jxa_uniqueFilePath.js

uniqueFilePath('~/Library/Preferences/com.apple.finder.plist')

function uniqueFilePath(parentFolderPath, fileName, suffix) {

	/*
        
        Only for use with JavaScript for Automation (JXA)
	
	Generates a unique path by appending a number
	to the end of the file name.
	
	If suffix is not specified it is extracted 
  	from the file name.
	
  	If neither file name nor suffix is specified, 
  	it is assumed that the first argument holds 
  	the complete path to file.
	
	*/
	
	if (!fileName) {
		
		// Get the file name from the first argument
		var components = $.NSString.alloc.initWithUTF8String(parentFolderPath).pathComponents.js // Return native array with NSStrings
		
		// Get an array of native strings
		var jsComponents = []
		components.forEach(function(component) {
			jsComponents.push(component.js)			
		})
		
		// Get the file name
		fileName = jsComponents[jsComponents.length - 1]
		
		// Get the parent folder path
		jsComponents.splice(-1, 1)
		parentFolderPath = jsComponents.join('/')

	}


	if (!suffix) {
		// Get suffix from file name
		fileNameNSS = $.NSString.alloc.initWithUTF8String(fileName)
		suffix = fileNameNSS.pathExtension.js
		fileName = fileNameNSS.stringByDeletingPathExtension.js
	}
	
	if (suffix != '' && suffix.indexOf('.') != 0) {
		// Add dot to beginning of suffix
		suffix = '.' + suffix
	}

	
	// Clean up file name
	fileName = fileName.replace(/[:\/\\]/gi,'-')
	
	// Shorten file name if necessary
	var availableFileNameLength = 255 - suffix.length
	if (fileName.length > availableFileNameLength) {
		fileName = fileName.substr(0, availableFileNameLength )
	}
	
	// Expand tilde in parent folder path
	parentFolderPath = $.NSString.alloc.initWithUTF8String(parentFolderPath).stringByExpandingTildeInPath.js
	
	// Add trailing colon to parent folder path
	if ( parentFolderPath.slice(-1) != '/') { parentFolderPath += '/' }

	var loopNumber = 2
	var tempFilePath = parentFolderPath + fileName + suffix
	
	while (Application('System Events').exists(Path(tempFilePath))) {
	
		// Shorten file name if necessary
		availableFileNameLength = 255 - suffix.length - loopNumber.toString().length - 1
		if (fileName.length > availableFileNameLength) {
			fileName = fileName.substr(0, availableFileNameLength)
		}
		
		tempFilePath = parentFolderPath + fileName + ' ' + loopNumber + suffix		
		loopNumber++
		
	}

	return tempFilePath
	
}