using API.DBAccess;
using API.Models.UserModels;
using API.Models.RecipeModels;
using Microsoft.AspNetCore.Mvc;
using Microsoft.IdentityModel.Tokens;
using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;
using System.Security.Cryptography;
using System.Text;
using System.Text.RegularExpressions;
using API.Models.ShoppingListModels;

namespace API.BusinessLogic
{
    public class UserLogic
    {
        private readonly UserDBAccess _dbAccess;
        private readonly IConfiguration _configuration;

        public UserLogic(IConfiguration configuration, UserDBAccess dbAccess)
        {
            _dbAccess = dbAccess;
            _configuration = configuration;
        }

        public async Task<IActionResult> GetUser(int userId)
        {
            User user = await _dbAccess.ReadUser(userId);

            if (user == null || user.Id == 0) { return new ConflictObjectResult(new { message = "Could not find user" }); }
            return new OkObjectResult(new { user.Id, user.UserName, user.Email });
        }

        public async Task<IActionResult> RegisterUser(CreateUserDTO userDTO)
        {
            if (!EmailCheck(userDTO.Email))
            {
                return new ConflictObjectResult(new { message = "Invalid email address" });
            }

            if (!PasswordSecurity(userDTO.Password))
            {
                return new ConflictObjectResult(new { message = "Password is not up to the security standard" });
            }

            if (await _dbAccess.UserNameInUse(userDTO.UserName))
            {
                return new ConflictObjectResult(new { message = "Username is already in use." });
            }

            if (await _dbAccess.EmailInUse(userDTO.Email))
            {
                return new ConflictObjectResult(new { message = "Email is already in use." });
            }

            string salt = Guid.NewGuid().ToString();
            string hashedPassword = ComputeHash(userDTO.Password, SHA256.Create(), salt);



            User user = new User
            {
                UserName = userDTO.UserName,
                Email = userDTO.Email,
                Password = hashedPassword,
                Salt = salt,
                Recipes = new List<Recipe>(),
                ShoppingList = new List<ShoppingList>(),
            };

            return await _dbAccess.CreateUser(user);
        }

        public async Task<IActionResult> Login(LoginDTO loginDTO)
        {
            var user = await _dbAccess.ReadUserForLogin(loginDTO.EmailUsr);

            if (user == null || user.Id == 0) { return new ConflictObjectResult(new { message = "Could not find user" }); }

            string hashedPassword = ComputeHash(loginDTO.Password, SHA256.Create(), user.Salt);

            if (user.Password == hashedPassword)
            {
                var token = GenerateJwtToken(user);

                user = await UpdateRefreshToken(user);

                return new OkObjectResult(new { token, user.UserName, user.Id, refreshToken = user.RefreshToken });
            }

            return new ConflictObjectResult(new { message = "Invalid password" });
        }

        public async Task<IActionResult> EditProfile(UpdateUserDTO userDTO, int userId)
        {
            var profile = await _dbAccess.ReadUser(userId);

            if (profile == null) { return new ConflictObjectResult(new { message = "User does not exist" }); }

            if (!EmailCheck(userDTO.Email))
            {
                return new ConflictObjectResult(new { message = "Invalid email address" });
            }

            if (userDTO.Email == "" || userDTO.Email == null)
            {
                return new ConflictObjectResult(new { message = "Please enter an email" });
            }

            if (userDTO.UserName == "" || userDTO.UserName == null)
            {
                return new ConflictObjectResult(new { message = "Please enter an userName" });
            }


            if (await _dbAccess.UserNameInUse(userDTO.UserName))
            {
                return new ConflictObjectResult(new { message = "Username is already in use." });
            }

            if (await _dbAccess.EmailInUse(userDTO.Email))
            {
                return new ConflictObjectResult(new { message = "Email is already in use." });
            }



            profile.Email = userDTO.Email;
            profile.UserName = userDTO.UserName;

            return await _dbAccess.UpdateUser(profile);
        }

        public async Task<IActionResult> ChangePassword(ChangePasswordDTO passwordDTO, int userId)
        {
            var user = await _dbAccess.ReadUser(userId);

            if (user == null) { return new ConflictObjectResult(new { message = "User does not exist" }); }

            string hashedPassword = ComputeHash(passwordDTO.OldPassword, SHA256.Create(), user.Salt);

            if (user.Password != hashedPassword)
            {
                return new ConflictObjectResult(new { message = "Old password is incorrect" });

            }

            if (!PasswordSecurity(passwordDTO.NewPassword))
            {
                return new ConflictObjectResult(new { message = "New password is not up to the security standard" });
            }

            string hashedNewPassword = ComputeHash(passwordDTO.NewPassword, SHA256.Create(), user.Salt);
            user.Password = hashedNewPassword;

            return await _dbAccess.UpdatePassword(user);
        }

        public async Task<IActionResult> DeleteUser(int userId)
        {
            var user = await _dbAccess.ReadUserForDelete(userId);

            if (user != null) { return await _dbAccess.DeleteUser(user); }

            return new ConflictObjectResult(new { message = "Invalid user" });
        }

        public async Task<IActionResult> RefreshToken(string refreshToken)
        {
            User user = await _dbAccess.ReadUserByRefreshToken(refreshToken);
            if (user == null) { return new ConflictObjectResult(new { message = "Could not match refreshtoken" }); }
            user = await UpdateRefreshToken(user);
            string jwtToken = GenerateJwtToken(user);
            return new OkObjectResult(new { token = jwtToken, refreshToken = user.RefreshToken });
        }

        private bool PasswordSecurity(string password)
        {
            var hasMinimum8Chars = new Regex(@".{8,}");

            return hasMinimum8Chars.IsMatch(password);
        }

        private bool EmailCheck(string email)
        {
            return new Regex(@".+@.+\..+").IsMatch(email);
        }

        private static string ComputeHash(string input, HashAlgorithm algorithm, string salt)
        {
            Byte[] inputBytes = Encoding.UTF8.GetBytes(input);
            Byte[] saltBytes = Encoding.UTF8.GetBytes(salt);

            // Combine salt and input bytes
            Byte[] saltedInput = new Byte[saltBytes.Length + inputBytes.Length];
            saltBytes.CopyTo(saltedInput, 0);
            inputBytes.CopyTo(saltedInput, saltBytes.Length);

            Byte[] hashedBytes = algorithm.ComputeHash(saltedInput);

            return BitConverter.ToString(hashedBytes);
        }

        private string GenerateJwtToken(User user)
        {
            var claims = new[]
            {
                new Claim(JwtRegisteredClaimNames.Sub, user.Id.ToString()),
                new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString()),
                new Claim(ClaimTypes.Name, user.UserName)
            };

            var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes
            (_configuration["JwtSettings:Key"]));
            var creds = new SigningCredentials(key, SecurityAlgorithms.HmacSha256);

            var token = new JwtSecurityToken(
                _configuration["JwtSettings:Issuer"],
                _configuration["JwtSettings:Audience"],
                claims,
                expires: DateTime.Now.AddHours(1),
                signingCredentials: creds);

            return new JwtSecurityTokenHandler().WriteToken(token);
        }

        private async Task<User> UpdateRefreshToken(User user)
        {
            user.RefreshToken = Guid.NewGuid().ToString();
            user.RefreshTokenExpireAt = DateTime.Now.AddDays(30);
            await _dbAccess.UpdateUser(user);
            return user;
        }
    }
}