using Data.SeaHavenIndustries;
using Microsoft.AspNetCore.Identity;
using Microsoft.Extensions.Options;
using Microsoft.IdentityModel.Tokens;
using SeaHaven.DataServices.Interfaces;
using SeaHaven.Services.Configuration;
using SeaHaven.Services.DTOs;
using SeaHaven.Services.Helpers;
using SeaHaven.Services.Interfaces;
using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;
using System.Security.Cryptography;
using System.Text;

namespace SeaHaven.Services.Implementation
{
    public class AuthenticationService : IAuthenticationService
    {
        private readonly UserManager<ApplicationUser> _userManager;
        private readonly JwtOptions _jwtOptions;
        private readonly IUserDataService _userDataService;
        private readonly IForgetPasswordDataService _forgetPasswordDataService;
        private readonly IEmailSender _emailSender;
        public AuthenticationService(
            UserManager<ApplicationUser> userManager,
            IOptions<JwtOptions> jwtOptions,
            IUserDataService userDataService,
            IForgetPasswordDataService forgetPasswordDataService,
            IEmailSender emailSender)
        {
            _userManager = userManager;
            _jwtOptions = jwtOptions.Value;
            _userDataService = userDataService;
            _forgetPasswordDataService = forgetPasswordDataService;
            _emailSender = emailSender;
        }

        public async Task<LoginResultDTO?> LoginAsync(string? username, string? password, CancellationToken cancellationToken)
        {
            var user = await _userManager.FindByNameAsync(username ?? "");
            if (user != null && user.IsDeleted != true && await _userManager.CheckPasswordAsync(user, password ?? ""))
                return await CreateSessionAsync(user, cancellationToken);

            return null;
        }

        public async Task<LoginResultDTO> CreateSessionAsync(ApplicationUser user, CancellationToken cancellationToken)
        {
            ArgumentNullException.ThrowIfNull(user);
            cancellationToken.ThrowIfCancellationRequested();

            var userRoles = await _userManager.GetRolesAsync(user);
            var authClaims = new List<Claim>
            {
                new Claim(ClaimTypes.Name, user.UserName ?? ""),
                new Claim(ClaimTypes.NameIdentifier, user.Id),
                new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString())
            };
            foreach (var userRole in userRoles)
            {
                authClaims.Add(new Claim(ClaimTypes.Role, userRole));
            }
            if (user.AccountId.HasValue)
            {
                authClaims.Add(new Claim(
                    SeaHavenClaimTypes.AccountId,
                    user.AccountId.Value.ToString()));
            }
            else if (userRoles.Contains("Admin"))
            {
                // Explicit signed org-wide elevation — never elevate via absence of account_id.
                authClaims.Add(new Claim(
                    SeaHavenClaimTypes.OrgScope,
                    SeaHavenClaimTypes.OrgScopeAll));
            }
            var token = GetToken(authClaims);
            return new LoginResultDTO
            {
                Token = new JwtSecurityTokenHandler().WriteToken(token),
                Expiration = token.ValidTo,
                Email = user.Email,
                UserRole = userRoles.FirstOrDefault(),
                PhoneNumber = user.PhoneNumber,
                Fullname = $"{user.FirstName} {user.LastName}".Trim(),
                Id = user.Id
            };
        }

        public async Task<ChangePasswordResultDTO> ChangePasswordAsync(string userId, string? currentPassword, string? newPassword, CancellationToken cancellationToken)
        {
            cancellationToken.ThrowIfCancellationRequested();
            var user = await _userManager.FindByIdAsync(userId);
            if (user == null || user.IsDeleted == true)
                return ChangePasswordResult(ChangePasswordStatus.CurrentPasswordIncorrect);

            // The current password is verified before the new one is evaluated, so a
            // caller without it learns nothing about the policy outcome.
            if (!await _userManager.CheckPasswordAsync(user, currentPassword ?? ""))
                return ChangePasswordResult(ChangePasswordStatus.CurrentPasswordIncorrect);

            var result = await _userManager.ChangePasswordAsync(user, currentPassword ?? "", newPassword ?? "");
            if (result.Succeeded)
                return ChangePasswordResult(ChangePasswordStatus.Succeeded);

            return ChangePasswordResult(IdentityPasswordPolicy.IsPolicyRejection(result)
                ? ChangePasswordStatus.PasswordRejected
                : ChangePasswordStatus.Failed);
        }

        private static ChangePasswordResultDTO ChangePasswordResult(ChangePasswordStatus status) =>
            new() { Status = status };

        public async Task<UserProfileDTO?> UpdateProfileAsync(string userId, UpdateProfileRequestDTO dto, CancellationToken cancellationToken)
        {
            var exists = await _userDataService.UpdateProfileAsync(
                userId,
                dto.Name,
                dto.Email,
                dto.Contact,
                cancellationToken);
            if (!exists)
                return null;

            var updated = await _userDataService.GetProfileAsync(userId, cancellationToken);
            if (updated == null) return null;
            return new UserProfileDTO
            {
                FirstName = updated.FirstName,
                Email = updated.Email,
                Contact = updated.Contact
            };
        }

        public async Task<bool> ForgetPasswordAsync(string email, CancellationToken cancellationToken)
        {
            var user = await _userDataService.GetByEmailNormalizedAsync(email, cancellationToken);
            if (user == null) return false;

            var code = GenerateRandomNo();
            await _forgetPasswordDataService.ReplaceCodeAsync(user.Email ?? "", user.Id, code, cancellationToken);
            var body = $"Your Password Reset Code is: " + code;
            await _emailSender.SendEmailAsync(user.Email ?? email, "Forget Password Request.", body);
            return true;
        }

        public async Task<bool> VerifyCodeAsync(string code, CancellationToken cancellationToken)
        {
            return await _forgetPasswordDataService.CodeExistsAsync(code, cancellationToken);
        }

        public async Task<bool> ResetPasswordAsync(string email, string? code, string? password, CancellationToken cancellationToken)
        {
            if (string.IsNullOrWhiteSpace(code) || string.IsNullOrWhiteSpace(password))
                return false;

            var matched = await _forgetPasswordDataService.ExistsByEmailAndCodeAsync(email, code, cancellationToken);
            if (!matched) return false;

            var record = await _forgetPasswordDataService.GetByEmailAsync(email, cancellationToken);
            if (record == null)
                return false;

            var user = await _userManager.FindByIdAsync(record.UserId);
            if (user == null)
                return false;

            var token = await _userManager.GeneratePasswordResetTokenAsync(user);
            var result = await _userManager.ResetPasswordAsync(user, token, password);
            if (!result.Succeeded)
                return false;

            await _forgetPasswordDataService.RemoveByEmailAsync(email, cancellationToken);
            return true;
        }

        private JwtSecurityToken GetToken(List<Claim> authClaims)
        {
            var authSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_jwtOptions.Secret));
            var token = new JwtSecurityToken(
                issuer: _jwtOptions.ValidIssuer,
                audience: _jwtOptions.ValidAudience,
                expires: DateTime.Now.AddDays(10),
                claims: authClaims,
                signingCredentials: new SigningCredentials(authSigningKey, SecurityAlgorithms.HmacSha256)
                );
            return token;
        }

        private static string GenerateRandomNo()
        {
            return RandomNumberGenerator.GetInt32(1_000_000).ToString("D6");
        }
    }
}