/*
 * Copyright (C) 2017 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 androidx.lifecycle;

import android.app.Activity;
import android.app.Application;
import android.os.Build;
import android.os.Bundle;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.RequiresApi;
import androidx.annotation.RestrictTo;

/**
 * Internal class that dispatches initialization events.
 *
 * @hide
 */
@SuppressWarnings({"UnknownNullness", "deprecation"})
// TODO https://issuetracker.google.com/issues/112197238
@RestrictTo(RestrictTo.Scope.LIBRARY_GROUP_PREFIX)
public class ReportFragment extends android.app.Fragment {
    private static final String REPORT_FRAGMENT_TAG = "androidx.lifecycle"
            + ".LifecycleDispatcher.report_fragment_tag";

    public static void injectIfNeededIn(Activity activity) {
        if (Build.VERSION.SDK_INT >= 29) {
            // On API 29+, we can register for the correct Lifecycle callbacks directly
            LifecycleCallbacks.registerIn(activity);
        }
        // Prior to API 29 and to maintain compatibility with older versions of
        // ProcessLifecycleOwner (which may not be updated when lifecycle-runtime is updated and
        // need to support activities that don't extend from FragmentActivity from support lib),
        // use a framework fragment to get the correct timing of Lifecycle events
        android.app.FragmentManager manager = activity.getFragmentManager();
        if (manager.findFragmentByTag(REPORT_FRAGMENT_TAG) == null) {
            manager.beginTransaction().add(new ReportFragment(), REPORT_FRAGMENT_TAG).commit();
            // Hopefully, we are the first to make a transaction.
            manager.executePendingTransactions();
        }
    }

    @SuppressWarnings("deprecation")
    static void dispatch(@NonNull Activity activity, @NonNull Lifecycle.Event event) {
        if (activity instanceof LifecycleRegistryOwner) {
            ((LifecycleRegistryOwner) activity).getLifecycle().handleLifecycleEvent(event);
            return;
        }

        if (activity instanceof LifecycleOwner) {
            Lifecycle lifecycle = ((LifecycleOwner) activity).getLifecycle();
            if (lifecycle instanceof LifecycleRegistry) {
                ((LifecycleRegistry) lifecycle).handleLifecycleEvent(event);
            }
        }
    }

    static ReportFragment get(Activity activity) {
        return (ReportFragment) activity.getFragmentManager().findFragmentByTag(
                REPORT_FRAGMENT_TAG);
    }

    private ActivityInitializationListener mProcessListener;

    private void dispatchCreate(ActivityInitializationListener listener) {
        if (listener != null) {
            listener.onCreate();
        }
    }

    private void dispatchStart(ActivityInitializationListener listener) {
        if (listener != null) {
            listener.onStart();
        }
    }

    private void dispatchResume(ActivityInitializationListener listener) {
        if (listener != null) {
            listener.onResume();
        }
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        dispatchCreate(mProcessListener);
        dispatch(Lifecycle.Event.ON_CREATE);
    }

    @Override
    public void onStart() {
        super.onStart();
        dispatchStart(mProcessListener);
        dispatch(Lifecycle.Event.ON_START);
    }

    @Override
    public void onResume() {
        super.onResume();
        dispatchResume(mProcessListener);
        dispatch(Lifecycle.Event.ON_RESUME);
    }

    @Override
    public void onPause() {
        super.onPause();
        dispatch(Lifecycle.Event.ON_PAUSE);
    }

    @Override
    public void onStop() {
        super.onStop();
        dispatch(Lifecycle.Event.ON_STOP);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        dispatch(Lifecycle.Event.ON_DESTROY);
        // just want to be sure that we won't leak reference to an activity
        mProcessListener = null;
    }

    private void dispatch(@NonNull Lifecycle.Event event) {
        if (Build.VERSION.SDK_INT < 29) {
            // Only dispatch events from ReportFragment on API levels prior
            // to API 29. On API 29+, this is handled by the ActivityLifecycleCallbacks
            // added in ReportFragment.injectIfNeededIn
            dispatch(getActivity(), event);
        }
    }

    void setProcessListener(ActivityInitializationListener processListener) {
        mProcessListener = processListener;
    }

    interface ActivityInitializationListener {
        void onCreate();

        void onStart();

        void onResume();
    }

    // this class isn't inlined only because we need to add a proguard rule for it (b/142778206)
    // In addition to that registerIn method allows to avoid class verification failure,
    // because registerActivityLifecycleCallbacks is available only since api 29.
    @RequiresApi(29)
    static class LifecycleCallbacks implements Application.ActivityLifecycleCallbacks {

        static void registerIn(Activity activity) {
            activity.registerActivityLifecycleCallbacks(new LifecycleCallbacks());
        }

        @Override
        public void onActivityCreated(@NonNull Activity activity,
                @Nullable Bundle bundle) {
        }

        @Override
        public void onActivityPostCreated(@NonNull Activity activity,
                @Nullable Bundle savedInstanceState) {
            dispatch(activity, Lifecycle.Event.ON_CREATE);
        }

        @Override
        public void onActivityStarted(@NonNull Activity activity) {
        }

        @Override
        public void onActivityPostStarted(@NonNull Activity activity) {
            dispatch(activity, Lifecycle.Event.ON_START);
        }

        @Override
        public void onActivityResumed(@NonNull Activity activity) {
        }

        @Override
        public void onActivityPostResumed(@NonNull Activity activity) {
            dispatch(activity, Lifecycle.Event.ON_RESUME);
        }

        @Override
        public void onActivityPrePaused(@NonNull Activity activity) {
            dispatch(activity, Lifecycle.Event.ON_PAUSE);
        }

        @Override
        public void onActivityPaused(@NonNull Activity activity) {
        }

        @Override
        public void onActivityPreStopped(@NonNull Activity activity) {
            dispatch(activity, Lifecycle.Event.ON_STOP);
        }

        @Override
        public void onActivityStopped(@NonNull Activity activity) {
        }

        @Override
        public void onActivitySaveInstanceState(@NonNull Activity activity,
                @NonNull Bundle bundle) {
        }

        @Override
        public void onActivityPreDestroyed(@NonNull Activity activity) {
            dispatch(activity, Lifecycle.Event.ON_DESTROY);
        }

        @Override
        public void onActivityDestroyed(@NonNull Activity activity) {
        }
    }
}