package solution.multithreading;

import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.concurrent.ConcurrentHashMap;

public class Main {

	private static Scanner scanner = new Scanner(System.in);
	
	// This map will hold the result of all directory scans.
	private static Map<String, List<File>> allResults = new ConcurrentHashMap<>();

	// This list will hold all the threads that have been started (so we can wait for them to finish when we quit). 
	private static List<Thread> allThreads = new ArrayList<>();
	
	
	// Application entry-point.
	public static void main(String[] args) {

		// Display the menu. 
		while (true) {
			System.out.println("\nChoose an option from the menu: ");
			System.out.println("  1. Search a directory");
			System.out.println("  2. List completed searches");
			System.out.println("  3. Show search results");
			System.out.println("  4. Quit");
			System.out.print("\n==> ");
	
			String option = scanner.nextLine();
			if (option.equals("1")) {
				doSearch();
			} 
			else if (option.equals("2")) {
				doListCompletedSearches();
			} 
			else if (option.equals("3")) {
				doShowSearchResult();
			} 
			else if (option.equals("4")) {
				doQuit();
				break;
			}
		}
		System.out.println("Goodbye!");
	}
	
	
	// Search a directory for its contents.
	private static void doSearch() {
		
		System.out.print("Enter a directory name: ");
		String directoryName = scanner.nextLine().toLowerCase();

		File file = new File(directoryName);
		if (!file.isDirectory()) {
			System.out.println("Directory does not exist!");
		}
		else {
			// Start a directory search in another thread.
			DirectorySearcher searcher = new DirectorySearcher(directoryName, allResults);
			Thread thread = new Thread(searcher);
			thread.start();
			System.out.println("Started search of " + directoryName);
			
			// Add the new thread to the list of all threads (so we can wait for it to finish when we quit).
			allThreads.add(thread);
		}
	}
	
	
	// List all the search operations that have completed so far.
	private static void doListCompletedSearches() {
	
		System.out.println("Here is a list of all completed searches:");
		for (String directoryName : allResults.keySet()) {
			System.out.println("  " + directoryName);
		}
	}
	
	
	// Show the results for a particular search.
	private static void doShowSearchResult() {
		
		System.out.print("Enter a directory name: ");
		String directoryName = scanner.nextLine();

		List<File> files = allResults.get(directoryName.toLowerCase());
		if (files == null) {
			System.out.println("No search results available for " + directoryName);
		} 
		else {
			System.out.println("Entries in directory " + directoryName);
			for (File file : files) {
				System.out.println("  " + (file.isDirectory() ? "[D] " : "[F] ") + file);
			}
		}
	}
	
	
	// Tidy-up before the application quits.
	private static void doQuit() {

		// Give each thread 3 seconds to finish.
		System.out.println("Giving each thread 3 seconds to finish...");
		for (Thread thread: allThreads) {
			try {
				thread.join(3000);
			} catch (InterruptedException ex) {}
		}
	}
}