action.php

<?php
header( 'Content-type: application/json; charset=utf-8' );

$DATA_FILE = __DIR__ . '/data/entries.json';
$DATA_LIMIT = 10;

handle_request();

/**
 * Handles incoming HTTP requests.
 */
function handle_request() {
	global $DATA_FILE;

	if (!isset($_POST['type'])) {
		die;
	}

	$list = isset($_POST['list']) && is_numeric($_POST['list']) && strlen($_POST['list']) < 5 ? $_POST['list'] : 0;
	$param = '';
	switch($_POST['type']) {
		case 'onload': // Load watchlist data
			echo load_data();
			return;
		case 'add': // Create new entry
			try {
				$param = add_entry($list) ? 'succ_add' : 'fail_add';
			} catch (Exception $e) {
				$param = 'fail_add';
			}
			break;
		case 'data':
			echo load_flight_info();
			return;
		case 'delete':
			$param = delete_entry($_POST['id']) ? 'succ_del' : 'fail_del';
			echo json_encode(file_get_contents($DATA_FILE));
			return;
		case 'list':
			$a = isset($_POST['action']) && is_string($_POST['action']) && strlen($_POST['action']) < 20 ? $_POST['action'] : '';
			switch ($a) {
				case 'rename':
					$param = rename_list($list, $_POST['newname']) ? 'succ_listren' : 'fail_list';
					break;
				case 'add':
					$param = add_list($_POST['newname']) ? 'succ_listadd' : 'fail_list';
					break;
				case 'delete':
					$param = delete_list($list) ? 'succ_listdel' : 'fail_list';
					break;
				default:
					$param = 'fail_list';
					break;
			}
			break;
		case 'state': // Load DOM state
			echo load_lists();
			return;
	}

	header('Location: ' . (!empty($_ENV['SERVERURL']) ? $_ENV['SERVERURL'] : 'http://localhost:8000') . '/?' . $param);
	http_response_code(303);
}

/**
 * Loads all available lists.
 */
function load_lists() {
	$file = __DIR__ . '/data/lists.json';
	if (!file_exists($file)) {
		file_put_contents($file, json_encode(array(array('Default watchlist' => 0)), JSON_PRETTY_PRINT));
	}
	
	return json_encode(file_get_contents($file));
}

/**
 * Renames a given list.
 * @param int $list The ID of the list which should be renamed.
 * @param string $newname The new name for the list.
 */
function rename_list($list, $newname) {
	if (!is_string($newname) || preg_match('/[^a-zA-Z0-9 ]/', $newname) || strlen($newname) > 50
			|| strlen(trim($newname)) < 1) {
		return false;
	}

	$file = __DIR__ . '/data/lists.json';
	$data = json_decode(file_get_contents($file));
	$new_data = array();
	foreach ($data as $json) {
		foreach ($json as $key => $val) {
			if (strval($val) === strval($list)) {
				$new_data[] = array(trim($newname) => $val);
			} else {
				$new_data[] = array($key => $val);
			}
		}
	}

	file_put_contents($file, json_encode($new_data, JSON_PRETTY_PRINT));

	return true;
}

/**
 * Adds a new list.
 * @param string $name The name of the list which should be added.
 */
function add_list($name) {
	if (!is_string($name) || preg_match('/[^a-zA-Z0-9 ]/', $name) || strlen($name) > 50
			|| strlen(trim($name)) < 1) {
		return false;
	}

	$file = __DIR__ . '/data/lists.json';
	$data = json_decode(file_get_contents($file));
	$last_num = -1;
	foreach ($data as $json) {
		foreach ($json as $key => $val) {
			if (strval($key) === strval($name)) { // Name already existing
				return false;
			}

			if (intval($val) > $last_num) {
				$last_num = intval($val);
			}
		}
	}
	$data[] = array($name => $last_num + 1);

	file_put_contents($file, json_encode($data, JSON_PRETTY_PRINT));

	return true;
}

/**
 * Deletes a given list.
 * @param int $list The ID of the list which should be deleted.
 */
function delete_list($list) {
	$file = __DIR__ . '/data/lists.json';
	$data = json_decode(file_get_contents($file));
	$new_data = array();
	foreach ($data as $json) {
		foreach ($json as $key => $val) {
			if (strval($val) !== strval($list)) {
				$new_data[] = array($key => $val);
			}
		}
	}

	file_put_contents($file, json_encode($new_data, JSON_PRETTY_PRINT));

	return true;
}

/**
 * Loads available data.
 * @return array Array of JSON objects for each entry.
 */
function load_data() {
	global $DATA_FILE;

	if (!file_exists($DATA_FILE)) {
		return json_encode(array());
	} else {
		return json_encode(file_get_contents($DATA_FILE));
	}
}

