package btelegram

import (
	"fmt"
	"html"
	"path/filepath"
	"strconv"
	"strings"
	"unicode/utf16"

	"github.com/42wim/matterbridge/bridge/config"
	"github.com/42wim/matterbridge/bridge/helper"
	"github.com/davecgh/go-spew/spew"
	tgbotapi "github.com/matterbridge/telegram-bot-api/v6"
)

func (b *Btelegram) handleUpdate(rmsg *config.Message, message, posted, edited *tgbotapi.Message) *tgbotapi.Message {
	// handle channels
	if posted != nil {
		if posted.Text == "/chatId" {
			chatID := strconv.FormatInt(posted.Chat.ID, 10)

			// Handle chat topics
			if posted.IsTopicMessage {
				chatID = chatID + "/" + strconv.Itoa(posted.MessageThreadID)
			}

			_, err := b.Send(config.Message{
				Channel: chatID,
				Text:    fmt.Sprintf("ID of this chat: %s", chatID),
			})
			if err != nil {
				b.Log.Warnf("Unable to send chatID to %s", chatID)
			}
		} else {
			message = posted
			rmsg.Text = message.Text
		}
	}

	// edited channel message
	if edited != nil && !b.GetBool("EditDisable") {
		message = edited
		rmsg.Text = rmsg.Text + message.Text + b.GetString("EditSuffix")
	}
	return message
}

// handleChannels checks if it's a channel message and if the message is a new or edited messages
func (b *Btelegram) handleChannels(rmsg *config.Message, message *tgbotapi.Message, update tgbotapi.Update) *tgbotapi.Message {
	return b.handleUpdate(rmsg, message, update.ChannelPost, update.EditedChannelPost)
}

// handleGroups checks if it's a group message and if the message is a new or edited messages
func (b *Btelegram) handleGroups(rmsg *config.Message, message *tgbotapi.Message, update tgbotapi.Update) *tgbotapi.Message {
	return b.handleUpdate(rmsg, message, update.Message, update.EditedMessage)
}

// handleForwarded handles forwarded messages
func (b *Btelegram) handleForwarded(rmsg *config.Message, message *tgbotapi.Message) {
	if message.ForwardDate == 0 {
		return
	}

	if message.ForwardFromChat != nil && message.ForwardFrom == nil {
		rmsg.Text = "Forwarded from " + message.ForwardFromChat.Title + ": " + rmsg.Text
		return
	}

	if message.ForwardFrom == nil {
		rmsg.Text = "Forwarded from " + unknownUser + ": " + rmsg.Text
		return
	}

	usernameForward := ""
	if b.GetBool("UseFirstName") {
		usernameForward = message.ForwardFrom.FirstName
	}
	if b.GetBool("UseFullName") {
		usernameForward = message.ForwardFrom.FirstName + " " + message.ForwardFrom.LastName
	}

	if usernameForward == "" {
		usernameForward = message.ForwardFrom.UserName
		if usernameForward == "" {
			usernameForward = message.ForwardFrom.FirstName
		}
	}

	if usernameForward == "" {
		usernameForward = unknownUser
	}

	rmsg.Text = "Forwarded from " + usernameForward + ": " + rmsg.Text
}

// handleQuoting handles quoting of previous messages
func (b *Btelegram) handleQuoting(rmsg *config.Message, message *tgbotapi.Message) {
	// Used to check if the message was a reply to the root topic
	if message.ReplyToMessage != nil && (!message.IsTopicMessage || message.ReplyToMessage.MessageID != message.MessageThreadID) { //nolint:nestif
		usernameReply := ""
		if message.ReplyToMessage.From != nil {
			if b.GetBool("UseFirstName") {
				usernameReply = message.ReplyToMessage.From.FirstName
			}
			if b.GetBool("UseFullName") {
				usernameReply = message.ReplyToMessage.From.FirstName + " " + message.ReplyToMessage.From.LastName
			}
			if usernameReply == "" {
				usernameReply = message.ReplyToMessage.From.UserName
				if usernameReply == "" {
					usernameReply = message.ReplyToMessage.From.FirstName
				}
			}
		}
		if usernameReply == "" {
			usernameReply = unknownUser
		}
		if !b.GetBool("QuoteDisable") {
			quote := message.ReplyToMessage.Text
			if quote == "" {
				quote = message.ReplyToMessage.Caption
			}
			rmsg.Text = b.handleQuote(rmsg.Text, usernameReply, quote)
		}
	}
}

