LevyraatiBot/spotify/spotify.go

package spotify

import (
	"context"
	"crypto/tls"
	"encoding/json"
	"errors"
	"fmt"
	"golang.org/x/oauth2"
	"golang.org/x/oauth2/clientcredentials"
	spotifyAuth "golang.org/x/oauth2/spotify"
	"io"
	"net/http"
	"net/url"
	"strings"
)

type SpotifyClient struct {
	clientID     string
	clientSecret string
	bearerAuth   string
	baseURL      *url.URL
	httpClient   *http.Client
	config       *oauth2.Config
	context      context.Context
}

type TrackInfo struct {
	Album        AlbumInfo    `json:"album"`
	Artists      []ArtistInfo `json:"artists"`
	DiskNumber   int          `json:"disc_number"`
	DurationMS   int          `json:"duration_ms"`
	Explicit     bool         `json:"explicit"`
	ExternalIds  ExternalIds  `json:"external_ids"`
	ExternalUrls ExternalUrls `json:"external_urls"`
	Href         string       `json:"href"`
	ID           string       `json:"id"`
	IsPlayable   bool         `json:"is_playable"`
	Name         string       `json:"name"`
	Popularity   int          `json:"popularity"`
	PreviewUrl   string       `json:"preview_url"`
	TrackNumber  int          `json:"track_number"`
	Type         string       `json:"type"`
	Uri          string       `json:"uri"`
}

type AlbumInfo struct {
	AlbumType    string       `json:"album_type"`
	Artists      []ArtistInfo `json:"artists"`
	ExternalUrls ExternalUrls `json:"external_urls"`
	Href         string       `json:"href"`
	ID           string       `json:"id"`
	Images       []ImageInfo  `json:"images"`
	Name         string       `json:"name"`
	Type         string       `json:"type"`
	Uri          string       `json:"uri"`
}

type ArtistInfo struct {
	ExternalUrls ExternalUrls `json:"external_urls"`
	Href         string       `json:"href"`
	ID           string       `json:"id"`
	Name         string       `json:"name"`
	Type         string       `json:"type"`
	Uri          string       `json:"uri"`
}

type ImageInfo struct {
	Height int    `json:"height"`
	URL    string `json:url`
	Width  int    `json:"width"`
}

type ExternalIds struct {
	ISRC string `json:"isrc"`
}
type ExternalUrls struct {
	Spotify string `json:"spotify"`
}

type TokenInfo struct {
	AccessToken string `json:"access_token"`
	TokenType   string `json:"token_type"`
	ExpiresIn   int    `json:"expires_in"`
}

type AuthErrorResponse struct {
	Error            string `json:"error"`
	ErrorDescription string `json:"error_description"`
}

type ErrorResponse struct {
	Error ErrorInfo `json:"error"`
}

type ErrorInfo struct {
	Status  int    `json:"status"`
	Message string `json:"message"`
}

type PlaylistInfo struct {
	Collaborative bool         `json:"collaborative"`
	Description   string       `json:"description"`
	ExternalUrls  ExternalUrls `json:"external_urls"`
	Followers     Followers    `json:"followers"`
	Href          string       `json:"href"`
	Id            string       `json:"id"`
	// TODO images
	Name string `json:"name"`
	// TODO owner
	Public     bool       `json:"public"`
	SnapshotId string     `json:"snapshot_id"`
	Tracks     TracksInfo `json:"tracks"`
	Type       string     `json:"type"`
	Uri        string     `json:"uri"`
}

type TracksInfo struct {
	Href     string          `json:"href"`
	Items    []PlaylistTrack `json:"items"`
	Limit    int             `json:"limit"`
	Next     string          `json:"next"`
	Offset   int             `json:"offset"`
	Type     string          `json:"type"`
	Previous string          `json:"string"`
	Total    int             `json:"total"`
}

type PlaylistTrack struct {
	AddedAt string    `json:"added_at"`
	AddedBy string    `json:"added_by"`
	IsLocal bool      `json:"is_local"`
	Track   TrackInfo `json":track"`
}

type Followers struct {
	Href  string `json:"href"`
	Total int    `json:"total"`
}

func NewClient(username, secret string) *SpotifyClient {
	baseURL, _ := url.Parse("https://api.spotify.com")
	httpClient := &http.Client{}
	return &SpotifyClient{
		clientID:     username,
		clientSecret: secret,
		baseURL:      baseURL,
		httpClient:   httpClient,
	}
}

