/*
 * Copyright (C) 2015 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.widget;

import android.os.SystemClock;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewParent;

import com.android.internal.view.menu.ShowableListMenu;

Abstract class that forwards touch events to a ShowableListMenu. 
@hide
/**
 * Abstract class that forwards touch events to a {@link ShowableListMenu}.
 *
 * @hide
 */
public abstract class ForwardingListener
        implements View.OnTouchListener, View.OnAttachStateChangeListener {

    
Scaled touch slop, used for detecting movement outside bounds. /** Scaled touch slop, used for detecting movement outside bounds. */
    private final float mScaledTouchSlop;

    
Timeout before disallowing intercept on the source's parent. /** Timeout before disallowing intercept on the source's parent. */
    private final int mTapTimeout;

    
Timeout before accepting a long-press to start forwarding. /** Timeout before accepting a long-press to start forwarding. */
    private final int mLongPressTimeout;

    
Source view from which events are forwarded. /** Source view from which events are forwarded. */
    private final View mSrc;

    
Runnable used to prevent conflicts with scrolling parents. /** Runnable used to prevent conflicts with scrolling parents. */
    private Runnable mDisallowIntercept;

    
Runnable used to trigger forwarding on long-press. /** Runnable used to trigger forwarding on long-press. */
    private Runnable mTriggerLongPress;

    
Whether this listener is currently forwarding touch events. /** Whether this listener is currently forwarding touch events. */
    private boolean mForwarding;

    
The id of the first pointer down in the current event stream. /** The id of the first pointer down in the current event stream. */
    private int mActivePointerId;

    public ForwardingListener(View src) {
        mSrc = src;
        src.setLongClickable(true);
        src.addOnAttachStateChangeListener(this);

        mScaledTouchSlop = ViewConfiguration.get(src.getContext()).getScaledTouchSlop();
        mTapTimeout = ViewConfiguration.getTapTimeout();

        // Use a medium-press timeout. Halfway between tap and long-press.
        mLongPressTimeout = (mTapTimeout + ViewConfiguration.getLongPressTimeout()) / 2;
    }

    
Returns the popup to which this listener is forwarding events.
 Override this to return the correct popup. If the popup is displayed asynchronously, you may also need to override onForwardingStopped to prevent premature cancellation of forwarding. 
Returns:
the popup to which this listener is forwarding events/**
     * Returns the popup to which this listener is forwarding events.
     * <p>
     * Override this to return the correct popup. If the popup is displayed
     * asynchronously, you may also need to override
     * {@link #onForwardingStopped} to prevent premature cancellation of
     * forwarding.
     *
     * @return the popup to which this listener is forwarding events
     */
    public abstract ShowableListMenu getPopup();

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        final boolean wasForwarding = mForwarding;
        final boolean forwarding;
        if (wasForwarding) {
            forwarding = onTouchForwarded(event) || !onForwardingStopped();
        } else {
            forwarding = onTouchObserved(event) && onForwardingStarted();

            if (forwarding) {
                // Make sure we cancel any ongoing source event stream.
                final long now = SystemClock.uptimeMillis();
                final MotionEvent e = MotionEvent.obtain(now, now, MotionEvent.ACTION_CANCEL,
                        0.0f, 0.0f, 0);
                mSrc.onTouchEvent(e);
                e.recycle();
            }
        }

        mForwarding = forwarding;
        return forwarding || wasForwarding;
    }

    @Override
    public void onViewAttachedToWindow(View v) {
    }

    @Override
    public void onViewDetachedFromWindow(View v) {
        mForwarding = false;
        mActivePointerId = MotionEvent.INVALID_POINTER_ID;

        if (mDisallowIntercept != null) {
            mSrc.removeCallbacks(mDisallowIntercept);
        }
    }

    
Called when forwarding would like to start.
 By default, this will show the popup returned by getPopup(). It may be overridden to perform another action, like clicking the source view or preparing the popup before showing it. 
Returns:
true to start forwarding, false otherwise/**
     * Called when forwarding would like to start.
     * <p>
     * By default, this will show the popup returned by {@link #getPopup()}.
     * It may be overridden to perform another action, like clicking the
     * source view or preparing the popup before showing it.
     *
     * @return true to start forwarding, false otherwise
     */
    protected boolean onForwardingStarted() {
        final ShowableListMenu popup = getPopup();
        if (popup != null && !popup.isShowing()) {
            popup.show();
        }
        return true;
    }

    
Called when forwarding would like to stop.
 By default, this will dismiss the popup returned by getPopup(). It may be overridden to perform some other action. 
Returns:
true to stop forwarding, false otherwise/**
     * Called when forwarding would like to stop.
     * <p>
     * By default, this will dismiss the popup returned by
     * {@link #getPopup()}. It may be overridden to perform some other
     * action.
     *
     * @return true to stop forwarding, false otherwise
     */
    protected boolean onForwardingStopped() {
        final ShowableListMenu popup = getPopup();
        if (popup != null && popup.isShowing()) {
            popup.dismiss();
        }
        return true;
    }

