package bslack

import (
	"bytes"
	"fmt"
	"html"
	"regexp"
	"time"

	"github.com/42wim/matterbridge/bridge/config"
	"github.com/42wim/matterbridge/bridge/helper"
	"github.com/nlopes/slack"
)

func (b *Bslack) handleSlack() {
	messages := make(chan *config.Message)
	if b.GetString(incomingWebhookConfig) != "" {
		b.Log.Debugf("Choosing webhooks based receiving")
		go b.handleMatterHook(messages)
	} else {
		b.Log.Debugf("Choosing token based receiving")
		go b.handleSlackClient(messages)
	}
	time.Sleep(time.Second)
	b.Log.Debug("Start listening for Slack messages")
	for message := range messages {
		b.Log.Debugf("<= Sending message from %s on %s to gateway", message.Username, b.Account)

		// cleanup the message
		message.Text = b.replaceMention(message.Text)
		message.Text = b.replaceVariable(message.Text)
		message.Text = b.replaceChannel(message.Text)
		message.Text = b.replaceURL(message.Text)
		message.Text = html.UnescapeString(message.Text)

		// Add the avatar
		message.Avatar = b.getAvatar(message.UserID)

		b.Log.Debugf("<= Message is %#v", message)
		b.Remote <- *message
	}
}

func (b *Bslack) handleSlackClient(messages chan *config.Message) {
	for msg := range b.rtm.IncomingEvents {
		if msg.Type != sUserTyping && msg.Type != sLatencyReport {
			b.Log.Debugf("== Receiving event %#v", msg.Data)
		}
		switch ev := msg.Data.(type) {
		case *slack.MessageEvent:
			if b.skipMessageEvent(ev) {
				b.Log.Debugf("Skipped message: %#v", ev)
				continue
			}
			rmsg, err := b.handleMessageEvent(ev)
			if err != nil {
				b.Log.Errorf("%#v", err)
				continue
			}
			messages <- rmsg
		case *slack.OutgoingErrorEvent:
			b.Log.Debugf("%#v", ev.Error())
		case *slack.ChannelJoinedEvent:
			b.populateUsers()
		case *slack.ConnectedEvent:
			b.si = ev.Info
			b.populateChannels()
			b.populateUsers()
		case *slack.InvalidAuthEvent:
			b.Log.Fatalf("Invalid Token %#v", ev)
		case *slack.ConnectionErrorEvent:
			b.Log.Errorf("Connection failed %#v %#v", ev.Error(), ev.ErrorObj)
		default:
		}
	}
}

func (b *Bslack) handleMatterHook(messages chan *config.Message) {
	for {
		message := b.mh.Receive()
		b.Log.Debugf("receiving from matterhook (slack) %#v", message)
		if message.UserName == "slackbot" {
			continue
		}
		messages <- &config.Message{
			Username: message.UserName,
			Text:     message.Text,
			Channel:  message.ChannelName,
		}
	}
}

var commentRE = regexp.MustCompile(`.*?commented: (.*)`)

// handleDownloadFile handles file download
func (b *Bslack) handleDownloadFile(rmsg *config.Message, file *slack.File) error {
	// if we have a file attached, download it (in memory) and put a pointer to it in msg.Extra
	// limit to 1MB for now
	comment := ""
	results := commentRE.FindAllStringSubmatch(rmsg.Text, -1)
	if len(results) > 0 {
		comment = results[0][1]
	}
	err := helper.HandleDownloadSize(b.Log, rmsg, file.Name, int64(file.Size), b.General)
	if err != nil {
		return err
	}
	// actually download the file
	data, err := helper.DownloadFileAuth(file.URLPrivateDownload, "Bearer "+b.GetString(tokenConfig))
	if err != nil {
		return fmt.Errorf("download %s failed %#v", file.URLPrivateDownload, err)
	}
	// add the downloaded data to the message
	helper.HandleDownloadData(b.Log, rmsg, file.Name, comment, file.URLPrivateDownload, data, b.General)
	return nil
}

