using Microsoft.AspNetCore.Identity;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using ROLAC.API.Data;
using ROLAC.API.DTOs.Auth;
using ROLAC.API.Entities;

namespace ROLAC.API.Services;

public class AuthService : IAuthService
{
    private readonly UserManager<AppUser> _userManager;
    private readonly ITokenService        _tokenService;
    private readonly AppDbContext         _db;
    private readonly int                  _refreshTokenExpiryDays;

    public AuthService(
        UserManager<AppUser> userManager,
        ITokenService        tokenService,
        AppDbContext         db,
        IConfiguration       config)
    {
        _userManager            = userManager;
        _tokenService           = tokenService;
        _db                     = db;
        _refreshTokenExpiryDays = int.Parse(config["Jwt:RefreshTokenExpiryDays"] ?? "30");
    }

    // -------------------------------------------------------------------------
    // Login
    // -------------------------------------------------------------------------

    public async Task<(LoginResponse Response, string RawRefreshToken)> LoginAsync(
        LoginRequest request, string? ipAddress = null, string? deviceInfo = null)
    {
        var user = await _userManager.FindByEmailAsync(request.Email);
        if (user is null)
            throw new UnauthorizedAccessException("Invalid credentials.");

        if (!await _userManager.CheckPasswordAsync(user, request.Password))
            throw new UnauthorizedAccessException("Invalid credentials.");

        if (!user.IsActive)
            throw new UnauthorizedAccessException("Account is inactive.");

        var roles       = await _userManager.GetRolesAsync(user);
        var accessToken = _tokenService.GenerateAccessToken(user, roles);
        var rawRefresh  = _tokenService.GenerateRefreshToken();
        var tokenHash   = _tokenService.HashToken(rawRefresh);

        _db.RefreshTokens.Add(new RefreshToken
        {
            UserId     = user.Id,
            TokenHash  = tokenHash,
            ExpiresAt  = DateTime.UtcNow.AddDays(_refreshTokenExpiryDays),
            CreatedAt  = DateTime.UtcNow,
            IpAddress  = ipAddress,
            DeviceInfo = deviceInfo,
        });

        user.LastLoginAt = DateTime.UtcNow;
        await _userManager.UpdateAsync(user);
        await _db.SaveChangesAsync();

        return (BuildResponse(accessToken, user, roles), rawRefresh);
    }

    // -------------------------------------------------------------------------
    // Refresh
    // -------------------------------------------------------------------------

    public async Task<(LoginResponse Response, string RawRefreshToken)> RefreshAsync(
        string rawRefreshToken, string? ipAddress = null)
    {
        var hash  = _tokenService.HashToken(rawRefreshToken);
        var token = await _db.RefreshTokens
            .FirstOrDefaultAsync(rt => rt.TokenHash == hash);

        if (token is null || !token.IsActive)
            throw new UnauthorizedAccessException("Invalid or expired refresh token.");

        var user = await _userManager.FindByIdAsync(token.UserId);
        if (user is null)
            throw new UnauthorizedAccessException("User not found.");

        var roles      = await _userManager.GetRolesAsync(user);
        var newAccess  = _tokenService.GenerateAccessToken(user, roles);
        var newRaw     = _tokenService.GenerateRefreshToken();
        var newHash    = _tokenService.HashToken(newRaw);

        // Rotate: mark old token replaced+revoked, create new token
        token.RevokedAt      = DateTime.UtcNow;
        token.ReplacedByHash = newHash;

        _db.RefreshTokens.Add(new RefreshToken
        {
            UserId     = user.Id,
            TokenHash  = newHash,
            ExpiresAt  = DateTime.UtcNow.AddDays(_refreshTokenExpiryDays),
            CreatedAt  = DateTime.UtcNow,
            IpAddress  = ipAddress,
            DeviceInfo = token.DeviceInfo,
        });

        await _db.SaveChangesAsync();

        return (BuildResponse(newAccess, user, roles), newRaw);
    }

    // -------------------------------------------------------------------------
    // Logout
    // -------------------------------------------------------------------------

    public async Task LogoutAsync(string rawRefreshToken)
    {
        var hash  = _tokenService.HashToken(rawRefreshToken);
        var token = await _db.RefreshTokens
            .FirstOrDefaultAsync(rt => rt.TokenHash == hash);

        if (token is not null && token.IsActive)
        {
            token.RevokedAt = DateTime.UtcNow;
            await _db.SaveChangesAsync();
        }
    }

    // -------------------------------------------------------------------------
    // Private helpers
    // -------------------------------------------------------------------------

    private static LoginResponse BuildResponse(
        string accessToken, AppUser user, IList<string> roles)
        => new()
        {
            AccessToken = accessToken,
            ExpiresIn   = 15 * 60,
            User = new UserInfo
            {
                Id                 = user.Id,
                Email              = user.Email!,
                Roles              = roles,
                LanguagePreference = user.LanguagePreference,
            },
        };
}