using Data.SeaHavenIndustries;
using Microsoft.AspNetCore.Identity;
using SeaHaven.DataServices.Interfaces;
using SeaHaven.Services.DTOs;
using SeaHaven.Services.Helpers;
using SeaHaven.Services.Interfaces;
using System.Security.Claims;
using System.Security.Cryptography;

namespace SeaHaven.Services.Implementation
{
    public class UserService : IUserService
    {
        private readonly UserManager<ApplicationUser> _userManager;
        private readonly IUserDataService _userDataService;
        private readonly IAccountDataService _accountDataService;
        private readonly IEmailSender _emailSender;

        public UserService(
            UserManager<ApplicationUser> userManager,
            IUserDataService userDataService,
            IAccountDataService accountDataService,
            IEmailSender emailSender)
        {
            _userManager = userManager;
            _userDataService = userDataService;
            _accountDataService = accountDataService;
            _emailSender = emailSender;
        }

        public async Task<IEnumerable<UserListRowDTO>> GetUsersAsync(CancellationToken cancellationToken)
        {
            var users = await _userDataService.GetAllForListAsync(cancellationToken);
            return users.Select(s => new UserListRowDTO
            {
                RoleName = s.RoleName,
                Email = s.Email,
                Name = s.Name,
                Date = s.CreatedDate != null ? s.CreatedDate.Value.Date.ToString("MMM dd yyyy") : "",
                Status = s.Status,
                Id = s.Id,
                Phone = s.Phone,
                Color = s.Color,
                PendingRegistration = s.PendingRegistration,
                ServiceAreas = s.ServiceAreas
            });
        }

        public async Task<AddUserOutcomeDTO> AddUserAsync(
            AddUserRequestDTO dto,
            ClaimsPrincipal caller,
            CancellationToken cancellationToken)
        {
            var authFailure = EnsureAdminCaller(caller);
            if (authFailure != null)
                return authFailure;

            var accountFailure = await EnsureAccountValidAsync(dto.AccountId);
            if (accountFailure != null)
                return accountFailure;

            var model = new ApplicationUser
            {
                UserName = dto.Email,
                FirstName = dto.Name,
                Email = dto.Email,
                AccountId = dto.AccountId
            };

            var exist = await _userDataService.GetByIdAsync(model.Id);
            if (exist == null)
            {
                model.EmailConfirmed = true;
                model.UserName = model.Email;
                model.CreatedDate = DateTime.UtcNow;
                model.UniqueName = "Active";
                model.PhoneNumber = dto.Role;

                var password = GenerateRandomPassword();

                var result = await _userManager.CreateAsync(model, password);
                if (result.Succeeded)
                {
                    await _userManager.AddToRoleAsync(model, dto.Role ?? "");
                }
                else
                {
                    return new AddUserOutcomeDTO { Success = false, Error = result.Errors.FirstOrDefault()?.Description ?? "error" };
                }
                var domain = "http://shoc-ui-app.s3-website-us-east-1.amazonaws.com/#";
                string subject = "Login Information";
                string greeting = $"Dear {model.FirstName},\n\n";
                string loginLink = $"Click here to login:<a href='{domain}/Login'>Login</a>\n";
                string passwordInfo = $"Your password is: {password}\n\n";
                string body = $"{greeting}\n\n{loginLink}\n\n{passwordInfo}";
                await _emailSender.SendEmailAsync(model?.Email ?? "", subject, body);
                return new AddUserOutcomeDTO { Success = true };
            }
            else
            {
                var exist1 = await _userDataService.GetForEditAsync(model.Id, cancellationToken);
                if (exist1 == null)
                    return new AddUserOutcomeDTO { Success = false, Error = UserMutationErrors.UserNotFound };

                var existingRole = await _userManager.GetRolesAsync(exist1);

                if (existingRole != null && existingRole.Any() && existingRole.FirstOrDefault() != exist1.PhoneNumber)
                {
                    await _userManager.RemoveFromRolesAsync(exist1, existingRole);
                }

                exist1.FirstName = model.FirstName;
                exist1.LastName = model.LastName;
                exist1.Contact = model.Contact;
                exist1.PhoneNumber = model.PhoneNumber;
                exist1.AccountId = dto.AccountId;

                await _userDataService.UpdateUserAsync(exist1, cancellationToken);

                await _userManager.AddToRoleAsync(exist1, dto.Role ?? "");
                await _userManager.UpdateAsync(exist1);
                return new AddUserOutcomeDTO { Success = true };
            }
        }

        public async Task<AddUserOutcomeDTO> EditUserAsync(
            EditUserRequestDTO dto,
            ClaimsPrincipal caller,
            CancellationToken cancellationToken)
        {
            var authFailure = EnsureAdminCaller(caller);
            if (authFailure != null)
                return authFailure;

            var accountFailure = await EnsureAccountValidAsync(dto.AccountId);
            if (accountFailure != null)
                return accountFailure;

            var exist = await _userDataService.GetForEditAsync(dto.Id ?? "", cancellationToken);
            if (exist == null)
                return new AddUserOutcomeDTO { Success = false, Error = UserMutationErrors.UserNotFound };

