/*
 * Copyright (C) 2010 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 com.android.internal.view.menu;

import com.android.internal.view.menu.MenuPresenter.Callback;

import android.annotation.AttrRes;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.annotation.StyleRes;
import android.content.Context;
import android.graphics.Point;
import android.graphics.Rect;
import android.util.DisplayMetrics;
import android.view.Display;
import android.view.Gravity;
import android.view.View;
import android.view.WindowManager;
import android.widget.PopupWindow.OnDismissListener;

Presents a menu as a small, simple popup anchored to another view.
/**
 * Presents a menu as a small, simple popup anchored to another view.
 */
public class MenuPopupHelper implements MenuHelper {
    private static final int TOUCH_EPICENTER_SIZE_DP = 48;

    private final Context mContext;

    // Immutable cached popup menu properties.
    private final MenuBuilder mMenu;
    private final boolean mOverflowOnly;
    private final int mPopupStyleAttr;
    private final int mPopupStyleRes;

    // Mutable cached popup menu properties.
    private View mAnchorView;
    private int mDropDownGravity = Gravity.START;
    private boolean mForceShowIcon;
    private Callback mPresenterCallback;

    private MenuPopup mPopup;
    private OnDismissListener mOnDismissListener;

    public MenuPopupHelper(@NonNull Context context, @NonNull MenuBuilder menu) {
        this(context, menu, null, false, com.android.internal.R.attr.popupMenuStyle, 0);
    }

    public MenuPopupHelper(@NonNull Context context, @NonNull MenuBuilder menu,
            @NonNull View anchorView) {
        this(context, menu, anchorView, false, com.android.internal.R.attr.popupMenuStyle, 0);
    }

    public MenuPopupHelper(@NonNull Context context, @NonNull MenuBuilder menu,
            @NonNull View anchorView,
            boolean overflowOnly, @AttrRes int popupStyleAttr) {
        this(context, menu, anchorView, overflowOnly, popupStyleAttr, 0);
    }

    public MenuPopupHelper(@NonNull Context context, @NonNull MenuBuilder menu,
            @NonNull View anchorView, boolean overflowOnly, @AttrRes int popupStyleAttr,
            @StyleRes int popupStyleRes) {
        mContext = context;
        mMenu = menu;
        mAnchorView = anchorView;
        mOverflowOnly = overflowOnly;
        mPopupStyleAttr = popupStyleAttr;
        mPopupStyleRes = popupStyleRes;
    }

    public void setOnDismissListener(@Nullable OnDismissListener listener) {
        mOnDismissListener = listener;
    }

    
Sets the view to which the popup window is anchored.

Changes take effect on the next call to show().
Params:
anchor – the view to which the popup window should be anchored/**
      * Sets the view to which the popup window is anchored.
      * <p>
      * Changes take effect on the next call to show().
      *
      * @param anchor the view to which the popup window should be anchored
      */
    public void setAnchorView(@NonNull View anchor) {
        mAnchorView = anchor;
    }

    
Sets whether the popup menu's adapter is forced to show icons in the
menu item views.

Changes take effect on the next call to show().
Params:
forceShowIcon – true to force icons to be shown, or false for icons to be optionally shown/**
     * Sets whether the popup menu's adapter is forced to show icons in the
     * menu item views.
     * <p>
     * Changes take effect on the next call to show().
     *
     * @param forceShowIcon {@code true} to force icons to be shown, or
     *                  {@code false} for icons to be optionally shown
     */
    public void setForceShowIcon(boolean forceShowIcon) {
        mForceShowIcon = forceShowIcon;
        if (mPopup != null) {
            mPopup.setForceShowIcon(forceShowIcon);
        }
    }

    
Sets the alignment of the popup window relative to the anchor view.

