<?php
/*
** Copyright (C) 2001-2024 Zabbix SIA
**
** This program is free software: you can redistribute it and/or modify it under the terms of
** the GNU Affero General Public License as published by the Free Software Foundation, version 3.
**
** This program 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 Affero General Public License for more details.
**
** You should have received a copy of the GNU Affero General Public License along with this program.
** If not, see <https://www.gnu.org/licenses/>.
**/


class CMacroParser extends CParser {

	const REFERENCE_NONE = 0;
	const REFERENCE_NUMERIC = 1;
	const REFERENCE_ALPHANUMERIC = 2;

	/**
	 * Macro name.
	 *
	 * @var string
	 */
	private $macro;

	/**
	 * Reference value.
	 *
	 * @var int|string
	 */
	private $reference;

	/**
	 * An options array.
	 *
	 * Supported options:
	 *   'macros' => true                                     All macros are supported.
	 *   'macros' => []                                       Array of supported macros. Empty or false means no macros.
	 *   'ref_type' => CMacroParser::REFERENCE_NONE           Default, do not support any reference type.
	 *   'ref_type' => CMacroParser::REFERENCE_NUMERIC        Support only numeric reference <1-9>, {HOST.HOST3}.
	 *   'ref_type' => CMacroParser::REFERENCE_ALPHANUMERIC   Allow alpha numeric reference, {EVENT.TAGS.issue_number}.
	 *                                                        Reference can be quoted if it contains non alphanumeric
	 *                                                        characters, {EVEN.TAGS."Jira ID"}.
	 *
	 * @var array
	 */
	private $options = [
		'macros' => [],
		'ref_type' => self::REFERENCE_NONE
	];

	/**
	 * Array of strings to search for.
	 *
	 * @param array      $options             Parser options.
	 * @param array|bool $options['macros']   The list of macros, for example ['{ITEM.VALUE}', '{HOST.HOST}']
	 * @param int        $options['ref_type'] Reference options.
	 */
	public function __construct(array $options = []) {
		if (array_key_exists('macros', $options)) {
			$this->options['macros'] = $options['macros'] === false ? [] : $options['macros'];
		}
		if (array_key_exists('ref_type', $options)) {
			$this->options['ref_type'] = $options['ref_type'];
		}

		if (is_array($this->options['macros'])) {
			usort($this->options['macros'], static function (string $a, string $b) {
				return strlen($b) <=> strlen($a);
			});
		}
	}

	/**
	 * Find one of the given strings at the given position.
	 *
	 * The parser implements a greedy algorithm, i.e., looks for the longest match.
	 *
	 * @param string $source    Search and replace string.
	 * @param int    $pos       Initial position in $source string.
	 */
	public function parse($source, $pos = 0) {
		$this->length = 0;
		$this->match = '';
		$this->macro = '';
		$this->reference = null;

		$p = $pos;

		if (!isset($source[$p]) || $source[$p] !== '{') {
			return self::PARSE_FAIL;
		}
		$p++;

		$macro_pos = $p;
		if (!$this->parseName($source, $p)) {
			return self::PARSE_FAIL;
		}
		$macro_len = $p - $macro_pos;

		if (!$this->parseReference($source, $p)) {
			return self::PARSE_FAIL;
		}

		if (!isset($source[$p]) || $source[$p] !== '}') {
			$this->reference = null;

			return self::PARSE_FAIL;
		}
		$p++;

		$this->length = $p - $pos;
		$this->match = substr($source, $pos, $this->length);
		$this->macro = substr($source, $macro_pos, $macro_len);

		return isset($source[$p]) ? self::PARSE_SUCCESS_CONT : self::PARSE_SUCCESS;
	}

	/**
	 * Parse macro name.
	 *
	 * @param string $source
	 * @param int $pos
	 *
	 * @return bool
	 */
	private function parseName(string $source, int &$pos): bool {
		if (is_array($this->options['macros'])) {
			foreach ($this->options['macros'] as $macro) {
				$macro = substr($macro, 1, -1);
				$len = strlen($macro);
				if (substr_compare($source, $macro, $pos, $len) == 0) {
					$pos += $len;

					return true;
				}
			}
		}
		else {
			if (preg_match('/(^[A-Z\._]+)/', substr($source, $pos), $matches)) {
				$pos += strlen($matches[0]);

				return true;
			}
		}

		return false;
	}

	/**
	 * Parse reference of type defined in "ref_type". Reference of type REFERENCE_ALPHANUMERIC containing non
	 * alphanumeric characters or underscore should be quoted. Inside quotes only " and \ escape sequences are allowed.
	 *
	 * @param  string $source
	 * @param  int    $pos
	 */
	private function parseReference($source, &$pos) {
		$p = $pos;

		switch ($this->options['ref_type']) {
			case self::REFERENCE_NUMERIC:
				$this->reference = 0;

				if (isset($source[$p]) && $source[$p] >= '1' && $source[$p] <= '9') {
					$this->reference = (int) $source[$p];
					$p++;
				}
				break;

			case self::REFERENCE_ALPHANUMERIC:
				$pattern_quoted = '"(?:\\\\["\\\\]|[^"\\\\])*"';
				$pattern_unquoted = '[A-Za-z0-9_]+';
				$pattern = '\.(?P<ref>'.$pattern_quoted.'|'.$pattern_unquoted.')';

				if (preg_match('/^'.$pattern.'/', substr($source, $pos), $matches)) {
					$this->reference = ($matches['ref'][0] === '"')
						? str_replace(['\\"', '\\\\'], ['"', '\\'], substr($matches['ref'], 1, -1))
						: $matches['ref'];
					$p += strlen($matches[0]);
				}
				else {
					return false;
				}
				break;
		}

		$pos = $p;

		return true;
	}

	/**
	 * Returns the macro name like HOST.HOST.
	 *
	 * @return string
	 */
	public function getMacro() {
		return $this->macro;
	}

	/**
	 * Returns reference value.
	 *
	 * @return int|string
	 */
	public function getReference() {
		return $this->reference;
	}
}
