/*
 * Copyright (C) 2007 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.inputmethodservice;

import static android.inputmethodservice.SoftInputWindowProto.WINDOW_STATE;

import static java.lang.annotation.RetentionPolicy.SOURCE;

import android.annotation.IntDef;
import android.app.Dialog;
import android.os.Debug;
import android.os.IBinder;
import android.util.Log;
import android.util.proto.ProtoOutputStream;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowManager;

import java.lang.annotation.Retention;

/**
 * A {@link SoftInputWindow} is a {@link Dialog} that is intended to be used for a top-level input
 * method window.  It will be displayed along the edge of the screen, moving the application user
 * interface away from it so that the focused item is always visible.
 */
final class SoftInputWindow extends Dialog {
    private static final boolean DEBUG = false;
    private static final String TAG = "SoftInputWindow";

    private final KeyEvent.DispatcherState mDispatcherState;
    private final InputMethodService mService;

    @Retention(SOURCE)
    @IntDef(value = {WindowState.TOKEN_PENDING, WindowState.TOKEN_SET,
            WindowState.SHOWN_AT_LEAST_ONCE, WindowState.REJECTED_AT_LEAST_ONCE,
            WindowState.DESTROYED})
    private @interface WindowState {
        /**
         * The window token is not set yet.
         */
        int TOKEN_PENDING = 0;
        /**
         * The window token was set, but the window is not shown yet.
         */
        int TOKEN_SET = 1;
        /**
         * The window was shown at least once.
         */
        int SHOWN_AT_LEAST_ONCE = 2;
        /**
         * {@link android.view.WindowManager.BadTokenException} was sent when calling
         * {@link Dialog#show()} at least once.
         */
        int REJECTED_AT_LEAST_ONCE = 3;
        /**
         * The window is considered destroyed.  Any incoming request should be ignored.
         */
        int DESTROYED = 4;
    }

    @WindowState
    private int mWindowState = WindowState.TOKEN_PENDING;

    @Override
    protected boolean allowsRegisterDefaultOnBackInvokedCallback() {
        // Do not register OnBackInvokedCallback from Dialog#onStart, InputMethodService will
        // register CompatOnBackInvokedCallback for input method window.
        return false;
    }

    /**
     * Set {@link IBinder} window token to the window.
     *
     * <p>This method can be called only once.</p>
     * @param token {@link IBinder} token to be associated with the window.
     */
    void setToken(IBinder token) {
        switch (mWindowState) {
            case WindowState.TOKEN_PENDING:
                // Normal scenario.  Nothing to worry about.
                WindowManager.LayoutParams lp = getWindow().getAttributes();
                lp.token = token;
                getWindow().setAttributes(lp);
                updateWindowState(WindowState.TOKEN_SET);

                // As soon as we have a token, make sure the window is added (but not shown) by
                // setting visibility to INVISIBLE and calling show() on Dialog. Note that
                // WindowInsetsController.OnControllableInsetsChangedListener relies on the window
                // being added to function.
                getWindow().getDecorView().setVisibility(View.INVISIBLE);
                show();
                return;
            case WindowState.TOKEN_SET:
            case WindowState.SHOWN_AT_LEAST_ONCE:
            case WindowState.REJECTED_AT_LEAST_ONCE:
                throw new IllegalStateException("setToken can be called only once");
            case WindowState.DESTROYED:
                // Just ignore.  Since there are multiple event queues from the token is issued
                // in the system server to the timing when it arrives here, it can be delivered
                // after the is already destroyed.  No one should be blamed because of such an
                // unfortunate but possible scenario.
                Log.i(TAG, "Ignoring setToken() because window is already destroyed.");
                return;
            default:
                throw new IllegalStateException("Unexpected state=" + mWindowState);
        }
    }

    /**
     * Create a SoftInputWindow that uses a custom style.
     *
     * @param service The {@link InputMethodService} in which the DockWindow should run. In
     *        particular, it uses the window manager and theme from this context
     *        to present its UI.
     * @param theme A style resource describing the theme to use for the window.
     *        See <a href="{@docRoot}reference/available-resources.html#stylesandthemes">Style
     *        and Theme Resources</a> for more information about defining and
     *        using styles. This theme is applied on top of the current theme in
     *        <var>context</var>. If 0, the default dialog theme will be used.
     */
    SoftInputWindow(InputMethodService service, int theme,
            KeyEvent.DispatcherState dispatcherState) {
        super(service, theme);
        mService = service;
        mDispatcherState = dispatcherState;
    }

    @Override
    public void onWindowFocusChanged(boolean hasFocus) {
        super.onWindowFocusChanged(hasFocus);
        mDispatcherState.reset();
    }

