_session)
):
    # Get city from settings
    result = await db.execute(select(Settings))
    settings_row = result.scalar_one_or_none()
    city = settings_row.weather_city if settings_row else None
    if not city:
        raise HTTPException(status_code=400, detail="No weather city configured")

    # Check cache (also invalidate if city changed)
    now = datetime.now()
    if _cache.get("expires_at") and now < _cache["expires_at"] and _cache.get("city") == city:
        return _cache["data"]

    api_key = app_settings.OPENWEATHERMAP_API_KEY
    if not api_key:
        raise HTTPException(status_code=500, detail="Weather API key not configured")

    try:
        loop = asyncio.get_event_loop()

        # Current weather + forecast in parallel via thread pool
        current_url = f"https://api.openweathermap.org/data/2.5/weather?q={urllib.parse.quote(city)}&units=metric&appid={api_key}"
        forecast_url = f"https://api.openweathermap.org/data/2.5/forecast?q={urllib.parse.quote(city)}&units=metric&cnt=8&appid={api_key}"

        current_data, forecast_data = await asyncio.gather(
            loop.run_in_executor(None, _fetch_json, current_url),
            loop.run_in_executor(None, _fetch_json, forecast_url),
        )

        rain_chance = 0
        for item in forecast_data.get("list", []):
            pop = item.get("pop", 0)
            if pop > rain_chance:
                rain_chance = pop

        weather_result = {
            "temp": round(current_data["main"]["temp"]),
            "temp_min": round(current_data["main"]["temp_min"]),
            "temp_max": round(current_data["main"]["temp_max"]),
            "description": current_data["weather"][0]["description"],
            "rain_chance": round(rain_chance * 100),
            "sunrise": current_data["sys"]["sunrise"],
            "sunset": current_data["sys"]["sunset"],
            "city": current_data["name"],
        }

        # Cache for 1 hour
        _cache["data"] = weather_result
        _cache["expires_at"] = now + timedelta(hours=1)
        _cache["city"] = city

        return weather_result

    except urllib.error.URLError:
        raise HTTPException(status_code=502, detail="Weather service unavailable")
    except (KeyError, json.JSONDecodeError):
        raise HTTPException(status_code=502, detail="Invalid weather data")