// handleUploadFile handles native upload of files
func (b *Bslack) handleUploadFile(msg *config.Message, channelID string) {
	for _, f := range msg.Extra["file"] {
		fi := f.(config.FileInfo)
		if msg.Text == fi.Comment {
			msg.Text = ""
		}
		/* because the result of the UploadFile is slower than the MessageEvent from slack
		we can't match on the file ID yet, so we have to match on the filename too
		*/
		b.Log.Debugf("Adding file %s to cache %s", fi.Name, time.Now().String())
		b.cache.Add("filename"+fi.Name, time.Now())
		res, err := b.sc.UploadFile(slack.FileUploadParameters{
			Reader:         bytes.NewReader(*fi.Data),
			Filename:       fi.Name,
			Channels:       []string{channelID},
			InitialComment: fi.Comment,
		})
		if res.ID != "" {
			b.Log.Debugf("Adding fileid %s to cache %s", res.ID, time.Now().String())
			b.cache.Add("file"+res.ID, time.Now())
		}
		if err != nil {
			b.Log.Errorf("uploadfile %#v", err)
		}
	}
}

// handleMessageEvent handles the message events
func (b *Bslack) handleMessageEvent(ev *slack.MessageEvent) (*config.Message, error) {
	var err error

	// update the userlist on a channel_join
	if ev.SubType == sChannelJoin {
		b.populateUsers()
	}

	// Edit message
	if !b.GetBool(editDisableConfig) && ev.SubMessage != nil && ev.SubMessage.ThreadTimestamp != ev.SubMessage.Timestamp {
		b.Log.Debugf("SubMessage %#v", ev.SubMessage)
		ev.User = ev.SubMessage.User
		ev.Text = ev.SubMessage.Text + b.GetString(editSuffixConfig)
	}

	// use our own func because rtm.GetChannelInfo doesn't work for private channels
	channelInfo, err := b.getChannelByID(ev.Channel)
	if err != nil {
		return nil, err
	}

	rmsg := config.Message{
		Text:    ev.Text,
		Channel: channelInfo.Name,
		Account: b.Account,
		ID:      "slack " + ev.Timestamp,
		Extra:   map[string][]interface{}{},
		ParentID: ev.ThreadTimestamp,
	}


	if b.useChannelID {
		rmsg.Channel = "ID:" + channelInfo.ID
	}

	// find the user id and name
	if ev.User != "" && ev.SubType != sMessageDeleted && ev.SubType != sFileComment {
		user, err := b.rtm.GetUserInfo(ev.User)
		if err != nil {
			return nil, err
		}
		rmsg.UserID = user.ID
		rmsg.Username = user.Name
		if user.Profile.DisplayName != "" {
			rmsg.Username = user.Profile.DisplayName
		}
	}

	// See if we have some text in the attachments
	if rmsg.Text == "" {
		for _, attach := range ev.Attachments {
			if attach.Text != "" {
				if attach.Title != "" {
					rmsg.Text = attach.Title + "\n"
				}
				rmsg.Text += attach.Text
			} else {
				rmsg.Text = attach.Fallback
			}
		}
	}

	// when using webhookURL we can't check if it's our webhook or not for now
	if rmsg.Username == "" && ev.BotID != "" && b.GetString(outgoingWebhookConfig) == "" {
		bot, err := b.rtm.GetBotInfo(ev.BotID)
		if err != nil {
			return nil, err
		}
		if bot.Name != "" {
			rmsg.Username = bot.Name
			if ev.Username != "" {
				rmsg.Username = ev.Username
			}
			rmsg.UserID = bot.ID
		}

		// fixes issues with matterircd users
		if bot.Name == "Slack API Tester" {
			user, err := b.rtm.GetUserInfo(ev.User)
			if err != nil {
				return nil, err
			}
			rmsg.UserID = user.ID
			rmsg.Username = user.Name
			if user.Profile.DisplayName != "" {
				rmsg.Username = user.Profile.DisplayName
			}
		}
	}