Changes take effect on the next call to show().
Params:
gravity – alignment of the popup relative to the anchor/**
      * Sets the alignment of the popup window relative to the anchor view.
      * <p>
      * Changes take effect on the next call to show().
      *
      * @param gravity alignment of the popup relative to the anchor
      */
    public void setGravity(int gravity) {
        mDropDownGravity = gravity;
    }

    
Returns:
alignment of the popup relative to the anchor/**
     * @return alignment of the popup relative to the anchor
     */
    public int getGravity() {
        return mDropDownGravity;
    }

    public void show() {
        if (!tryShow()) {
            throw new IllegalStateException("MenuPopupHelper cannot be used without an anchor");
        }
    }

    public void show(int x, int y) {
        if (!tryShow(x, y)) {
            throw new IllegalStateException("MenuPopupHelper cannot be used without an anchor");
        }
    }

    @NonNull
    public MenuPopup getPopup() {
        if (mPopup == null) {
            mPopup = createPopup();
        }
        return mPopup;
    }

    
Attempts to show the popup anchored to the view specified by setAnchorView(View). 
Returns:
true if the popup was shown or was already showing prior to calling this method, false otherwise/**
     * Attempts to show the popup anchored to the view specified by {@link #setAnchorView(View)}.
     *
     * @return {@code true} if the popup was shown or was already showing prior to calling this
     *         method, {@code false} otherwise
     */
    public boolean tryShow() {
        if (isShowing()) {
            return true;
        }

        if (mAnchorView == null) {
            return false;
        }

        showPopup(0, 0, false, false);
        return true;
    }

    
Shows the popup menu and makes a best-effort to anchor it to the
specified (x,y) coordinate relative to the anchor view.
 Additionally, the popup's transition epicenter (see PopupWindow.setEpicenterBounds(Rect) will be centered on the specified coordinate, rather than using the bounds of the anchor view. 
 If the popup's resolved gravity is Gravity.LEFT, this will display the popup with its top-left corner at (x,y) relative to the anchor view. If the resolved gravity is Gravity.RIGHT, the popup's top-right corner will be at (x,y). 

If the popup cannot be displayed fully on-screen, this method will
attempt to scroll the anchor view's ancestors and/or offset the popup
such that it may be displayed fully on-screen.
Params:
x – x coordinate relative to the anchor view
y – y coordinate relative to the anchor view
Returns:
true if the popup was shown or was already showing prior to calling this method, false otherwise/**
     * Shows the popup menu and makes a best-effort to anchor it to the
     * specified (x,y) coordinate relative to the anchor view.
     * <p>
     * Additionally, the popup's transition epicenter (see
     * {@link android.widget.PopupWindow#setEpicenterBounds(Rect)} will be
     * centered on the specified coordinate, rather than using the bounds of
     * the anchor view.
     * <p>
     * If the popup's resolved gravity is {@link Gravity#LEFT}, this will
     * display the popup with its top-left corner at (x,y) relative to the
     * anchor view. If the resolved gravity is {@link Gravity#RIGHT}, the
     * popup's top-right corner will be at (x,y).
     * <p>
     * If the popup cannot be displayed fully on-screen, this method will
     * attempt to scroll the anchor view's ancestors and/or offset the popup
     * such that it may be displayed fully on-screen.
     *
     * @param x x coordinate relative to the anchor view
     * @param y y coordinate relative to the anchor view
     * @return {@code true} if the popup was shown or was already showing prior
     *         to calling this method, {@code false} otherwise
     */
    public boolean tryShow(int x, int y) {
        if (isShowing()) {
            return true;
        }

        if (mAnchorView == null) {
            return false;
        }

        showPopup(x, y, true, true);
        return true;
    }

    
Creates the popup and assigns cached properties.
Returns:
an initialized popup/**
     * Creates the popup and assigns cached properties.
     *
     * @return an initialized popup
     */
    @NonNull
    private MenuPopup createPopup() {
        final WindowManager windowManager = (WindowManager) mContext.getSystemService(
            Context.WINDOW_SERVICE);
        final Display display = windowManager.getDefaultDisplay();
        final Point displaySize = new Point();
        display.getRealSize(displaySize);

