using System.Security.Claims;
using Asp.Versioning;
using MediatR;
using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using OpenIddict.Abstractions;
using OpenIddict.Server.AspNetCore;
using OpenIddict.Validation.AspNetCore;
using Swashbuckle.AspNetCore.Annotations;
using IamService.API.Application.Commands.Auth;
using IamService.API.Application.Common;
using IamService.Domain.AggregatesModel.UserAggregate;
using static OpenIddict.Abstractions.OpenIddictConstants;

namespace IamService.API.Controllers;

/// <summary>
/// EN: Authentication controller with OpenIddict OAuth2/OIDC endpoints.
/// VI: Controller xác thực với OpenIddict OAuth2/OIDC endpoints.
/// </summary>
[ApiController]
[ApiVersion("1.0")]
[Route("api/v{version:apiVersion}/auth")]
[SwaggerTag("Authentication endpoints - OAuth2/OIDC")]
public class AuthController : ControllerBase
{
    private readonly IMediator _mediator;
    private readonly UserManager<ApplicationUser> _userManager;
    private readonly SignInManager<ApplicationUser> _signInManager;
    private readonly ILogger<AuthController> _logger;

    public AuthController(
        IMediator mediator,
        UserManager<ApplicationUser> userManager,
        SignInManager<ApplicationUser> signInManager,
        ILogger<AuthController> logger)
    {
        _mediator = mediator;
        _userManager = userManager;
        _signInManager = signInManager;
        _logger = logger;
    }

    /// <summary>
    /// EN: Register a new user.
    /// VI: Đăng ký user mới.
    /// </summary>
    /// <param name="command">User registration data</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>Registered user information</returns>
    [HttpPost("register")]
    [SwaggerOperation(
        Summary = "Register a new user",
        Description = "Creates a new user account with email and password.",
        OperationId = "RegisterUser")]
    [SwaggerResponse(StatusCodes.Status201Created, "User successfully registered", typeof(ApiResponse<RegisterUserCommandResult>))]
    [SwaggerResponse(StatusCodes.Status400BadRequest, "Invalid registration data")]
    [SwaggerResponse(StatusCodes.Status409Conflict, "User with this email already exists")]
    [ProducesResponseType(typeof(ApiResponse<RegisterUserCommandResult>), StatusCodes.Status201Created)]
    [ProducesResponseType(StatusCodes.Status400BadRequest)]
    [ProducesResponseType(StatusCodes.Status409Conflict)]
    public async Task<IActionResult> Register(
        [FromBody, SwaggerRequestBody("User registration details", Required = true)] RegisterUserCommand command,
        CancellationToken cancellationToken)
    {
        var result = await _mediator.Send(command, cancellationToken);
        return CreatedAtAction(nameof(Register), new { id = result.UserId }, ApiResponse<RegisterUserCommandResult>.Ok(result));
    }


    /// <summary>
    /// EN: OAuth2 Token endpoint - supports password, refresh_token, and client_credentials grants.
    /// VI: OAuth2 Token endpoint - hỗ trợ password, refresh_token, và client_credentials grants.
    /// </summary>
    /// <remarks>
    /// **Password Grant (Login):**
    /// ```
    /// POST /connect/token
    /// Content-Type: application/x-www-form-urlencoded
    /// 
    /// grant_type=password&amp;username=user@example.com&amp;password=YourPassword&amp;scope=openid profile email roles api
    /// ```
    /// 
    /// **Refresh Token Grant:**
    /// ```
    /// POST /connect/token
    /// Content-Type: application/x-www-form-urlencoded
    /// 
    /// grant_type=refresh_token&amp;refresh_token=YOUR_REFRESH_TOKEN
    /// ```
    /// 
    /// **Client Credentials Grant:**
    /// ```
    /// POST /connect/token
    /// Content-Type: application/x-www-form-urlencoded
    /// 
    /// grant_type=client_credentials&amp;client_id=YOUR_CLIENT_ID&amp;client_secret=YOUR_CLIENT_SECRET&amp;scope=api
    /// ```
    /// </remarks>
    /// <returns>OAuth2 token response with access_token, refresh_token, expires_in</returns>
    [HttpPost("~/connect/token")]
    [Consumes("application/x-www-form-urlencoded")]
    [Produces("application/json")]
    [SwaggerOperation(
        Summary = "OAuth2 Token Endpoint",
        Description = "Exchanges credentials for access tokens. Supports password, refresh_token, and client_credentials grant types.",
        OperationId = "GetToken",
        Tags = new[] { "Authentication" })]
    [SwaggerResponse(StatusCodes.Status200OK, "Token issued successfully", typeof(TokenResponse))]
    [SwaggerResponse(StatusCodes.Status400BadRequest, "Invalid request (missing parameters)")]
    [SwaggerResponse(StatusCodes.Status401Unauthorized, "Invalid credentials or token")]
    [SwaggerResponse(StatusCodes.Status403Forbidden, "Account locked or unsupported grant type")]
    [ProducesResponseType(typeof(TokenResponse), StatusCodes.Status200OK)]
    [ProducesResponseType(StatusCodes.Status400BadRequest)]
    [ProducesResponseType(StatusCodes.Status401Unauthorized)]
    [ProducesResponseType(StatusCodes.Status403Forbidden)]
    public async Task<IActionResult> Exchange()
    {
        var request = HttpContext.GetOpenIddictServerRequest()
            ?? throw new InvalidOperationException("The OpenID Connect request cannot be retrieved.");

