using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Text;
using System.Text.Encodings.Web;
using System.Threading.Tasks;
using Marechai.Database.Models;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Identity.UI.Services;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.AspNetCore.WebUtilities;
using Microsoft.Extensions.Logging;

namespace Marechai.Areas.Identity.Pages.Account
{
    [AllowAnonymous]
    public class RegisterModel : PageModel
    {
        readonly IEmailSender                   _emailSender;
        readonly ILogger<RegisterModel>         _logger;
        readonly SignInManager<ApplicationUser> _signInManager;
        readonly UserManager<ApplicationUser>   _userManager;

        public RegisterModel(UserManager<ApplicationUser> userManager, SignInManager<ApplicationUser> signInManager,
                             ILogger<RegisterModel> logger, IEmailSender emailSender)
        {
            _userManager   = userManager;
            _signInManager = signInManager;
            _logger        = logger;
            _emailSender   = emailSender;
        }

        [BindProperty]
        public InputModel Input { get; set; }

        public string ReturnUrl { get; set; }

        public IList<AuthenticationScheme> ExternalLogins { get; set; }

        public async Task OnGetAsync(string returnUrl = null)
        {
            ReturnUrl      = returnUrl;
            ExternalLogins = (await _signInManager.GetExternalAuthenticationSchemesAsync()).ToList();
        }

        public async Task<IActionResult> OnPostAsync(string returnUrl = null)
        {
            returnUrl      = returnUrl ?? Url.Content("~/");
            ExternalLogins = (await _signInManager.GetExternalAuthenticationSchemesAsync()).ToList();

            if(ModelState.IsValid)
            {
                var user = new ApplicationUser
                {
                    UserName = Input.Email,
                    Email    = Input.Email
                };

                IdentityResult result = await _userManager.CreateAsync(user, Input.Password);

                if(result.Succeeded)
                {
                    _logger.LogInformation("User created a new account with password.");

                    string code = await _userManager.GenerateEmailConfirmationTokenAsync(user);
                    code = WebEncoders.Base64UrlEncode(Encoding.UTF8.GetBytes(code));

                    string callbackUrl = Url.Page("/Account/ConfirmEmail", null, new
                    {
                        area   = "Identity",
                        userId = user.Id,
                        code,
                        returnUrl
                    }, Request.Scheme);

                    await _emailSender.SendEmailAsync(Input.Email, "Confirm your email",
                                                      $"Please confirm your account by <a href='{HtmlEncoder.Default.Encode(callbackUrl)}'>clicking here</a>.");

                    if(_userManager.Options.SignIn.RequireConfirmedAccount)
                    {
                        return RedirectToPage("RegisterConfirmation", new
                        {
                            email = Input.Email,
                            returnUrl
                        });
                    }

                    await _signInManager.SignInAsync(user, false);

                    return LocalRedirect(returnUrl);
                }

                foreach(IdentityError error in result.Errors)
                {
                    ModelState.AddModelError(string.Empty, error.Description);
                }
            }

            // If we got this far, something failed, redisplay form
            return Page();
        }

        public class InputModel
        {
            [Required, EmailAddress, Display(Name = "Email")]
            public string Email { get; set; }

            [Required,
             StringLength(100, ErrorMessage = "The {0} must be at least {2} and at max {1} characters long.",
                          MinimumLength     = 6), DataType(DataType.Password), Display(Name = "Password")]
            public string Password { get; set; }

            [DataType(DataType.Password), Display(Name = "Confirm password"),
             Compare("Password", ErrorMessage          = "The password and confirmation password do not match.")]
            public string ConfirmPassword { get; set; }
        }
    }
}