using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using SecureCore.Services;
using System.Security.Cryptography;
using Microsoft.AspNetCore.Cryptography.KeyDerivation;

namespace SecureCore.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class EmployeeController : Controller
    {
        private readonly IDataService DataService;


        public EmployeeController(IDataService dataService)
        {
            DataService = dataService;
        }

        [HttpGet]
        public IActionResult Get()
        {
            return Ok(DataService.Get());
        }

        [HttpGet("{id}", Name = "Get")]
        public IActionResult Get(int id)
        {
            return Ok(DataService.GetById(id));
        }

        [HttpPost("login")]
        [AcceptVerbs("POST")]
        public IActionResult Login(LoginInfo info)
        {
            var hash = Auth.HashPassword(info.Password);
            var h2 = Auth.HashPassword("Nonesense", "vRWp9TP1nQDLGtDZrd2yuw==");

            return Ok($"Session Key: {Auth.CreateSessionId()}{Environment.NewLine}Password Hash: {hash.Hash}{Environment.NewLine}Salt: {hash.Salt}{Environment.NewLine}{h2 == "+IGLf8scewY2LOObXqfF5IkIbhcEuPrMFc12d78jH6ZyBEMQI+Z9zixWgkQANeV3VYvURBEXIVI0/TPZrnML3w=="}");
        }
    }

    public class LoginInfo
    {
        public string UserName { get; set; }
        public string Password { get; set; }
    }

    public static class Auth
    {
        private static int Iterations { get; set; } = 100000;
        private static KeyDerivationPrf KeyType { get; } = KeyDerivationPrf.HMACSHA512;
        private static int KeySize { get; } = 512 / 8;
        private static int SaltSize { get; } = 128 / 8; //128 bit salt
        private static int SessionKeySize { get; } = 32; //32 bytes

        public static string CreateSessionId()
        {
            var sessionId = new byte[SessionKeySize];

            GetRandomBytes(ref sessionId);

            return Convert.ToBase64String(sessionId);
        }

        public static (string Hash, string Salt) HashPassword(string password)
        {
            var salt = new byte[SaltSize];

            GetRandomBytes(ref salt);

            return (GetPasswordHash(password, salt), Convert.ToBase64String(salt));
        }

        public static string HashPassword(string password, string hash)
        {
            var salt = Convert.FromBase64String(hash);

            return GetPasswordHash(password, salt);
        }

        private static string GetPasswordHash(string password, byte[] salt)
        {
            return Convert.ToBase64String(KeyDerivation.Pbkdf2(password, salt, KeyType, Iterations, KeySize));
        }

        private static void GetRandomBytes(ref byte[] bytes)
        {
            using var rng = RandomNumberGenerator.Create();
            rng.GetBytes(bytes);
        }
    }
}