    @Override
    public void show() {
        switch (mWindowState) {
            case WindowState.TOKEN_PENDING:
                throw new IllegalStateException("Window token is not set yet.");
            case WindowState.TOKEN_SET:
            case WindowState.SHOWN_AT_LEAST_ONCE:
                // Normal scenario.  Nothing to worry about.
                try {
                    super.show();
                    updateWindowState(WindowState.SHOWN_AT_LEAST_ONCE);
                } catch (WindowManager.BadTokenException
                         | WindowManager.InvalidDisplayException e) {
                    // Just ignore this exception.  Since show() can be requested from other
                    // components such as the system and there could be multiple event queues before
                    // the request finally arrives here, the system may have already invalidated the
                    // window token attached to our window.  In such a scenario, receiving
                    // BadTokenException here is an expected behavior.  We just ignore it and update
                    // the state so that we do not touch this window later.
                    Log.i(TAG, "Probably the IME window token is already invalidated."
                            + " show() does nothing.");
                    updateWindowState(WindowState.REJECTED_AT_LEAST_ONCE);
                }
                return;
            case WindowState.REJECTED_AT_LEAST_ONCE:
                // Just ignore.  In general we cannot completely avoid this kind of race condition.
                Log.i(TAG, "Not trying to call show() because it was already rejected once.");
                return;
            case WindowState.DESTROYED:
                // Just ignore.  In general we cannot completely avoid this kind of race condition.
                Log.i(TAG, "Ignoring show() because the window is already destroyed.");
                return;
            default:
                throw new IllegalStateException("Unexpected state=" + mWindowState);
        }
    }

    void dismissForDestroyIfNecessary() {
        switch (mWindowState) {
            case WindowState.TOKEN_PENDING:
            case WindowState.TOKEN_SET:
                // nothing to do because the window has never been shown.
                updateWindowState(WindowState.DESTROYED);
                return;
            case WindowState.SHOWN_AT_LEAST_ONCE:
                // Disable exit animation for the current IME window
                // to avoid the race condition between the exit and enter animations
                // when the current IME is being switched to another one.
                try {
                    getWindow().setWindowAnimations(0);
                    dismiss();
                } catch (WindowManager.BadTokenException e) {
                    // Just ignore this exception.  Since show() can be requested from other
                    // components such as the system and there could be multiple event queues before
                    // the request finally arrives here, the system may have already invalidated the
                    // window token attached to our window.  In such a scenario, receiving
                    // BadTokenException here is an expected behavior.  We just ignore it and update
                    // the state so that we do not touch this window later.
                    Log.i(TAG, "Probably the IME window token is already invalidated. "
                            + "No need to dismiss it.");
                }
                // Either way, consider that the window is destroyed.
                updateWindowState(WindowState.DESTROYED);
                return;
            case WindowState.REJECTED_AT_LEAST_ONCE:
                // Just ignore.  In general we cannot completely avoid this kind of race condition.
                Log.i(TAG,
                        "Not trying to dismiss the window because it is most likely unnecessary.");
                // Anyway, consider that the window is destroyed.
                updateWindowState(WindowState.DESTROYED);
                return;
            case WindowState.DESTROYED:
                throw new IllegalStateException(
                        "dismissForDestroyIfNecessary can be called only once");
            default:
                throw new IllegalStateException("Unexpected state=" + mWindowState);
        }
    }

    private void updateWindowState(@WindowState int newState) {
        if (DEBUG) {
            if (mWindowState != newState) {
                Log.d(TAG, "WindowState: " + stateToString(mWindowState) + " -> "
                        + stateToString(newState) + " @ " + Debug.getCaller());
            }
        }
        mWindowState = newState;
    }

    private static String stateToString(@WindowState int state) {
        switch (state) {
            case WindowState.TOKEN_PENDING:
                return "TOKEN_PENDING";
            case WindowState.TOKEN_SET:
                return "TOKEN_SET";
            case WindowState.SHOWN_AT_LEAST_ONCE:
                return "SHOWN_AT_LEAST_ONCE";
            case WindowState.REJECTED_AT_LEAST_ONCE:
                return "REJECTED_AT_LEAST_ONCE";
            case WindowState.DESTROYED:
                return "DESTROYED";
            default:
                throw new IllegalStateException("Unknown state=" + state);
        }
    }

    void dumpDebug(ProtoOutputStream proto, long fieldId) {
        final long token = proto.start(fieldId);
        proto.write(WINDOW_STATE, mWindowState);
        proto.end(token);
    }
}