package de.visualmeta;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Possible to do a lot safer and cleaner, but proceeded from the problem
 * statement. And it is not very concretized in some moments.
 * 
 * @author JDev
 *
 */
public class Crawler {

	private final String LINK_PATTERN= "\\(?\\b(http://|www[.])[-A-Za-z0-9+&@#/%?=~_()|!:,.;]*[-A-Za-z0-9+&@#/%=~_()|]";
	private Pattern linkPattern = Pattern.compile(LINK_PATTERN, Pattern.CASE_INSENSITIVE | Pattern.DOTALL);

	private final String START_URL = "http://google.com/";

	private int linksArrayCounter = 0;

	private ArrayList<String> links = new ArrayList<String>();
	private int step = 0;

	public Crawler() {

		// I understand that there is a possible recursion.
		while (true) {
			if (links.isEmpty()) {
				parseLinksFromHtml(START_URL);
			} else if (linksArrayCounter < links.size()) {
				parseLinksFromHtml(links.get(linksArrayCounter));
				linksArrayCounter++;
			} else {
				linksArrayCounter = 0;
			}
			step++;
		}
	}

	private void parseLinksFromHtml(String stringUrl) {

		URL url;
		InputStream inputStream = null;
		BufferedReader bReader;
		String line;

		StringBuilder stringBuilder = new StringBuilder();

		try {
			url = new URL(stringUrl);
			inputStream = url.openStream();
			bReader = new BufferedReader(new InputStreamReader(inputStream));

			while ((line = bReader.readLine()) != null) {
				stringBuilder.append(line);
			}

			Matcher pageMatcher = linkPattern.matcher(stringBuilder.toString());

			while (pageMatcher.find()) {
				links.add(pageMatcher.group());
				if (links.size() >= 1000) {
					for (int i = 0; i < links.size(); i++) {
						System.out.println(i + 1 + "> " + links.get(i));
					}
					System.out.println("\n -------------------------------------\n Parsed 1000 links in " + step
							+ " steps \n -------------------------------------\n");
					System.exit(0);
				}
			}
		} catch (MalformedURLException muException) {
			muException.printStackTrace();
			linksArrayCounter++;
		} catch (IOException ioException) {
			ioException.printStackTrace();
		} finally {
			try {
				if (inputStream != null) {
					inputStream.close();
				}
			} catch (IOException ioException) {
			}
		}
	}

	public static void main(String[] args) {

		new Crawler();
	}
}