        final int smallestWidth = Math.min(displaySize.x, displaySize.y);
        final int minSmallestWidthCascading = mContext.getResources().getDimensionPixelSize(
            com.android.internal.R.dimen.cascading_menus_min_smallest_width);
        final boolean enableCascadingSubmenus = smallestWidth >= minSmallestWidthCascading;

        final MenuPopup popup;
        if (enableCascadingSubmenus) {
            popup = new CascadingMenuPopup(mContext, mAnchorView, mPopupStyleAttr,
                    mPopupStyleRes, mOverflowOnly);
        } else {
            popup = new StandardMenuPopup(mContext, mMenu, mAnchorView, mPopupStyleAttr,
                    mPopupStyleRes, mOverflowOnly);
        }

        // Assign immutable properties.
        popup.addMenu(mMenu);
        popup.setOnDismissListener(mInternalOnDismissListener);

        // Assign mutable properties. These may be reassigned later.
        popup.setAnchorView(mAnchorView);
        popup.setCallback(mPresenterCallback);
        popup.setForceShowIcon(mForceShowIcon);
        popup.setGravity(mDropDownGravity);

        return popup;
    }

    private void showPopup(int xOffset, int yOffset, boolean useOffsets, boolean showTitle) {
        final MenuPopup popup = getPopup();
        popup.setShowTitle(showTitle);

        if (useOffsets) {
            // If the resolved drop-down gravity is RIGHT, the popup's right
            // edge will be aligned with the anchor view. Adjust by the anchor
            // width such that the top-right corner is at the X offset.
            final int hgrav = Gravity.getAbsoluteGravity(mDropDownGravity,
                    mAnchorView.getLayoutDirection()) & Gravity.HORIZONTAL_GRAVITY_MASK;
            if (hgrav == Gravity.RIGHT) {
                xOffset -= mAnchorView.getWidth();
            }

            popup.setHorizontalOffset(xOffset);
            popup.setVerticalOffset(yOffset);

            // Set the transition epicenter to be roughly finger (or mouse
            // cursor) sized and centered around the offset position. This
            // will give the appearance that the window is emerging from
            // the touch point.
            final float density = mContext.getResources().getDisplayMetrics().density;
            final int halfSize = (int) (TOUCH_EPICENTER_SIZE_DP * density / 2);
            final Rect epicenter = new Rect(xOffset - halfSize, yOffset - halfSize,
                    xOffset + halfSize, yOffset + halfSize);
            popup.setEpicenterBounds(epicenter);
        }

        popup.show();
    }

    
Dismisses the popup, if showing.
/**
     * Dismisses the popup, if showing.
     */
    @Override
    public void dismiss() {
        if (isShowing()) {
            mPopup.dismiss();
        }
    }

    
Called after the popup has been dismissed.

Note: Subclasses should call the super implementation last to ensure that any necessary tear down has occurred before the listener specified by setOnDismissListener(OnDismissListener) is called. /**
     * Called after the popup has been dismissed.
     * <p>
     * <strong>Note:</strong> Subclasses should call the super implementation
     * last to ensure that any necessary tear down has occurred before the
     * listener specified by {@link #setOnDismissListener(OnDismissListener)}
     * is called.
     */
    protected void onDismiss() {
        mPopup = null;

        if (mOnDismissListener != null) {
            mOnDismissListener.onDismiss();
        }
    }

    public boolean isShowing() {
        return mPopup != null && mPopup.isShowing();
    }

    @Override
    public void setPresenterCallback(@Nullable MenuPresenter.Callback cb) {
        mPresenterCallback = cb;
        if (mPopup != null) {
            mPopup.setCallback(cb);
        }
    }

    
Listener used to proxy dismiss callbacks to the helper's owner.
/**
     * Listener used to proxy dismiss callbacks to the helper's owner.
     */
    private final OnDismissListener mInternalOnDismissListener = new OnDismissListener() {
        @Override
        public void onDismiss() {
            MenuPopupHelper.this.onDismiss();
        }
    };
}