<?php
// ─── Password reset over the shared SMTP transport ───────────────────────────
//
// Recovery used to be somebody else's problem: silver's views/auth/restore.php
// and reset_password.php were one-line redirects to id.andmore.pt, which no
// longer exists, so nobody could recover an account at all. This implements it
// locally, delivering through platform_mail_send() with platform_smtp_config()
// -- the same transport the rest of the estate already uses, so a site that can
// send any mail can send these.
//
// Token handling, and why:
//   - The token is 32 random bytes, hex. Only its SHA-256 is stored, so a
//     leaked database dump cannot be used to reset anyone's password.
//   - Requesting a reset for an unknown address returns the same result as a
//     known one. Otherwise the form enumerates which addresses have accounts.
//   - Consuming a token deletes every outstanding token for that user, so a
//     forwarded or resent link cannot be replayed after the real reset.
//   - The session is regenerated on success: a password reset is a privilege
//     change, and any session an attacker already holds must not survive it.

require_once __DIR__ . '/functions_auth.php';
require_once __DIR__ . '/functions_mail.php';
require_once __DIR__ . '/functions_settings.php';

const PASSWORD_RESET_TTL_SECONDS = 3600;   // one hour

function password_reset_ensure_table(PDO $pdo): void {
    $pdo->exec(
        "CREATE TABLE IF NOT EXISTS `password_resets` (
            `id`         BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
            `user_id`    INT NOT NULL,
            `token_hash` CHAR(64) NOT NULL,
            `expires_at` DATETIME NOT NULL,
            `used_at`    DATETIME NULL,
            `requested_ip` VARCHAR(45) NULL,
            `created_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
            PRIMARY KEY (`id`),
            UNIQUE KEY `uq_token_hash` (`token_hash`),
            KEY `idx_user` (`user_id`)
         ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci"
    );
}

function password_reset_hash(string $token): string {
    return hash('sha256', $token);
}

/**
 * Issue a reset link and mail it.
 *
 * $resetUrl receives the token: "https://site/auth/reset.php?token=%s".
 *
 * 'ok' is what the public form should show, and it is true for every
 * well-formed address -- known or not, delivered or not. A transport failure
 * comes back separately in 'delivery_error', because if that were folded into
 * 'ok' the form would answer differently for a known address than an unknown
 * one whenever SMTP is down, which is the enumeration leak this is avoiding.
 * Show 'delivery_error' to an operator, never to an anonymous visitor.
 */
function password_reset_request(PDO $pdo, string $email, string $resetUrl, array $opts = []): array {
    password_reset_ensure_table($pdo);
    $s     = auth_schema();
    $email = mb_strtolower(trim($email));

    if ($email === '' || !filter_var($email, FILTER_VALIDATE_EMAIL)) {
        return ['ok' => false, 'sent' => false, 'error' => 'Endereço de email inválido.',
                'delivery_error' => null];
    }

    $st = $pdo->prepare(
        "SELECT * FROM `{$s['table']}` WHERE `{$s['email']}` = ? AND " . auth_active_sql() . " LIMIT 1"
    );
    $st->execute([$email]);
    $user = $st->fetch(PDO::FETCH_ASSOC) ?: null;

    if ($user === null) {
        error_log("[password_reset] request for unknown or inactive address: {$email}");
        return ['ok' => true, 'sent' => false, 'error' => null, 'delivery_error' => null];
    }

    $token = bin2hex(random_bytes(32));
    $pdo->prepare(
        "INSERT INTO password_resets (user_id, token_hash, expires_at, requested_ip)
         VALUES (?, ?, DATE_ADD(NOW(), INTERVAL ? SECOND), ?)"
    )->execute([
        (int) $user[$s['id']],
        password_reset_hash($token),
        (int) ($opts['ttl'] ?? PASSWORD_RESET_TTL_SECONDS),
        auth_client_ip(),
    ]);

    $link     = sprintf($resetUrl, urlencode($token));
    $appName  = (string) ($opts['app_name'] ?? 'a plataforma');
    $name     = trim((string) ($user[$s['name']] ?? '')) ?: $email;
    $minutes  = (int) round(((int) ($opts['ttl'] ?? PASSWORD_RESET_TTL_SECONDS)) / 60);

    $safeName = htmlspecialchars($name, ENT_QUOTES, 'UTF-8');
    $safeApp  = htmlspecialchars($appName, ENT_QUOTES, 'UTF-8');
    $safeLink = htmlspecialchars($link, ENT_QUOTES, 'UTF-8');

    $html = "<p>Olá {$safeName},</p>"
          . "<p>Recebemos um pedido para redefinir a palavra-passe da tua conta em <strong>{$safeApp}</strong>.</p>"
          . "<p><a href=\"{$safeLink}\">Definir uma nova palavra-passe</a></p>"
          . "<p>O link expira dentro de {$minutes} minutos e só pode ser usado uma vez.</p>"
          . "<p>Se não foste tu, ignora este email — a palavra-passe atual mantém-se.</p>";

