/*
 * Copyright (C) 2006 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.view;

import android.annotation.NonNull;
import android.annotation.Nullable;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.os.Parcel;
import android.os.Parcelable;
import android.os.RemoteException;

import java.util.HashMap;

Safe identifier for a window. This currently allows you to retrieve and observe the input focus state of the window. Most applications will not use this, instead relying on the simpler (and more efficient) methods available on View. This classes is useful when window input interactions need to be done across processes: the class itself is a Parcelable that can be passed to other processes for them to interact with your window, and it provides a limited safe API that doesn't allow the other process to negatively harm your window. /**
 * Safe identifier for a window.  This currently allows you to retrieve and observe
 * the input focus state of the window.  Most applications will
 * not use this, instead relying on the simpler (and more efficient) methods available
 * on {@link View}.  This classes is useful when window input interactions need to be
 * done across processes: the class itself is a Parcelable that can be passed to other
 * processes for them to interact with your window, and it provides a limited safe API
 * that doesn't allow the other process to negatively harm your window.
 */
public class WindowId implements Parcelable {
    @NonNull
    private final IWindowId mToken;

    
Subclass for observing changes to the focus state of an WindowId. You should use the same instance of this class for observing multiple WindowId objects, since this class is fairly heavy-weight -- the base class includes all of the mechanisms for connecting to and receiving updates from the window. /**
     * Subclass for observing changes to the focus state of an {@link WindowId}.
     * You should use the same instance of this class for observing multiple
     * {@link WindowId} objects, since this class is fairly heavy-weight -- the
     * base class includes all of the mechanisms for connecting to and receiving updates
     * from the window.
     */
    public static abstract class FocusObserver {
        final IWindowFocusObserver.Stub mIObserver = new IWindowFocusObserver.Stub() {

            @Override
            public void focusGained(IBinder inputToken) {
                WindowId token;
                synchronized (mRegistrations) {
                    token = mRegistrations.get(inputToken);
                }
                if (mHandler != null) {
                    mHandler.sendMessage(mHandler.obtainMessage(1, token));
                } else {
                    onFocusGained(token);
                }
            }

            @Override
            public void focusLost(IBinder inputToken) {
                WindowId token;
                synchronized (mRegistrations) {
                    token = mRegistrations.get(inputToken);
                }
                if (mHandler != null) {
                    mHandler.sendMessage(mHandler.obtainMessage(2, token));
                } else {
                    onFocusLost(token);
                }
            }
        };

        final HashMap<IBinder, WindowId> mRegistrations = new HashMap<>();

        class H extends Handler {
            @Override
            public void handleMessage(Message msg) {
                switch (msg.what) {
                    case 1:
                        onFocusGained((WindowId)msg.obj);
                        break;
                    case 2:
                        onFocusLost((WindowId)msg.obj);
                        break;
                    default:
                        super.handleMessage(msg);
                }
            }
        }

        final Handler mHandler;

        
Construct a new observer.  This observer will be configured so that all
of its callbacks are dispatched on the current calling thread.
/**
         * Construct a new observer.  This observer will be configured so that all
         * of its callbacks are dispatched on the current calling thread.
         */
        public FocusObserver() {
            mHandler = new H();
        }

        
Called when one of the monitored windows gains input focus.
/**
         * Called when one of the monitored windows gains input focus.
         */
        public abstract void onFocusGained(WindowId token);

        
Called when one of the monitored windows loses input focus.
/**
         * Called when one of the monitored windows loses input focus.
         */
        public abstract void onFocusLost(WindowId token);
    }

    
Retrieve the current focus state of the associated window.
/**
     * Retrieve the current focus state of the associated window.
     */
    public boolean isFocused() {
        try {
            return mToken.isFocused();
        } catch (RemoteException e) {
            return false;
        }
    }

    
Start monitoring for changes in the focus state of the window.
/**
     * Start monitoring for changes in the focus state of the window.
     */
    public void registerFocusObserver(FocusObserver observer) {
        synchronized (observer.mRegistrations) {
            if (observer.mRegistrations.containsKey(mToken.asBinder())) {
                throw new IllegalStateException(
                        "Focus observer already registered with input token");
            }
            observer.mRegistrations.put(mToken.asBinder(), this);
            try {
                mToken.registerFocusObserver(observer.mIObserver);
            } catch (RemoteException e) {
            }
        }
    }

    
Stop monitoring changes in the focus state of the window.
/**
     * Stop monitoring changes in the focus state of the window.
     */
    public void unregisterFocusObserver(FocusObserver observer) {
        synchronized (observer.mRegistrations) {
            if (observer.mRegistrations.remove(mToken.asBinder()) == null) {
                throw new IllegalStateException("Focus observer not registered with input token");
            }
            try {
                mToken.unregisterFocusObserver(observer.mIObserver);
            } catch (RemoteException e) {
            }
        }
    }

    
Comparison operator on two IntentSender objects, such that true
is returned then they both represent the same operation from the
same package.
/**
     * Comparison operator on two IntentSender objects, such that true
     * is returned then they both represent the same operation from the
     * same package.
     */
    @Override
    public boolean equals(@Nullable Object otherObj) {
        if (otherObj instanceof WindowId) {
            return mToken.asBinder().equals(((WindowId) otherObj).mToken.asBinder());
        }
        return false;
    }

    @Override
    public int hashCode() {
        return mToken.asBinder().hashCode();
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder(128);
        sb.append("IntentSender{");
        sb.append(Integer.toHexString(System.identityHashCode(this)));
        sb.append(": ");
        sb.append(mToken.asBinder());
        sb.append('}');
        return sb.toString();
    }

    public int describeContents() {
        return 0;
    }

    public void writeToParcel(Parcel out, int flags) {
        out.writeStrongBinder(mToken.asBinder());
    }

    public static final Parcelable.Creator<WindowId> CREATOR = new Parcelable.Creator<WindowId>() {
        @Override
        public WindowId createFromParcel(Parcel in) {
            IBinder target = in.readStrongBinder();
            return target != null ? new WindowId(target) : null;
        }

        @Override
        public WindowId[] newArray(int size) {
            return new WindowId[size];
        }
    };

    
@hide
/** @hide */
    @NonNull
    public IWindowId getTarget() {
        return mToken;
    }

    
@hide
/** @hide */
    public WindowId(@NonNull IWindowId target) {
        mToken = target;
    }

    
@hide
/** @hide */
    public WindowId(@NonNull IBinder target) {
        mToken = IWindowId.Stub.asInterface(target);
    }
}