/*
 * Copyright (C) 2016 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.server.wm;

import static com.android.server.wm.WindowManagerDebugConfig.TAG_WITH_CLASS_NAME;
import static com.android.server.wm.WindowManagerDebugConfig.TAG_WM;

import android.content.res.Resources;
import android.graphics.Rect;
import android.os.IBinder;
import android.os.RemoteException;
import android.util.Log;
import android.util.Slog;
import android.view.IPinnedTaskListener;

import java.io.PrintWriter;

/**
 * Holds the common state of the pinned task between the system and SystemUI. If SystemUI ever
 * needs to be restarted, it will be notified with the last known state.
 *
 * Changes to the pinned task also flow through this controller, and generally, the system only
 * changes the pinned task bounds through this controller in two ways:
 *
 * 1) When first entering PiP: the controller returns the valid bounds given, taking aspect ratio
 *    and IME state into account.
 * 2) When rotating the device: the controller calculates the new bounds in the new orientation,
 *    taking the IME state into account. In this case, we currently ignore the
 *    SystemUI adjustments (ie. expanded for menu, interaction, etc).
 *
 * Other changes in the system, including adjustment of IME, configuration change, and more are
 * handled by SystemUI (similar to the docked task divider).
 */
class PinnedTaskController {

    private static final String TAG = TAG_WITH_CLASS_NAME ? "PinnedTaskController" : TAG_WM;

    private final WindowManagerService mService;
    private final DisplayContent mDisplayContent;

    private IPinnedTaskListener mPinnedTaskListener;
    private final PinnedTaskListenerDeathHandler mPinnedTaskListenerDeathHandler =
            new PinnedTaskListenerDeathHandler();

    /** Whether to skip task configuration change once. */
    private boolean mFreezingTaskConfig;

    private boolean mIsImeShowing;
    private int mImeHeight;

    // The aspect ratio bounds of the PIP.
    private float mMinAspectRatio;
    private float mMaxAspectRatio;

    /**
     * Handler for the case where the listener dies.
     */
    private class PinnedTaskListenerDeathHandler implements IBinder.DeathRecipient {

        @Override
        public void binderDied() {
            synchronized (mService.mGlobalLock) {
                mPinnedTaskListener = null;
                mFreezingTaskConfig = false;
            }
        }
    }

    PinnedTaskController(WindowManagerService service, DisplayContent displayContent) {
        mService = service;
        mDisplayContent = displayContent;
        reloadResources();
    }

    /** Updates the resources used by pinned controllers.  */
    void onPostDisplayConfigurationChanged() {
        reloadResources();
        mFreezingTaskConfig = false;
    }

    /**
     * Reloads all the resources for the current configuration.
     */
    private void reloadResources() {
        final Resources res = mService.mContext.getResources();
        mMinAspectRatio = res.getFloat(
                com.android.internal.R.dimen.config_pictureInPictureMinAspectRatio);
        mMaxAspectRatio = res.getFloat(
                com.android.internal.R.dimen.config_pictureInPictureMaxAspectRatio);
    }

    /**
     * Registers a pinned task listener.
     */
    void registerPinnedTaskListener(IPinnedTaskListener listener) {
        try {
            listener.asBinder().linkToDeath(mPinnedTaskListenerDeathHandler, 0);
            mPinnedTaskListener = listener;
            notifyImeVisibilityChanged(mIsImeShowing, mImeHeight);
            notifyMovementBoundsChanged(false /* fromImeAdjustment */);
        } catch (RemoteException e) {
            Log.e(TAG, "Failed to register pinned task listener", e);
        }
    }

    /**
     * @return whether the given {@param aspectRatio} is valid, i.e. min <= ratio <= max.
     */
    public boolean isValidPictureInPictureAspectRatio(float aspectRatio) {
        return Float.compare(mMinAspectRatio, aspectRatio) <= 0
                && Float.compare(aspectRatio, mMaxAspectRatio) <= 0;
    }

    /**
     * @return whether the given {@param aspectRatio} is valid, i.e. ratio < min or ratio > max.
     */
    public boolean isValidExpandedPictureInPictureAspectRatio(float aspectRatio) {
        return Float.compare(mMinAspectRatio, aspectRatio) > 0
                || Float.compare(aspectRatio, mMaxAspectRatio) > 0;
    }

    /**
     * Sets a hint if the orientation of display will be changed. This is only called when
     * finishing recents animation with pending orientation change that will be handled by
     * {@link DisplayContent.FixedRotationTransitionListener}.
     */
    void setEnterPipWithRotatedTransientLaunch() {
        mFreezingTaskConfig = true;
    }

    /**
     * Returns {@code true} to skip {@link Task#onConfigurationChanged} because it is expected that
     * there will be a orientation change and a PiP configuration change.
     */
    boolean isFreezingTaskConfig(Task task) {
        return mFreezingTaskConfig
                && task == mDisplayContent.getDefaultTaskDisplayArea().getRootPinnedTask();
    }

    /** Resets the states which were used to perform fixed rotation with PiP task. */
    void onCancelFixedRotationTransform() {
        mFreezingTaskConfig = false;
    }

    /**
     * Sets the Ime state and height.
     */
    void setAdjustedForIme(boolean adjustedForIme, int imeHeight) {
        // Due to the order of callbacks from the system, we may receive an ime height even when
        // {@param adjustedForIme} is false, and also a zero height when {@param adjustedForIme}
        // is true.  Instead, ensure that the ime state changes with the height and if the ime is
        // showing, then the height is non-zero.
        final boolean imeShowing = adjustedForIme && imeHeight > 0;
        imeHeight = imeShowing ? imeHeight : 0;
        if (imeShowing == mIsImeShowing && imeHeight == mImeHeight) {
            return;
        }

        mIsImeShowing = imeShowing;
        mImeHeight = imeHeight;
        notifyImeVisibilityChanged(imeShowing, imeHeight);
        notifyMovementBoundsChanged(true /* fromImeAdjustment */);
    }

    /**
     * Notifies listeners that the PIP needs to be adjusted for the IME.
     */
    private void notifyImeVisibilityChanged(boolean imeVisible, int imeHeight) {
        if (mPinnedTaskListener == null) {
            return;
        }

        try {
            mPinnedTaskListener.onImeVisibilityChanged(imeVisible, imeHeight);
        } catch (RemoteException e) {
            Slog.e(TAG_WM, "Error delivering ime visibility changed event.", e);
        }
    }

    /**
     * Notifies listeners that the PIP movement bounds have changed.
     */
    private void notifyMovementBoundsChanged(boolean fromImeAdjustment) {
        if (mPinnedTaskListener == null) {
            return;
        }

        try {
            mPinnedTaskListener.onMovementBoundsChanged(fromImeAdjustment);
        } catch (RemoteException e) {
            Slog.e(TAG_WM, "Error delivering movement bounds changed event.", e);
        }
    }

    void dump(String prefix, PrintWriter pw) {
        pw.println(prefix + "PinnedTaskController");
        if (mFreezingTaskConfig) pw.println(prefix + "  mFreezingTaskConfig=true");
        pw.println(prefix + "  mIsImeShowing=" + mIsImeShowing);
        pw.println(prefix + "  mImeHeight=" + mImeHeight);
        pw.println(prefix + "  mMinAspectRatio=" + mMinAspectRatio);
        pw.println(prefix + "  mMaxAspectRatio=" + mMaxAspectRatio);
    }
}