package main

import (
	"encoding/base64"
	"encoding/json"
	"fmt"
	"os"
	"strings"
)

func main() {
	if len(os.Args) < 2 {
		fmt.Println("Usage: decode-token <jwt-token>")
		os.Exit(1)
	}

	token := os.Args[1]
	parts := strings.Split(token, ".")
	
	if len(parts) != 3 {
		fmt.Println("Invalid JWT token format")
		os.Exit(1)
	}

	// Decode header
	fmt.Println("=== JWT HEADER ===")
	headerBytes, err := base64.RawStdEncoding.DecodeString(parts[0])
	if err != nil {
		fmt.Printf("Failed to decode header: %v\n", err)
		os.Exit(1)
	}
	
	var header map[string]interface{}
	if err := json.Unmarshal(headerBytes, &header); err != nil {
		fmt.Printf("Failed to parse header: %v\n", err)
		os.Exit(1)
	}
	
	headerJSON, _ := json.MarshalIndent(header, "", "  ")
	fmt.Println(string(headerJSON))

	// Decode payload
	fmt.Println("\n=== JWT PAYLOAD (CLAIMS) ===")
	payloadBytes, err := base64.RawStdEncoding.DecodeString(parts[1])
	if err != nil {
		fmt.Printf("Failed to decode payload: %v\n", err)
		os.Exit(1)
	}
	
	var payload map[string]interface{}
	if err := json.Unmarshal(payloadBytes, &payload); err != nil {
		fmt.Printf("Failed to parse payload: %v\n", err)
		os.Exit(1)
	}
	
	payloadJSON, _ := json.MarshalIndent(payload, "", "  ")
	fmt.Println(string(payloadJSON))
	
	fmt.Println("\n=== KEY FIELDS ===")
	if sub, ok := payload["sub"].(string); ok {
		fmt.Printf("User ID (sub): %s\n", sub)
	}
	if typ, ok := payload["typ"].(string); ok {
		fmt.Printf("Token Type (typ): %s\n", typ)
	}
	if aud, ok := payload["aud"].(string); ok {
		fmt.Printf("Audience (aud): %s\n", aud)
	}
	if exp, ok := payload["exp"].(float64); ok {
		fmt.Printf("Expires (exp): %v\n", exp)
	}
	if iat, ok := payload["iat"].(float64); ok {
		fmt.Printf("Issued At (iat): %v\n", iat)
	}
	
	// Check for user profile fields
	fmt.Println("\n=== USER PROFILE FIELDS ===")
	hasProfile := false
	for key, value := range payload {
		if strings.Contains(strings.ToLower(key), "name") || 
		   strings.Contains(strings.ToLower(key), "user") ||
		   strings.Contains(strings.ToLower(key), "display") ||
		   strings.Contains(strings.ToLower(key), "email") {
			fmt.Printf("%s: %v\n", key, value)
			hasProfile = true
		}
	}
	if !hasProfile {
		fmt.Println("(No user profile fields found in token)")
	}
}