            if (await _userDataService.IsAccountOwnerAsync(exist.Id, cancellationToken))
                return new AddUserOutcomeDTO { Success = false, Error = UserMutationErrors.Forbidden };

            exist.FirstName = dto.Name;
            if (string.IsNullOrWhiteSpace(dto.Email))
                throw new ArgumentException("Email is required.", nameof(dto));

            exist.EmailConfirmed = true;
            exist.UserName = dto.Email;
            exist.Email = dto.Email;
            exist.NormalizedEmail = dto.Email.ToUpperInvariant();
            exist.NormalizedUserName = dto.Email.ToUpperInvariant();
            exist.CreatedDate = DateTime.UtcNow;
            exist.UniqueName = "Active";
            exist.PhoneNumber = dto.Role;
            exist.AccountId = dto.AccountId;

            var existingRole = await _userManager.GetRolesAsync(exist);
            if (existingRole != null && existingRole.Any())
            {
                await _userManager.RemoveFromRolesAsync(exist, existingRole);
            }
            await _userManager.AddToRoleAsync(exist, dto.Role ?? "");

            await _userDataService.UpdateUserAsync(exist, cancellationToken);
            return new AddUserOutcomeDTO { Success = true };
        }

        public async Task<AddUserOutcomeDTO> DeleteUserAsync(
            string id,
            ClaimsPrincipal caller,
            CancellationToken cancellationToken)
        {
            var authFailure = EnsureAdminCaller(caller);
            if (authFailure != null)
                return authFailure;

            var data = await _userDataService.GetForEditAsync(id, cancellationToken);
            if (data == null)
                return new AddUserOutcomeDTO { Success = false, Error = UserMutationErrors.UserNotFound };

            if (await _userDataService.IsAccountOwnerAsync(data.Id, cancellationToken))
                return new AddUserOutcomeDTO { Success = false, Error = UserMutationErrors.Forbidden };

            await _userDataService.DeleteUserWithCascadeAsync(data, cancellationToken);
            return new AddUserOutcomeDTO { Success = true };
        }

        public async Task DeleteCurrentUserAsync(string userId, CancellationToken cancellationToken)
        {
            var exist = await _userDataService.GetForEditAsync(userId, cancellationToken);
            if (exist != null && !await _userDataService.IsAccountOwnerAsync(exist.Id, cancellationToken))
            {
                exist.IsDeleted = true;
                await _userDataService.UpdateUserAsync(exist, cancellationToken);
            }
        }

        public async Task<IReadOnlyList<UserProfileRowDTO>> GetUserProfileAsync(string userId, CancellationToken cancellationToken)
        {
            var user = await _userDataService.GetProfileAsync(userId, cancellationToken);
            if (user == null)
                return Array.Empty<UserProfileRowDTO>();

            return new List<UserProfileRowDTO>
            {
                new UserProfileRowDTO
                {
                    Id = user.Id,
                    Name = user.FirstName,
                    AddedDate = user.CreatedDate,
                    Email = user.Email,
                    Contact = user.Contact
                }
            };
        }

        private static AddUserOutcomeDTO? EnsureAdminCaller(ClaimsPrincipal caller)
        {
            if (caller is null || !caller.IsInRole("Admin"))
            {
                return new AddUserOutcomeDTO { Success = false, Error = UserMutationErrors.Forbidden };
            }

            return null;
        }

        private async Task<AddUserOutcomeDTO?> EnsureAccountValidAsync(int? accountId)
        {
            if (!accountId.HasValue)
                return null;

            if (accountId.Value <= 0 || !await _accountDataService.ExistsAsync(accountId.Value))
            {
                return new AddUserOutcomeDTO { Success = false, Error = UserMutationErrors.AccountNotFound };
            }

            return null;
        }

        private static string GenerateRandomPassword(int length = 8)
        {
            const string validChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890!@#$%^&*()_-+=<>?";
            const string capitalLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
            const string digits = "1234567890";
            const string symbols = "!@#$%^&*()_-+=<>?";

            var passwordChars = new char[length];

            passwordChars[0] = capitalLetters[RandomNumberGenerator.GetInt32(capitalLetters.Length)];
            passwordChars[1] = digits[RandomNumberGenerator.GetInt32(digits.Length)];
            passwordChars[2] = symbols[RandomNumberGenerator.GetInt32(symbols.Length)];
            passwordChars[3] = "abcdefghijklmnopqrstuvwxyz"[RandomNumberGenerator.GetInt32(26)];

            for (int i = 4; i < length; i++)
            {
                passwordChars[i] = validChars[RandomNumberGenerator.GetInt32(validChars.Length)];
            }

            for (int i = passwordChars.Length - 1; i > 0; i--)
            {
                int j = RandomNumberGenerator.GetInt32(i + 1);
                (passwordChars[i], passwordChars[j]) = (passwordChars[j], passwordChars[i]);
            }

            return new string(passwordChars);
        }
    }
}