<?php

namespace SeriouslySimplePodcasting\Handlers;

use SeriouslySimplePodcasting\Interfaces\Service;

/**
 * UUID class
 *
 * The following class generates VALID RFC 4122 COMPLIANT
 * Universally Unique IDentifiers (UUID) version 3, 4 and 5.
 *
 * UUIDs generated validates using OSSP UUID Tool, and output
 * for named-based UUIDs are exactly the same. This is a pure
 * PHP implementation.
 *
 * @author Andrew Moore, Sergey Zakharchenko
 * @link http://www.php.net/manual/en/function.uniqid.php#94959
 * @package Seriously Simple Podcasting
 */
class UUID_Handler implements Service {
	/**
	 * Generate v3 UUID
	 *
	 * Version 3 UUIDs are named based. They require a namespace (another
	 * valid UUID) and a value (the name). Given the same namespace and
	 * name, the output is always the same.
	 *
	 * @param string $namespace
	 * @param string $name
	 *
	 * @return false|string
	 */
	public function v3( $namespace, $name ) {
		if ( ! $this->is_valid( $namespace ) ) {
			return false;
		}

		// Get hexadecimal components of namespace
		$nhex = str_replace( array( '-', '{', '}' ), '', $namespace );

		// Binary Value
		$nstr = '';

		// Convert Namespace UUID to bits
		for ( $i = 0; $i < strlen( $nhex ); $i += 2 ) {
			$nstr .= chr( hexdec( $nhex[ $i ] . $nhex[ $i + 1 ] ) );
		}

		// Calculate hash value
		$hash = md5( $nstr . $name );

		return sprintf( '%08s-%04s-%04x-%04x-%12s',

			// 32 bits for "time_low"
			substr( $hash, 0, 8 ),

			// 16 bits for "time_mid"
			substr( $hash, 8, 4 ),

			// 16 bits for "time_hi_and_version",
			// four most significant bits holds version number 3
			( hexdec( substr( $hash, 12, 4 ) ) & 0x0fff ) | 0x3000,

			// 16 bits, 8 bits for "clk_seq_hi_res",
			// 8 bits for "clk_seq_low",
			// two most significant bits holds zero and one for variant DCE1.1
			( hexdec( substr( $hash, 16, 4 ) ) & 0x3fff ) | 0x8000,

			// 48 bits for "node"
			substr( $hash, 20, 12 )
		);
	}

	/**
	 *
	 * Generate v4 UUID
	 *
	 * Version 4 UUIDs are pseudo-random.
	 */
	public static function v4() {
		return sprintf( '%04x%04x-%04x-%04x-%04x-%04x%04x%04x',

			// 32 bits for "time_low"
			mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff ),

			// 16 bits for "time_mid"
			mt_rand( 0, 0xffff ),

			// 16 bits for "time_hi_and_version",
			// four most significant bits holds version number 4
			mt_rand( 0, 0x0fff ) | 0x4000,

			// 16 bits, 8 bits for "clk_seq_hi_res",
			// 8 bits for "clk_seq_low",
			// two most significant bits holds zero and one for variant DCE1.1
			mt_rand( 0, 0x3fff ) | 0x8000,

			// 48 bits for "node"
			mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff )
		);
	}

	/**
	 * Generate v5 UUID
	 *
	 * Version 5 UUIDs are named based. They require a namespace (another
	 * valid UUID) and a value (the name). Given the same namespace and
	 * name, the output is always the same.
	 *
	 * @param string $namespace
	 * @param string $name
	 *
	 * @return string
	 */
	public static function v5( $namespace, $name ) {
		if ( ! self::is_valid( $namespace ) ) {
			return false;
		}

		// Get hexadecimal components of namespace
		$nhex = str_replace( array( '-', '{', '}' ), '', $namespace );

		// Binary Value
		$nstr = '';

		// Convert Namespace UUID to bits
		for ( $i = 0; $i < strlen( $nhex ); $i += 2 ) {
			$nstr .= chr( hexdec( $nhex[ $i ] . $nhex[ $i + 1 ] ) );
		}

		// Calculate hash value
		$hash = sha1( $nstr . $name );

		return sprintf( '%08s-%04s-%04x-%04x-%12s',

			// 32 bits for "time_low"
			substr( $hash, 0, 8 ),

			// 16 bits for "time_mid"
			substr( $hash, 8, 4 ),

			// 16 bits for "time_hi_and_version",
			// four most significant bits holds version number 5
			( hexdec( substr( $hash, 12, 4 ) ) & 0x0fff ) | 0x5000,

			// 16 bits, 8 bits for "clk_seq_hi_res",
			// 8 bits for "clk_seq_low",
			// two most significant bits holds zero and one for variant DCE1.1
			( hexdec( substr( $hash, 16, 4 ) ) & 0x3fff ) | 0x8000,

			// 48 bits for "node"
			substr( $hash, 20, 12 )
		);
	}

	public static function is_valid( $uuid ) {
		return preg_match( '/^\{?[0-9a-f]{8}\-?[0-9a-f]{4}\-?[0-9a-f]{4}\-?' .
		                   '[0-9a-f]{4}\-?[0-9a-f]{12}\}?$/i', $uuid ) === 1;
	}
}
