using Microsoft.AspNetCore.Authorization;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Options;
using Microsoft.IdentityModel.Tokens;
using System;
using System.Collections.Generic;
using System.IdentityModel.Tokens.Jwt;
using System.Linq;
using System.Security.Claims;
using System.Text;
using UnivateProperties_API.Containers;
using UnivateProperties_API.Containers.Users;
using UnivateProperties_API.Context;
using UnivateProperties_API.Helpers;
using UnivateProperties_API.Model.Users;

namespace UnivateProperties_API.Repository.Users
{
    public class RegisterRepository : IRegisterRepository
    {
        private readonly DataContext _dbContext;

        private readonly AppSettings _appSettings;

        public RegisterRepository(DataContext dbContext, IOptions<AppSettings> appSettings)
        {
            _dbContext = dbContext;
            _appSettings = appSettings.Value;
        }

        public User Authenticate(string username, string password)
        {
            if (string.IsNullOrEmpty(username) || string.IsNullOrEmpty(password))
                return null;

            var user = _dbContext.Users.SingleOrDefault(x => x.Username == username);

            // check if username exists
            if (user == null)
                return null;

            // check if password is correct
            if (!VerifyPasswordHash(password, user.PasswordHash, user.PasswordSalt))
                return null;

            // authentication successful
            return user;
        }

        public User Create(User user, string password, bool save)
        {
            // validation
            if (string.IsNullOrWhiteSpace(password))
                throw new AppException("Password is required");

            if (_dbContext.Users.Any(x => x.Username == user.Username))
                throw new AppException("Username \"" + user.Username + "\" is already taken");

            byte[] passwordHash, passwordSalt;
            CreatePasswordHash(password, out passwordHash, out passwordSalt);

            user.PasswordHash = passwordHash;
            user.PasswordSalt = passwordSalt;

            _dbContext.Users.Add(user);
            if (save)
            {
                _dbContext.SaveChanges();
            }

            return user;
        }

        public Agency CreateAgency(AgencyDto agency)
        {
            // validation
            if (string.IsNullOrWhiteSpace(agency.EaabeffcNumber))
                throw new AppException("eaabeffcNumber is required");

            if (_dbContext.Agencies.Any(x => x.EAABEFFCNumber == agency.EaabeffcNumber))
                throw new AppException("eaabeffcNumber \"" + agency.EaabeffcNumber + "\" already exists");

            Agency a = new Agency()
            {
                AgencyName = agency.Name,
                EAABEFFCNumber = agency.EaabeffcNumber,
                CompanyRegNumber = agency.RegNo
            };

            _dbContext.Agencies.Add(a);
            CreatePerson(agency.User, PersonType.Agent, false, a);

            _dbContext.SaveChanges();

            return a;
        }

        public void CreatePerson(UserDto individual, PersonType personType, bool save, Agency agency)
        {
            // validation
            if (string.IsNullOrWhiteSpace(individual.Password))
                throw new AppException("Password is required");

            if (_dbContext.Users.Any(x => x.Username == individual.Username))
                throw new AppException("Individual \"" + individual.Username + "\" is already taken");
            byte[] passwordHash, passwordSalt;

            CreatePasswordHash(individual.Password, out passwordHash, out passwordSalt);

            User createUser = new User()
            {
                Username = individual.Username,
                PasswordHash = passwordHash,
                PasswordSalt = passwordSalt
            };
            Create(createUser, individual.Password, save);
            Person person = new Person()
            {
            };
            if (personType == PersonType.Agent)
            {
                Agent agent = new Agent()
                {
                    Name = individual.Name,
                    Surname = individual.Surname,
                    User = createUser,
                    Email = individual.Email,
                    CellNumber = individual.CellNumber,
                    Telephone = individual.Telephone,
                    Agency = agency
                };
                _dbContext.Agents.Add(agent);
            }
            else if (personType == PersonType.Individual)
            {
                Individual i = new Individual()
                {
                    Name = individual.Name,
                    Surname = individual.Surname,
                    User = createUser,
                    Email = individual.Email,
                    CellNumber = individual.CellNumber,
                    Telephone = individual.Telephone
                };
                _dbContext.Individuals.Add(i);
            }
            if (save)
            {
                Save();
            }
        }

        public void UpdatePerson(Person person, PersonType personType)
        {
            if (personType == PersonType.Agent)
            {
                var item = (person as Agent);
                _dbContext.Entry(item).State = EntityState.Modified;
                Save();
            }
            else if (personType == PersonType.Individual)
            {
                var item = (person as Individual);
                _dbContext.Entry(item).State = EntityState.Modified;
                Save();
            }
        }

        public void Update(User userParam, string password = null)
        {
            var user = _dbContext.Users.Find(userParam.Id);

            if (user == null)
                throw new AppException("User not found");

            if (userParam.Username != user.Username)
            {
                // username has changed so check if the new username is already taken
                if (_dbContext.Users.Any(x => x.Username == userParam.Username))
                    throw new AppException("Username " + userParam.Username + " is already taken");
            }