// handleUsername handles the correct setting of the username
func (b *Btelegram) handleUsername(rmsg *config.Message, message *tgbotapi.Message) {
	if message.From != nil {
		rmsg.UserID = strconv.FormatInt(message.From.ID, 10)
		if b.GetBool("UseFirstName") {
			rmsg.Username = message.From.FirstName
		}
		if b.GetBool("UseFullName") {
			if message.From.FirstName != "" && message.From.LastName != "" {
				rmsg.Username = message.From.FirstName + " " + message.From.LastName
			}
		}
		if rmsg.Username == "" {
			rmsg.Username = message.From.UserName
			if rmsg.Username == "" {
				rmsg.Username = message.From.FirstName
			}
		}
		// only download avatars if we have a place to upload them (configured mediaserver)
		if b.General.MediaServerUpload != "" || (b.General.MediaServerDownload != "" && b.General.MediaDownloadPath != "") {
			b.handleDownloadAvatar(message.From.ID, rmsg.Channel)
		}
	}

	if message.SenderChat != nil { //nolint:nestif
		rmsg.UserID = strconv.FormatInt(message.SenderChat.ID, 10)
		if b.GetBool("UseFirstName") {
			rmsg.Username = message.SenderChat.FirstName
		}
		if b.GetBool("UseFullName") {
			if message.SenderChat.FirstName != "" && message.SenderChat.LastName != "" {
				rmsg.Username = message.SenderChat.FirstName + " " + message.SenderChat.LastName
			}
		}

		if rmsg.Username == "" || rmsg.Username == "Channel_Bot" {
			rmsg.Username = message.SenderChat.UserName

			if rmsg.Username == "" || rmsg.Username == "Channel_Bot" {
				rmsg.Username = message.SenderChat.FirstName
			}
		}
		// only download avatars if we have a place to upload them (configured mediaserver)
		if b.General.MediaServerUpload != "" || (b.General.MediaServerDownload != "" && b.General.MediaDownloadPath != "") {
			b.handleDownloadAvatar(message.SenderChat.ID, rmsg.Channel)
		}
	}

	// Fallback on author signature (used in "channel" type of chat)
	if rmsg.Username == "" && message.AuthorSignature != "" {
		rmsg.Username = message.AuthorSignature
	}

	// if we really didn't find a username, set it to unknown
	if rmsg.Username == "" {
		rmsg.Username = unknownUser
	}
}

func (b *Btelegram) handleRecv(updates <-chan tgbotapi.Update) {
	for update := range updates {
		b.Log.Debugf("== Receiving event: %#v", update.Message)

		if update.Message == nil && update.ChannelPost == nil &&
			update.EditedMessage == nil && update.EditedChannelPost == nil {
			b.Log.Info("Received event without messages, skipping.")
			continue
		}

		if b.GetInt("debuglevel") == 1 {
			spew.Dump(update.Message)
		}

		b.handleGroupUpdate(update)

		var message *tgbotapi.Message

		rmsg := config.Message{Account: b.Account, Extra: make(map[string][]interface{})}

		// handle channels
		message = b.handleChannels(&rmsg, message, update)

		// handle groups
		message = b.handleGroups(&rmsg, message, update)

		if message == nil {
			b.Log.Error("message is nil, this shouldn't happen.")
			continue
		}

		// set the ID's from the channel or group message
		rmsg.ID = strconv.Itoa(message.MessageID)
		rmsg.Channel = strconv.FormatInt(message.Chat.ID, 10)
		if message.IsTopicMessage {
			rmsg.Channel += "/" + strconv.Itoa(message.MessageThreadID)
		}

