// This is the main package
package main

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"path"
	"runtime/debug"
	"strings"
	"sync"
	"time"

	"go.balki.me/anyhttp"
	"go.balki.me/anyhttp/idle"
	"go.balki.me/tglistbot/glist"
)

// Version will be set from build commandline
var Version string
var apiToken string

var usage = `Telegram List bot
Environment variables:
TGLB_API_TOKEN (required)      : See https://core.telegram.org/bots#how-do-i-create-a-bot
TGLB_ADDR      (default 28923) : See https://pkg.go.dev/go.balki.me/anyhttp#readme-address-syntax
TGLB_DATA_PATH (default .)     : Directory path where list data is stored
TGLB_TIMEOUT   (default 30m)   : Timeout to auto shutdown if using systemd-fd, See https://pkg.go.dev/time#ParseDuration
`

func main() {

	log.SetFlags(log.Flags() | log.Lshortfile)
	apiToken = os.Getenv("TGLB_API_TOKEN")

	if apiToken == "" {
		log.Print(usage)
		log.Panicln("TGLB_API_TOKEN is empty")
	}

	addr := func() string {
		addr := os.Getenv("TGLB_ADDR")
		if addr == "" {
			return "28923"
		}
		return addr
	}()

	dataPath := func() string {
		dataPath := os.Getenv("TGLB_DATA_PATH")
		if dataPath == "" {
			return "."
		}

		if err := os.MkdirAll(dataPath, 0755); err != nil {
			log.Panicf("Failed to create datapath, path: %q, err: %s\n", dataPath, err)
		}
		return dataPath
	}()

	timeout := func() time.Duration {
		timeoutStr := os.Getenv("TGLB_TIMEOUT")
		if timeoutStr == "" {
			return 30 * time.Minute
		}
		timeout, err := time.ParseDuration(timeoutStr)
		if err != nil {
			log.Panicf("Invalid timeout: %q\n", timeoutStr)
		}
		return timeout
	}()

	glist.DataPath = dataPath

	version := func() string {
		if Version != "" {
			return Version
		}
		if bi, ok := debug.ReadBuildInfo(); ok {
			for _, s := range bi.Settings {
				if s.Key == "vcs.revision" {
					return s.Value[:8]
				}
			}
		}
		return "unknown"
	}()

	log.Printf("List bot (%s) starting with datapath: %q, %s\n", version, dataPath, addr)

	var chats sync.Map
	if err := loadData(dataPath, &chats); err != nil {
		log.Panicf("failed to load data, err: %s\n", err)
	}
	botPath := fmt.Sprintf("/bot%s", apiToken)
	http.HandleFunc(botPath, func(w http.ResponseWriter, r *http.Request) {
		defer func() {
			if _, err := w.Write([]byte("ok")); err != nil {
				log.Println(err)
			}
		}()
		body, err := io.ReadAll(r.Body)
		if err != nil {
			log.Println(err)
			return
		}
		log.Println(string(body))

		update := struct {
			Message *struct {
				ID   int `json:"message_id"`
				Chat struct {
					ID int `json:"id"`
				}
				Text string
			}
			CallbackQuery *struct {
				ID      string `json:"id"`
				Message struct {
					ID   int `json:"message_id"`
					Chat struct {
						ID int `json:"id"`
					}
				}
				Data string
			} `json:"callback_query"`
		}{}

		if err := json.Unmarshal(body, &update); err != nil {
			log.Println(err)
			return
		}

		// Ignore if Text is empty or is a command
		if update.Message != nil && update.Message.Text != "" && update.Message.Text[0] != '/' {

			chatID := update.Message.Chat.ID
			if len(update.Message.Text) > 60 {
				replyURL := fmt.Sprintf("https://api.telegram.org/bot%s/sendMessage?chat_id=%d&reply_to_message_id=%d&text=ItemTooLong-Max60", apiToken, chatID, update.Message.ID)
				resp, err := http.Get(replyURL)
				if err != nil {
					log.Println(err)
					return
				}
				logBody(resp.Body)
				return
			}
			g, _ := chats.LoadOrStore(chatID, glist.NewGList(chatID))
			gl := g.(*glist.GList)
			go handleTextAdded(gl, update.Message.Text)

		} else if update.CallbackQuery != nil {

			defer func() { go answerCallbackQuery(update.CallbackQuery.ID) }()

			chatID := update.CallbackQuery.Message.Chat.ID
			g, ok := chats.Load(chatID)
			if !ok {
				log.Printf("Chat not found: %v\n", chatID)
				return
			}
			gl := g.(*glist.GList)
			go handleButtonClick(gl, update.CallbackQuery.Message.ID, update.CallbackQuery.Data)

