<?php

/**
 * DeterminePhpBinary
 * 
 * @author Martin Kuckert
 * @copyright Copyright &copy; 2009 Martin Kuckert
 * @license New BSD License
 * @since 1.0 - 14.12.2009
 * @version 1.0
 */
class DeterminePhpBinary {
	
	private static $possibleNames=array(
		'php-cli', 'php', 'php5'
	);
	
	/**
	 * @return string
	 */
	public function determine() {
		// Allow configuration by environment
		$path=getenv('PHP_PATH');
		if(is_string($path) and is_file($path)) {
			return $path;
		}
		
		if(stristr(PHP_OS, 'win')!==false) {
			return $this->determineWin();
		}
		else if(stristr(PHP_OS, 'linux')!==false) {
			return $this->determineLinux();
		}
		else {
			return $this->determineOther();
		}
	}
	
	/**
	 * @return string
	 */
	protected function determineWin() {
		$file=$this->findInDirs(array(
			PHP_BINDIR,
			getenv('PHP_BINDIR')
		), '.exe');
		if($file!==NULL) {
			return $file;
		}
		
		$file=$this->findInPathEnv('.exe');
		if($file!==NULL) {
			return $file;
		}
		
		//return $this->searchRecursive();
		return NULL;
	}
	
	/**
	 * @return string
	 */
	protected function determineLinux() {
		$file=$this->findInDirs(array(
			PHP_BINDIR,
			getenv('PHP_BINDIR')
		));
		if($file!==NULL) {
			return $file;
		}
	
		$file=$this->findInPathEnv();
		if($file!==NULL) {
			return $file;
		}
		
		$file=$this->findWithWhich();
		if($file!==NULL) {
			return $file;
		}
		
		//return $this->searchRecursive();
		return NULL;
	}
	
	/**
	 * @return string
	 */
	protected function determineOther() {
		throw new BadMethodCallException('Not yet for other environments implemented');
	}
	
	/**
	 * Tryes to find a file with one of the names in $possibleNames in one of
	 * the given directories.
	 * 
	 * @return string or NULL on failure
	 * @param array Directory names
	 * @param string optional suffix for each file
	 */
	protected function findInDirs(array $dirs, $suffix='') {
		foreach($dirs as $dir) {
			if(is_string($dir) and is_dir($dir)) {
				$file=$this->findFile($dir, $suffix);
				if($file!==NULL) {
					return $file;
				}
			}
		}
	}
	
	/**
	 * Tryes to find a file within on of the directories in the PATH env var.
	 * 
	 * @return string or NULL on failure
	 * @param string optional suffix for each file
	 */
	protected function findInPathEnv($suffix='') {
		$path=getenv('PATH');
		if(!is_string($path)) {
			return NULL;
		}
		
		$path=explode(PATH_SEPARATOR, $path);
		foreach($path as $key=>$p) {
			if($p[0]==='"' and $p[strlen($p)-1]==='"') {
				$p=substr($p, 1, -1);
				$p=str_replace('\"', '"', $p);
			}
			$path[$key]=$p;
		}
		
		return $this->findInDirs($path, $suffix);
	}
	
	/**
	 * Tryes to find a file with one of the names in $possibleNames in the
	 * given directory. If a suffix is given, it will be appended to the file name.
	 * 
	 * @return string or NULL on failure
	 * @param string Directory name
	 * @param string optional suffix for each file
	 */
	protected function findFile($dir, $suffix='') {
		foreach(self::$possibleNames as $name) {
			if(is_file($dir.DIRECTORY_SEPARATOR.$name.$suffix)) {
				return $dir.DIRECTORY_SEPARATOR.$name.$suffix;
			}
		}
		return NULL;
	}
	
	/**
	 * Tryes to find a file with one of the names in $possibleNames with the
	 * shell command "which".
	 * 
	 * @return string or NULL on failure
	 */
	protected function findWithWhich() {
		foreach(self::$possibleNames as $name) {
			$path=trim(shell_exec('which '.$name));
			if($path!=='') {
				return $path;
			}
		}
		
		return NULL;
	}
	
}

$determine=new DeterminePhpBinary();
$path=$determine->determine();
if($path===NULL) {
	echo 'php binary not found';
	exit(1);
}
else {
	echo 'php binary found at '.$path.PHP_EOL;
	echo shell_exec('"'.$path.'" -v');
}