        if (request.IsPasswordGrantType())
        {
            return await HandlePasswordGrantAsync(request);
        }

        if (request.IsRefreshTokenGrantType())
        {
            return await HandleRefreshTokenGrantAsync();
        }

        if (request.IsClientCredentialsGrantType())
        {
            return await HandleClientCredentialsGrantAsync(request);
        }

        _logger.LogWarning("Unsupported grant type: {GrantType}", request.GrantType);
        return Forbid(
            authenticationSchemes: OpenIddictServerAspNetCoreDefaults.AuthenticationScheme,
            properties: new AuthenticationProperties(new Dictionary<string, string?>
            {
                [OpenIddictServerAspNetCoreConstants.Properties.Error] = Errors.UnsupportedGrantType,
                [OpenIddictServerAspNetCoreConstants.Properties.ErrorDescription] = "The specified grant type is not supported."
            }));
    }

    private async Task<IActionResult> HandlePasswordGrantAsync(OpenIddictRequest request)
    {
        var user = await _userManager.FindByEmailAsync(request.Username!);
        if (user == null)
        {
            _logger.LogWarning("Login failed: user not found for {Email}", request.Username);
            return Forbid(
                authenticationSchemes: OpenIddictServerAspNetCoreDefaults.AuthenticationScheme,
                properties: new AuthenticationProperties(new Dictionary<string, string?>
                {
                    [OpenIddictServerAspNetCoreConstants.Properties.Error] = Errors.InvalidGrant,
                    [OpenIddictServerAspNetCoreConstants.Properties.ErrorDescription] = "Invalid email or password."
                }));
        }

        // EN: Check password
        // VI: Kiểm tra password
        var result = await _signInManager.CheckPasswordSignInAsync(user, request.Password!, lockoutOnFailure: true);

        if (result.IsLockedOut)
        {
            _logger.LogWarning("Login failed: user {UserId} is locked out", user.Id);
            return Forbid(
                authenticationSchemes: OpenIddictServerAspNetCoreDefaults.AuthenticationScheme,
                properties: new AuthenticationProperties(new Dictionary<string, string?>
                {
                    [OpenIddictServerAspNetCoreConstants.Properties.Error] = Errors.InvalidGrant,
                    [OpenIddictServerAspNetCoreConstants.Properties.ErrorDescription] = "Account is locked. Please try again later."
                }));
        }

        if (!result.Succeeded)
        {
            _logger.LogWarning("Login failed: invalid password for user {UserId}", user.Id);
            return Forbid(
                authenticationSchemes: OpenIddictServerAspNetCoreDefaults.AuthenticationScheme,
                properties: new AuthenticationProperties(new Dictionary<string, string?>
                {
                    [OpenIddictServerAspNetCoreConstants.Properties.Error] = Errors.InvalidGrant,
                    [OpenIddictServerAspNetCoreConstants.Properties.ErrorDescription] = "Invalid email or password."
                }));
        }

        // EN: Record login and create claims
        // VI: Ghi nhận login và tạo claims
        user.RecordLogin();

        var identity = new ClaimsIdentity(
            authenticationType: OpenIddictServerAspNetCoreDefaults.AuthenticationScheme,
            nameType: Claims.Name,
            roleType: Claims.Role);

