Add JWT Decoder. #119

Assets/Sui-Unity-SDK/Code/Sui.ZKLogin/JwtDecoder.cs

@@ -0,0 +1,131 @@
+using UnityEngine;
+using System;
+using System.Text;
+using System.Collections.Generic;
+
+namespace OpenDive.Utils.Jwt
+{
+    [Serializable]
+    public class JwtPayload
+    {
+        public string Iss;    // Issuer
+        public string Aud;    // Audience
+        public string Sub;    // Subject
+        public long Exp;      // Expiration Time
+        public long Iat;      // Issued At
+        public Dictionary<string, string> claims;
+
+        public JwtPayload()
+        {
+            claims = new Dictionary<string, string>();
+        }
+    }
+
+    public static class JwtDecoder
+    {
+        public static JwtPayload DecodeJwt(string jwt)
+        {
+            try
+            {
+                // Split the JWT into its three parts
+                string[] parts = jwt.Split('.');
+                if (parts.Length != 3)
+                {
+                    throw new ArgumentException("Invalid JWT format");
+                }
+
+                // Decode the payload (second part)
+                string payloadJson = DecodeBase64Url(parts[1]);
+
+                // Parse using Unity's JSON utility
+                var payload = new JwtPayload();
+                var tempPayload = JsonUtility.FromJson<JwtPayload>(payloadJson);
+
+                // Copy standard claims
+                payload.Iss = tempPayload.Iss;
+                payload.Aud = tempPayload.Aud;
+                payload.Sub = tempPayload.Sub;
+                payload.Exp = tempPayload.Exp;
+                payload.Iat = tempPayload.Iat;
+
+                // Parse the JSON manually to get all claims
+                // (because JsonUtility doesn't support Dictionary directly)
+                ParseCustomClaims(payloadJson, payload.claims);
+
+                return payload;
+            }
+            catch (Exception ex)
+            {
+                Debug.LogError($"Failed to decode JWT: {ex.Message}");
+                throw;
+            }
+        }
+
+        private static void ParseCustomClaims(string json, Dictionary<string, string> claims)
+        {
+            // Simple JSON parsing for claims
+            // Remove the first and last curly braces and split by commas
+            json = json.Trim('{', '}');
+            string[] pairs = json.Split(',');
+
+            foreach (string pair in pairs)
+            {
+                try
+                {
+                    string[] keyValue = pair.Split(':');
+                    if (keyValue.Length == 2)
+                    {
+                        string key = keyValue[0].Trim('"', ' ');
+                        string value = keyValue[1].Trim('"', ' ');
+
+                        // Skip standard claims
+                        if (!IsStandardClaim(key))
+                        {
+                            claims[key] = value;
+                        }
+                    }
+                }
+                catch (Exception ex)
+                {
+                    Debug.LogWarning($"Failed to parse claim pair: {pair}. Error: {ex.Message}");
+                }
+            }
+        }
+
+        private static string DecodeBase64Url(string base64Url)
+        {
+            string padded = base64Url.PadRight(4 * ((base64Url.Length + 3) / 4), '=');
+            string base64 = padded.Replace('-', '+').Replace('_', '/');
+            byte[] bytes = Convert.FromBase64String(base64);
+            return Encoding.UTF8.GetString(bytes);
+        }
+
+        private static bool IsStandardClaim(string claimName)
+        {
+            return claimName == "iss" ||
+                   claimName == "sub" ||
+                   claimName == "aud" ||
+                   claimName == "exp" ||
+                   claimName == "nbf" ||
+                   claimName == "iat" ||
+                   claimName == "jti";
+        }
+
+        // Helper methods
+        public static bool IsTokenExpired(JwtPayload payload)
+        {
+            var now = (long)(DateTime.UtcNow - new DateTime(1970, 1, 1)).TotalSeconds;
+            return now >= payload.Exp;
+        }
+
+        public static DateTime GetTokenExpirationTime(JwtPayload payload)
+        {
+            return DateTime.UnixEpoch.AddSeconds(payload.Exp);
+        }
+
+        public static DateTime GetTokenIssuedTime(JwtPayload payload)
+        {
+            return DateTime.UnixEpoch.AddSeconds(payload.Iat);
+        }
+    }
+}