		// preserve threading from telegram reply
		if message.ReplyToMessage != nil &&
			// Used to check if the message was a reply to the root topic
			(!message.IsTopicMessage || message.ReplyToMessage.MessageID != message.MessageThreadID) {
			rmsg.ParentID = strconv.Itoa(message.ReplyToMessage.MessageID)
		}

		// handle entities (adding URLs)
		b.handleEntities(&rmsg, message)

		// handle username
		b.handleUsername(&rmsg, message)

		// handle any downloads
		err := b.handleDownload(&rmsg, message)
		if err != nil {
			b.Log.Errorf("download failed: %s", err)
		}

		// handle forwarded messages
		b.handleForwarded(&rmsg, message)

		// quote the previous message
		b.handleQuoting(&rmsg, message)

		if rmsg.Text != "" || len(rmsg.Extra) > 0 {
			// Comment the next line out due to avoid removing empty lines in Telegram
			// rmsg.Text = helper.RemoveEmptyNewLines(rmsg.Text)
			// channels don't have (always?) user information. see #410
			if message.From != nil {
				rmsg.Avatar = helper.GetAvatar(b.avatarMap, strconv.FormatInt(message.From.ID, 10), b.General)
			}

			b.Log.Debugf("<= Sending message from %s on %s to gateway", rmsg.Username, b.Account)
			b.Log.Debugf("<= Message is %#v", rmsg)
			b.Remote <- rmsg
		}
	}
}

func (b *Btelegram) handleGroupUpdate(update tgbotapi.Update) {
	msg := update.Message

	switch {
	case msg.NewChatMembers != nil:
		b.handleUserJoin(update)
	case msg.LeftChatMember != nil:
		b.handleUserLeave(update)
	}
}

func (b *Btelegram) handleUserJoin(update tgbotapi.Update) {
	msg := update.Message
	for _, user := range msg.NewChatMembers {
		rmsg := config.Message{
			UserID:   strconv.FormatInt(user.ID, 10),
			Username: user.FirstName, // for some reason all the other name felids are empty on this event (at least for me)
			Channel:  strconv.FormatInt(msg.Chat.ID, 10),
			Account:  b.Account,
			Protocol: b.Protocol,
			Event:    config.EventJoinLeave,
			Text:     "joined chat",
		}
		b.Remote <- rmsg
	}
}

func (b *Btelegram) handleUserLeave(update tgbotapi.Update) {
	msg := update.Message
	user := msg.LeftChatMember

	rmsg := config.Message{
		UserID:   strconv.FormatInt(user.ID, 10),
		Username: user.FirstName, // for some reason all the other name felids are empty on this event (at least for me)
		Channel:  strconv.FormatInt(msg.Chat.ID, 10),
		Account:  b.Account,
		Protocol: b.Protocol,
		Event:    config.EventJoinLeave,
		Text:     "left chat",
	}

	b.Remote <- rmsg
}

// handleDownloadAvatar downloads the avatar of userid from channel
// sends a EVENT_AVATAR_DOWNLOAD message to the gateway if successful.
// logs an error message if it fails
func (b *Btelegram) handleDownloadAvatar(userid int64, channel string) {
	rmsg := config.Message{
		Username: "system",
		Text:     "avatar",
		Channel:  channel,
		Account:  b.Account,
		UserID:   strconv.FormatInt(userid, 10),
		Event:    config.EventAvatarDownload,
		Extra:    make(map[string][]interface{}),
	}

	if _, ok := b.avatarMap[strconv.FormatInt(userid, 10)]; ok {
		return
	}

	photos, err := b.c.GetUserProfilePhotos(tgbotapi.UserProfilePhotosConfig{UserID: userid, Limit: 1})
	if err != nil {
		b.Log.Errorf("Userprofile download failed for %#v %s", userid, err)
	}

	if len(photos.Photos) > 0 {
		photo := photos.Photos[0][0]
		url := b.getFileDirectURL(photo.FileID)
		name := strconv.FormatInt(userid, 10) + ".png"
		b.Log.Debugf("trying to download %#v fileid %#v with size %#v", name, photo.FileID, photo.FileSize)