    $text = "Olá {$name},\n\n"
          . "Recebemos um pedido para redefinir a palavra-passe da tua conta em {$appName}.\n\n"
          . "{$link}\n\n"
          . "O link expira dentro de {$minutes} minutos e só pode ser usado uma vez.\n"
          . "Se não foste tu, ignora este email — a palavra-passe atual mantém-se.\n";

    $res = platform_mail_send(
        [
            'to'       => $email,
            'to_name'  => $name,
            'subject'  => 'Redefinir a palavra-passe — ' . $appName,
            'body'     => $html,
            'alt_body' => $text,
        ],
        (string) ($opts['repo_root'] ?? ''),
        platform_smtp_config($pdo)
    );

    if (empty($res['ok'])) {
        error_log('[password_reset] send failed: ' . (string) ($res['error'] ?? 'unknown'));
        return ['ok' => true, 'sent' => false, 'error' => null,
                'delivery_error' => 'Não foi possível enviar o email. Verifica a configuração de SMTP.'];
    }
    return ['ok' => true, 'sent' => true, 'error' => null, 'delivery_error' => null];
}

/** Returns the user row a valid, unexpired, unused token belongs to. */
function password_reset_validate(PDO $pdo, string $token): ?array {
    password_reset_ensure_table($pdo);
    $s = auth_schema();

    $st = $pdo->prepare(
        "SELECT r.id AS reset_id, r.user_id
           FROM password_resets r
          WHERE r.token_hash = ? AND r.used_at IS NULL AND r.expires_at > NOW()
          LIMIT 1"
    );
    $st->execute([password_reset_hash($token)]);
    $row = $st->fetch(PDO::FETCH_ASSOC);
    if (!$row) return null;

    $st = $pdo->prepare(
        "SELECT * FROM `{$s['table']}` WHERE `{$s['id']}` = ? AND " . auth_active_sql() . " LIMIT 1"
    );
    $st->execute([(int) $row['user_id']]);
    $user = $st->fetch(PDO::FETCH_ASSOC) ?: null;
    if ($user === null) return null;

    $user['_reset_id'] = (int) $row['reset_id'];
    return $user;
}

/**
 * Set the new password and burn every outstanding token for that user.
 *
 * Wrapped in a transaction: a password changed without its token being
 * invalidated would leave a working reset link behind.
 */
function password_reset_consume(PDO $pdo, string $token, string $newPassword, array $opts = []): array {
    $minLength = (int) ($opts['min_length'] ?? 10);
    if (mb_strlen($newPassword) < $minLength) {
        return ['ok' => false, 'error' => "A palavra-passe tem de ter pelo menos {$minLength} caracteres."];
    }

    $user = password_reset_validate($pdo, $token);
    if ($user === null) {
        return ['ok' => false, 'error' => 'Link inválido ou expirado. Pede um novo.'];
    }

    $s = auth_schema();
    try {
        $pdo->beginTransaction();
        $pdo->prepare("UPDATE `{$s['table']}` SET `{$s['password']}` = ? WHERE `{$s['id']}` = ?")
            ->execute([auth_password_hash($newPassword), (int) $user[$s['id']]]);
        $pdo->prepare("UPDATE password_resets SET used_at = NOW() WHERE user_id = ? AND used_at IS NULL")
            ->execute([(int) $user[$s['id']]]);
        $pdo->commit();
    } catch (Throwable $e) {
        if ($pdo->inTransaction()) $pdo->rollBack();
        error_log('[password_reset] consume failed: ' . $e->getMessage());
        return ['ok' => false, 'error' => 'Não foi possível guardar a nova palavra-passe.'];
    }

    // A completed reset is a privilege change; no pre-existing session survives.
    auth_session_regenerate();
    auth_throttle_clear($pdo, (string) ($user[$s['email']] ?? ''));

    // Uma palavra-passe reposta termina as sessões lembradas em todos os
    // dispositivos: repor é o que se faz quando se suspeita de que alguém a tem.
    // (O dance fazia-o à mão; passou a ser aqui, para toda a frota.)
    require_once __DIR__ . '/functions_remember.php';
    try { auth_remember_forget_user($pdo, (int) $user[$s['id']]); }
    catch (Throwable $e) { error_log('[password_reset] remember: ' . $e->getMessage()); }

    return ['ok' => true, 'error' => null, 'user_id' => (int) $user[$s['id']]];
}

/** Housekeeping for a cron job: drop spent and expired rows. */
function password_reset_prune(PDO $pdo, int $keepDays = 7): int {
    password_reset_ensure_table($pdo);
    $st = $pdo->prepare(
        "DELETE FROM password_resets
          WHERE (used_at IS NOT NULL OR expires_at < NOW())
            AND created_at < (NOW() - INTERVAL ? DAY)"
    );
    $st->execute([$keepDays]);
    return $st->rowCount();
}