CommitController.java

package se.chalmers.dat255.grupp12;

import com.google.gson.Gson;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;

/**
 * Created with IntelliJ IDEA.
 * User: Patrik
 * Date: 10/4/13
 * Time: 1:48 PM
 * To change this template use File | Settings | File Templates.
 */
public class CommitController {

	private CommitHandler taskCommitHandler;
	private CommitHandler listCommitHandler;
	private ClientChangeList changes = new ClientChangeList();
	private User user;

	/**
	 * Constructor that sets the current user and creates new CommitHandlers
	 *
	 * @param sessionUser - The current user
	 */
	public CommitController(User sessionUser) {

		this.user = sessionUser;
		this.taskCommitHandler = new TaskCommitHandler(changes,user);
		this.listCommitHandler = new ListCommitHandler(changes,user);

	}

	/**
	 * Performs the requested operations to the database and returns all the changes made
	 *
	 * @param element - A Json-array containing all the changes to be made
	 * @return - A CommitChangeList containing all the changes made
	 */
	public synchronized ClientChangeList getChanges(JsonArray element) {
		Gson gson = new Gson();
		for(JsonElement change : element){
			Modification m = gson.fromJson(change, Modification.class);
			performOperation(m);
		}
		changes.setUserLists(user);
		return changes;
	}

	/**
	 * Handles a Modification which contains an action and a change
	 * Performs an operation depending on what the action of the modification contains
	 *
	 * @param m - The modification to be handled
	 */
	private void performOperation(Modification m) {
		String action = m.getAction();
		CommitHandler handler;
		if (action.contains("TASK")) {
			handler = taskCommitHandler;
		} else {
			handler = listCommitHandler;
		}
		action = action.substring(0,action.length() - 4);
		switch (action) {
			case "ADD": {
				handler.insert(m);
				break;
			}
			case "CHANGE": {
				handler.update(m);
				break;
			}
			case "REMOVE":
				handler.delete(m);
				break;
			default:
				throw new UnsupportedOperationException("UNSUPPORTED OPERATION: " + action);
		}
	}
}