Add config map

ref #1

config.go

@@ -0,0 +1,118 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+)
+
+type Config struct {
+	Services []Service `json:"service"`
+}
+
+type Service struct {
+	URL string `json:"url"`
+	Env Env    `json:"env"`
+}
+
+type Env struct {
+	Credentials string `json:"GOOGLE_APPLICATION_CREDENTIALS"`
+	ClientID    string `json:"IAP_CLIENT_ID"`
+	Binary      string `json:"IAP_CURL_BIN"`
+}
+
+func configDir() (string, error) {
+	var dir string
+
+	switch runtime.GOOS {
+	default:
+		dir = filepath.Join(os.Getenv("HOME"), ".config")
+	case "windows":
+		dir = os.Getenv("APPDATA")
+		if dir == "" {
+			dir = filepath.Join(os.Getenv("USERPROFILE"), "Application Data")
+		}
+	}
+	dir = filepath.Join(dir, "iap_curl")
+
+	err := os.MkdirAll(dir, 0700)
+	if err != nil {
+		return dir, fmt.Errorf("cannot create directory: %v", err)
+	}
+
+	return dir, nil
+}
+
+func (cfg *Config) LoadFile(file string) error {
+	_, err := os.Stat(file)
+	if err == nil {
+		raw, _ := ioutil.ReadFile(file)
+		if err := json.Unmarshal(raw, cfg); err != nil {
+			return err
+		}
+		return nil
+	}
+
+	if !os.IsNotExist(err) {
+		return err
+	}
+	f, err := os.Create(file)
+	if err != nil {
+		return err
+	}
+
+	// Insert sample config map as a default
+	if len(cfg.Services) == 0 {
+		cfg.Services = []Service{Service{
+			URL: "https://iap-protected-app-url",
+			Env: Env{
+				Credentials: "/path/to/google-credentials.json",
+				ClientID:    "foobar.apps.googleusercontent.com",
+				Binary:      "curl",
+			},
+		}}
+	}
+
+	return json.NewEncoder(f).Encode(cfg)
+}
+
+func (cfg *Config) GetEnv(url string) (env Env) {
+	for _, service := range cfg.Services {
+		if strings.Contains(service.URL, url) {
+			return service.Env
+		}
+	}
+	return env
+}
+
+func (cfg *Config) GetURLs() (list []string) {
+	for _, service := range cfg.Services {
+		list = append(list, service.URL)
+	}
+	return
+}
+
+func (cfg *Config) Edit() error {
+	dir, _ := configDir()
+	json := filepath.Join(dir, "config.json")
+	editor := os.Getenv("EDITOR")
+	if editor == "" {
+		editor = "vim"
+	}
+	command := fmt.Sprintf("%s %s", editor, json)
+	var cmd *exec.Cmd
+	if runtime.GOOS == "windows" {
+		cmd = exec.Command("cmd", "/c", command)
+	} else {
+		cmd = exec.Command("sh", "-c", command)
+	}
+	cmd.Stderr = os.Stderr
+	cmd.Stdout = os.Stdout
+	cmd.Stdin = os.Stdin
+	return cmd.Run()
+}

main.go

@@ -3,6 +3,8 @@ package main
 import (
 	"fmt"
 	"os"
+	"path/filepath"
+	"strings"
 )
 
 const (
@@ -13,42 +15,81 @@ const (
 	IAPCurlBinary                = "IAP_CURL_BIN"
 )
 
-var helpText string = `Usage: curl
+const helpText string = `Usage: curl
+
+Extended options:
+  --list-urls    List service URLs
+  --edit-config  Edit config file
 `
 
+var (
+	credentials string
+	clientID    string
+	binary      string
+
+	cfg Config
+)
+
 func main() {
+	dir, _ := configDir()
+	json := filepath.Join(dir, "config.json")
+
+	err := cfg.LoadFile(json)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+		os.Exit(1)
+	}
+
+	credentials = os.Getenv(GoogleApplicationCredentials)
+	clientID = os.Getenv(IAPClientID)
+	binary = os.Getenv(IAPCurlBinary)
+
 	os.Exit(run(os.Args[1:]))
 }
 
 func run(args []string) int {
-	var (
-		creds    = os.Getenv(GoogleApplicationCredentials)
-		clientID = os.Getenv(IAPClientID)
-		binary   = os.Getenv(IAPCurlBinary)
-	)
-
 	if len(args) > 0 {
-		if args[0] == "-h" || args[0] == "--help" {
+		switch args[0] {
+		case "-h", "--help":
 			fmt.Fprint(os.Stderr, helpText)
 			return 1
+		case "--list-urls":
+			fmt.Println(strings.Join(cfg.GetURLs(), "\n"))
+			return 0
+		case "--edit-config":
+			err := cfg.Edit()
+			if err == nil {
+				return 0
+			}
+			fmt.Fprintf(os.Stderr, "Error: %s\n", err.Error())
+			return 1
+		}
+
+		env := cfg.GetEnv(args[0])
+		if credentials == "" {
+			credentials = env.Credentials
+		}
+		if clientID == "" {
+			clientID = env.ClientID
+		}
+		if binary == "" {
+			binary = env.Binary
 		}
 	}
 
-	if creds == "" {
+	if credentials == "" {
 		fmt.Fprintf(os.Stderr, "Error: %s is missing\n", GoogleApplicationCredentials)
 		return 1
 	}
-
 	if clientID == "" {
 		fmt.Fprintf(os.Stderr, "Error: %s is missing\n", IAPClientID)
 		return 1
 	}
-
 	if binary == "" {
 		binary = "curl"
 	}
 
-	token, err := getToken(creds, clientID)
+	token, err := getToken(credentials, clientID)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "Error: %v\n", err.Error())
 		return 1