Add Last.FM Authentication methods

core/agents/lastfm/client.go

@@ -2,12 +2,17 @@ package lastfm
 
 import (
 	"context"
+	"crypto/md5"
+	"encoding/hex"
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"net/http"
 	"net/url"
+	"sort"
 	"strconv"
+	"strings"
+
+	"github.com/navidrome/navidrome/utils"
 )
 
 const (
@@ -27,52 +32,17 @@ type httpDoer interface {
 	Do(req *http.Request) (*http.Response, error)
 }
 
-func NewClient(apiKey string, lang string, hc httpDoer) *Client {
-	return &Client{apiKey, lang, hc}
+func NewClient(apiKey string, secret string, lang string, hc httpDoer) *Client {
+	return &Client{apiKey, secret, lang, hc}
 }
 
 type Client struct {
 	apiKey string
+	secret string
 	lang   string
 	hc     httpDoer
 }
 
-func (c *Client) makeRequest(params url.Values) (*Response, error) {
-	params.Add("format", "json")
-	params.Add("api_key", c.apiKey)
-
-	req, _ := http.NewRequest("GET", apiBaseUrl, nil)
-	req.URL.RawQuery = params.Encode()
-
-	resp, err := c.hc.Do(req)
-	if err != nil {
-		return nil, err
-	}
-
-	defer resp.Body.Close()
-	data, err := ioutil.ReadAll(resp.Body)
-	if err != nil {
-		return nil, err
-	}
-
-	var response Response
-	jsonErr := json.Unmarshal(data, &response)
-
-	if resp.StatusCode != 200 && jsonErr != nil {
-		return nil, fmt.Errorf("last.fm http status: (%d)", resp.StatusCode)
-	}
-
-	if jsonErr != nil {
-		return nil, jsonErr
-	}
-
-	if response.Error != 0 {
-		return &response, &lastFMError{Code: response.Error, Message: response.Message}
-	}
-
-	return &response, nil
-}
-
 func (c *Client) ArtistGetInfo(ctx context.Context, name string, mbid string) (*Artist, error) {
 	params := url.Values{}
 	params.Add("method", "artist.getInfo")
@@ -111,3 +81,76 @@ func (c *Client) ArtistGetTopTracks(ctx context.Context, name string, mbid strin
 	}
 	return &response.TopTracks, nil
 }
+
+func (c *Client) GetToken(ctx context.Context) (string, error) {
+	params := url.Values{}
+	params.Add("method", "auth.getToken")
+	c.sign(params)
+	response, err := c.makeRequest(params)
+	if err != nil {
+		return "", err
+	}
+	return response.Token, nil
+}
+
+func (c *Client) GetSession(ctx context.Context, token string) (string, error) {
+	params := url.Values{}
+	params.Add("method", "auth.getSession")
+	params.Add("token", token)
+	c.sign(params)
+	response, err := c.makeRequest(params)
+	if err != nil {
+		return "", err
+	}
+	return response.Session.Key, nil
+}
+
+func (c *Client) makeRequest(params url.Values) (*Response, error) {
+	params.Add("format", "json")
+	params.Add("api_key", c.apiKey)
+
+	req, _ := http.NewRequest("GET", apiBaseUrl, nil)
+	req.URL.RawQuery = params.Encode()
+
+	resp, err := c.hc.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	defer resp.Body.Close()
+	decoder := json.NewDecoder(resp.Body)
+
+	var response Response
+	jsonErr := decoder.Decode(&response)
+	if resp.StatusCode != 200 && jsonErr != nil {
+		return nil, fmt.Errorf("last.fm http status: (%d)", resp.StatusCode)
+	}
+	if jsonErr != nil {
+		return nil, jsonErr
+	}
+	if response.Error != 0 {
+		return &response, &lastFMError{Code: response.Error, Message: response.Message}
+	}
+
+	return &response, nil
+}
+
+func (c *Client) sign(params url.Values) {
+	// the parameters must be in order before hashing
+	keys := make([]string, 0, len(params))
+	for k := range params {
+		if utils.StringInSlice(k, []string{"format", "callback"}) {
+			continue
+		}
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+	msg := strings.Builder{}
+	for _, k := range keys {
+		msg.WriteString(k)
+		msg.WriteString(params[k][0])
+	}
+	msg.WriteString(c.secret)
+	hash := md5.Sum([]byte(msg.String()))
+	params.Add("api_sig", hex.EncodeToString(hash[:]))
+}