/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * 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 android.support.v4.view.accessibility;

import android.os.Build;
import android.view.accessibility.AccessibilityEvent;

/**
 * Helper for accessing features in {@link AccessibilityEvent}
 * introduced after API level 4 in a backwards compatible fashion.
 */
public class AccessibilityEventCompat {

    static interface AccessibilityEventVersionImpl {
        public int getRecordCount(AccessibilityEvent event);
        public void appendRecord(AccessibilityEvent event, Object record);
        public Object getRecord(AccessibilityEvent event, int index);
    }

    static class AccessibilityEventStubImpl implements AccessibilityEventVersionImpl {

        public void appendRecord(AccessibilityEvent event, Object record) {

        }

        public Object getRecord(AccessibilityEvent event, int index) {
            return null;
        }

        public int getRecordCount(AccessibilityEvent event) {
            return 0;
        }
    }

    static class AccessibilityEventIcsImpl extends AccessibilityEventStubImpl {

        @Override
        public void appendRecord(AccessibilityEvent event, Object record) {
            AccessibilityEventCompatIcs.appendRecord(event, record);
        }

        @Override
        public Object getRecord(AccessibilityEvent event, int index) {
            return AccessibilityEventCompatIcs.getRecord(event, index);
        }

        @Override
        public int getRecordCount(AccessibilityEvent event) {
            return AccessibilityEventCompatIcs.getRecordCount(event);
        }
    }

    private final static AccessibilityEventVersionImpl IMPL;

    static {
        if (Build.VERSION.SDK_INT >= 14) { // ICS
            IMPL = new AccessibilityEventIcsImpl();
        } else {
            IMPL = new AccessibilityEventStubImpl();
        }
    }

    /**
     * Represents the event of a hover enter over a {@link android.view.View}.
     */
    public static final int TYPE_VIEW_HOVER_ENTER = 0x00000080;

    /**
     * Represents the event of a hover exit over a {@link android.view.View}.
     */
    public static final int TYPE_VIEW_HOVER_EXIT = 0x00000100;

    /**
     * Represents the event of starting a touch exploration gesture.
     */
    public static final int TYPE_TOUCH_EXPLORATION_GESTURE_START = 0x00000200;

    /**
     * Represents the event of ending a touch exploration gesture.
     */
    public static final int TYPE_TOUCH_EXPLORATION_GESTURE_END = 0x00000400;

    /**
     * Represents the event of changing the content of a window.
     */
    public static final int TYPE_WINDOW_CONTENT_CHANGED = 0x00000800;

    /**
     * Represents the event of scrolling a view.
     */
    public static final int TYPE_VIEW_SCROLLED = 0x00001000;

    /**
     * Represents the event of changing the selection in an {@link android.widget.EditText}.
     */
    public static final int TYPE_VIEW_TEXT_SELECTION_CHANGED = 0x00002000;

    /*
     * Hide constructor from clients.
     */
    private AccessibilityEventCompat() {

    }

    /**
     * Gets the number of records contained in the event.
     *
     * @return The number of records.
     */
    public static int getRecordCount(AccessibilityEvent event) {
        return IMPL.getRecordCount(event);
    }

    /**
     * Appends an {@link android.view.accessibility.AccessibilityRecord} to the end of
     * event records.
     *
     * @param record The record to append.
     *
     * @throws IllegalStateException If called from an AccessibilityService.
     */
    public static void appendRecord(AccessibilityEvent event, AccessibilityRecordCompat record) {
        IMPL.appendRecord(event, record.getImpl());
    }

    /**
     * Gets the record at a given index.
     *
     * @param index The index.
     * @return The record at the specified index.
     */
    public static AccessibilityRecordCompat getRecord(AccessibilityEvent event, int index) {
        return new AccessibilityRecordCompat(IMPL.getRecord(event, index));
    }
}