LevyraatiBot/spotify/spotify.go

package spotify

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"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
}

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"`
}

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) 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) 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
	}
	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

}