it.jaschke.alexandria.model.view.BookListViewModel.java Source code

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Here is the source code for it.jaschke.alexandria.model.view.BookListViewModel.java

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/*
 * Copyright 2015 Jess Adolfo Garca Pasquel
 *
 * 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 it.jaschke.alexandria.model.view;

import android.net.Uri;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.widget.AdapterView;

import org.apache.commons.lang3.StringUtils;
import org.parceler.Parcel;

import de.greenrobot.event.EventBus;
import it.jaschke.alexandria.data.BookContract;
import it.jaschke.alexandria.model.domain.Book;
import it.jaschke.alexandria.model.event.BookSelectionEvent;
import it.jaschke.alexandria.model.event.SearchStringChangeEvent;
import it.jaschke.alexandria.view.adapter.BookListAdapter;

import static it.jaschke.alexandria.data.BookContract.BookEntry;

/**
 * View model for the book list's view. Provides data and behaviour.
 *
 * @author Jess Adolfo Garca Pasquel
 */
@Parcel(Parcel.Serialization.BEAN)
public class BookListViewModel {

    /**
     * Identifies messages written to the log by this class.
     */
    private static final String LOG_TAG = BookListViewModel.class.getSimpleName();

    /**
     * Selection clause used to search for text in the title or subtitle of
     * a book.
     */
    private static final String SELECTION_PARTIAL_TITLE = BookEntry.COLUMN_TITLE + " LIKE ? OR "
            + BookEntry.COLUMN_SUBTITLE + " LIKE ? ";

    /**
     * The position of the currently selected book, possibly
     * {@link AdapterView#INVALID_POSITION}.
     */
    private int mSelectedPosition = AdapterView.INVALID_POSITION;

    /**
     * The text entered by the user to limit the books listed to those
     * containing this value.
     */
    private String mSearchString;

    /**
     * Updates the value of the search string with the changes entered by
     * the user.
     */
    private final TextWatcher mSearchStringWatcher = new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            // Ignored
        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            // Ignored
        }

        @Override
        public void afterTextChanged(Editable s) {
            setSearchString(s != null ? s.toString() : null);
        }
    };

    /**
     * Updates the value of {@link #mSelectedPosition} and publishes a
     * {@link BookSelectionEvent} on the {@link EventBus}, containing a new
     * instance of {@link Book} with only its id (the ISBN-13) assigned.
     *
     * @param parent ignored.
     * @param view ignored.
     * @param position the book's position in the list.
     * @param id the book's identifier.
     */
    public void onBookSelected(AdapterView<?> parent, View view, int position, long id) {
        mSelectedPosition = position;
        Book selectedBook = new Book();
        selectedBook.setId(id);
        EventBus.getDefault().post(new BookSelectionEvent(selectedBook));
    }

    public int getSelectedPosition() {
        return mSelectedPosition;
    }

    public void setSelectedPosition(int selectedPosition) {
        mSelectedPosition = selectedPosition;
    }

    /**
     * Sets the value of the selected position to
     * {@link AdapterView#INVALID_POSITION}.
     */
    public void clearSelectedPosition() {
        mSelectedPosition = AdapterView.INVALID_POSITION;
    }

    public String getSearchString() {
        return mSearchString;
    }

    /**
     * Updates the value of the search string to the one passed. If the new
     * value is different than the current one, publishes a
     * {@link SearchStringChangeEvent} on the {@link EventBus}.
     *
     * @param searchString the new value of the search string.
     */
    public void setSearchString(String searchString) {
        if (StringUtils.equals(mSearchString, searchString)) {
            return;
        }
        String old = mSearchString;
        mSearchString = searchString;
        EventBus.getDefault().post(new SearchStringChangeEvent(old, mSearchString));
    }

    /**
     * Returns a reference to {@link #onBookSelected(AdapterView, View, int, long)}.
     *
     * @return a reference to {@link #onBookSelected(AdapterView, View, int, long)}
     */
    public AdapterView.OnItemClickListener getBookClickListener() {
        return this::onBookSelected;
    }

    public TextWatcher getSearchStringWatcher() {
        return mSearchStringWatcher;
    }

    /**
     * Returns the content {@link Uri} from which the list of books is retrieved.
     *
     * @return the content {@link Uri} from which the list of books is retrieved.
     */
    public Uri getBookListQueryUri() {
        return BookContract.BookEntry.CONTENT_URI;
    }

    /**
     * Returns the projection used on the query to retrieve the list of books.
     *
     * @return the projection used on the query to retrieve the list of books.
     * @see BookListAdapter#PROJECTION_BOOK_LIST
     */
    public String[] getBookListQueryProjection() {
        return BookListAdapter.PROJECTION_BOOK_LIST;
    }

    /**
     * Returns the selection clause used on the query to retrieve the list of books.
     *
     * @return the selection clause used on the query to retrieve the list of books.
     */
    public String getBookListQuerySelection() {
        return StringUtils.trimToNull(mSearchString) != null ? SELECTION_PARTIAL_TITLE : null;
    }

    /**
     * Returns the arguments for the selection clause used on the query to
     * retrieve the list of books.
     *
     * @return the arguments for the selection clause used on the query to
     *     retrieve the list of books.
     */
    public String[] getBookListQuerySelectionArguments() {
        String searchPattern = "%" + mSearchString + "%";
        return StringUtils.trimToNull(mSearchString) != null ? new String[] { searchPattern, searchPattern } : null;
    }

}