using System;
using System.Net.Http;
using System.Security.Cryptography;
using System.Text;
using UnityEngine;
using System.Text.Json;
using System.IO;

// this entire file could be better

namespace undead_universal_patch_il2cpp.Galvanic
{
    public class GalvanicAuth
    {
        public static void PrepareKeys()
        {
            PlayerPrefs.DeleteKey("GalvanicPublicKey");
            PlayerPrefs.DeleteKey("GalvanicPrivateKey");
            using (ECDsa ecdsa = ECDsa.Create(ECCurve.NamedCurves.nistP256))
            {
                byte[] publicKeyBytes = ecdsa.ExportSubjectPublicKeyInfo();
                string publicKeyBase64 = Convert.ToBase64String(publicKeyBytes);

                byte[] privateKeyBytes = ecdsa.ExportPkcs8PrivateKey();
                string privateKeyBase64 = Convert.ToBase64String(privateKeyBytes);

                PlayerPrefs.SetString("GalvanicPublicKey", publicKeyBase64);
                PlayerPrefs.SetString("GalvanicPrivateKey", privateKeyBase64);
                PlayerPrefs.Save();

                Plugin.Log.LogInfo("Created new keypair for Galvanic authentication.");
            }
        }

        public static string GetPubKey()
        {
            string publicKey = PlayerPrefs.GetString("GalvanicPublicKey", null);
            if (string.IsNullOrEmpty(publicKey))
            {
                Plugin.Log.LogInfo("No keypair found, generating new.");
                PrepareKeys();
                return GetPubKey();
            } else return publicKey;
        }

        private static ECDsa GetPrivKey()
        {
            string privateKey = PlayerPrefs.GetString("GalvanicPrivateKey", null);
            if (string.IsNullOrEmpty(privateKey))
            {
                Plugin.Log.LogInfo("No keypair found, generating new.");
                PrepareKeys();
                return GetPrivKey();
            }

            byte[] privKeyBytes = Convert.FromBase64String(privateKey);
            ECDsa crypt = ECDsa.Create();
            crypt.ImportPkcs8PrivateKey(privKeyBytes, out _);
            return crypt;
        }

        public static string SignPayload(string message)
        {
            using (ECDsa ecdsa = GetPrivKey())
            {
                if (ecdsa == null) return null;

                byte[] payloadBytes = Encoding.UTF8.GetBytes(message);
                byte[] signature = ecdsa.SignData(payloadBytes, HashAlgorithmName.SHA256);

                return Convert.ToBase64String(signature);
            }
        }
        public static void Export()
        {
            File.WriteAllText("./galvanic_keys_export.txt", $"{GetPubKey()}\n{Convert.ToBase64String(GetPrivKey().ExportPkcs8PrivateKey())}");
            Plugin.Log.LogWarning("Galvanic Authentication keys were exported.");
        }
        public static void Import()
        {
            try
            {
                string imported = File.ReadAllText("./galvanic_keys_export.txt").ToString();
                string privkey = imported.Split("\n")[1];
                string pubkey = imported.Split("\n")[0];
                if (privkey == null || pubkey == null) throw new Exception("Either imported key was null");

                PlayerPrefs.SetString("GalvanicPrivateKey", privkey);
                PlayerPrefs.SetString("GalvanicPublicKey", pubkey);
                PlayerPrefs.Save();
            } catch (Exception err)
            {
                Plugin.Log.LogError($"Could not import Galvanic Authentication keys: {err}");
            }
        }
        public static ServerInfoRes GetServerInfo()
        {
            UriBuilder nameserver = new(NameserverConfig.NewUrl.Value);
            nameserver.Path = "/info";
            nameserver.Query = "";

            using HttpClient client = new();
            var response = client.GetAsync(nameserver.ToString()).Result;
            if (!response.IsSuccessStatusCode) return null;

            var str = response.Content.ReadAsStringAsync().Result;
            var res = JsonSerializer.Deserialize<ServerInfoRes>(str);

