using CalendarReminder.Api.Data;
using CalendarReminder.Api.Models;
using CalendarReminder.Api.Services;
using CalendarReminder.Domain.Entities;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;

namespace CalendarReminder.Api.Controllers;

[ApiController]
[Route("api/[controller]")]
public class AuthController : ControllerBase
{
    private readonly AppDbContext _db;
    private readonly TokenService _tokenService;
    private readonly EmailService _emailService;

    public AuthController(AppDbContext db, TokenService tokenService, EmailService emailService)
    {
        _db = db;
        _tokenService = tokenService;
        _emailService = emailService;
    }

    // POST api/auth/register  (interný endpoint — nie je vystavený vo frontende)
    [HttpPost("register")]
    public async Task<IActionResult> Register(RegisterRequest req)
    {
        if (await _db.Users.AnyAsync(u => u.Email == req.Email))
            return BadRequest("Email je už registrovaný.");
        if (await _db.Users.AnyAsync(u => u.Username == req.Username))
            return BadRequest("Používateľské meno je obsadené.");

        var user = new User
        {
            Username = req.Username,
            Email    = req.Email,
            PasswordHash = BCrypt.Net.BCrypt.HashPassword(req.Password)
        };
        _db.Users.Add(user);
        await _db.SaveChangesAsync();

        var token = _tokenService.GenerateToken(user);
        return Ok(new AuthResponse(token, user.Username, user.Email, user.IsAdmin, user.MustChangePassword));
    }

    // POST api/auth/login
    [HttpPost("login")]
    public async Task<IActionResult> Login(LoginRequest req)
    {
        // Podpor prihlásenie cez email aj username
        var user = await _db.Users.FirstOrDefaultAsync(u =>
            u.Email == req.Email || u.Username == req.Email);

        if (user is null || !BCrypt.Net.BCrypt.Verify(req.Password, user.PasswordHash))
            return Unauthorized("Nesprávny email/meno alebo heslo.");

        var token = _tokenService.GenerateToken(user);
        return Ok(new AuthResponse(token, user.Username, user.Email, user.IsAdmin, user.MustChangePassword));
    }

    // POST api/auth/send-reset-code
    // Vygeneruje 8-znakový kód a odošle ho emailom (pre budúce použitie)
    [HttpPost("send-reset-code")]
    public async Task<IActionResult> SendResetCode([FromBody] SendResetCodeRequest req)
    {
        var user = await _db.Users.FirstOrDefaultAsync(u => u.Email == req.Email);
        if (user is null)
            return BadRequest("Email neexistuje.");

        // Zneplatni staré tokeny
        var old = _db.PasswordResetTokens.Where(t => t.Email == req.Email && !t.Used);
        _db.PasswordResetTokens.RemoveRange(old);

        // Vygeneruj nový 8-znakový kód
        const string chars = "ABCDEFGHJKLMNPQRSTUVWXYZ23456789";
        var rng  = new Random();
        var code = new string(Enumerable.Range(0, 8).Select(_ => chars[rng.Next(chars.Length)]).ToArray());

        _db.PasswordResetTokens.Add(new PasswordResetToken
        {
            Email     = req.Email,
            Code      = code,
            ExpiresAt = DateTime.UtcNow.AddMinutes(30),
            Used      = false
        });
        await _db.SaveChangesAsync();

        await _emailService.SendAsync(req.Email, user.Username,
            "🔑 Obnova hesla — Calendar Reminder",
            $"""
            <div style="font-family:Segoe UI,sans-serif;max-width:480px;margin:auto;background:#161b22;color:#e1e4e8;border-radius:10px;overflow:hidden">
              <div style="background:#1f6feb;padding:1.2rem 1.5rem">
                <h2 style="margin:0;color:#fff;font-size:1.1rem">🔑 Obnova hesla</h2>
              </div>
              <div style="padding:1.5rem">
                <p style="margin:0 0 1rem">Tvoj kód na obnovu hesla:</p>
                <div style="background:#0d1117;border:1px solid #30363d;border-radius:8px;padding:1rem;text-align:center;font-size:2rem;font-weight:700;letter-spacing:0.4rem;color:#58a6ff">{code}</div>
                <p style="margin:1rem 0 0;color:#8b949e;font-size:0.85rem">Kód je platný 30 minút. Ak si o reset nepožiadal, ignoruj tento email.</p>
              </div>
            </div>
            """);

        return Ok("Kód bol odoslaný na email.");
    }

    // POST api/auth/reset-password
    [HttpPost("reset-password")]
    public async Task<IActionResult> ResetPassword([FromBody] ResetPasswordRequest req)
    {
        var user = await _db.Users.FirstOrDefaultAsync(u => u.Email == req.Email);
        if (user is null)
            return BadRequest("Email neexistuje.");

        // Ak je kód zadaný — over ho
        if (!string.IsNullOrEmpty(req.Code))
        {
            var resetToken = await _db.PasswordResetTokens
                .Where(t => t.Email == req.Email && !t.Used && t.ExpiresAt > DateTime.UtcNow)
                .OrderByDescending(t => t.ExpiresAt)
                .FirstOrDefaultAsync();

            if (resetToken is null || resetToken.Code != req.Code.ToUpper())
                return BadRequest("Nesprávny alebo expirovaný kód.");

            resetToken.Used = true;
        }

        user.PasswordHash = BCrypt.Net.BCrypt.HashPassword(req.NewPassword);
        await _db.SaveChangesAsync();

        return Ok("Heslo bolo úspešne zmenené.");
    }
}

public record SendResetCodeRequest(string Email);
public record ResetPasswordRequest(string Email, string NewPassword, string? Code);