using System.Text.RegularExpressions;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using TicketOffice.Data;
using TicketOffice.Models;

namespace TicketOffice.Pages.Auth;

public class LoginModel : PageModel
{
    // Error massage displaying when email validation failed.
    public string EmailValidationError = null!;
    
    // Error massage displaying when password validation failed.
    public string PasswordValidationError = null!;

    private readonly TicketOfficeContext context;
    
    public LoginModel(TicketOfficeContext context)
    {
        this.context = context;
    }
    
    // Object representing a user who wants to login.
    [BindProperty] 
    public new User? User { get; set; }

    // Called when GET request is sent to the page. Validates the session and
    // redirects to "Account" page if user already logged in.
    public ActionResult OnGet()
    {
        if (ValidateSession())
        {
            return RedirectToPage("/Auth/Account");
        }

        return Page();
    }

    // Called when POST request is sent to the page. Validates login form and
    // redirects to "Account" page if the validation succeed.
    public ActionResult OnPost()
    {
        if (ValidateForm())
        {
            User? user = context.User
                .FirstOrDefault(u => u.Email == User!.Email);
            
            HttpContext.Session.SetInt32("UserId", user!.Id);
            return RedirectToPage("/Auth/Account");
        }

        return Page();
    }

    private bool ValidateForm()
    {
        User? user = context.User.FirstOrDefault(u => u.Email == User!.Email);

        return ValidateEmail(User!.Email, out EmailValidationError) &&
               ValidatePassword(User.Password, out PasswordValidationError);
        
        bool ValidateEmail(string email, out string validationError)
        {
            if (user != null)
            {
                validationError = String.Empty;
                return true;
            }
        
            if (String.IsNullOrWhiteSpace(email))
            {
                validationError = "Поле має бути заповненим";
                return false;
            }
        
            Regex emailRegex = new Regex(@"^[^@\s]+@[^@\s]+\.[^@\s]+$");
        
            if (!emailRegex.IsMatch(email))
            {
                validationError = "E-mail некоректний";
                return false;
            }

            validationError = "E-mail не зареєстровано";
            return false;
        }

        bool ValidatePassword(string password, out string validationError)
        {
            if (user!.Password == password)
            {
                validationError = String.Empty;
                return true;
            }
        
            if (String.IsNullOrWhiteSpace(password))
            {
                validationError = "Поле має бути заповненим";
                return false;
            }

            validationError = "Неправильний пароль";
            return false;
        }
    }

    private bool ValidateSession()
    {
        return HttpContext.Session.GetInt32("UserId") != null;
    }
}