func (s *SpotifyClient) Authenticate() error {
	config := &clientcredentials.Config{
		ClientID:     s.clientID,
		ClientSecret: s.clientSecret,
		TokenURL:     spotifyAuth.Endpoint.TokenURL,
	}
	token, err := config.Token(context.Background())
	if err != nil {
		fmt.Println(err)
		return err
	}
	s.bearerAuth = token.AccessToken
	return nil
}

func (s *SpotifyClient) SetupUserAuthenticate() error {
	s.config = &oauth2.Config{
		ClientID:     s.clientID,
		ClientSecret: s.clientSecret,
		RedirectURL:  "http://localhost:8080/callback",
		Scopes:       []string{"playlist-modify-public"},
		Endpoint:     spotifyAuth.Endpoint,
	}
	tr := &http.Transport{
		TLSNextProto: map[string]func(authority string, c *tls.Conn) http.RoundTripper{},
	}
	s.context = context.WithValue(context.Background(), oauth2.HTTPClient, &http.Client{Transport: tr})
	return nil
}

func (s *SpotifyClient) GetTrack(trackId string) (*TrackInfo, error) {
	var trackInfo TrackInfo
	url := s.urlFromBase(fmt.Sprintf("/v1/tracks/%s", trackId))
	err := s.doRequest("GET", url, &trackInfo, nil)
	if err != nil {
		return nil, err
	} else {
		return &trackInfo, nil
	}
}

func (s *SpotifyClient) NewPlaylist(name, userId string) (*PlaylistInfo, error) {
	var playlistInfo PlaylistInfo
	values := &url.Values{}
	values.Add("name", name)
	url := s.urlFromBase(fmt.Sprintf("/v1/users/%s/playlists", userId))
	err := s.doRequest("POST", url, &playlistInfo, values)
	if err != nil {
		return nil, err
	} else {
		return &playlistInfo, nil
	}
}

func (s *SpotifyClient) UpdatePlaylist(userId, playlistId string, tracks []string) error {
	values := &url.Values{}
	uris := make([]string, 0)
	for _, track := range tracks {
		uris = append(uris, "spotify:track:"+track)
	}
	values.Add("uris", strings.Join(uris, ","))

	url := s.urlFromBase(fmt.Sprintf("/v1/users/%s/playlists/%s", userId, playlistId))
	err := s.doRequest("PUT", url, nil, values)
	return err
}

func (s *SpotifyClient) urlFromBase(path string) *url.URL {
	endpoint := &url.URL{Path: path}
	return s.baseURL.ResolveReference(endpoint)
}

func (s *SpotifyClient) doRequest(method string, url *url.URL, object interface{}, values *url.Values) error {
	var bodyReader io.Reader
	if values != nil {
		s := values.Encode()
		bodyReader = strings.NewReader(s)
	}

	req, err := http.NewRequest(method, url.String(), bodyReader)
	if err != nil {
		return err
	}

	if s.bearerAuth != "" {
		req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", s.bearerAuth))
	}

	if values != nil {
		req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	}

	req.Header.Set("Accept", "application/json")
	req.Header.Set("User-Agent", "github.com/lamperi/e4bot/spotify")

	resp, err := s.httpClient.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != 200 {
		var errorResp ErrorResponse
		err = json.NewDecoder(resp.Body).Decode(&errorResp)
		return errors.New(fmt.Sprintf("Spotify API returned: %d: %s", resp.StatusCode, errorResp.Error.Message))
	}

	err = json.NewDecoder(resp.Body).Decode(object)
	if err != nil {
		return err
	}
	return nil

}

func (s *SpotifyClient) GetAuthUrl(state string) string {
	return s.config.AuthCodeURL(state)
}

func (s *SpotifyClient) HandleToken(state string, r *http.Request) error {
	values := r.URL.Query()
	if e := values.Get("error"); e != "" {
		return errors.New("spotify: auth failed - " + e)
	}
	code := values.Get("code")
	if code == "" {
		return errors.New("spotify: didn't get access code")
	}
	actualState := values.Get("state")
	if actualState != state {
		return errors.New("spotify: redirect state parameter doesn't match")
	}
	token, err := s.config.Exchange(s.context, code)
	if err != nil {
		return err
	}

	fmt.Println("Got token from Spotify", token)

	client := s.config.Client(s.context, token)
	s.httpClient = client
	return nil
}

func (s *SpotifyClient) HasUserLogin() bool {
	return s.httpClient != nil && s.config != nil && s.context != nil
}