package threadPool;

import java.io.*;
import java.util.*;
import java.util.concurrent.*;

public class ThreadPoolTest {

	public static void main(String[] args) throws Exception{
		// TODO Auto-generated method stub
		Scanner in=new Scanner(System.in);
		System.out.print("Enter base directory(e.g. /usr/local/jdk5.0/src):");
		String directory=in.next();
		System.out.print("Enter keyword (e.g. volatile):");
		String keyword=in.next();
		
		System.out.println("keyword:"+keyword+"directory:"+directory);
		
		ExecutorService pool=Executors.newCachedThreadPool();
		
		MatchCounter counter=new MatchCounter(new File(directory),keyword,pool);
		Future<Integer> result=pool.submit(counter);
		
		try{
			System.out.println(result.get()+"matching files");
		}catch(ExecutionException e){
			e.printStackTrace();
		}catch(InterruptedException e){
			
		}
		pool.shutdown();
		
		int largestPoolSize=((ThreadPoolExecutor) pool).getLargestPoolSize();
		System.out.println("largest pool size="+largestPoolSize);
	}

}

class MatchCounter implements Callable<Integer>{
	
	private File directory;
	private String keyword;
	private ExecutorService pool;
	private int count;
	
	public MatchCounter(File directory,String keyword,ExecutorService pool){
		
		this.directory=directory;
		this.keyword=keyword;
		this.pool=pool;
	}
	
	public Integer call(){
		
		count=0;
		
		try {
			File[] files=directory.listFiles();
			List<Future<Integer>> results=new ArrayList<>();
			
			for(File file:files)
				if(file.isDirectory()){
					
					MatchCounter counter=new MatchCounter(file,keyword,pool);
					Future<Integer> result=pool.submit(counter);
					results.add(result);
				}
				else{
					
					if(search(file)) count++;
				}
				
			for(Future<Integer> result:results)
				try {
					count+=result.get();
				} catch (ExecutionException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	return count;
	}
	
	public boolean search(File file){
		
		try{
			try(Scanner in=new Scanner(file)){
				boolean found=false;
				while(!found&&in.hasNext()){
					String line=in.nextLine();
					if(line.contains(keyword))
						found=true;
				}
				return found;
			}
			
		}catch(IOException e){
			return false;
		}
	}
}