package main

import (
	"context"
	"fmt"
	"io"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"
)

const radarCacheTTL = 10 * time.Minute

func requireMPV() error {
	if _, err := exec.LookPath("mpv"); err != nil {
		return fmt.Errorf("mpv is required for radar mode")
	}
	return nil
}

func runRadar(ctx context.Context, cache *Cache, loc Location, searchQuery string, userAgent string) error {
	station := strings.TrimSpace(loc.RadarStation)
	if station == "" {
		client := NewNWSClient(userAgent)
		var err error
		station, err = client.FetchRadarStation(ctx, loc)
		if err != nil {
			return err
		}
		loc.RadarStation = station
		if err := cache.UpdateLocation(loc); err != nil {
			if searchQuery == "" {
				return err
			}
			if err := cache.SaveLocation(searchQuery, loc); err != nil {
				return err
			}
		}
	}

	url, err := radarURL(station)
	if err != nil {
		return err
	}

	radarPath, err := cacheRadarGIF(ctx, cache, url, userAgent)
	if err != nil {
		return err
	}

	cmd := exec.CommandContext(ctx, "mpv", "--fs", "--loop-file", radarPath)
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	cmd.Stdin = os.Stdin
	return cmd.Run()
}

func radarURL(station string) (string, error) {
	station = strings.TrimSpace(station)
	if station == "" {
		return "", fmt.Errorf("radar station not set")
	}
	station = strings.ToUpper(station)
	return fmt.Sprintf("https://radar.weather.gov/ridge/standard/%s_loop.gif", station), nil
}

func cacheRadarGIF(ctx context.Context, cache *Cache, url, userAgent string) (string, error) {
	if err := cache.ensureDir(); err != nil {
		return "", err
	}
	path := filepath.Join(cache.dir, "radar.gif")
	if !shouldRefreshFile(path, radarCacheTTL) {
		return path, nil
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return "", err
	}
	req.Header.Set("User-Agent", userAgent)

	client := &http.Client{Timeout: 20 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()

	if resp.StatusCode > 299 {
		return "", fmt.Errorf("radar request failed with status %d", resp.StatusCode)
	}

	tmpPath := path + ".tmp"
	tmp, err := os.Create(tmpPath)
	if err != nil {
		return "", err
	}
	_, copyErr := io.Copy(tmp, resp.Body)
	closeErr := tmp.Close()
	if copyErr != nil {
		_ = os.Remove(tmpPath)
		return "", copyErr
	}
	if closeErr != nil {
		_ = os.Remove(tmpPath)
		return "", closeErr
	}

	if err := os.Rename(tmpPath, path); err != nil {
		_ = os.Remove(tmpPath)
		return "", err
	}

	return path, nil
}

func shouldRefreshFile(path string, ttl time.Duration) bool {
	info, err := os.Stat(path)
	if err != nil {
		return true
	}
	return time.Since(info.ModTime()) > ttl
}