using DocumentFormat.OpenXml.Wordprocessing;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace KssSmaPlaLib.Encryption
{
    public static class SimpleEncryptUxer
    {
        public static readonly string FixedPassword = "KssSmaPlaDxer!";
        private static readonly byte[] FixedIV = new byte[16];

        public static bool TuckIntoMain(string[] args)
        {
            if (args.Length != 2) return false;

            if (args[0].ToLower() == "/enc")
            {
                if (SimpleEncryptUxer.Encrypt(args[1], out var resultText, out var resultMessage))
                {
                    Console.WriteLine($"暗号化結果[{resultText}]");
                }
                else
                {
                    Console.WriteLine(resultMessage);
                }
                return true;
            }
            else if (args[0].ToLower() == "/dec")
            {
                if (SimpleEncryptUxer.Decrypt(args[1], out var resultText, out var resultMessage))
                {
                    Console.WriteLine($"複合化結果[{resultText}]");
                }
                else
                {
                    Console.WriteLine(resultMessage);
                }
                return true;
            }
            return false;
        }

        public static bool Encrypt(string plainText, out string resultText, out string resultMessage, string password = "")
        {
            resultText = string.Empty;
            resultMessage = string.Empty;
            password = string.IsNullOrEmpty(password) ? FixedPassword : password;
            try
            {
                byte[] key = SHA256.Create().ComputeHash(Encoding.UTF8.GetBytes(password));
                // 固定IV（簡易仕様とする）※IVはオールゼロ
                using (var aes = new AesManaged { Key = key, IV = FixedIV })
                using (var encryptor = aes.CreateEncryptor())
                {
                    byte[] inputBytes = Encoding.UTF8.GetBytes(plainText);
                    byte[] encryptedBytes = encryptor.TransformFinalBlock(inputBytes, 0, inputBytes.Length);
                    resultText = Convert.ToBase64String(encryptedBytes);
                    return true;
                }
            }
            catch (Exception ex)
            {
                resultMessage = $"暗号化に失敗しました。[エラー内容:{ex.Message}]";
                return false;
            }
        }

        public static bool Decrypt(string encryptedText, out string resultText, out string resultMessage, string password = "")
        {
            resultText = string.Empty;
            resultMessage = string.Empty;
            password = string.IsNullOrEmpty(password) ? FixedPassword : password;
            try
            {
                byte[] key = SHA256.Create().ComputeHash(Encoding.UTF8.GetBytes(password));
                byte[] encryptedBytes = Convert.FromBase64String(encryptedText);
                using (var aes = new AesManaged { Key = key, IV = FixedIV })
                using (var decryptor = aes.CreateDecryptor())
                {
                    byte[] decryptedBytes = decryptor.TransformFinalBlock(encryptedBytes, 0, encryptedBytes.Length);
                    resultText = Encoding.UTF8.GetString(decryptedBytes);
                    return true;
                }
            }
            catch (Exception ex)
            {
                resultMessage = $"複合化に失敗しました。[エラー内容:{ex.Message}]";
                return false;
            }
        }
    }
}