package main

import (
	"bufio"
	"bytes"
	"flag"
	"fmt"
	"html/template"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/fsnotify/fsnotify"
	tgbotapi "github.com/go-telegram-bot-api/telegram-bot-api/v5"
	"github.com/russross/blackfriday/v2"
)

const (
	dataDir               = "./data"
	templateDir           = "./templates"
	staticDir             = "./static"
	notifiedFilePath      = "./notified_entries.json"
	defaultPort           = 8080
	pageSize              = 5                         // Number of blog entries per page
	botTokenEnv           = "YOUR_TELEGRAM_BOT_TOKEN" // Replace with your bot's token or set via environment variable
	YOUR_TELEGRAM_CHAT_ID = 0
	discordWebhookURL     = "YOUR_DISCORD_WEBHOOK_URL"
)

type Blog struct {
	Name    string
	Entries []BlogEntry
}

type BlogEntry struct {
	Title       string
	Description string
	Author      string
	Content     string
	Date        time.Time
	Number      int
	Notified    bool // To track if the notification was sent
}

type PageData struct {
	Title    string
	Date     string
	Desc     string
	Author   string
	Content  template.HTML
	PrevLink string
	NextLink string
}

var (
	blogs           []Blog
	bot             *tgbotapi.BotAPI
	port            int
	creationTimes   = make(map[string]time.Time)
	creationTimesM  sync.Mutex
	notifiedEntries = make(map[int]bool)
)

func init() {
	flag.IntVar(&port, "p", defaultPort, "Specify the port to run the server on")
	flag.IntVar(&port, "port", defaultPort, "Specify the port to run the server on")
}

func main() {
	// Parse the flags
	flag.Parse()

	// Load the notified entries from the file
	loadNotifiedEntries()

	// Retrieve the Telegram bot token from the environment variable
	botToken := os.Getenv("TELEGRAM_BOT_TOKEN")
	if botToken == "" {
		botToken = botTokenEnv
	}

	// Initialize the Telegram bot
	var err error
	bot, err = tgbotapi.NewBotAPI(botToken)
	if err != nil {
		log.Printf("Warning: Error creating Telegram bot: %v", err)
	} else {
		go startTelegramBot()
	}

	// Retrieve blog entries from the data directory
	blogs, err = getBlogs(dataDir)
	if err != nil {
		log.Fatalf("Error getting blogs: %v", err)
	}

	// Start watching for changes in the data directory
	go watchForChanges(dataDir)

	// Serve static files (CSS, JS, etc.) from the /static directory
	http.Handle("/static/", http.StripPrefix("/static/", http.FileServer(http.Dir(staticDir))))

	// Serve files in the /data/news/ directory under /news-assets/
	http.Handle("/news-assets/", http.StripPrefix("/news-assets/", http.FileServer(http.Dir(dataDir+"/news/"))))

	// Serve downloads.html at /downloads
	http.HandleFunc("/download", func(w http.ResponseWriter, r *http.Request) {
		renderTemplate(w, "download.html", nil)
	})

	// Serve download-linux.html at /download-linux
	http.HandleFunc("/download-linux", func(w http.ResponseWriter, r *http.Request) {
		renderTemplate(w, "download-linux.html", nil)
	})

	http.HandleFunc("/suggestions", handleSuggestions)

	// Route for generating the RSS feed for all blogs
	http.HandleFunc("/rss", func(w http.ResponseWriter, r *http.Request) {
		siteURL := fmt.Sprintf("http://%s", r.Host) // or you can use a fixed base URL
		generateAtomFeed(w, blogs, siteURL)
	})

	// Route for generating the RSS feed for a specific blog
	http.HandleFunc("/rss/", func(w http.ResponseWriter, r *http.Request) {
		pathParts := strings.Split(r.URL.Path, "/")
		if len(pathParts) < 3 {
			http.NotFound(w, r)
			return
		}

		blogName := pathParts[2]
		for _, blog := range blogs {
			if blog.Name == blogName {
				siteURL := fmt.Sprintf("http://%s", r.Host) // or you can use a fixed base URL
				generateBlogAtomFeed(w, blog, siteURL)
				return
			}
		}

		http.NotFound(w, r)
	})