	// file comments are set by the system (because there is no username given)
	if ev.SubType == sFileComment {
		rmsg.Username = sSystemUser
	}

	// do we have a /me action
	if ev.SubType == sMeMessage {
		rmsg.Event = config.EVENT_USER_ACTION
	}

	// Handle join/leave
	if ev.SubType == sChannelLeave || ev.SubType == sChannelJoin {
		rmsg.Username = sSystemUser
		rmsg.Event = config.EVENT_JOIN_LEAVE
	}

	// edited messages have a submessage, use this timestamp
	if ev.SubMessage != nil {
		rmsg.ID = "slack " + ev.SubMessage.Timestamp
	}

	// deleted message event
	if ev.SubType == sMessageDeleted {
		rmsg.Text = config.EVENT_MSG_DELETE
		rmsg.Event = config.EVENT_MSG_DELETE
		rmsg.ID = "slack " + ev.DeletedTimestamp
	}

	// topic change event
	if ev.SubType == sChannelTopic || ev.SubType == sChannelPurpose {
		rmsg.Event = config.EVENT_TOPIC_CHANGE
	}

	// Only deleted messages can have a empty username and text
	if (rmsg.Text == "" || rmsg.Username == "") && ev.SubType != sMessageDeleted && len(ev.Files) == 0 {
		// this is probably a webhook we couldn't resolve
		if ev.BotID != "" {
			return nil, fmt.Errorf("probably an incoming webhook we couldn't resolve (maybe ourselves)")
		}
		return nil, fmt.Errorf("empty message and not a deleted message")
	}

	// save the attachments, so that we can send them to other slack (compatible) bridges
	if len(ev.Attachments) > 0 {
		rmsg.Extra[sSlackAttachment] = append(rmsg.Extra[sSlackAttachment], ev.Attachments)
	}

	// if we have a file attached, download it (in memory) and put a pointer to it in msg.Extra
	for _, f := range ev.Files {
		err := b.handleDownloadFile(&rmsg, &f)
		if err != nil {
			b.Log.Errorf("download failed: %s", err)
		}
	}

	return &rmsg, nil
}

// skipMessageEvent skips event that need to be skipped :-)
func (b *Bslack) skipMessageEvent(ev *slack.MessageEvent) bool {
	if ev.SubType == sChannelLeave || ev.SubType == sChannelJoin {
		return b.GetBool(noSendJoinConfig)
	}

	// ignore pinned items
	if ev.SubType == sPinnedItem || ev.SubType == sUnpinnedItem {
		return true
	}

	// do not send messages from ourself
	if b.GetString(outgoingWebhookConfig) == "" && b.GetString(incomingWebhookConfig) == "" && ev.Username == b.si.User.Name {
		return true
	}

	// skip messages we made ourselves
	if len(ev.Attachments) > 0 {
		if ev.Attachments[0].CallbackID == "matterbridge_"+b.uuid {
			return true
		}
	}

	if !b.GetBool(editDisableConfig) && ev.SubMessage != nil && ev.SubMessage.ThreadTimestamp != ev.SubMessage.Timestamp {
		// it seems ev.SubMessage.Edited == nil when slack unfurls
		// do not forward these messages #266
		if ev.SubMessage.Edited == nil {
			return true
		}
	}

	for _, f := range ev.Files {
		// if the file is in the cache and isn't older then a minute, skip it
		if ts, ok := b.cache.Get("file" + f.ID); ok && time.Since(ts.(time.Time)) < time.Minute {
			b.Log.Debugf("Not downloading file id %s which we uploaded", f.ID)
			return true
		} else if ts, ok := b.cache.Get("filename" + f.Name); ok && time.Since(ts.(time.Time)) < 10*time.Second {
			b.Log.Debugf("Not downloading file name %s which we uploaded", f.Name)
			return true
		}
		b.Log.Debugf("Not skipping %s %s", f.Name, time.Now().String())
	}

	return false
}