		err := helper.HandleDownloadSize(b.Log, &rmsg, name, int64(photo.FileSize), b.General)
		if err != nil {
			b.Log.Error(err)
			return
		}
		data, err := helper.DownloadFile(url)
		if err != nil {
			b.Log.Errorf("download %s failed %#v", url, err)
			return
		}
		helper.HandleDownloadData(b.Log, &rmsg, name, rmsg.Text, "", data, b.General)
		b.Remote <- rmsg
	}
}

func (b *Btelegram) maybeConvertTgs(name *string, data *[]byte) {
	format := b.GetString("MediaConvertTgs")
	if helper.SupportsFormat(format) {
		b.Log.Debugf("Format supported by %s, converting %v", helper.LottieBackend(), name)
	} else {
		// Otherwise, no conversion was requested. Trying to run the usual webp
		// converter would fail, because '.tgs.webp' is actually a gzipped JSON
		// file, and has nothing to do with WebP.
		return
	}
	err := helper.ConvertTgsToX(data, format, b.Log)
	if err != nil {
		b.Log.Errorf("conversion failed: %v", err)
	} else {
		*name = strings.Replace(*name, "tgs.webp", format, 1)
	}
}

func (b *Btelegram) maybeConvertWebp(name *string, data *[]byte) {
	if b.GetBool("MediaConvertWebPToPNG") {
		b.Log.Debugf("WebP to PNG conversion enabled, converting %v", name)
		err := helper.ConvertWebPToPNG(data)
		if err != nil {
			b.Log.Errorf("conversion failed: %v", err)
		} else {
			*name = strings.Replace(*name, ".webp", ".png", 1)
		}
	}
}

// handleDownloadFile handles file download
func (b *Btelegram) handleDownload(rmsg *config.Message, message *tgbotapi.Message) error {
	size := int64(0)
	var url, name, text string
	switch {
	case message.Sticker != nil:
		text, name, url = b.getDownloadInfo(message.Sticker.FileID, ".webp", true)
		size = int64(message.Sticker.FileSize)
	case message.Voice != nil:
		text, name, url = b.getDownloadInfo(message.Voice.FileID, ".ogg", true)
		size = message.Voice.FileSize
	case message.Video != nil:
		text, name, url = b.getDownloadInfo(message.Video.FileID, "", true)
		size = message.Video.FileSize
	case message.Audio != nil:
		text, name, url = b.getDownloadInfo(message.Audio.FileID, "", true)
		size = message.Audio.FileSize
	case message.Document != nil:
		_, _, url = b.getDownloadInfo(message.Document.FileID, "", false)
		size = message.Document.FileSize
		name = message.Document.FileName
		text = " " + message.Document.FileName + " : " + url
	case message.Photo != nil:
		photos := message.Photo
		size = int64(photos[len(photos)-1].FileSize)
		text, name, url = b.getDownloadInfo(photos[len(photos)-1].FileID, "", true)
	}

	// if name is empty we didn't match a thing to download
	if name == "" {
		return nil
	}
	// use the URL instead of native upload
	if b.GetBool("UseInsecureURL") {
		b.Log.Debugf("Setting message text to :%s", text)
		rmsg.Text += text
		return nil
	}
	// if we have a file attached, download it (in memory) and put a pointer to it in msg.Extra
	err := helper.HandleDownloadSize(b.Log, rmsg, name, int64(size), b.General)
	if err != nil {
		return err
	}
	data, err := helper.DownloadFile(url)
	if err != nil {
		return err
	}

	if strings.HasSuffix(name, ".tgs.webp") {
		b.maybeConvertTgs(&name, data)
	} else if strings.HasSuffix(name, ".webp") {
		b.maybeConvertWebp(&name, data)
	}

	// rename .oga to .ogg  https://github.com/42wim/matterbridge/issues/906#issuecomment-741793512
	if strings.HasSuffix(name, ".oga") && message.Audio != nil {
		name = strings.Replace(name, ".oga", ".ogg", 1)
	}

	helper.HandleDownloadData(b.Log, rmsg, name, message.Caption, "", data, b.General)
	return nil
}

func (b *Btelegram) getDownloadInfo(id string, suffix string, urlpart bool) (string, string, string) {
	url := b.getFileDirectURL(id)
	name := ""
	if urlpart {
		urlPart := strings.Split(url, "/")
		name = urlPart[len(urlPart)-1]
	}
	if suffix != "" && !strings.HasSuffix(name, suffix) && !strings.HasSuffix(name, ".webm") {
		name += suffix
	}
	text := " " + url
	return text, name, url
}

