<?php
include_once __DIR__ . "/logging.php";
include_once __DIR__ . "/cors.php";
cors();

$config_data = get_config();
define("ROOT_URL", $config_data["ROOT_URL"]);
define("ROOT_DIR", $config_data["ROOT_DIR"]);
define("IMG_DIR", $config_data["IMG_DIR"]);
define("THUMBNAIL_DIR", $config_data["THUMBNAIL_DIR"]);
define("THUMBNAIL_SCRIPT", __DIR__ . "/../scripts/resize-img");

define("IMAGE_EXTENSIONS", [
	'jpg',
	'jpeg',
	'png',
	'gif',
	'tiff',
	'bmp',
	'webp',
	'svg',
]);

define("VIDEO_EXTENSIONS", [
	'mp4',
]);

define("FILE_EXTENSIONS", array_merge(IMAGE_EXTENSIONS, VIDEO_EXTENSIONS));

function main(): void {
	$data = json_decode(file_get_contents('php://input'), true);
	$array = [];

	$category = $data["category"];
	$directory = ROOT_DIR.IMG_DIR.$category;

	if (!is_dir($directory)) goto encode;
	foreach (scandir($directory) as $file) {
		if ($file === ".") continue;
		if ($category === "" && $file === "..") continue;

		$path = add_seperator_ab("/", $category, $file);
		$is_dir = is_dir(ROOT_DIR.IMG_DIR.$path);
		if (!$is_dir && !is_valid_file_type($file)) continue;

		$url = ROOT_URL.IMG_DIR.$path;
		$thumbnail_url = null;

		if (!$is_dir) {
			$thumbnail_url = create_thumbnail($category, $file);
		}

		$file_item = [];
		$file_item["is_dir"] = $is_dir;
		$file_item["url"] = $url;
		$file_item["thumbnail_url"] = $thumbnail_url;
		array_push($array, $file_item);
	}

	encode:
	echo json_encode($array);
}

function create_thumbnail(string $category, string $file): string | null {
	if (!is_image_file_type($file)) return null;

	$path = add_seperator_ab("/", $category, $file);
	$original_file = ROOT_DIR.IMG_DIR.$path;
	# use fast hashing algo, see: https://github.com/Cyan4973/xxHash
	$hash = hash_file("xxh3", $original_file);

	$thumbnail_directory = ROOT_DIR.THUMBNAIL_DIR;
	$thumbnail_name = "$hash.jpg";
	$thumbnail_file = $thumbnail_directory.$thumbnail_name;

	if (file_exists($thumbnail_file)) {
		log_print("thumbnail for $original_file exists, skipping generation");
		goto return_thumbnail;
	}

	try {
		if (!is_dir($thumbnail_directory)) mkdir($thumbnail_directory, 0777, true);
	}
	catch(Exception $e) {
		log_error($e->getMessage());
	}

	log_print("generating thumbnail for $original_file");
	$output = shell_exec(THUMBNAIL_SCRIPT." '$original_file' '$thumbnail_file' 2>&1");
	if ($output) log_print($output);
	if (substr_count(strtolower((string) $output), "error")) {
		log_error("Thumbnail failed");
		log_print(ROOT_URL.IMG_DIR.$path);
		return ROOT_URL.IMG_DIR.$path;
	}

	return_thumbnail:
	return ROOT_URL.THUMBNAIL_DIR.$thumbnail_name;
}

function add_seperator_ab(string $separator, string $a, string $b): string {
	if ($a === "") return $b;
	return $a.$separator.$b;
}

function is_valid_file_type(string $filename): bool {
	foreach (FILE_EXTENSIONS as $file_extension) {
		if (str_ends_with($filename, $file_extension)) return true;
	}
	return false;
}

function is_image_file_type(string $filename): bool {
	foreach(IMAGE_EXTENSIONS as $file_extension) {
		if(str_ends_with($filename, $file_extension)) return true;
	}
	return false;
}

function get_config(): array {
	$config_data = file_exists(__DIR__ . "/../config.json") ?
		json_decode(file_get_contents(__DIR__ . "/../config.json"), true) : null;

	if (!is_valid_config_data($config_data)) {
		log_error("Config invalid, falling back to default. Please check config.json");

		$config_data = json_decode(file_get_contents(__DIR__ . "/../config.default.json"), true);
		if (!is_valid_config_data($config_data))
			log_error("Default config invalid. Please check or create config.json");
	}
	return $config_data;
}


function is_valid_config_data(?array $data): bool {
	if (!$data) return false;
	$keys = ["ROOT_URL", "ROOT_DIR", "IMG_DIR", "THUMBNAIL_DIR"];
	foreach ($keys as $key) {
		if (!isset($data[$key])) return false;
		switch ($key) {
		case "ROOT_URL":
		case "THUMBNAIL_DIR":
			break;
		case "ROOT_DIR":
			if (!is_dir($data[$key])) return false;
			break;
		case "IMG_DIR":
			if (!is_dir($data["ROOT_DIR"].$data[$key])) return false;
			break;
		}
	}
	return true;
}

main();
?>