1 files changed, 111 insertions, 0 deletions
diff --git a/lib/auth.go b/lib/auth.go
new file mode 100644
index 0000000..b5bc06a
--- /dev/null
+++ b/lib/auth.go
@@ -0,0 +1,111 @@
+package lib
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"os/exec"
+	"runtime"
+	"strings"
+	"yato/config"
+)
+
+func GetNewCodeVerifier() (string, error) {
+	bytes := make([]byte, 100)
+	_, err := rand.Read(bytes)
+	if err != nil {
+		return "", fmt.Errorf("failed to generate code verifier: %w", err)
+	}
+
+	encoded := base64.RawURLEncoding.EncodeToString(bytes)
+
+	// Truncate to 128 characters
+	if len(encoded) > 128 {
+		encoded = encoded[:128]
+	}
+
+	return encoded, nil
+}
+
+func GetOAuthURL(codeVerifier string) string {
+	return fmt.Sprintf("%s?response_type=code&client_id=%s&redirect_uri=%s&code_challenge=%s&code_challenge_method=plain",
+		config.MALOAuthBaseURL, config.MALClientID, config.MALRedirectURI, codeVerifier)
+}
+
+func OpenBrowser(url string) error {
+	var err error
+
+	switch runtime.GOOS {
+	case "linux":
+		err = exec.Command("xdg-open", url).Start()
+	case "windows":
+		err = exec.Command("rundll32", "url.dll,FileProtocolHandler", url).Start()
+	case "darwin":
+		err = exec.Command("open", url).Start()
+	default:
+		err = fmt.Errorf("unsupported platform")
+	}
+
+	return err
+}
+
+func ExchangeToken(code, codeVerifier string) (*config.MyAnimeListConfig, error) {
+	data := url.Values{}
+	data.Set("grant_type", "authorization_code")
+	data.Set("client_id", config.MALClientID)
+	data.Set("client_secret", config.MALClientSecret)
+	data.Set("redirect_uri", config.MALRedirectURI)
+	data.Set("code", code)
+
+	if codeVerifier != "" {
+		data.Set("code_verifier", codeVerifier)
+	}
+
+	// POST request to MAL API
+	req, err := http.NewRequest("POST", "https://myanimelist.net/v1/oauth2/token", strings.NewReader(data.Encode()))
+	if err != nil {
+		return nil, fmt.Errorf("failed to create request: %w", err)
+	}
+
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+
+	client := &http.Client{}
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("failed to send request: %w", err)
+	}
+
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read response body: %w", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	var malConfig config.MyAnimeListConfig
+	var tokenResponse struct {
+		TokenType    string `json:"token_type"`
+		ExpiresIn    int    `json:"expires_in"`
+		AccessToken  string `json:"access_token"`
+		RefreshToken string `json:"refresh_token"`
+	}
+
+	if err := json.Unmarshal(body, &tokenResponse); err != nil {
+		return nil, fmt.Errorf("failed to unmarshal response: %w", err)
+	}
+
+	malConfig.TokenType = tokenResponse.TokenType
+	malConfig.ExpiresIn = tokenResponse.ExpiresIn
+	malConfig.AccessToken = tokenResponse.AccessToken
+	malConfig.RefreshToken = tokenResponse.RefreshToken
+
+	return &malConfig, nil
+}