	// Define route handlers
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path == "/" {
			renderIndex(w)
			return
		}

		pathParts := strings.Split(r.URL.Path, "/")
		if len(pathParts) < 2 {
			http.NotFound(w, r)
			return
		}

		if len(pathParts) == 3 {
			blogName := pathParts[1]
			entryNumber, err := strconv.Atoi(pathParts[2])
			if err == nil {
				renderBlogEntry(w, r, blogName, entryNumber)
				return
			}
		}

		blogName := pathParts[1]
		for _, blog := range blogs {
			if blog.Name == blogName {
				http.Redirect(w, r, fmt.Sprintf("/%s/%d", blogName, blog.Entries[0].Number), http.StatusFound)
				return
			}
		}

		http.NotFound(w, r)
	})

	// Start the HTTP server on the specified port
	serverURL := fmt.Sprintf("http://localhost:%d", port)
	log.Printf("Starting server on %s", serverURL)
	log.Fatal(http.ListenAndServe(fmt.Sprintf(":%d", port), nil))
}

func renderTemplate(w http.ResponseWriter, tmpl string, data interface{}) {
	tmplPath := filepath.Join(templateDir, tmpl)
	t, err := template.ParseFiles(tmplPath)
	if err != nil {
		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
		log.Printf("Error parsing template %s: %v", tmpl, err)
		return
	}

	err = t.Execute(w, data)
	if err != nil {
		http.Error(w, "Internal Server Error", http.StatusInternalServerError)
		log.Printf("Error executing template %s: %v", tmpl, err)
	}
}

func renderIndex(w http.ResponseWriter) {
	renderTemplate(w, "index.html", nil)
}

func renderBlogEntry(w http.ResponseWriter, r *http.Request, blogName string, entryNumber int) {
	var blog Blog
	for _, b := range blogs {
		if b.Name == blogName {
			blog = b
			break
		}
	}

	var entry BlogEntry
	var prevLink, nextLink string
	for i, e := range blog.Entries {
		if e.Number == entryNumber {
			// Check if the entry date is in the future
			if time.Now().Before(e.Date) {
				http.NotFound(w, r) // If the post date is in the future, do not show the entry
				return
			}
			entry = e

			// Check if the previous entry is visible
			if i > 0 && !time.Now().Before(blog.Entries[i-1].Date) {
				prevLink = fmt.Sprintf("/%s/%d", blog.Name, blog.Entries[i-1].Number)
			}

			// Check if the next entry is visible
			if i < len(blog.Entries)-1 && !time.Now().Before(blog.Entries[i+1].Date) {
				nextLink = fmt.Sprintf("/%s/%d", blog.Name, blog.Entries[i+1].Number)
			}
			break
		}
	}

	htmlContent := blackfriday.Run([]byte(entry.Content))

	htmlContent = bytes.ReplaceAll(htmlContent, []byte("src=\"./"), []byte(fmt.Sprintf("src=\"/news-assets/%d/", entryNumber)))

	pageData := PageData{
		Title:    entry.Title,
		Date:     entry.Date.Format("2006-01-02 15:04"),
		Desc:     entry.Description,
		Author:   entry.Author,
		Content:  template.HTML(htmlContent),
		PrevLink: prevLink,
		NextLink: nextLink,
	}

	renderTemplate(w, "news.html", pageData)

	// Handle notifications if they haven't been sent yet
	if !entry.Notified {
		sendNotifications(entry)
		entry.Notified = true
		saveNotifiedEntry(entry.Number)
	}
}

func getBlogs(dir string) ([]Blog, error) {
	var blogs []Blog

	files, err := ioutil.ReadDir(dir)
	if err != nil {
		return nil, err
	}

	for _, file := range files {
		if file.IsDir() {
			blog, err := getBlogEntries(filepath.Join(dir, file.Name()))
			if err != nil {
				return nil, err
			}
			blogs = append(blogs, blog)
		}
	}

	return blogs, nil
}

func getBlogEntries(dir string) (Blog, error) {
	var entries []BlogEntry

	files, err := ioutil.ReadDir(dir)
	if err != nil {
		return Blog{}, err
	}

	for _, file := range files {
		if filepath.Ext(file.Name()) == ".md" {
			entry, err := parseMarkdownFile(filepath.Join(dir, file.Name()))
			if err != nil {
				return Blog{}, err
			}

			entries = append(entries, entry)
		}
	}

	sort.Slice(entries, func(i, j int) bool {
		return entries[i].Number > entries[j].Number
	})

	blog := Blog{
		Name:    filepath.Base(dir),
		Entries: entries,
	}

	return blog, nil
}

func parseMarkdownFile(path string) (BlogEntry, error) {
	content, err := ioutil.ReadFile(path)
	if err != nil {
		return BlogEntry{}, err
	}

	scanner := bufio.NewScanner(strings.NewReader(string(content)))

	var title, description, postTime, author string
	var articleContent strings.Builder
	var insideHeader bool

