package bmsteams

import (
	"context"
	"os"
	"regexp"
	"strings"
	"time"

	"github.com/42wim/matterbridge/bridge"
	"github.com/42wim/matterbridge/bridge/config"
	"github.com/mattn/godown"
	msgraph "github.com/yaegashi/msgraph.go/beta"
	"github.com/yaegashi/msgraph.go/msauth"

	"golang.org/x/oauth2"
)

//var defaultScopes = []string{"openid", "profile", "offline_access", "User.Read", "Files.Read", "ChannelMessage.Read.All", "Chat.ReadWrite", "User.Read.All", "User.ReadWrite.All", "Group.Read.All", "Group.ReadWrite.All"}
var defaultScopes = []string{"openid", "profile", "offline_access", "Group.Read.All", "Group.ReadWrite.All"}

type Bmsteams struct {
	gc    *msgraph.GraphServiceRequestBuilder
	ctx   context.Context
	botID string
	*bridge.Config
}

func New(cfg *bridge.Config) bridge.Bridger {
	return &Bmsteams{Config: cfg}
}

func (b *Bmsteams) Connect() error {
	tokenCachePath := b.GetString("sessionFile")
	if tokenCachePath == "" {
		tokenCachePath = "msteams_session.json"
	}
	ctx := context.Background()
	m := msauth.NewManager()
	m.LoadFile(tokenCachePath) //nolint:errcheck
	ts, err := m.DeviceAuthorizationGrant(ctx, b.GetString("TenantID"), b.GetString("ClientID"), defaultScopes, nil)
	if err != nil {
		return err
	}
	err = m.SaveFile(tokenCachePath)
	if err != nil {
		b.Log.Errorf("Couldn't save sessionfile in %s: %s", tokenCachePath, err)
	}
	// make file readable only for matterbridge user
	err = os.Chmod(tokenCachePath, 0600)
	if err != nil {
		b.Log.Errorf("Couldn't change permissions for %s: %s", tokenCachePath, err)
	}
	httpClient := oauth2.NewClient(ctx, ts)
	graphClient := msgraph.NewClient(httpClient)
	b.gc = graphClient
	b.ctx = ctx

	err = b.setBotID()
	if err != nil {
		return err
	}
	b.Log.Info("Connection succeeded")
	return nil
}

func (b *Bmsteams) Disconnect() error {
	return nil
}

func (b *Bmsteams) JoinChannel(channel config.ChannelInfo) error {
	go b.poll(channel.Name)
	return nil
}

func (b *Bmsteams) Send(msg config.Message) (string, error) {
	b.Log.Debugf("=> Receiving %#v", msg)
	ct := b.gc.Teams().ID(b.GetString("TeamID")).Channels().ID(msg.Channel).Messages().Request()
	text := msg.Username + msg.Text
	content := &msgraph.ItemBody{Content: &text}
	rmsg := &msgraph.ChatMessage{Body: content}
	res, err := ct.Add(b.ctx, rmsg)
	if err != nil {
		return "", err
	}
	return *res.ID, nil
}

func (b *Bmsteams) getMessages(channel string) ([]msgraph.ChatMessage, error) {
	ct := b.gc.Teams().ID(b.GetString("TeamID")).Channels().ID(channel).Messages().Request()
	rct, err := ct.Get(b.ctx)
	if err != nil {
		return nil, err
	}
	b.Log.Debugf("got %#v messages", len(rct))
	return rct, nil
}

func (b *Bmsteams) poll(channelName string) {
	re := regexp.MustCompile(`<attachment id=.*?attachment>`)
	msgmap := make(map[string]time.Time)
	b.Log.Debug("getting initial messages")
	res, err := b.getMessages(channelName)
	if err != nil {
		panic(err)
	}
	for _, msg := range res {
		msgmap[*msg.ID] = *msg.CreatedDateTime
		if msg.LastModifiedDateTime != nil {
			msgmap[*msg.ID] = *msg.LastModifiedDateTime
		}
	}
	time.Sleep(time.Second * 5)
	b.Log.Debug("polling for messages")
	for {
		res, err := b.getMessages(channelName)
		if err != nil {
			panic(err)
		}
		for i := len(res) - 1; i >= 0; i-- {
			msg := res[i]
			if mtime, ok := msgmap[*msg.ID]; ok {
				if mtime == *msg.CreatedDateTime && msg.LastModifiedDateTime == nil {
					continue
				}
				if msg.LastModifiedDateTime != nil && mtime == *msg.LastModifiedDateTime {
					continue
				}
			}
			if *msg.From.User.ID == b.botID {
				b.Log.Debug("skipping own message")
				msgmap[*msg.ID] = *msg.CreatedDateTime
				continue
			}
			msgmap[*msg.ID] = *msg.CreatedDateTime
			if msg.LastModifiedDateTime != nil {
				msgmap[*msg.ID] = *msg.LastModifiedDateTime
			}
			b.Log.Debugf("<= Sending message from %s on %s to gateway", *msg.From.User.DisplayName, b.Account)
			text := b.convertToMD(*msg.Body.Content)
			rmsg := config.Message{
				Username: *msg.From.User.DisplayName,
				Text:     text,
				Channel:  channelName,
				Account:  b.Account,
				Avatar:   "",
				UserID:   *msg.From.User.ID,
				ID:       *msg.ID,
				Extra:    make(map[string][]interface{}),
			}

			if len(msg.Attachments) > 0 {
				for _, a := range msg.Attachments {
					//remove the attachment tags from the text
					rmsg.Text = re.ReplaceAllString(rmsg.Text, "")
					//handle the download
					err := b.handleDownloadFile(&rmsg, *a.Name, *a.ContentURL)
					if err != nil {
						b.Log.Errorf("download of %s failed: %s", *a.Name, err)
					}
				}
			}
			b.Log.Debugf("<= Message is %#v", rmsg)
			b.Remote <- rmsg
		}
		time.Sleep(time.Second * 5)
	}
}

func (b *Bmsteams) setBotID() error {
	req := b.gc.Me().Request()
	r, err := req.Get(b.ctx)
	if err != nil {
		return err
	}
	b.botID = *r.ID
	return nil
}

func (b *Bmsteams) convertToMD(text string) string {
	if !strings.Contains(text, "<div>") {
		return text
	}
	var sb strings.Builder
	err := godown.Convert(&sb, strings.NewReader(text), nil)
	if err != nil {
		b.Log.Errorf("Couldn't convert message to markdown %s", text)
		return text
	}
	return sb.String()
}