/**
 * Adds a new entry to the watchlist.
 * @param int $list ID of the list to which data should be added.
 * @return bool True if entry was added successfully, else false.
 */
function add_entry($list) {
	global $DATA_FILE;

	if (!isset($_POST['from']) || !isset($_POST['to'])
		|| !isset($_POST['depart']) || !isset($_POST['return'])
		|| !isset($_POST['cabin']) || !isset($_POST['travellers'])
	) {
		return false;
	}

	if (!is_string($_POST['from']) || preg_match('/[^a-zA-Zöäüß ]/', $_POST['from']) || strlen($_POST['from']) > 50
		|| !is_string($_POST['to']) || preg_match('/[^a-zA-Zöäüß ]/', $_POST['to']) || strlen($_POST['to']) > 50
		|| !is_string($_POST['depart']) || !preg_match('/\d\d\d\d-\d\d-\d\d/', $_POST['depart'])
		|| !is_string($_POST['return']) || !preg_match('/\d\d\d\d-\d\d-\d\d/', $_POST['return'])
		|| !is_string($_POST['cabin']) || !in_array($_POST['cabin'], array('Economy', 'Premium Economy', 'Business class', 'First class'))
		|| !is_numeric($_POST['travellers']) || preg_match('/[^0-9]/', $_POST['travellers']) || strlen($_POST['travellers']) > 1
		|| preg_match('/[^0-9]/', $_POST['threshold']) || strlen($_POST['threshold']) > 6
	) {
		return false;
	}

	$timestamp = time();
	$data = array(
		'id' => sha1($timestamp),
		'date' => strval($timestamp),
		'list' => $list,
		'from' => $_POST['from'],
		'to' => $_POST['to'],
		'depart' => $_POST['depart'],
		'return' => $_POST['return'],
		'cabin' => $_POST['cabin'],
		'travellers' => $_POST['travellers'],
		'threshold' => strlen($_POST['threshold']) > 0 ? $_POST['threshold'] : 0
	);

	if (!file_exists($DATA_FILE)) {
		$content = array();
	} else {
		$content = json_decode(file_get_contents($DATA_FILE), true);
	}

	$content[] = $data;
	file_put_contents($DATA_FILE, json_encode($content, JSON_PRETTY_PRINT));

	return true;
}

/**
 * Removes an entry from the watchlist.
 * @param string $id The ID of the entry which should be deleted.
 */
function delete_entry($id) {
	global $DATA_FILE;

	if (!isset($id) || !is_string($id) || strlen($id) > 50) {
		return false;
	}

	if (!file_exists($DATA_FILE)) {
		return false;
	} else {
		$data = json_decode(file_get_contents($DATA_FILE), true);
		$new_data = array();
		foreach ($data as $entry) {
			if (strval($entry['id']) !== strval($id)) {
				$new_data[] = $entry;
			}
		}
		file_put_contents($DATA_FILE, json_encode($new_data, JSON_PRETTY_PRINT));

		return true;
	}
}

/**
 * Loads available information for currently watched flights.
 * @return array Array of JSON objects for each entry.
 */
function load_flight_info() {
	global $DATA_FILE;
	$flight_info = array();

	$entries = json_decode(file_get_contents($DATA_FILE), true);
	foreach ($entries as $entry) {
		$file = __DIR__ . '/data/' . strval($entry['id']) . '.json';
		if (file_exists($file)) {
			$info = filter_flight_info(json_decode(file_get_contents($file), true));
			$info['id'] = strval($entry['id']);
			$flight_info[] = $info;
		}
	}

	return json_encode($flight_info);
}

/**
 * Filters flight information such that the amount of sent data does not get too large.
 * @param array $flight_info The flight information to be filtered.
 * @return array The filtered flight information.
 */
function filter_flight_info($flight_info) {
	global $DATA_LIMIT;

	$filter_keys = array();
	$latest_info = get_last_not_empty($flight_info);
	foreach ($latest_info as $key => $val) {
		if (isset($val['airlines']) && isset($val['time'])) {
			$filter_keys[] = implode(', ', $val['airlines']) . $val['time'];
		}

		if ($DATA_LIMIT <= $key + 1) {
			break;
		}
	}

	$filtered_info = array();
	foreach ($flight_info as $key => $val) {		
		$filtered_info[$key] = array();
		foreach ($val as $entry) {
			if (!isset($entry['airlines']) && !isset($entry['time'])) {
				$filtered_info[$key][] = $entry;
			} else {
				$composed_key = implode(', ', $entry['airlines']) . $entry['time'];

				if (in_array($composed_key, $filter_keys)) {
					$filtered_info[$key][] = $entry;
				}
			}
		}
	}

	return $filtered_info;
}

/**
 * Returns the latest flight information. If no information exists, it returns an empty array.
 * @param array $array The flight information array.
 * @return array The latest flight information.
 */
function get_last_not_empty(array $array) : array {
	$last = end($array);

	while (empty($last)) {
		$last = prev($array);

		if ($last === false && key($array) === NULL) {
			return array();
		}
	}

	return $last;
}
?>