package main

import (
	"encoding/json"
	"fmt"
	"io"
	"math/rand"
	"net/http"
	"net/url"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"strings"
	"time"
)

const (
	wallhavenAPI = "https://wallhaven.cc/api/v1"
	wallpaperDir = "Pictures/wallpapers/wallhaven"
)

type Config struct {
	Topics []string `json:"topics"`
}

var defaultTopics = []string{
	"lofi",
}

func loadConfig() []string {
	homeDir, err := os.UserHomeDir()
	if err != nil {
		return defaultTopics
	}
	configPath := filepath.Join(homeDir, ".config", "change-wallpaper", "config.json")
	file, err := os.Open(configPath)
	if err != nil {
		return defaultTopics
	}
	defer file.Close()
	var cfg Config
	if err := json.NewDecoder(file).Decode(&cfg); err != nil || len(cfg.Topics) == 0 {
		return defaultTopics
	}
	return cfg.Topics
}

type WallhavenResponse struct {
	Data []struct {
		Path string `json:"path"`
	} `json:"data"`
}

func main() {
	// Initialize random source
	r := rand.New(rand.NewSource(time.Now().UnixNano()))

	// Load topics from config or use defaults
	topics := loadConfig()

	// Check if a file path was provided as argument
	if len(os.Args) > 1 {
		imgPath := os.Args[1]
		if _, err := os.Stat(imgPath); err == nil {
			changeWallpaper(imgPath, "")
			return
		}
	}

	// Create wallpaper directory if it doesn't exist
	homeDir, err := os.UserHomeDir()
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error getting home directory: %v\n", err)
		os.Exit(1)
	}

	wallpaperPath := filepath.Join(homeDir, wallpaperDir)
	if err := os.MkdirAll(wallpaperPath, 0755); err != nil {
		fmt.Fprintf(os.Stderr, "Error creating wallpaper directory: %v\n", err)
		os.Exit(1)
	}

	// Download and set new wallpaper
	newWallpaper, topic := downloadRandomWallpaper(wallpaperPath, r, topics)
	if newWallpaper != "" {
		changeWallpaper(newWallpaper, topic)
	} else {
		notify("Failed to download new wallpaper", "critical")
		os.Exit(1)
	}
}

func downloadRandomWallpaper(wallpaperPath string, r *rand.Rand, topics []string) (string, string) {
	// Select random topic
	topic := topics[r.Intn(len(topics))]
	var query string
	var displayName string

	// Check if the topic is a tag ID with name
	if tagRegex := regexp.MustCompile(`^(\d+)\s*-\s*(.+)$`); tagRegex.MatchString(topic) {
		matches := tagRegex.FindStringSubmatch(topic)
		query = fmt.Sprintf("id:%s", matches[1])
		displayName = strings.TrimSpace(matches[2])
	} else {
		query = url.QueryEscape(topic)
		displayName = topic
	}

	fmt.Fprintf(os.Stderr, "Searching for wallpapers related to: %s\n", displayName)

	// Get wallpapers from Wallhaven API
	resp, err := http.Get(fmt.Sprintf("%s/search?q=%s&purity=100&categories=110&sorting=random", wallhavenAPI, query))
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error fetching from Wallhaven: %v\n", err)
		return "", ""
	}
	defer resp.Body.Close()

	// Parse response
	var wallhavenResp WallhavenResponse
	if err := json.NewDecoder(resp.Body).Decode(&wallhavenResp); err != nil {
		fmt.Fprintf(os.Stderr, "Error parsing response: %v\n", err)
		return "", ""
	}

	if len(wallhavenResp.Data) == 0 {
		fmt.Fprintf(os.Stderr, "No wallpapers found for topic: %s\n", displayName)
		return "", ""
	}

	// Select a random image from the results
	randomIndex := r.Intn(len(wallhavenResp.Data))
	wallpaperURL := wallhavenResp.Data[randomIndex].Path
	orig := filepath.Base(wallpaperURL)
	sanitizedTopic := strings.ReplaceAll(strings.ToLower(displayName), " ", "-")
	filename := fmt.Sprintf("%s-%s", sanitizedTopic, orig)
	filepath := filepath.Join(wallpaperPath, filename)

	fmt.Fprintf(os.Stderr, "Downloading: %s\n", filename)

	resp, err = http.Get(wallpaperURL)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error downloading wallpaper: %v\n", err)
		return "", ""
	}
	defer resp.Body.Close()

	file, err := os.Create(filepath)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error creating file: %v\n", err)
		return "", ""
	}
	defer file.Close()

	if _, err := io.Copy(file, resp.Body); err != nil {
		fmt.Fprintf(os.Stderr, "Error saving wallpaper: %v\n", err)
		return "", ""
	}

	return filepath, displayName
}

func changeWallpaper(wallpaperPath, topic string) {
	// Save current wallpaper path
	homeDir, _ := os.UserHomeDir()
	wallpaperFile := filepath.Join(homeDir, ".wallpaper")
	if err := os.WriteFile(wallpaperFile, []byte(wallpaperPath), 0644); err != nil {
		fmt.Fprintf(os.Stderr, "Error saving wallpaper path: %v\n", err)
	}

	// Change wallpaper using hyprctl
	cmd := exec.Command("hyprctl", "hyprpaper", "reload", ","+wallpaperPath)
	if err := cmd.Run(); err != nil {
		fmt.Fprintf(os.Stderr, "Error changing wallpaper: %v\n", err)
	}

	// Send notification with wallpaper as icon
	filename := filepath.Base(wallpaperPath)
	message := fmt.Sprintf("Wallpaper changed to %s", filename)
	if topic != "" {
		message += fmt.Sprintf(" (%s)", topic)
	}
	notifyWithIcon(message, "normal", wallpaperPath)
}

func notify(message, urgency string) {
	cmd := exec.Command("notify-send", "-a", "change-wallpaper", "-i", "hyprpaper", "-u", urgency, "change-wallpaper.go", message)
	if err := cmd.Run(); err != nil {
		fmt.Fprintf(os.Stderr, "Error sending notification: %v\n", err)
	}
}

// notifyWithIcon sends a notification with a custom icon (wallpaper image)
func notifyWithIcon(message, urgency, iconPath string) {
	cmd := exec.Command("notify-send", "-a", "change-wallpaper", "-i", iconPath, "-u", urgency, "change-wallpaper.go", message)
	if err := cmd.Run(); err != nil {
		fmt.Fprintf(os.Stderr, "Error sending notification: %v\n", err)
	}
}
