package cachingfilter;

import java.io.File;
import java.io.IOException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


final class CachedDir implements CachedPage {
	private static final Logger logger = LoggerFactory.getLogger(CachedDir.class);
	private static final long tooLong = 1000L*60*10;  // 10 minutes
	private final File dir;
	private File newFile;

	CachedDir( File parent, String child ) {
		this.dir = new File(parent,child);
	}

	public String name() {
		return dir.getName();
	}

	public boolean exists() {
		if( !dir.exists() )
			return false;
		File[] files = dir.listFiles();
		if( files == null )
			throw new RuntimeException("error doing listFiles of "+dir);
		return files.length >= 1;
	}

	public File lastFile() {
		File[] files = dir.listFiles();
		if( files.length == 1 ) {
			return files[0];
		}
		int n = 0;
		File lastFile = null;
		for( File file : files ) {
			String name = file.getName();
			int i = Integer.parseInt(name);
			if( n < i ) {
				if( lastFile != null )
					lastFile.delete();
				n = i;
				lastFile = file;
			} else {
				file.delete();
			}
		}
		if( lastFile==null )
			throw new RuntimeException(dir.toString());
		return lastFile;
	}

	public File newFile() throws IOException {
		if( !dir.exists() && !dir.mkdir() )
			throw new RuntimeException("couldn't create "+dir);
		int n = 0;
		for( File file : dir.listFiles() ) {
			String name = file.getName();
			int i = Integer.parseInt(name);
			if( n < i )
				n = i;
			file.delete();
		}
		newFile = new File( dir, Integer.toString( n + 1 ) );
		if( !newFile.createNewFile() )
			throw new RuntimeException("couldn't create "+newFile);
		return newFile;
	}

	public void deleteNewFile() {
		if( !newFile.delete() )
			throw new RuntimeException("couldn't delete new file "+newFile);
	}

	public boolean delete() {
		File die = new File(dir.getParentFile(),"~die");
		if( die.exists() ) {
			for( File f : die.listFiles() ) {
				if( !f.delete() ) {
					logger.error("couldn't delete "+f);
					return false;
				}
			}
			if( !die.delete() ) {
				logger.error("couldn't delete "+die);
				return false;
			}
		}
		return dir.renameTo(die);
	}

	public String toString() {
		return dir.toString();
	}

}