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, out string salt);
            return Ok($"Session Key: {Auth.CreateSessionId()}{Environment.NewLine}Password Hash: {hash}{Environment.NewLine}Salt: {salt}{Environment.NewLine}");
        }
    }

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

    public static class Auth
    {
        public static string CreateSessionId()
        {
            var sessionId = new byte[32];

            GetRandomBytes(ref sessionId);

            return ConvertToHex(sessionId);
        }

        public static string HashPassword(string password, out string saltString)
        {
            //Generate a 128 bit salt
            var salt = new byte[128 / 8];

            GetRandomBytes(ref salt);

            saltString = ConvertToHex(salt);

            return Convert.ToBase64String(KeyDerivation.Pbkdf2(password, salt, KeyDerivationPrf.HMACSHA512, 50000, 512 / 8));
        }

        private static string ConvertToHex(byte[] bytes)
        {
            var stringBuilder = new StringBuilder();

            foreach (var b in bytes)
                stringBuilder.AppendFormat("{0:x2}", b);

            return stringBuilder.ToString();
        }

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