    
Observes motion events and determines when to start forwarding.
Params:
srcEvent – motion event in source view coordinates
Returns:
true to start forwarding motion events, false otherwise/**
     * Observes motion events and determines when to start forwarding.
     *
     * @param srcEvent motion event in source view coordinates
     * @return true to start forwarding motion events, false otherwise
     */
    private boolean onTouchObserved(MotionEvent srcEvent) {
        final View src = mSrc;
        if (!src.isEnabled()) {
            return false;
        }

        final int actionMasked = srcEvent.getActionMasked();
        switch (actionMasked) {
            case MotionEvent.ACTION_DOWN:
                mActivePointerId = srcEvent.getPointerId(0);

                if (mDisallowIntercept == null) {
                    mDisallowIntercept = new DisallowIntercept();
                }
                src.postDelayed(mDisallowIntercept, mTapTimeout);

                if (mTriggerLongPress == null) {
                    mTriggerLongPress = new TriggerLongPress();
                }
                src.postDelayed(mTriggerLongPress, mLongPressTimeout);
                break;
            case MotionEvent.ACTION_MOVE:
                final int activePointerIndex = srcEvent.findPointerIndex(mActivePointerId);
                if (activePointerIndex >= 0) {
                    final float x = srcEvent.getX(activePointerIndex);
                    final float y = srcEvent.getY(activePointerIndex);

                    // Has the pointer moved outside of the view?
                    if (!src.pointInView(x, y, mScaledTouchSlop)) {
                        clearCallbacks();

                        // Don't let the parent intercept our events.
                        src.getParent().requestDisallowInterceptTouchEvent(true);
                        return true;
                    }
                }
                break;
            case MotionEvent.ACTION_CANCEL:
            case MotionEvent.ACTION_UP:
                clearCallbacks();
                break;
        }

        return false;
    }

    private void clearCallbacks() {
        if (mTriggerLongPress != null) {
            mSrc.removeCallbacks(mTriggerLongPress);
        }

        if (mDisallowIntercept != null) {
            mSrc.removeCallbacks(mDisallowIntercept);
        }
    }

    private void onLongPress() {
        clearCallbacks();

        final View src = mSrc;
        if (!src.isEnabled() || src.isLongClickable()) {
            // Ignore long-press if the view is disabled or has its own
            // handler.
            return;
        }

        if (!onForwardingStarted()) {
            return;
        }

        // Don't let the parent intercept our events.
        src.getParent().requestDisallowInterceptTouchEvent(true);

        // Make sure we cancel any ongoing source event stream.
        final long now = SystemClock.uptimeMillis();
        final MotionEvent e = MotionEvent.obtain(now, now, MotionEvent.ACTION_CANCEL, 0, 0, 0);
        src.onTouchEvent(e);
        e.recycle();

        mForwarding = true;
    }

    
Handles forwarded motion events and determines when to stop
forwarding.
Params:
srcEvent – motion event in source view coordinates
Returns:
true to continue forwarding motion events, false to cancel/**
     * Handles forwarded motion events and determines when to stop
     * forwarding.
     *
     * @param srcEvent motion event in source view coordinates
     * @return true to continue forwarding motion events, false to cancel
     */
    private boolean onTouchForwarded(MotionEvent srcEvent) {
        final View src = mSrc;
        final ShowableListMenu popup = getPopup();
        if (popup == null || !popup.isShowing()) {
            return false;
        }

        final DropDownListView dst = (DropDownListView) popup.getListView();
        if (dst == null || !dst.isShown()) {
            return false;
        }

        // Convert event to destination-local coordinates.
        final MotionEvent dstEvent = MotionEvent.obtainNoHistory(srcEvent);
        src.toGlobalMotionEvent(dstEvent);
        dst.toLocalMotionEvent(dstEvent);

        // Forward converted event to destination view, then recycle it.
        final boolean handled = dst.onForwardedEvent(dstEvent, mActivePointerId);
        dstEvent.recycle();

        // Always cancel forwarding when the touch stream ends.
        final int action = srcEvent.getActionMasked();
        final boolean keepForwarding = action != MotionEvent.ACTION_UP
                && action != MotionEvent.ACTION_CANCEL;

        return handled && keepForwarding;
    }

    private class DisallowIntercept implements Runnable {
        @Override
        public void run() {
            final ViewParent parent = mSrc.getParent();
            if (parent != null) {
                parent.requestDisallowInterceptTouchEvent(true);
            }
        }
    }

    private class TriggerLongPress implements Runnable {
        @Override
        public void run() {
            onLongPress();
        }
    }
}