<?php


class PxeLinux
{

	/**
	 * Takes a (partial) pxelinux menu and parses it into
	 * a PxeMenu object.
	 *
	 * @param string $input The pxelinux menu to parse
	 * @return ?PxeMenu the parsed menu, or null if input is not a PXELinux menu
	 */
	public static function parsePxeLinux(string $input, bool $isCp437): ?PxeMenu
	{
		if (empty($input))
			return null;
		if ($isCp437) {
			$input = iconv('IBM437', 'UTF8//TRANSLIT//IGNORE', $input);
		}
		$menu = new PxeMenu;
		$sectionPropMap = [
			'menu label' => ['string', 'title'],
			'menu default' => ['true', 'isDefault'],
			'menu hide' => ['true', 'isHidden'],
			'menu disabled' => ['true', 'isDisabled'],
			'menu indent' => ['int', 'indent'],
			'kernel' => ['string', 'kernel'],
			'com32' => ['string', 'kernel'],
			'pxe' => ['string', 'kernel'],
			'initrd' => ['string', 'initrd'],
			'append' => ['string', 'append'],
			'ipappend' => ['int', 'ipAppend'],
			'sysappend' => ['int', 'ipAppend'],
			'localboot' => ['int', 'localBoot'],
		];
		$globalPropMap = [
			'timeout' => ['int', 'timeoutMs', 100],
			'totaltimeout' => ['int', 'totalTimeoutMs', 100],
			'menu title' => ['string', 'title'],
			'menu clear' => ['true', 'menuClear'],
			'menu immediate' => ['true', 'immediateHotkeys'],
			'ontimeout' => ['string', 'timeoutLabel'],
			'default' => ['string', 'default'],
		];
		$lines = preg_split('/[\r\n]+/', $input);
		$section = null;
		$count = count($lines);
		for ($li = 0; $li < $count; ++$li) {
			$line =& $lines[$li];
			if (!preg_match('/^\s*([^m]\S*|menu\s+\S+)(\s+.*?|)\s*$/i', $line, $out))
				continue;
			$val = trim($out[2]);
			$key = trim($out[1]);
			$key = strtolower($key);
			$key = preg_replace('/\s+/', ' ', $key);
			if ($key === 'label') {
				if ($section !== null) {
					$menu->sections[] = $section;
				}
				$section = new PxeSection($val);
			} elseif ($key === 'menu separator') {
				if ($section !== null) {
					$menu->sections[] = $section;
					$section = null;
				}
				$menu->sections[] = new PxeSection(null);
			} elseif (self::handleKeyword($key, $val, $globalPropMap, $menu)) {
				continue;
			} elseif ($section === null) {
				continue;
			} elseif ($key === 'text' && strtolower($val) === 'help') {
				$text = '';
				while (++$li < $count) {
					$line =& $lines[$li];
					if (strtolower(trim($line)) === 'endtext')
						break;
					$text .= $line . "\n";
				}
				$section->helpText = $text;
			} elseif (self::handleKeyword($key, $val, $sectionPropMap, $section)) {
				//continue;
			}
		}
		if ($section !== null) {
			$menu->sections[] = $section;
		}
		if (empty($menu->sections))
			return null; // Probably not a PXE menu but random text?
		foreach ($menu->sections as $section) {
			$section->mangle();
		}
		return $menu;
	}

	/**
	 * Check if keyword is valid and if so, add its interpreted value
	 * to the given object. The map to look up the keyword has to be passed
	 * as well as the object to set the value in. Map and object should
	 * obviously match.
	 *
	 * @param string $key keyword of parsed line
	 * @param string $val raw value of currently parsed line (empty if not present)
	 * @param array $map Map in which $key is looked up as key
	 * @param PxeMenu|PxeSection $object The object to set the parsed and sanitized value in
	 * @return bool true if the value was found in the map (and set in the object), false otherwise
	 */
	private static function handleKeyword(string $key, string $val, array $map, $object): bool
	{
		if (!isset($map[$key]))
			return false;
		$opt = $map[$key];
		// opt[0] is the type the value should be cast to; special case "true" means
		// this is a bool option that will be set as soon as the keyword is present,
		// as it doesn't have any parameters
		if ($opt[0] === 'true') {
			$val = true;
		} else {
			settype($val, $opt[0]);
		}
		// If opt[2] is present it's a multiplier for the value
		if (isset($opt[2])) {
			$val *= $opt[2];
		}
		$object->{$opt[1]} = $val;
		return true;
	}

}