package discord

import (
	"bytes"
	"crypto/sha256"
	"encoding/base64"
	"errors"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"os"

	"git.lalonde.me/matth/AltVRBot/pkg/discord/mux"
	"github.com/bwmarrin/discordgo"
)

// Discord bot
type Discord struct {
	token      string
	sID        string
	cID        string
	avatarHash []byte
	Emojis     []*discordgo.Emoji
	Session    *discordgo.Session
	Router     *mux.Mux
	User       *discordgo.User
}

// New instanciates a new discord bot
func New(token, sID, cID string) (*Discord, error) {
	dg := &Discord{
		Router: mux.New(),
		token:  token,
		sID:    sID,
		cID:    cID,
	}

	// Create a new Discord session using the provided bot token.
	session, err := discordgo.New("Bot " + token)
	if err != nil {
		return dg, fmt.Errorf("Failed to create Discord session: %s", err)
	}

	// Verify a Token was provided
	if session.Token == "" {
		return dg, errors.New("You must provide a Discord authentication token")
	}

	dg.Session = session

	dg.addHandlers()

	// Open a websocket connection to Discord
	err = dg.Session.Open()
	if err != nil {
		log.Printf("error opening connection to Discord, %s\n", err)
		os.Exit(1)
	}

	dg.User, _ = dg.Session.User("@me")
	dg.Emojis, _ = dg.Session.GuildEmojis(sID)

	return dg, nil
}

// Close terminates the discord session
func (dg *Discord) Close() {
	dg.Session.Close()
}

// UpdateAvatar Updates the bot user avatar if it has changed
func (dg *Discord) UpdateAvatar(url string) error {
	if url == "" {
		return nil
	}

	resp, err := http.Get(url)
	if err != nil {
		return fmt.Errorf("Error retrieving the file, %s", err)
	}
	defer resp.Body.Close()

	img, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return fmt.Errorf("Error reading the response, %s", err)
	}

	h := sha256.Sum256(img)

	if bytes.Compare(h[:], dg.avatarHash) != 0 {
		base64img := base64.StdEncoding.EncodeToString(img)
		contentType := http.DetectContentType(img)
		if base64img != "" {
			avatar := fmt.Sprintf("data:%s;base64,%s", contentType, base64img)
			_, err = dg.Session.UserUpdate("", "", "", avatar, "")
			if err != nil {
				return err
			}
		}
	}
	return nil
}

func (dg *Discord) addHandlers() {
	dg.Session.AddHandler(dg.Router.OnMessageCreate)

	dg.Router.Route("help", "Display this message.", dg.Router.Help)
}