	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())

		if line == "[HEADER]" {
			insideHeader = true
			continue
		} else if line == "[END]" {
			insideHeader = false
			continue
		}

		if insideHeader {
			if strings.HasPrefix(line, "t:") {
				title = strings.TrimSpace(line[2:])
			} else if strings.HasPrefix(line, "d:") {
				description = strings.TrimSpace(line[2:])
			} else if strings.HasPrefix(line, "p:") {
				postTime = strings.TrimSpace(line[2:])
			} else if strings.HasPrefix(line, "a:") {
				author = strings.TrimSpace(line[2:])
			}
		} else {
			articleContent.WriteString(line + "\n")
		}
	}

	date := time.Now()
	if postTime != "" {
		date, err = time.Parse("2006-01-02 15:04", postTime)
		if err != nil {
			log.Printf("Error parsing date in file %s: %v", path, err)
		}
	}

	number, err := strconv.Atoi(strings.TrimSuffix(filepath.Base(path), filepath.Ext(path)))
	if err != nil {
		log.Printf("Error extracting number from file %s: %v", path, err)
		return BlogEntry{}, err
	}

	// Check if the entry has already been notified
	notified := notifiedEntries[number]

	entry := BlogEntry{
		Title:       title,
		Description: description,
		Author:      author,
		Content:     articleContent.String(),
		Date:        date,
		Number:      number,
		Notified:    notified,
	}

	return entry, nil
}

func watchForChanges(dir string) {
	watcher, err := fsnotify.NewWatcher()
	if err != nil {
		log.Fatalf("Error creating file watcher: %v", err)
	}
	defer watcher.Close()

	go func() {
		for {
			select {
			case event, ok := <-watcher.Events:
				if !ok {
					return
				}
				if event.Op&fsnotify.Create == fsnotify.Create {
					handleFileChange(event.Name, true)
				} else if event.Op&fsnotify.Write == fsnotify.Write {
					handleFileChange(event.Name, false)
				}
			case err, ok := <-watcher.Errors:
				if !ok {
					return
				}
				log.Printf("File watcher error: %v", err)
			}
		}
	}()

	err = watcher.Add(dir)
	if err != nil {
		log.Fatalf("Error adding directory to watcher: %v", err)
	}

	// Add subdirectories
	err = filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if info.IsDir() && path != dir {
			return watcher.Add(path)
		}
		return nil
	})
	if err != nil {
		log.Fatalf("Error adding subdirectories to watcher: %v", err)
	}

	// Block forever
	select {}
}

func handleFileChange(path string, isNew bool) {
	if filepath.Ext(path) == ".md" {
		creationTimesM.Lock()
		defer creationTimesM.Unlock()
		if isNew {
			creationTimes[path] = time.Now()
		}

		dir := filepath.Dir(path)
		blogName := filepath.Base(dir)
		updateBlogEntries(blogName, path)
	}
}

func updateBlogEntries(blogName, path string) {
	for i, blog := range blogs {
		if blog.Name == blogName {
			entry, err := parseMarkdownFile(path)
			if err != nil {
				log.Printf("Error parsing markdown file: %v", err)
				return
			}

			updated := false
			for j, e := range blogs[i].Entries {
				if e.Number == entry.Number {
					blogs[i].Entries[j] = entry
					updated = true
					break
				}
			}

			if !updated {
				blogs[i].Entries = append(blogs[i].Entries, entry)
			}

			sort.Slice(blogs[i].Entries, func(a, b int) bool {
				return blogs[i].Entries[a].Number > blogs[i].Entries[b].Number
			})

			log.Printf("Updated blog %s with entry %d", blogName, entry.Number)
			return
		}
	}

	// If blog not found, create new one
	entry, err := parseMarkdownFile(path)
	if err != nil {
		log.Printf("Error parsing markdown file: %v", err)
		return
	}

	newBlog := Blog{
		Name:    blogName,
		Entries: []BlogEntry{entry},
	}

	blogs = append(blogs, newBlog)
	log.Printf("Created new blog %s with entry %d", blogName, entry.Number)
}

func sendNotifications(entry BlogEntry) {
	message := fmt.Sprintf("New blog post published!\nTitle: %s\nDescription: %s\nAuthor: %s\nDate: %s",
		entry.Title, entry.Description, entry.Author, entry.Date.Format("2006-01-02 15:04"))

	// Send notification to Telegram
	sendTelegramNotification(message)

	// Send notification to Discord
	sendDiscordNotification(message)

	log.Printf("Sent notifications for entry %d: %s", entry.Number, entry.Title)
}