VulnerabilityScriptRunner.java

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Random;
import java.util.Set;

/**
 * @author Manjeer
 * 
 *         2. Let's say I have a database of scripts. Each script has an
 *         arbitrary number of dependencies. The dependencies are expressed as a
 *         list of scriptIds that need to be executed before a given script.
 *         There are no circular dependencies. I want to come up with an
 *         execution plan so that I can run all of the scripts in a sane order.
 *         Below is the script representation.
 *
 */
class VulnerabilityScript {

	private final int scriptId;
	private final List<Integer> dependencies;

	public VulnerabilityScript(int scriptId, List<Integer> dependencies) {
		this.scriptId = scriptId;
		this.dependencies = dependencies;
	}

	public int getScriptId() {
		return scriptId;
	}

	public List<Integer> getDependencies() {
		return dependencies;
	}

}

public class VulnerabilityScriptRunner {

	/**
	 * @param args
	 *  Main method
	 */
	public static void main(String[] args) {
		new VulnerabilityScriptRunner().generatePlan(VulnerabilityScriptRunner.getScriptById(10))
				.forEach(x -> System.out.println(x.getScriptId()));
	}

	/**
	 * @param script
	 * @return
	 * 
	 * 		Plan generator
	 */
	public List<VulnerabilityScript> generatePlan(VulnerabilityScript script) {
		if (script == null) {
			return null;
		}
		return generatePlan(script.getScriptId(), script);
	}

	/**
	 * @param id
	 * @param script
	 * @return
	 * 
	 * 		Plan generator (private)
	 */
	private List<VulnerabilityScript> generatePlan(Integer id, VulnerabilityScript script) {

		if (script == null) {
			script = VulnerabilityScriptRunner.getScriptById(id);
		}
		if (script == null) {
			return null;
		}
		List<VulnerabilityScript> plan = new ArrayList<>();
		if (script.getDependencies() != null && script.getDependencies().size() > 0) {
			for (Integer scriptId : script.getDependencies()) {
				List<VulnerabilityScript> subPlan = generatePlan(scriptId, null);
				if (subPlan != null && subPlan.size() > 0) {
					plan.addAll(subPlan);
				}
			}
		}
		plan.add(script);
		return plan;
	}

	private static Set<Integer> dup = new HashSet<>();

	/**
	 * @param id
	 * @return
	 * 
	 * 		Need to write script to get Object from DB. The following is just a
	 *         random code
	 */
	private static VulnerabilityScript getScriptById(Integer id) {

		Random r = new Random();
		List<Integer> list = new ArrayList<>();
		if (r.nextInt(100) % 2 == 0) {
			int rand = r.nextInt(100);
			if (!dup.contains(rand)) {
				list.add(rand);
				dup.add(rand);
			}

			rand = r.nextInt(100);
			if (!dup.contains(rand)) {
				list.add(rand);
				dup.add(rand);
			}
			list.add(r.nextInt(100));
		}
		return new VulnerabilityScript(id, list);
	}

}