<?php

declare(strict_types=1);

namespace App\Http\Controllers;

use App\Auth\SessionPayload;
use App\Exception\ApiException;
use App\Exception\ValidationException;
use App\Mail\EmailVerifier;
use App\Mail\MailException;
use App\Repository\UserRepository;
use Psr\Http\Message\ResponseInterface as Response;
use Psr\Http\Message\ServerRequestInterface as Request;

final class AuthController extends Controller
{
    private const PASSWORD_MIN = 8;

    // bcrypt (password_hash's current default) only considers the first 72 bytes.
    private const PASSWORD_MAX = 72;

    private const EMAIL_MAX = 255;

    public function __construct(
        private readonly UserRepository $users,
        private readonly SessionPayload $session,
        private readonly EmailVerifier $verifier,
    ) {
    }

    /**
     * POST /api/auth/register
     */
    public function register(Request $request, Response $response): Response
    {
        [$email, $password] = $this->credentials($request);

        if ($this->users->findByEmail($email) !== null) {
            throw new ApiException('That email address is already registered.', 409);
        }

        $user = $this->users->create($email, password_hash($password, PASSWORD_DEFAULT));

        // Best effort: a failed send must not fail registration — the user can
        // resend from their profile.
        try {
            $this->verifier->sendVerification($user);
        } catch (MailException $e) {
            error_log('Verification email failed for user ' . $user['id'] . ': ' . $e->getMessage());
        }

        return $this->json($response, $this->session->forUser($user), 201);
    }

    /**
     * POST /api/auth/login
     */
    public function login(Request $request, Response $response): Response
    {
        [$email, $password] = $this->credentials($request);

        $user = $this->users->findByEmail($email);

        if ($user === null || !password_verify($password, $user['password_hash'])) {
            // Same message either way so we don't reveal which emails are registered.
            throw new ApiException('Invalid email or password.', 401);
        }

        return $this->json($response, $this->session->forUser($user));
    }

    /**
     * POST /api/auth/magic-link  (public)
     *
     * Emails a one-time login link for the given address. Always responds the
     * same way so registered addresses can't be enumerated; a link is only sent
     * when the account exists and hasn't been sent one in the last minute.
     * Opening the link signs the user in and verifies the address.
     */
    public function requestLoginLink(Request $request, Response $response): Response
    {
        $body = (array) ($request->getParsedBody() ?? []);
        $email = is_string($body['email'] ?? null) ? mb_strtolower(trim($body['email'])) : '';

        if ($email === '' || !filter_var($email, FILTER_VALIDATE_EMAIL) || strlen($email) > self::EMAIL_MAX) {
            throw new ValidationException(['email' => ['Enter a valid email address.']]);
        }

        $user = $this->users->findByEmail($email);
        if ($user !== null && !$this->recentlyEmailed($user)) {
            try {
                $this->verifier->sendLoginLink($user);
            } catch (MailException $e) {
                error_log('Login link failed for user ' . $user['id'] . ': ' . $e->getMessage());
            }
        }

        return $this->json($response, [
            'message' => 'If that address has an account, a login link is on its way.',
        ], 202);
    }

    /**
     * GET /api/me  (requires AuthMiddleware)
     */
    public function me(Request $request, Response $response): Response
    {
        return $this->json($response, ['user' => $this->session->present($this->user($request))]);
    }

    /**
     * @param array{verification_email_sent_at?: string|null} $user
     */
    private function recentlyEmailed(array $user): bool
    {
        $lastSent = $user['verification_email_sent_at'] ?? null;

        return $lastSent !== null
            && (time() - (int) strtotime($lastSent)) < EmailVerifier::RESEND_INTERVAL_SECONDS;
    }

    /**
     * Extract and validate the email/password pair from the request body.
     *
     * @return array{0: string, 1: string} Normalised email and raw password.
     */
    private function credentials(Request $request): array
    {
        $body = (array) ($request->getParsedBody() ?? []);

        $email = is_string($body['email'] ?? null) ? trim($body['email']) : '';
        $password = is_string($body['password'] ?? null) ? $body['password'] : '';

        $errors = [];

        if ($email === '') {
            $errors['email'][] = 'Email is required.';
        } elseif (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
            $errors['email'][] = 'Email must be a valid address.';
        } elseif (strlen($email) > self::EMAIL_MAX) {
            $errors['email'][] = sprintf('Email must be at most %d characters.', self::EMAIL_MAX);
        }

        if ($password === '') {
            $errors['password'][] = 'Password is required.';
        } elseif (strlen($password) < self::PASSWORD_MIN) {
            $errors['password'][] = sprintf('Password must be at least %d characters.', self::PASSWORD_MIN);
        } elseif (strlen($password) > self::PASSWORD_MAX) {
            $errors['password'][] = sprintf('Password must be at most %d characters.', self::PASSWORD_MAX);
        }

        if ($errors !== []) {
            throw new ValidationException($errors);
        }

        return [mb_strtolower($email), $password];
    }
}