feat: Add support for iFlow provider

internal/auth/iflow/iflow_token.go

@@ -0,0 +1,43 @@
+package iflow
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/misc"
+)
+
+// IFlowTokenStorage persists iFlow OAuth credentials alongside the derived API key.
+type IFlowTokenStorage struct {
+	AccessToken  string `json:"access_token"`
+	RefreshToken string `json:"refresh_token"`
+	LastRefresh  string `json:"last_refresh"`
+	Expire       string `json:"expired"`
+	APIKey       string `json:"api_key"`
+	Email        string `json:"email"`
+	TokenType    string `json:"token_type"`
+	Scope        string `json:"scope"`
+	Type         string `json:"type"`
+}
+
+// SaveTokenToFile serialises the token storage to disk.
+func (ts *IFlowTokenStorage) SaveTokenToFile(authFilePath string) error {
+	misc.LogSavingCredentials(authFilePath)
+	ts.Type = "iflow"
+	if err := os.MkdirAll(filepath.Dir(authFilePath), 0o700); err != nil {
+		return fmt.Errorf("iflow token: create directory failed: %w", err)
+	}
+
+	f, err := os.Create(authFilePath)
+	if err != nil {
+		return fmt.Errorf("iflow token: create file failed: %w", err)
+	}
+	defer func() { _ = f.Close() }()
+
+	if err = json.NewEncoder(f).Encode(ts); err != nil {
+		return fmt.Errorf("iflow token: encode token failed: %w", err)
+	}
+	return nil
+}