// handleDelete handles message deleting
func (b *Btelegram) handleDelete(msg *config.Message, chatid int64) (string, error) {
	if msg.ID == "" {
		return "", nil
	}

	msgid, err := strconv.Atoi(msg.ID)
	if err != nil {
		return "", err
	}

	cfg := tgbotapi.NewDeleteMessage(chatid, msgid)
	_, err = b.c.Request(cfg)

	return "", err
}

// handleEdit handles message editing.
func (b *Btelegram) handleEdit(msg *config.Message, chatid int64) (string, error) {
	msgid, err := strconv.Atoi(msg.ID)
	if err != nil {
		return "", err
	}
	if strings.ToLower(b.GetString("MessageFormat")) == HTMLNick {
		b.Log.Debug("Using mode HTML - nick only")
		msg.Text = html.EscapeString(msg.Text)
	}
	m := tgbotapi.NewEditMessageText(chatid, msgid, msg.Username+msg.Text)
	switch b.GetString("MessageFormat") {
	case HTMLFormat:
		b.Log.Debug("Using mode HTML")
		m.ParseMode = tgbotapi.ModeHTML
	case "Markdown":
		b.Log.Debug("Using mode markdown")
		m.ParseMode = tgbotapi.ModeMarkdown
	case MarkdownV2:
		b.Log.Debug("Using mode MarkdownV2")
		m.ParseMode = MarkdownV2
	}
	if strings.ToLower(b.GetString("MessageFormat")) == HTMLNick {
		b.Log.Debug("Using mode HTML - nick only")
		m.ParseMode = tgbotapi.ModeHTML
	}
	_, err = b.c.Send(m)
	if err != nil {
		return "", err
	}
	return "", nil
}

// handleUploadFile handles native upload of files
func (b *Btelegram) handleUploadFile(msg *config.Message, chatid int64, threadid int, parentID int) (string, error) {
	var media []interface{}
	for _, f := range msg.Extra["file"] {
		fi := f.(config.FileInfo)
		file := tgbotapi.FileBytes{
			Name:  fi.Name,
			Bytes: *fi.Data,
		}

		if b.GetString("MessageFormat") == HTMLFormat {
			fi.Comment = makeHTML(html.EscapeString(fi.Comment))
		}

		switch filepath.Ext(fi.Name) {
		case ".jpg", ".jpe", ".png":
			pc := tgbotapi.NewInputMediaPhoto(file)
			if fi.Comment != "" {
				pc.Caption, pc.ParseMode = TGGetParseMode(b, msg.Username, fi.Comment)
			}
			media = append(media, pc)
		case ".mp4", ".m4v":
			vc := tgbotapi.NewInputMediaVideo(file)
			if fi.Comment != "" {
				vc.Caption, vc.ParseMode = TGGetParseMode(b, msg.Username, fi.Comment)
			}
			media = append(media, vc)
		case ".mp3", ".oga":
			ac := tgbotapi.NewInputMediaAudio(file)
			if fi.Comment != "" {
				ac.Caption, ac.ParseMode = TGGetParseMode(b, msg.Username, fi.Comment)
			}
			media = append(media, ac)
		case ".ogg":
			voc := tgbotapi.NewVoice(chatid, file)
			voc.Caption, voc.ParseMode = TGGetParseMode(b, msg.Username, fi.Comment)
			voc.ReplyToMessageID = parentID
			res, err := b.c.Send(voc)
			if err != nil {
				return "", err
			}
			return strconv.Itoa(res.MessageID), nil
		default:
			dc := tgbotapi.NewInputMediaDocument(file)
			if fi.Comment != "" {
				dc.Caption, dc.ParseMode = TGGetParseMode(b, msg.Username, fi.Comment)
			}
			media = append(media, dc)
		}
	}

