Deezer authentication and loves export

backends/deezer/auth.go

@@ -0,0 +1,83 @@
+/*
+Copyright © 2023 Philipp Wolfer <phw@uploadedlobster.com>
+
+Scotty is free software: you can redistribute it and/or modify it under the
+terms of the GNU General Public License as published by the Free Software
+Foundation, either version 3 of the License, or (at your option) any later version.
+
+Scotty is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+Scotty. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+package deezer
+
+import (
+	"encoding/json"
+	"io"
+	"net/http"
+	"time"
+
+	"go.uploadedlobster.com/scotty/internal/auth"
+	"golang.org/x/oauth2"
+)
+
+type deezerStrategy struct {
+	conf oauth2.Config
+}
+
+func (s deezerStrategy) Config() oauth2.Config {
+	return s.conf
+}
+
+func (s deezerStrategy) AuthCodeURL(verifier string, state string) string {
+	return s.conf.AuthCodeURL(state, oauth2.AccessTypeOffline, oauth2.S256ChallengeOption(verifier))
+}
+
+func (s deezerStrategy) ExchangeToken(code auth.CodeResponse, verifier string) (*oauth2.Token, error) {
+	// Deezer has a non-standard token exchange, expecting all parameters in the URL's query
+	req, err := http.NewRequest(http.MethodGet, s.conf.Endpoint.TokenURL, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	q := req.URL.Query()
+	q.Add("app_id", s.conf.ClientID)
+	q.Add("secret", s.conf.ClientSecret)
+	q.Add("code", code.Code)
+	q.Add("output", "json")
+	req.URL.RawQuery = q.Encode()
+
+	res, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	reqBody, err := io.ReadAll(res.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	token := deezerToken{}
+	if err = json.Unmarshal(reqBody, &token); err != nil {
+		return nil, err
+	}
+
+	return token.Token(), nil
+}
+
+type deezerToken struct {
+	AccessToken string `json:"access_token"`
+	ExpiresIn   int64  `json:"expires"`
+}
+
+func (t deezerToken) Token() *oauth2.Token {
+	token := &oauth2.Token{AccessToken: t.AccessToken}
+	if t.ExpiresIn > 0 {
+		token.Expiry = time.Now().Add(time.Duration(t.ExpiresIn * time.Second.Nanoseconds()))
+	}
+	return token
+}