gavalink/node.go

package gavalink

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"strconv"

	"github.com/gorilla/websocket"
)

// NodeConfig configures a Lavalink Node
type NodeConfig struct {
	// REST is the host where Lavalink's REST server runs
	//
	// This value is expected without a trailing slash, e.g. like
	// `http://localhost:2333`
	REST string
	// WebSocket is the host where Lavalink's WebSocket server runs
	//
	// This value is expected without a trailing slash, e.g. like
	// `http://localhost:8012`
	WebSocket string
	// Password is the expected Authorization header for the Node
	Password string
}

// Node wraps a Lavalink Node
type Node struct {
	config  NodeConfig
	shards  int
	userID  int
	manager *Lavalink
	wsConn  *websocket.Conn
}

func (node *Node) open() error {
	header := http.Header{}
	header.Set("Authorization", node.config.Password)

	ws, resp, err := websocket.DefaultDialer.Dial(node.config.WebSocket, header)
	if err != nil {
		return err
	}
	vstr := resp.Header.Get("Lavalink-Major-Version")
	v, err := strconv.Atoi(vstr)
	if err != nil {
		return err
	}
	if v < 3 {
		return errInvalidVersion
	}

	node.wsConn = ws
	go node.listen()

	log.Println("node", node.config.WebSocket, "opened")

	return nil
}

func (node *Node) stop() {
	// someone already stopped this
	if node.wsConn == nil {
		return
	}
	_ = node.wsConn.Close()
}

func (node *Node) listen() {
	for {
		msgType, msg, err := node.wsConn.ReadMessage()
		if err != nil {
			// try to reconnect
			oerr := node.open()
			if oerr != nil {
				log.Println("node", node.config.WebSocket, "failed and could not reconnect, destroying.", err, oerr)
				node.manager.RemoveNode(node)
				return
			}
			log.Println("node", node.config.WebSocket, "reconnected")
			return
		}
		err = node.onEvent(msgType, msg)
		// TODO: better error handling
		log.Println(err)
	}
}

func (node *Node) onEvent(msgType int, msg []byte) error {
	if msgType != websocket.TextMessage {
		return errUnknownPayload
	}
	return nil
}

// LoadTracks queries lavalink to return a Tracks object
//
// query should be a valid Lavaplayer query, including but not limited to:
// - A direct media URI
// - A direct Youtube /watch URI
// - A search query, prefixed with ytsearch: or scsearch:
//
// See the Lavaplayer Source Code for all valid options.
func (node *Node) LoadTracks(query string) (*Tracks, error) {
	url := fmt.Sprintf("%s/loadtracks?identifier=%s", node.config.REST, query)
	req, err := http.NewRequest(http.MethodGet, url, nil)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Authorization", node.config.Password)

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return nil, err
	}
	data, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}
	tracks := new(Tracks)
	err = json.Unmarshal(data, &tracks)
	if err != nil {
		return nil, err
	}
	return tracks, nil
}