refactor: use a better API to download playlists with more than 40 tracks

internal/deezer/session.go

@@ -0,0 +1,82 @@
+package deezer
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/cookiejar"
+)
+
+type UserDataResponse struct {
+	Results struct {
+		APIToken string `json:"checkForm"`
+		User     struct {
+			Id      int `json:"USER_ID"`
+			Options struct {
+				LicenseToken  string `json:"license_token"`
+				MobileOffline bool   `json:"mobile_offline"`
+				WebOffline    bool   `json:"web_offline"`
+			} `json:"OPTIONS"`
+		} `json:"USER"`
+	} `json:"results"`
+}
+
+type Session struct {
+	ArlCookie    string
+	APIToken     string
+	LicenseToken string
+	Client       *http.Client
+}
+
+func Authenticate(arlCookie string) (*Session, error) {
+	jar, err := cookiejar.New(nil)
+	if err != nil {
+		return nil, err
+	}
+	client := &http.Client{
+		Jar: jar,
+	}
+
+	url := "https://www.deezer.com/ajax/gw-light.php?method=deezer.getUserData&input=3&api_version=1.0&api_token="
+	req, err := http.NewRequest("GET", url, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	req.AddCookie(&http.Cookie{
+		Name:  "arl",
+		Value: arlCookie,
+	})
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	body, _ := io.ReadAll(resp.Body)
+
+	var res UserDataResponse
+	if err := json.Unmarshal(body, &res); err != nil {
+		return nil, err
+	}
+
+	if res.Results.User.Id == 0 {
+		return nil, fmt.Errorf("invalid arl cookie")
+	}
+	if !res.Results.User.Options.MobileOffline && !res.Results.User.Options.WebOffline {
+		return nil, fmt.Errorf("premium account required")
+	}
+
+	return &Session{
+		ArlCookie:    arlCookie,
+		APIToken:     res.Results.APIToken,
+		LicenseToken: res.Results.User.Options.LicenseToken,
+		Client:       client,
+	}, nil
+}