            // update user properties
            user.Name = userParam.Name;
            user.Surname = userParam.Surname;
            user.Username = userParam.Username;

            // update password if it was entered
            if (!string.IsNullOrWhiteSpace(password))
            {
                byte[] passwordHash, passwordSalt;
                CreatePasswordHash(password, out passwordHash, out passwordSalt);

                user.PasswordHash = passwordHash;
                user.PasswordSalt = passwordSalt;
            }

            _dbContext.Users.Update(user);
            _dbContext.SaveChanges();
        }

        public void UpdateAgency(Agency agencyParam, string agencyname = null)
        {
            var agency = _dbContext.Agencies.Find(agencyParam.Id);

            if (agency == null)
                throw new AppException("Agency not found");

            if (agencyParam.AgencyName != agency.AgencyName)
            {
                // username has changed so check if the new username is already taken
                if (_dbContext.Agencies.Any(x => x.AgencyName == agencyParam.AgencyName))
                    throw new AppException("AgencyName " + agencyParam.AgencyName + " is already taken");
            }

            // update user properties
            agency.AgencyName = agencyParam.AgencyName;
            agency.EAABEFFCNumber = agencyParam.EAABEFFCNumber;
            agency.CompanyRegNumber = agencyParam.CompanyRegNumber;

            // update password if it was entered
            _dbContext.Agencies.Update(agency);
            _dbContext.SaveChanges();
        }

        [Authorize(Roles = Role.SuperAdmin)]
        public IEnumerable<User> GetAllUsers()
        {
            return _dbContext.Users;
        }

        [Authorize(Roles = Role.SuperAdmin)]
        public IEnumerable<Agency> GetAllAgencies()
        {
            return _dbContext.Agencies;
        }

        [Authorize(Roles = Role.SuperAdmin)]
        public IEnumerable<Individual> GetAllIndividuals()
        {
            return _dbContext.Individuals;
        }

        public User GetById(int id)
        {
            return _dbContext.Users.Find(id);
        }

        public Agency GetByAgencyId(int id)
        {
            return _dbContext.Agencies.Find(id);
        }

        public Individual GetByIndividualId(int id)
        {
            return _dbContext.Individuals.Find(id);
        }

        public void Delete(int id)
        {
            var user = _dbContext.Users.Find(id);
            if (user != null)
            {
                _dbContext.Users.Remove(user);
                _dbContext.SaveChanges();
            }
        }

        public void DeleteAgency(int id)
        {
            var agency = _dbContext.Agencies.Find(id);
            if (agency != null)
            {
                _dbContext.Remove(agency);
                _dbContext.SaveChanges();
            }
        }

        public void DeleteIndividual(int id)
        {
            var individual = _dbContext.Individuals.Find(id);
            if (individual != null)
            {
                _dbContext.Individuals.Remove(individual);
                _dbContext.SaveChanges();
            }
        }

        private void Save()
        {
            _dbContext.SaveChanges();
        }

        private static void CreatePasswordHash(string password, out byte[] passwordHash, out byte[] passwordSalt)
        {
            if (password == null) throw new ArgumentNullException("password");
            if (string.IsNullOrWhiteSpace(password)) throw new ArgumentException("Value cannot be empty or whitespace only string.", "password");

            using (var hmac = new System.Security.Cryptography.HMACSHA512())
            {
                passwordSalt = hmac.Key;
                passwordHash = hmac.ComputeHash(System.Text.Encoding.UTF8.GetBytes(password));
            }
        }

        private static bool VerifyPasswordHash(string password, byte[] storedHash, byte[] storedSalt)
        {
            if (password == null) throw new ArgumentNullException("password");
            if (string.IsNullOrWhiteSpace(password)) throw new ArgumentException("Value cannot be empty or whitespace only string.", "password");
            if (storedHash.Length != 64) throw new ArgumentException("Invalid length of password hash (64 bytes expected).", "passwordHash");
            if (storedSalt.Length != 128) throw new ArgumentException("Invalid length of password salt (128 bytes expected).", "passwordHash");

            using (var hmac = new System.Security.Cryptography.HMACSHA512(storedSalt))
            {
                var computedHash = hmac.ComputeHash(System.Text.Encoding.UTF8.GetBytes(password));
                for (int i = 0; i < computedHash.Length; i++)
                {
                    if (computedHash[i] != storedHash[i]) return false;
                }
            }

            return true;
        }
    }
}