import os

from fastapi import APIRouter, HTTPException, Query
from fastapi.responses import FileResponse
from typing import Optional

from app.core.config import settings
from app.services.terrain_service import terrain_service
from app.services.los_service import los_service

router = APIRouter()


@router.get("/elevation")
async def get_elevation(
    lat: float = Query(..., ge=-90, le=90, description="Latitude"),
    lon: float = Query(..., ge=-180, le=180, description="Longitude")
):
    """Get elevation at a specific point"""
    elevation = await terrain_service.get_elevation(lat, lon)
    return {
        "lat": lat,
        "lon": lon,
        "elevation": elevation,
        "unit": "meters"
    }


@router.get("/profile")
async def get_elevation_profile(
    lat1: float = Query(..., description="Start latitude"),
    lon1: float = Query(..., description="Start longitude"),
    lat2: float = Query(..., description="End latitude"),
    lon2: float = Query(..., description="End longitude"),
    points: int = Query(100, ge=10, le=500, description="Number of sample points")
):
    """Get elevation profile between two points"""
    profile = await terrain_service.get_elevation_profile(lat1, lon1, lat2, lon2, points)

    return {
        "start": {"lat": lat1, "lon": lon1},
        "end": {"lat": lat2, "lon": lon2},
        "num_points": len(profile),
        "profile": profile
    }


@router.get("/los")
async def check_line_of_sight(
    tx_lat: float = Query(..., description="Transmitter latitude"),
    tx_lon: float = Query(..., description="Transmitter longitude"),
    tx_height: float = Query(..., ge=0, description="Transmitter height above ground (m)"),
    rx_lat: float = Query(..., description="Receiver latitude"),
    rx_lon: float = Query(..., description="Receiver longitude"),
    rx_height: float = Query(1.5, ge=0, description="Receiver height above ground (m)")
):
    """Check line-of-sight between transmitter and receiver"""
    result = await los_service.check_line_of_sight(
        tx_lat, tx_lon, tx_height,
        rx_lat, rx_lon, rx_height
    )
    return result


@router.get("/fresnel")
async def check_fresnel_clearance(
    tx_lat: float = Query(..., description="Transmitter latitude"),
    tx_lon: float = Query(..., description="Transmitter longitude"),
    tx_height: float = Query(..., ge=0, description="Transmitter height (m)"),
    rx_lat: float = Query(..., description="Receiver latitude"),
    rx_lon: float = Query(..., description="Receiver longitude"),
    rx_height: float = Query(1.5, ge=0, description="Receiver height (m)"),
    frequency: float = Query(..., ge=100, le=6000, description="Frequency (MHz)")
):
    """Calculate Fresnel zone clearance"""
    result = await los_service.calculate_fresnel_clearance(
        tx_lat, tx_lon, tx_height,
        rx_lat, rx_lon, rx_height,
        frequency
    )
    return result


@router.get("/tiles")
async def list_cached_tiles():
    """List cached SRTM tiles"""
    tiles = list(terrain_service.cache_dir.glob("*.hgt"))
    return {
        "cache_dir": str(terrain_service.cache_dir),
        "tiles": [t.stem for t in tiles],
        "count": len(tiles)
    }


@router.get("/file/{region}")
async def get_terrain_file(region: str):
    """Serve raw SRTM terrain .hgt files (legacy compatibility)."""
    terrain_path = os.path.join(settings.TERRAIN_DATA_DIR, f"{region}.hgt")
    if os.path.exists(terrain_path):
        return FileResponse(terrain_path)
    raise HTTPException(status_code=404, detail=f"Region '{region}' not found")