video_metadata/image_cache.php

<?php
/*
 *	This file is part of video_metadata.
 *
 *	video_metadata is free software: you can redistribute it and/or modify
 *	it under the terms of the GNU General Public License as published by
 *	the Free Software Foundation, either version 3 of the License, or
 *	(at your option) any later version.
 *
 *	video_metadata is distributed in the hope that it will be useful,
 *	but WITHOUT ANY WARRANTY; without even the implied warranty of
 *	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *	GNU General Public License for more details.
 *
 *	You should have received a copy of the GNU General Public License
 *	along with video_metadata.  If not, see <https://www.gnu.org/licenses/>.
 */


const POSTER_DIR = './image_cache/poster';
const BACKDROP_DIR = './image_cache/backdrop';
const POSTER_SIZE = 'w92';
const BACKDROP_SIZE = 'w300';
const BASE_IMAGE_URL = 'https://image.tmdb.org/t/p/';


function validate_input($url, $image_type) {
	if (preg_match('/[^a-z0-9_\.]/i', $url) || !preg_match('/\.(png|jpeg|jpg)$/', $url)) {
		header('Content-Type: text/plain');
		echo 'invalid image name: "' . @$raw_query . '"';
		die();
	}

	if ($image_type !== 'poster' && $image_type !== 'backdrop') {
		header('Content-Type: text/plain');
		echo 'invalid image type: "' . @$raw_image_type . '"';
		die();
	}
}

function cache_image($remote_url, $fs_dir, $fs_path, &$errors)
{
	if (is_writable($fs_dir)) {
		$data = @file_get_contents($remote_url);

		if ($data) {
			if (file_put_contents($fs_path, $data) === false) {
				$errors[] =  __FUNCTION__ . ", error writing file, $fs_path";
				return false;
			}
		} else {
			$errors[] = __FUNCTION__ . ", error fetching url: $remote_url";
			return false;
		}
	} else {
		$errors[] = __FUNCTION__ . ", cannot write path: $fs_path";
		return false;
	}

	return true;
}

function log_errors($errors) {
	header('Content-Type: text/plain');
	foreach ($errors as $err)
		echo $err . "\n";

	die();
}

function display_local_image($fs_path) {
	$extension_mapping = [
		'jpeg' => 'image/jpeg',
		'jpg' => 'image/jpeg',
		'png' => 'image/png'
	];

	$content_type = $extension_mapping[pathinfo($fs_path, PATHINFO_EXTENSION)];

	header("Content-Type: $content_type");
	readfile($fs_path);
}


$raw_query = @$_GET['image_url'];
$image_name = basename($raw_query);
$raw_image_type = @$_GET['image_type'];
$image_type = basename(strtolower($raw_image_type));

validate_input($image_name, $image_type);

$local_dir = ($image_type == 'poster') ? POSTER_DIR : BACKDROP_DIR;
$size_part = ($image_type == 'poster') ? POSTER_SIZE : BACKDROP_SIZE;
$local_path = $local_dir . '/' . $size_part . '/' . $image_name;
$remote_url = BASE_IMAGE_URL . $size_part . '/' . $image_name;

$errors = [];

if (is_file($local_path)) {
	display_local_image($local_path);
} elseif (empty($errors)) {
	if (cache_image($remote_url, $local_dir, $local_path, $errors))
		display_local_image($local_path);
	else
		log_errors($errors);
} else {
	log_errors($errors);
}

?>