hook.php

<?php

date_default_timezone_set('Asia/Taipei');
if (array_key_exists('hub_mode', $_GET) and $_GET['hub_mode'] == 'subscribe' and $_GET['hub_verify_token'] == getenv('VERIFY_TOKEN')) {
    echo $_GET['hub_challenge'];
    exit;
}

$access_token = getenv('PAGE_TOKEN');

$reply = function($recipient, $message) use ($access_token) {
    $curl = curl_init('https://graph.facebook.com/v2.6/me/messages?access_token=' . urlencode($access_token));
    curl_setopt($curl, CURLOPT_HTTPHEADER, array('Content-Type: application/json'));
    $json = (array(
        'recipient' => array('id' => $recipient),
        'message' => array('text' => $message),
    ));
    var_dump($json);
    curl_setopt($curl, CURLOPT_POSTFIELDS, json_encode($json));
    curl_exec($curl);
    curl_close($curl);
};

if (file_exists('/tmp/db.json')) {
    $db = json_decode(file_get_contents('/tmp/db.json'));
} else {
    $db = new StdClass;
    $db->links = new StdClass;
}

$body = file_get_contents('php://input');
$body = json_decode($body);
foreach ($body->entry as $entry) {
    foreach ($entry->messaging as $message) {
        $reply_message = array();

        foreach ($message->message->attachments as $attachment) {
            $url = ($attachment->url);
            while (true) {
                if (strpos($url, 'https://l.facebook.com/l.php') === 0) {
                    parse_str(explode('?', $url)[1], $ret);
                    $url = $ret['u'];
                } elseif (strpos($url, 'https://goo.gl/') === 0) {
                    $curl = curl_init($url);
                    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
                    curl_exec($curl);
                    $info = curl_getinfo($curl);
                    curl_close($curl);
                    $url = ($info['redirect_url']);
                } else {
                    break;
                }
            }

            $first = false;
            if (!property_exists($db->links, $url)) {
                $db->links->{$url} = new StdClass;
                $db->links->{$url}->title = $attachment->title;
                $db->links->{$url}->followers = new StdClass;

                $first = true;
            }

            if (!property_exists($db->links->{$url}->followers, $message->sender->id)) {
                $db->links->{$url}->followers->{$message->sender->id} = time();
                $count = count(array_values(get_object_vars($db->links->{$url}->followers)));
                if ($first) {
                    $reply_message[] = "您是第一個回報 $url 的人";
                } else {
                    $reply_message[] = "加上您共有 {$count} 人回報 {$url}";
                }
            } else {
                $reply_message[] = "您已經於 " . date('Y-m-d H:i:s', $db->links->{$url}->followers->{$message->sender->id}) . " 回報過 {$url}";
            }
            file_put_contents('/tmp/db.json', json_encode($db));
            
        }
        if (!$reply_message) {
            $reply_message[] = '我不知道您要做什麼';
        }
        $reply($message->sender->id, implode("\n", $reply_message));
    }
}