using System.ComponentModel.DataAnnotations;
using System.Security.Claims;
using line_gestao_api.Dtos;
using line_gestao_api.Models;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;

namespace line_gestao_api.Controllers;

[ApiController]
[Route("api/profile")]
[Authorize]
public class ProfileController : ControllerBase
{
    private static readonly EmailAddressAttribute EmailValidator = new();
    private readonly UserManager<ApplicationUser> _userManager;

    public ProfileController(UserManager<ApplicationUser> userManager)
    {
        _userManager = userManager;
    }

    [HttpGet("me")]
    public async Task<ActionResult<ProfileMeDto>> GetMe()
    {
        var user = await GetAuthenticatedUserAsync();
        if (user == null)
        {
            return Unauthorized(new { message = "Usuário não autenticado." });
        }

        return Ok(ToProfileDto(user));
    }

    [HttpPatch]
    public async Task<ActionResult<ProfileMeDto>> UpdateProfile([FromBody] UpdateProfileRequest req)
    {
        var user = await GetAuthenticatedUserAsync();
        if (user == null)
        {
            return Unauthorized(new { message = "Usuário não autenticado." });
        }

        var errors = await ValidateProfileUpdateAsync(user.Id, req);
        if (errors.Count > 0)
        {
            return BadRequest(new ValidationErrorResponse { Errors = errors });
        }

        var nome = req.Nome.Trim();
        var email = req.Email.Trim().ToLowerInvariant();

        user.Name = nome;

        if (!string.Equals(user.Email, email, StringComparison.OrdinalIgnoreCase))
        {
            var setEmailResult = await _userManager.SetEmailAsync(user, email);
            if (!setEmailResult.Succeeded)
            {
                return BadRequest(ToValidationErrorResponse("email", setEmailResult.Errors));
            }

            var setUserNameResult = await _userManager.SetUserNameAsync(user, email);
            if (!setUserNameResult.Succeeded)
            {
                return BadRequest(ToValidationErrorResponse("email", setUserNameResult.Errors));
            }
        }

        var updateResult = await _userManager.UpdateAsync(user);
        if (!updateResult.Succeeded)
        {
            return BadRequest(ToValidationErrorResponse("perfil", updateResult.Errors));
        }

        return Ok(ToProfileDto(user));
    }

    [HttpPost("change-password")]
    public async Task<IActionResult> ChangePassword([FromBody] ChangeMyPasswordRequest req)
    {
        var errors = ValidatePasswordChange(req);
        if (errors.Count > 0)
        {
            return BadRequest(new ValidationErrorResponse { Errors = errors });
        }

        var user = await GetAuthenticatedUserAsync();
        if (user == null)
        {
            return Unauthorized(new { message = "Usuário não autenticado." });
        }

        var result = await _userManager.ChangePasswordAsync(user, req.CredencialAtual, req.NovaCredencial);
        if (!result.Succeeded)
        {
            return BadRequest(MapPasswordChangeErrors(result.Errors));
        }

        return NoContent();
    }

    private async Task<ApplicationUser?> GetAuthenticatedUserAsync()
    {
        var userIdRaw = User.FindFirstValue(ClaimTypes.NameIdentifier)
            ?? User.FindFirstValue("sub");

        if (!Guid.TryParse(userIdRaw, out var userId))
        {
            return null;
        }

        return await _userManager.Users
            .FirstOrDefaultAsync(u => u.Id == userId && u.IsActive);
    }

    private async Task<List<ValidationErrorDto>> ValidateProfileUpdateAsync(Guid userId, UpdateProfileRequest req)
    {
        var errors = new List<ValidationErrorDto>();

        if (string.IsNullOrWhiteSpace(req.Nome) || req.Nome.Trim().Length < 2)
        {
            errors.Add(new ValidationErrorDto
            {
                Field = "nome",
                Message = "Nome é obrigatório e deve ter pelo menos 2 caracteres."
            });
        }

        if (string.IsNullOrWhiteSpace(req.Email))
        {
            errors.Add(new ValidationErrorDto
            {
                Field = "email",
                Message = "Email é obrigatório."
            });
        }
        else
        {
            var email = req.Email.Trim().ToLowerInvariant();
            if (!EmailValidator.IsValid(email))
            {
                errors.Add(new ValidationErrorDto
                {
                    Field = "email",
                    Message = "Email inválido."
                });
            }
            else
            {
                var normalized = _userManager.NormalizeEmail(email);
                var exists = await _userManager.Users
                    .AnyAsync(u => u.Id != userId && u.NormalizedEmail == normalized);

                if (exists)
                {
                    errors.Add(new ValidationErrorDto
                    {
                        Field = "email",
                        Message = "E-mail já cadastrado."
                    });
                }
            }
        }

        return errors;
    }

    private static List<ValidationErrorDto> ValidatePasswordChange(ChangeMyPasswordRequest req)
    {
        var errors = new List<ValidationErrorDto>();

        if (string.IsNullOrWhiteSpace(req.CredencialAtual))
        {
            errors.Add(new ValidationErrorDto
            {
                Field = "credencialAtual",
                Message = "Credencial atual é obrigatória."
            });
        }

        if (string.IsNullOrWhiteSpace(req.NovaCredencial))
        {
            errors.Add(new ValidationErrorDto
            {
                Field = "novaCredencial",
                Message = "Nova credencial é obrigatória."
            });
        }
        else if (req.NovaCredencial.Length < 8)
        {
            errors.Add(new ValidationErrorDto
            {
                Field = "novaCredencial",
                Message = "Nova credencial deve ter pelo menos 8 caracteres."
            });
        }

        if (string.IsNullOrWhiteSpace(req.ConfirmarNovaCredencial))
        {
            errors.Add(new ValidationErrorDto
            {
                Field = "confirmarNovaCredencial",
                Message = "Confirmação da nova credencial é obrigatória."
            });
        }
        else if (!string.Equals(req.NovaCredencial, req.ConfirmarNovaCredencial, StringComparison.Ordinal))
        {
            errors.Add(new ValidationErrorDto
            {
                Field = "confirmarNovaCredencial",
                Message = "Confirmação da nova credencial inválida."
            });
        }

        return errors;
    }

    private static ValidationErrorResponse ToValidationErrorResponse(string field, IEnumerable<IdentityError> identityErrors)
    {
        return new ValidationErrorResponse
        {
            Errors = identityErrors.Select(e => new ValidationErrorDto
            {
                Field = field,
                Message = e.Description
            }).ToList()
        };
    }

    private static ValidationErrorResponse MapPasswordChangeErrors(IEnumerable<IdentityError> identityErrors)
    {
        var errors = identityErrors.Select(e =>
        {
            var field = string.Equals(e.Code, "PasswordMismatch", StringComparison.OrdinalIgnoreCase)
                ? "credencialAtual"
                : "novaCredencial";

            var message = string.Equals(e.Code, "PasswordMismatch", StringComparison.OrdinalIgnoreCase)
                ? "Credencial atual inválida."
                : e.Description;

            return new ValidationErrorDto
            {
                Field = field,
                Message = message
            };
        }).ToList();

        return new ValidationErrorResponse { Errors = errors };
    }

    private static ProfileMeDto ToProfileDto(ApplicationUser user)
    {
        return new ProfileMeDto
        {
            Id = user.Id,
            Nome = user.Name,
            Email = user.Email ?? string.Empty
        };
    }
}