gistfile1.php

<?php namespace Vapor\Theme\Composer;

use Composer\Package\PackageInterface;
use Composer\Installer\LibraryInstaller;
use Composer\Repository\InstalledRepositoryInterface;

class ThemeInstaller extends LibraryInstaller {

	protected $type = 'vapor-theme';

	protected $thumbnailFile = 'thumbnail.png';

	public function install(InstalledRepositoryInterface $repo, PackageInterface $package){
		parent::install($repo, $package);

		//copy thumbnail
	}

	public function update(InstalledRepositoryInterface $repo, PackageInterface $initial, PackageInterface $target){
		parent::update($repo, $initial, $target);

		$this->removeThumbnail($initial);
		$this->installThumbnail($target);
	}

	public function uninstall(InstalledRepositoryInterface $repo, PackageInterface $package){
		parent::uninstall($repo, $package);

		$this->removeThumbnail($package);
	}

	protected function installThumbnail(PackageInterface $package){
		if(!file_exists($this->getInstallPath($package).$this->thumbnailFile)){
			$this->io->write('    <warning>Skipped installation of '.$this->thumbnailFile.' for package '.$package->getName().': file not found in package</warning>');
			return;
		}
		$this->removeThumbnail($package);
		$source = $this->getInstallPath($package).$this->thumbnailFile;
		$destination = $this->vendorDir.'/../public/packages/'.$package->getPrettyName().'/';

		$this->filesystem->ensureDirectoryExists($destination);
		copy($source, $destination.$this->thumbnailFile);

	}

	protected function removeThumbnail(PackageInterface $package){
		$this->filesystem->remove($this->vendorDir.'/../public/packages/'.$package->getPrettyName().'/'.$this->thumbnailFile);
	}
}