            GalvanicCorrosion.Name = res.name;
            GalvanicCorrosion.Id = res.id;
            GalvanicCorrosion.Motd = res.motd;
            GalvanicCorrosion.Patches = res.patches;

            return res;
        }
    }

    public static class GalvanicCorrosion
    {
        public static string Name { get; set; } = "Galvanic Corrosion";
        public static string Id { get; set; } = "galvanic-corrosion-default";
        public static string Motd { get; set; } = "A Galvanic Corrosion server.";
        public static string[] Patches { get; set; } = [];
    }

    public static class GalvanicWebAuth
    {
        public static string Token { get; private set; } = null;
        public static void TokenExpiry()
        {
            string url = NameserverConfig.NewUrl.Value;
            UriBuilder uri = new(url);
            uri.Path = "/user/checkExpired";
            uri.Query = "";

            HttpClient client = new();
            client.DefaultRequestHeaders.Add("GalvanicAuth", Token);
            HttpResponseMessage res = client.GetAsync(uri.ToString()).Result;
            if (res.IsSuccessStatusCode)
            {
                bool expired = JsonSerializer.Deserialize<bool>(res.Content.ReadAsStringAsync().Result.ToString());
                if (expired) GetToken();
            }
        }

        public static void GetToken()
        {
            string url = NameserverConfig.NewUrl.Value;
            UriBuilder uri = new(url);
            uri.Path = "/user/auth";
            uri.Query = "";

            var info = GalvanicAuth.GetServerInfo();
            Plugin.Log.LogInfo($"Sending authentication request to server ID '{info.id}'");
            if (uri.Scheme == "http") Plugin.Log.LogWarning("The server is not secure! Please use HTTPS.");

            UserAuthPayload payload = new UserAuthPayload
            {
                timestamp = ((DateTimeOffset)DateTime.Now).ToUnixTimeSeconds(),
                nonce = Guid.NewGuid().ToString(),
                server_id = info.id,
            };
            
            UserAuthRequest request = new UserAuthRequest
            {
                message = payload,
                signature = GalvanicAuth.SignPayload($"{JsonSerializer.Serialize(payload)}"),
                client_id = UniqueID.GetUniqueId(),
                pubkey = GalvanicAuth.GetPubKey()
            };

            HttpClient client = new();
            HttpResponseMessage res = client.PostAsync(uri.ToString(), new StringContent(JsonSerializer.Serialize(request,
                new JsonSerializerOptions { 
                    PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
                    Encoder = System.Text.Encodings.Web.JavaScriptEncoder.UnsafeRelaxedJsonEscaping
                }), 
                Encoding.UTF8,
                "application/json")).Result;
            if (!res.IsSuccessStatusCode)
            {
                Plugin.Log.LogError("The GalvanicWeb auth response was not successful.");
                return;
            }
            string str = res.Content.ReadAsStringAsync().Result;
            TokenRes token = JsonSerializer.Deserialize<TokenRes>(str);

            Token = token.token;
        }
    }

    public static class UniqueID
    {
        public static string GetUniqueId()
        {
            if (!PlayerPrefs.HasKey("UniqueId")) SaveUniqueId(GenerateUniqueId());
            return PlayerPrefs.GetString("UniqueId");
        }
        public static void SaveUniqueId(string id)
        {
            PlayerPrefs.SetString("UniqueId", id);
            PlayerPrefs.Save();
        }
        public static string GenerateUniqueId()
        {
            byte[] buffer = new byte[128];
            new System.Random().NextBytes(buffer);
            return System.Convert.ToBase64String(buffer).Substring(0, 128);

            // god help me
        }
    }

    public class ServerInfoRes
    {
        public string name { get; set; }
        public string id { get; set; }
        public string motd { get; set; }
        public string[] patches { get; set; }
    }

    class TokenRes
    {
        public string token { get; set; }
    }

    class UserAuthPayload
    {
        public long timestamp { get; set; }
        public string nonce { get; set; }
        public string server_id { get; set; }
    }

    class UserAuthRequest
    {
        public string client_id { get; set; }
        public UserAuthPayload message { get; set; }
        public string signature { get; set; }
        public string pubkey { get; set; }
    }
}