// ===========================================================================
// Copyright 2018 Autodesk, Inc. All rights reserved.
//
// Use of this software is subject to the terms of the Autodesk license
// agreement provided at the time of installation or download, or which
// otherwise accompanies this software in either electronic or hard copy form.
// ===========================================================================
//
//
//
//<doc>
//<name searchPathArray>
//
//<synopsis>
//		searchPathArray( string $name, string $pathArray[] )
//
//<returns>
//		string Full path to file.
//
//<description>
//		Looks for a readable file in the directories listed in pathArray.
//<P>
//	Notes:<br>
//		Intial white space in $name is ignored (chopped)<br>
//		Name beginning with "/" are returned as-is<br>
//		Empty string entries in pathArray are skipped, use . for cwd.<br>
//		Path elements beginning in "$" are treated as environment variables.
//
//<flags>
//		string $name Name of the file being searched for
//		string $pathArray[] Array of directory paths.
//
//<examples>
//	string $path[] = { ".", "$HOME/maya/projects/default" };
//	searchPathArray( "workspace.mel", $path );
//
//</doc>

proc int existsReadable(string $filename)
{
	int $debug = 0;
	string $func  = "existsReadable";

	if ( $debug ) trace("// " + $func + "( " + $filename + " )\n" );

//	int $id = fopen($filename,"r");
//	if ( $id != 0 ) {
//		fclose($id);
//	}
	int $id = filetest("-r",$filename);

	if ( $debug ) trace("// " + $func + " return " + ( $id != 0 ) + " \n" );

	return ( $id != 0 );
}

proc string chopGetenv(string $envNameWithDollar)
{
//	int $debug = 1;
//	string $func  = "chopGetenv";

	string $chopped = substitute("^\\$", $envNameWithDollar, "" );
//	if ( $debug ) trace("// " + $func + ": chopped:" + $chopped + "\n");
	return getenv( $chopped );
}
	

proc string expandEnv(string $path)
//	Description:
//		Expand file name paths containing environment variables
//
//	Notes:
//		We assume that any whole component of the path can be
// 		an environment variable.  This means we can parse
//		/usr/people/$USER/foo  but not
//		/usr/people/$USER.foo/bar
{
	int $debug = 0;
	string $func  = "expandEnv";

	if ( $debug ) trace("// " + $func + "( " + $path + " )\n" );

	// If no $ sign, no expansion		
	if ( "" == match("\\\$",$path ) ) {
		if ( $debug ) trace(" Tried to match \\\$\n" );
		if ( $debug ) trace("// " + $func + ": not env.\n");
		return $path;
	}
	
	// If no /, simple variable name only
	if ( "" == match("/",$path ) ) {
		if ( $debug ) trace("// " + $func + ": simple expansion\n");
		
		return chopGetenv($path);
	}

	// Aha! the path is comprised of literal and env components...
	if ( $debug ) trace("// " + $func + ": multi part\n");

	string $result = "";

	if ( match("^/",$path ) != "" )
		$result = "/";
		
	string $parts[];
	tokenize( $path, "/", $parts );

	// Reconstruct the path, expanding the env components
	string $dir;
	for ($dir in $parts) {
		if ( "" != match("^\\\$",$dir ) ) {
			$dir =  chopGetenv($dir);
			// fail on any unset envs
			if ( $dir == "" ) {
				if ( $debug ) trace("// " + $func + ": env part not set\n");
				return "";
			}
		}

		$result = $result + "/" + $dir;
	}
		
	return $result;
		
}

global proc string searchPathArray( string $name, string $pathArray[] )
{
	int $debug = 0;
	string $func  = "searchPathArray";

	// strip off leading white space
	$name = substitute("^[ 	]*", $name, "" );

	// return empty names directly
	if ($name == "" )
		return $name;

	// return absolute paths directly
	if ( match("^/",$name ) != "" ) {
		if ($debug) trace("// " + $func + ": absolute path\n");
		return $name;
	}
	// Search for $name in the path list
	string $fullPath;
	for ( $dir in $pathArray ) {
		// Expand environment variables
		if ( $debug ) trace("// " + $dir + ": before expansion\n");
		$dir = expandEnv($dir);
		if ( $debug ) trace("// " + $dir + ": after expansion\n");

		// Skip empty path entries
		if ( "" == $dir )
			continue;

		// strip off trailing white space
		$dir = substitute("[ 	]*$", $dir, "" );

		// Test this path and return if successful
		$fullPath = $dir + "/" + $name;
		if ( existsReadable($fullPath) )
			return ($fullPath);	
	}

	return "";
}