	return b.sendMediaFiles(msg, chatid, threadid, parentID, media)
}

func (b *Btelegram) handleQuote(message, quoteNick, quoteMessage string) string {
	format := b.GetString("quoteformat")
	if format == "" {
		format = "{MESSAGE} (re @{QUOTENICK}: {QUOTEMESSAGE})"
	}
	quoteMessagelength := len([]rune(quoteMessage))
	if b.GetInt("QuoteLengthLimit") != 0 && quoteMessagelength >= b.GetInt("QuoteLengthLimit") {
		runes := []rune(quoteMessage)
		quoteMessage = string(runes[0:b.GetInt("QuoteLengthLimit")])
		if quoteMessagelength > b.GetInt("QuoteLengthLimit") {
			quoteMessage += "..."
		}
	}
	format = strings.Replace(format, "{MESSAGE}", message, -1)
	format = strings.Replace(format, "{QUOTENICK}", quoteNick, -1)
	format = strings.Replace(format, "{QUOTEMESSAGE}", quoteMessage, -1)
	return format
}

// handleEntities handles messageEntities
func (b *Btelegram) handleEntities(rmsg *config.Message, message *tgbotapi.Message) {
	if message.Entities == nil {
		return
	}

	indexMovedBy := 0
	prevLinkOffset := -1

	for _, e := range message.Entities {

		asRunes := utf16.Encode([]rune(rmsg.Text))

		if e.Type == "text_link" {
			offset := e.Offset + indexMovedBy
			url, err := e.ParseURL()
			if err != nil {
				b.Log.Errorf("entity text_link url parse failed: %s", err)
				continue
			}
			utfEncodedString := utf16.Encode([]rune(rmsg.Text))
			if offset+e.Length > len(utfEncodedString) {
				b.Log.Errorf("entity length is too long %d > %d", offset+e.Length, len(utfEncodedString))
				continue
			}
			rmsg.Text = string(utf16.Decode(asRunes[:offset+e.Length])) + " (" + url.String() + ")" + string(utf16.Decode(asRunes[offset+e.Length:]))
			indexMovedBy += len(url.String()) + 3
			prevLinkOffset = e.Offset
		}

		if e.Offset == prevLinkOffset {
			continue
		}

		if e.Type == "code" {
			offset := e.Offset + indexMovedBy
			rmsg.Text = string(utf16.Decode(asRunes[:offset])) + "`" + string(utf16.Decode(asRunes[offset:offset+e.Length])) + "`" + string(utf16.Decode(asRunes[offset+e.Length:]))
			indexMovedBy += 2
		}

		if e.Type == "pre" {
			offset := e.Offset + indexMovedBy
			rmsg.Text = string(utf16.Decode(asRunes[:offset])) + "```\n" + string(utf16.Decode(asRunes[offset:offset+e.Length])) + "```\n" + string(utf16.Decode(asRunes[offset+e.Length:]))
			indexMovedBy += 8
		}

		if e.Type == "bold" {
			offset := e.Offset + indexMovedBy
			rmsg.Text = string(utf16.Decode(asRunes[:offset])) + "*" + string(utf16.Decode(asRunes[offset:offset+e.Length])) + "*" + string(utf16.Decode(asRunes[offset+e.Length:]))
			indexMovedBy += 2
		}
		if e.Type == "italic" {
			offset := e.Offset + indexMovedBy
			rmsg.Text = string(utf16.Decode(asRunes[:offset])) + "_" + string(utf16.Decode(asRunes[offset:offset+e.Length])) + "_" + string(utf16.Decode(asRunes[offset+e.Length:]))
			indexMovedBy += 2
		}
		if e.Type == "strike" {
			offset := e.Offset + indexMovedBy
			rmsg.Text = string(utf16.Decode(asRunes[:offset])) + "~" + string(utf16.Decode(asRunes[offset:offset+e.Length])) + "~" + string(utf16.Decode(asRunes[offset+e.Length:]))
			indexMovedBy += 2
		}
	}
}