		}
	})
	addrType, server, done, err := anyhttp.Serve(addr, idle.WrapHandler(nil))
	if err != nil {
		log.Panicln(err)
	}
	if addrType == anyhttp.SystemdFD {
		log.Println("server started")
		if err := idle.Wait(timeout); err != nil {
			log.Panicln(err)
		}
		log.Printf("server idle for %v, shutting down\n", timeout)
		ctx, cancel := context.WithTimeout(context.Background(), 1*time.Minute) // Don't want any stuck connections
		defer cancel()
		if err := server.Shutdown(ctx); err != nil {
			log.Panicln(err)
		}
	} else {
		<-done
	}
}

func handleTextAdded(gl *glist.GList, text string) {
	gl.Mutex.Lock()
	defer gl.Mutex.Unlock()
	gl.Add(text)
	count := gl.AllMsgCounter + 1
	gl.AllMsgCounter = count
	time.AfterFunc(3*time.Second, func() {
		gl.Mutex.Lock()
		defer gl.Mutex.Unlock()
		if count == gl.AllMsgCounter {
			resp := sendList(gl, glist.NEWLIST)
			if resp == nil {
				return
			}
			response := struct {
				Ok     bool `json:"ok"`
				Result struct {
					MessageID int `json:"message_id"`
				} `json:"result"`
			}{}
			if err := json.Unmarshal(resp, &response); err != nil {
				log.Println(err)
				return
			}
			if !response.Ok {
				log.Println("not ok")
				return
			}

			if gl.MessageID != nil {
				deleteMessage(gl.ChatID, *gl.MessageID)
			}
			gl.MessageID = &response.Result.MessageID
		}
	})
}

func handleButtonClick(gl *glist.GList, messageID int, text string) {
	gl.Mutex.Lock()
	defer gl.Mutex.Unlock()
	gl.MessageID = &messageID
	if text == "clear" {
		gl.ClearChecked()

	} else {
		gl.Toggle(text)
	}

	if len(gl.Items) == 0 {
		deleteMessage(gl.ChatID, messageID)
		gl.MessageID = nil
	} else {
		sendList(gl, glist.EDITLIST)
	}
}

func sendList(gl *glist.GList, method glist.SendMethod) []byte {
	url := fmt.Sprintf("https://api.telegram.org/bot%s/%s", apiToken, method)
	sendMsgReq, err := gl.GenSendListReq(method)
	if err != nil {
		log.Println(err)
		return nil
	}
	log.Println(string(sendMsgReq))
	resp, err := http.Post(url, "application/json", bytes.NewReader(sendMsgReq))
	if err != nil {
		log.Println(err)
		return nil
	}
	return logBody(resp.Body)
}

func answerCallbackQuery(callbackQueryID string) {
	answerURL := fmt.Sprintf("https://api.telegram.org/bot%s/answerCallbackQuery?callback_query_id=%stext=ok", apiToken, callbackQueryID)
	resp, err := http.Get(answerURL)
	if err != nil {
		log.Println(err)
		return
	}
	logBody(resp.Body)
}

func deleteMessage(chatID int, messageID int) {
	deleteURL := fmt.Sprintf("https://api.telegram.org/bot%s/deleteMessage?chat_id=%d&message_id=%d", apiToken, chatID, messageID)
	resp, err := http.Get(deleteURL)
	if err != nil {
		log.Println(err)
		return
	}
	body := logBody(resp.Body)
	ok := struct {
		Ok bool `json:"ok"`
	}{}

	if err := json.Unmarshal(body, &ok); err != nil {
		log.Println(err)
		return
	}
	//Old messages can't be deleted, so edit text instead
	if !ok.Ok {
		updateURL := fmt.Sprintf("https://api.telegram.org/bot%s/editMessageText?chat_id=%d&message_id=%d&text=%s", apiToken, chatID, messageID, "<list updated>")
		resp, err := http.Get(updateURL)
		if err != nil {
			log.Println(err)
			return
		}
		logBody(resp.Body)
	}

}

func logBody(respBody io.ReadCloser) []byte {
	defer func() {
		err := respBody.Close()
		if err != nil {
			log.Println(err)
		}
	}()
	body, err := io.ReadAll(respBody)
	if err != nil {
		log.Println(err)
		return nil
	}
	log.Println(string(body))
	return body
}

func loadData(dataPath string, chats *sync.Map) error {
	items, err := os.ReadDir(dataPath)
	if err != nil {
		return err
	}
	for _, de := range items {
		if de.IsDir() {
			continue
		}
		name := de.Name()
		if !strings.HasPrefix(name, "chkchat") {
			continue
		}
		var gl glist.GList
		data, err := os.ReadFile(path.Join(dataPath, name))
		if err != nil {
			return fmt.Errorf("failed read file, name: %q, err:%w", name, err)
		}
		err = json.Unmarshal(data, &gl)
		if err != nil {
			return fmt.Errorf("failed to parse data, data:%q, err:%w", data, err)
		}
		chats.Store(gl.ChatID, &gl)
	}
	return nil
}