        // EN: Add claims
        // VI: Thêm claims
        identity.SetClaim(Claims.Subject, user.Id.ToString())
                .SetClaim(Claims.Email, user.Email)
                .SetClaim(Claims.Name, user.FullName)
                .SetClaim("first_name", user.FirstName)
                .SetClaim("last_name", user.LastName);

        // EN: Add roles to claims
        // VI: Thêm roles vào claims
        var roles = await _userManager.GetRolesAsync(user);
        identity.SetClaims(Claims.Role, [.. roles]);

        // EN: Set destinations for claims
        // VI: Set destinations cho claims
        identity.SetDestinations(GetDestinations);

        var principal = new ClaimsPrincipal(identity);

        // EN: Set scopes
        // VI: Set scopes
        principal.SetScopes(request.GetScopes());

        _logger.LogInformation("User {UserId} logged in successfully", user.Id);

        return SignIn(principal, OpenIddictServerAspNetCoreDefaults.AuthenticationScheme);
    }

    private async Task<IActionResult> HandleRefreshTokenGrantAsync()
    {
        var result = await HttpContext.AuthenticateAsync(OpenIddictServerAspNetCoreDefaults.AuthenticationScheme);
        var userId = result.Principal?.GetClaim(Claims.Subject);

        if (string.IsNullOrEmpty(userId))
        {
            return Forbid(
                authenticationSchemes: OpenIddictServerAspNetCoreDefaults.AuthenticationScheme,
                properties: new AuthenticationProperties(new Dictionary<string, string?>
                {
                    [OpenIddictServerAspNetCoreConstants.Properties.Error] = Errors.InvalidGrant,
                    [OpenIddictServerAspNetCoreConstants.Properties.ErrorDescription] = "The refresh token is no longer valid."
                }));
        }

        var user = await _userManager.FindByIdAsync(userId);
        if (user == null)
        {
            return Forbid(
                authenticationSchemes: OpenIddictServerAspNetCoreDefaults.AuthenticationScheme,
                properties: new AuthenticationProperties(new Dictionary<string, string?>
                {
                    [OpenIddictServerAspNetCoreConstants.Properties.Error] = Errors.InvalidGrant,
                    [OpenIddictServerAspNetCoreConstants.Properties.ErrorDescription] = "The user no longer exists."
                }));
        }

        // EN: Recreate principal with updated claims
        // VI: Tạo lại principal với claims đã cập nhật
        var identity = new ClaimsIdentity(result.Principal!.Claims,
            authenticationType: OpenIddictServerAspNetCoreDefaults.AuthenticationScheme,
            nameType: Claims.Name,
            roleType: Claims.Role);

        identity.SetDestinations(GetDestinations);

        return SignIn(new ClaimsPrincipal(identity), OpenIddictServerAspNetCoreDefaults.AuthenticationScheme);
    }

    private Task<IActionResult> HandleClientCredentialsGrantAsync(OpenIddictRequest request)
    {
        var identity = new ClaimsIdentity(
            authenticationType: OpenIddictServerAspNetCoreDefaults.AuthenticationScheme,
            nameType: Claims.Name,
            roleType: Claims.Role);

        identity.SetClaim(Claims.Subject, request.ClientId);

        identity.SetDestinations(GetDestinations);

        var principal = new ClaimsPrincipal(identity);
        principal.SetScopes(request.GetScopes());

        return Task.FromResult<IActionResult>(
            SignIn(principal, OpenIddictServerAspNetCoreDefaults.AuthenticationScheme));
    }

    /// <summary>
    /// EN: Change user password.
    /// VI: Đổi mật khẩu user.
    /// </summary>
    /// <param name="request">Change password request data</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>Result of password change operation</returns>
    [HttpPost("change-password")]
    [Microsoft.AspNetCore.Authorization.Authorize(AuthenticationSchemes = OpenIddictValidationAspNetCoreDefaults.AuthenticationScheme)]
    [SwaggerOperation(
        Summary = "Change password",
        Description = "Changes the password for the currently authenticated user. Requires current password verification.",
        OperationId = "ChangePassword")]
    [SwaggerResponse(StatusCodes.Status200OK, "Password changed successfully", typeof(ChangePasswordResponse))]
    [SwaggerResponse(StatusCodes.Status400BadRequest, "Invalid request (current password incorrect)")]
    [SwaggerResponse(StatusCodes.Status401Unauthorized, "Authentication required")]
    [ProducesResponseType(typeof(ChangePasswordResponse), StatusCodes.Status200OK)]
    [ProducesResponseType(StatusCodes.Status400BadRequest)]
    [ProducesResponseType(StatusCodes.Status401Unauthorized)]
    public async Task<IActionResult> ChangePassword(
        [FromBody, SwaggerRequestBody("Password change data", Required = true)] ChangePasswordRequest request,
        CancellationToken cancellationToken)
    {
        var userIdClaim = User.FindFirst("sub")?.Value;
        if (string.IsNullOrEmpty(userIdClaim) || !Guid.TryParse(userIdClaim, out var userId))
        {
            return Unauthorized();
        }

