helper.gradle

import java.text.MessageFormat

class UpdateLibrariesTask extends DefaultTask {
	File directory
	List<Map> libraries

	@TaskAction
	def update() {
		Set<String> librariesNames = new HashSet<>()

		libraries.each({
			String url = it.get("url")
			String libraryName = it.get("name")

			librariesNames.add(libraryName)

			File libraryFile = new File(directory, libraryName)
			if (!libraryFile.exists()) {
				logger.lifecycle(MessageFormat.format("Downloading library {0} from {1}", libraryName, url))
				ant.get(src: url, dest: libraryFile)
			} else {
				logger.lifecycle(MessageFormat.format("Skipping download of library {0} because it already exists", libraryName))
			}
		})

		directory.listFiles()
		.findAll({
			!librariesNames.contains(it.getName())
		})
		.each({
			logger.lifecycle(MessageFormat.format("Deleting old library {0}", it.getName()))
			it.delete()
		})
	}

}

ext.UpdateLibrariesTask = UpdateLibrariesTask