first commit

internal/auth/auth.go

@@ -0,0 +1,94 @@
+package auth
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"os"
+
+	"git.directme.in/Joren/CanvasArchiver/internal/config"
+	"git.directme.in/Joren/CanvasArchiver/internal/models"
+)
+
+type Authenticator struct {
+	HTTPClient *http.Client
+}
+
+func NewAuthenticator(client *http.Client) *Authenticator {
+	return &Authenticator{
+		HTTPClient: client,
+	}
+}
+
+func (a *Authenticator) GetAccessToken() (string, error) {
+	creds, err := LoadCredentials()
+	if err != nil {
+
+		fmt.Println("--- Initial Canvas Login Required ---")
+		fmt.Printf("Visit: %s/login/oauth2/auth?client_id=%s&response_type=code&redirect_uri=%s\n",
+			config.BaseURL, config.ClientID, url.QueryEscape(config.RedirectURI))
+		fmt.Print("Enter Code: ")
+		var code string
+		fmt.Scanln(&code)
+
+		tr, err := a.doTokenRequest(url.Values{
+			"grant_type":    {"authorization_code"},
+			"client_id":     {config.ClientID},
+			"client_secret": {config.ClientSecret},
+			"redirect_uri":  {config.RedirectURI},
+			"code":          {code},
+		})
+		if err != nil {
+			return "", err
+		}
+
+		SaveCredentials(&models.Credentials{RefreshToken: tr.RefreshToken})
+		fmt.Println("[+] Login successful.")
+		return tr.AccessToken, nil
+	}
+
+	fmt.Println("[*] Reusing saved refresh token...")
+	tr, err := a.doTokenRequest(url.Values{
+		"grant_type":    {"refresh_token"},
+		"client_id":     {config.ClientID},
+		"client_secret": {config.ClientSecret},
+		"refresh_token": {creds.RefreshToken},
+	})
+	if err != nil {
+		return "", err
+	}
+	fmt.Println("[+] Session refreshed.")
+	return tr.AccessToken, nil
+}
+
+func (a *Authenticator) doTokenRequest(v url.Values) (*models.TokenResponse, error) {
+	resp, err := a.HTTPClient.PostForm(config.BaseURL+"/login/oauth2/token", v)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != 200 {
+		return nil, fmt.Errorf("token request failed: %d", resp.StatusCode)
+	}
+
+	var tr models.TokenResponse
+	json.NewDecoder(resp.Body).Decode(&tr)
+	return &tr, nil
+}
+
+func SaveCredentials(creds *models.Credentials) {
+	data, _ := json.MarshalIndent(creds, "", "  ")
+	os.WriteFile(config.CredsFile, data, 0o644)
+}
+
+func LoadCredentials() (*models.Credentials, error) {
+	data, err := os.ReadFile(config.CredsFile)
+	if err != nil {
+		return nil, err
+	}
+	var creds models.Credentials
+	json.Unmarshal(data, &creds)
+	return &creds, nil
+}