com.google.mobile.trippy.web.client.presenter.CommentListItemPresenter.java Source code

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Here is the source code for com.google.mobile.trippy.web.client.presenter.CommentListItemPresenter.java

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/*
 * Copyright 2010 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.mobile.trippy.web.client.presenter;

import com.google.common.annotations.VisibleForTesting;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.event.dom.client.HasClickHandlers;
import com.google.gwt.event.shared.HandlerManager;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.rpc.AsyncCallback;
import com.google.mobile.trippy.web.client.base.Constants;
import com.google.mobile.trippy.web.client.base.SingletonComponents;
import com.google.mobile.trippy.web.client.view.View;
import com.google.mobile.trippy.web.client.widget.Toast;
import com.google.mobile.trippy.web.shared.exception.AuthorizationException;
import com.google.mobile.trippy.web.shared.models.Comment;

import java.util.ArrayList;
import java.util.List;

/**
 * Presenter for a single comment in comment list.
 * 
 * This presenter is responsible for filling a comment view. It will fill
 * comment text as entered by user, the date on which comment posted, User who 
 * posted the comment, and will show the delete button (if the viewer is same
 *  as owner of the comment). 
 * 
 */
public class CommentListItemPresenter implements EventHandlerPresenter<CommentListItemPresenter.Display> {

    /**
     * View interface for this presenter
     */
    public interface Display extends View {
        public HasClickHandlers getDeleteButton();

        public void setCommentText(final String text);

        public void setDate(final String dateString);

        public void setUser(final String userString);

        public void setDeleteButtonVisible(final boolean visible);
    }

    /** Object to contain the reference of associated view. */
    private final Display display;

    /** Common container for all the singleton components of this application. */
    private final SingletonComponents provider;

    private final List<HandlerRegistration> handlers;

    /** Boolean to check whether current viewer is owner or not. */
    private boolean isOwner;
    private Comment comment;

    public CommentListItemPresenter(final Display display, final SingletonComponents provider) {
        this.display = display;
        this.provider = provider;
        this.handlers = new ArrayList<HandlerRegistration>();
    }

    /**
     * Method takes the responsibility for handling all the events and firing
     * the events.
     * 
     * Click Handlers:
     * 1) It will have a click handler on Click event of Delete button, which will
     *    send delete request for this comment to comment service.
     */
    @Override
    public void bind() {
        if (isOwner) {
            handlers.add(display.getDeleteButton().addClickHandler(new ClickHandler() {
                @Override
                public void onClick(ClickEvent event) {
                    final Toast toast = provider.getToast();
                    try {
                        if (Window.confirm(provider.getMessage().confirmCommentDelete())) {
                            toast.showLoading(provider.getMessage().deleting(Constants.COMMENT_LOWER_CASE_STR));
                            provider.getCommentService().deleteComment(comment, new AsyncCallback<Void>() {
                                @Override
                                public void onSuccess(Void result) {
                                    toast.hideLoading();
                                    toast.showToast(provider.getMessage().commentDeleted());
                                }

                                @Override
                                public void onFailure(Throwable caught) {
                                    toast.hideLoading();
                                    if (caught instanceof AuthorizationException) {
                                        toast.showToast(provider.getMessage()
                                                .unauthorizedDelete(Constants.COMMENT_LOWER_CASE_STR));
                                    } else {
                                        toast.showToast(provider.getMessage().commentDeletionFailed());
                                    }
                                }
                            });
                        }
                    } catch (AuthorizationException e) {
                        toast.hideLoading();
                        toast.showToast(provider.getMessage().unauthorizedDelete(Constants.COMMENT_LOWER_CASE_STR));
                    }
                }
            }));
        }
    }

    @Override
    public HandlerManager getEventBus() {
        return provider.getEventBus();
    }

    @Override
    public void release() {
        for (HandlerRegistration handler : handlers) {
            if (handler != null) {
                handler.removeHandler();
            }
        }
        handlers.clear();
    }

    @Override
    public Display getDisplay() {
        return display;
    }

    /**
     * Method is used to populate the Comment Item View. 
     * 
     * It will set comment text, user name and date into display.
     * It also hide delete button, if user is not the owner of comment. 
     */
    @VisibleForTesting
    void populateView(final Comment commentToAdd) {
        display.setCommentText(commentToAdd.getComment());
        display.setDate(provider.getUtils().getDateTimeString(commentToAdd.getAddedOn()));
        display.setUser(commentToAdd.getUserId());
        display.setDeleteButtonVisible(isOwner);
    }

    /** 
     * Method will be used to set comment by the {@link CommentsPresenter}. 
     */
    void setComment(final Comment comment, final boolean owner) {
        this.comment = comment;
        setOwner(owner);
        populateView(comment);
    }

    /**
     *  Method will be used by test cases only. 
     */
    @VisibleForTesting
    void setOwner(final boolean owner) {
        this.isOwner = owner;
    }
}