<?php
/**
 * Finds file in a database and shows its content.
 *
 * @copyright Copyright (c) 2017 Paulina Laura Emilia <vilene@posteo.net>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

require_once 'includes/database.inc.php';

// Seconds in one non-leap year
define('ONE_YEAR', 31536000);

/**
 * Converts timestamp to HTTP-date format as defined by RFC 7231.
 *
 * @param int $timestamp
 *
 * @return string
 */
function httpDate($timestamp)
{
    return gmdate('D, d M Y H:i:s T', $timestamp);
}

$q = $db->prepare('SELECT filename, mime, size, date FROM files
                    WHERE filename = (:filename)');
$q->bindValue(':filename', $_GET['filename'], PDO::PARAM_STR);

if ($q->execute()) {
    if ($q->rowCount() > 0) {
        $file = $q->fetch(PDO::FETCH_OBJ);

        // File metadata
        header('Content-Length: ' . $file->size);
        header('Content-Type: ' . $file->mime);

        // Cache control
        header('Cache-Control: public, immutable, max-age=' . ONE_YEAR);
        header('Expires: ' . httpDate(time() + ONE_YEAR));
        header('Last-Modified: ' . httpDate(strtotime($file->date)));
        header('Pragma: public');

        readfile(POMF_FILES_ROOT . $file->filename);
        exit;
    } else {
        // If file not found, show 404 page
        header('Cache-Control: no-cache, no-store, must-revalidate');
        header('Pragma: no-cache');
        http_response_code(404);

        include '404.html';
    }
} else {
    header('Content-Type: text/plain', true, 500);
    echo $q->errorInfo()[2];
}