using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.Security.Policy;
using System.Text;
using System.Threading.Tasks;

namespace EVCB_OCPP.WSServer.Service
{
    public class EnvCheckService
    {
        public EnvCheckService(
            IConfiguration configuration,
            ILogger<EnvCheckService> logger)
        {
            this.configuration = configuration;
            this.logger = logger;

            CheckVariable();
        }

        private readonly IConfiguration configuration;
        private readonly ILogger<EnvCheckService> logger;

        private const string certPath = "/run/secrets";
        private const string certFileName1 = "cert1";
        private const string certFileName2 = "cert2";
        private const string certFileName3 = "licence";

        private const string key1 = "MYkGePq3yYw0w4FYKXSl2KP4erMVos+WtkZS+SKnD+E=/BhbnUz7mYSSzr8xfSFp3Q==";
        private const string key2 = "MIIBCgKCAQEAnsVwgEb9IVBDZrYE42KOMuI5RWAgnk4OsUWMu/UuHLbQyUxv9cNTSQqWnUgEU4J1Dys8cbRT+qsND9eJHFkxnGE1vpXO04ADDCTBBPn1b3J6Wj6lp5Wy/feREg6oiCGJB7nAK1SzmFLKQxKmJX09vbveE02JNvU3KqmFuOthuNqzCCjht8o58+68as3tldskrGy2OjQwBp5rPL0lT9x2tBStm6xiBKPmG87WBjBqPL9LwXI+lmGnfJOABmbddjMp746RCUjzTr/40tXSjL1LZKEA/4vv5qnqIWz+peHfyu8L+XjJjipQ8OKATB6vUWAVrDBH6uHPvpU3G5eNq/o5TQIDAQAB";
        //private const string key3 = "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";

        public void CheckVariable()
        {
            var connectionSectionString = JsonConvert.SerializeObject(configuration.GetSection("ConnectionStrings").AsEnumerable());
            var dbSn = Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(connectionSectionString)));

            if (!CheckIsInDocker() ||
                CheckIsInAzureAppService() ||
                CheckVariable(dbSn, key1, key2)
                )
            {
                return;
            }

            Console.WriteLine($"Error:{dbSn}");
            Environment.Exit(401);
        }

        private static bool CheckVariable(string dbSn ,string key1, string key2)
        {
            if (!File.Exists(Path.Combine(certPath, certFileName1)) ||
                !File.Exists(Path.Combine(certPath, certFileName2)) )
            {
                return false;
            }

            var cert1 = File.ReadAllText(Path.Combine(certPath, certFileName1));
            var cert2 = File.ReadAllText(Path.Combine(certPath, certFileName2));

            string keySn = GetSn(cert1, key1);
            //if (string.IsNullOrEmpty(dbSn) ||
            //    !keySn.StartsWith(dbSn))
            //{
            //    return false;
            //}
            return CheckSn(keySn, cert2, key2);
        }

        private static string GetSn(string cert, string key)
        {
            var aesDecrept = Aes.Create();
            (byte[] aesKey, byte[] aesIv) = GetAesKey(key);
            aesDecrept.Key = aesKey;
            aesDecrept.IV = aesIv;

            var toDecryptStream = new MemoryStream(Convert.FromBase64String(cert));
            CryptoStream deCryptoStream = new CryptoStream(
                   toDecryptStream,
                   aesDecrept.CreateDecryptor(),
                   CryptoStreamMode.Read);
            StreamReader sr = new StreamReader(deCryptoStream);
            var deceypedString = sr.ReadToEnd();
            return deceypedString;
        }

        private static bool CheckSn(string sn, string cert2, string key)
        {
            var encryptor = new System.Security.Cryptography.RSACryptoServiceProvider();
            encryptor.ImportRSAPublicKey(Convert.FromBase64String(key), out var bytesRead);
            var isValid = encryptor.VerifyData(Encoding.UTF8.GetBytes(sn), SHA1.Create(), Convert.FromBase64String(cert2));
            return isValid;
        }

        private static (byte[] key, byte[] iv) GetAesKey(string key)
        {
            var keyString = key.Substring(0, 44);
            var ivString = key.Substring(44);

            return (Convert.FromBase64String(keyString), Convert.FromBase64String(ivString));
        }

        private bool CheckEnv()
        {
            return !CheckIsInDocker() || CheckIsInAzureAppService();
        }

        private bool CheckIsInAzureAppService()
        {
            return !String.IsNullOrEmpty(configuration["WEBSITE_SITE_NAME"]);
        }

        private bool CheckIsInDocker()
        {
            return !String.IsNullOrEmpty(configuration["RUNNING_IN_CONTAINER"]);
        }
    }
}