        var command = new ChangePasswordCommand(userId, request.CurrentPassword, request.NewPassword);
        var result = await _mediator.Send(command, cancellationToken);

        if (!result.Success)
        {
            return BadRequest(new ChangePasswordResponse { Success = false, Message = result.Message });
        }

        return Ok(new ChangePasswordResponse { Success = true, Message = result.Message });
    }

    /// <summary>
    /// EN: Logout user and revoke tokens.
    /// VI: Logout user và thu hồi tokens.
    /// </summary>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>Result of logout operation</returns>
    [HttpPost("logout")]
    [Microsoft.AspNetCore.Authorization.Authorize(AuthenticationSchemes = OpenIddictValidationAspNetCoreDefaults.AuthenticationScheme)]
    [SwaggerOperation(
        Summary = "Logout",
        Description = "Logs out the current user and revokes all associated tokens.",
        OperationId = "Logout")]
    [SwaggerResponse(StatusCodes.Status200OK, "User logged out successfully", typeof(LogoutResponse))]
    [SwaggerResponse(StatusCodes.Status401Unauthorized, "Authentication required")]
    [ProducesResponseType(typeof(LogoutResponse), StatusCodes.Status200OK)]
    [ProducesResponseType(StatusCodes.Status401Unauthorized)]
    public async Task<IActionResult> Logout(CancellationToken cancellationToken)
    {
        var userIdClaim = User.FindFirst("sub")?.Value;
        if (string.IsNullOrEmpty(userIdClaim) || !Guid.TryParse(userIdClaim, out var userId))
        {
            return Unauthorized();
        }

        var command = new LogoutCommand(userId);
        var result = await _mediator.Send(command, cancellationToken);

        return Ok(new LogoutResponse { Success = result.Success, Message = result.Message });
    }

    private static IEnumerable<string> GetDestinations(Claim claim)
    {
        switch (claim.Type)
        {
            case Claims.Name or Claims.Email:
                yield return Destinations.AccessToken;
                if (claim.Subject?.HasScope(Scopes.Profile) == true)
                    yield return Destinations.IdentityToken;
                yield break;

            case Claims.Role:
                yield return Destinations.AccessToken;
                if (claim.Subject?.HasScope(Scopes.Roles) == true)
                    yield return Destinations.IdentityToken;
                yield break;

            default:
                yield return Destinations.AccessToken;
                yield break;
        }
    }
}

/// <summary>
/// EN: Request body for changing password.
/// VI: Request body để đổi mật khẩu.
/// </summary>
public class ChangePasswordRequest
{
    /// <summary>
    /// EN: Current password.
    /// VI: Mật khẩu hiện tại.
    /// </summary>
    /// <example>OldPassword123!</example>
    public string CurrentPassword { get; set; } = string.Empty;

    /// <summary>
    /// EN: New password.
    /// VI: Mật khẩu mới.
    /// </summary>
    /// <example>NewPassword456!</example>
    public string NewPassword { get; set; } = string.Empty;
}

/// <summary>
/// EN: Response for change password operation.
/// VI: Response cho thao tác đổi mật khẩu.
/// </summary>
public class ChangePasswordResponse
{
    /// <summary>
    /// EN: Whether the operation was successful.
    /// VI: Thao tác có thành công không.
    /// </summary>
    public bool Success { get; set; }

    /// <summary>
    /// EN: Result message.
    /// VI: Thông điệp kết quả.
    /// </summary>
    public string Message { get; set; } = string.Empty;
}

/// <summary>
/// EN: Response for logout operation.
/// VI: Response cho thao tác logout.
/// </summary>
public class LogoutResponse
{
    /// <summary>
    /// EN: Whether the operation was successful.
    /// VI: Thao tác có thành công không.
    /// </summary>
    public bool Success { get; set; }

    /// <summary>
    /// EN: Result message.
    /// VI: Thông điệp kết quả.
    /// </summary>
    public string Message { get; set; } = string.Empty;
}