/*
 * Copyright (C) 2024 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.systemui.animation;

import android.annotation.IntDef;
import android.annotation.Nullable;
import android.app.ActivityOptions;
import android.app.ActivityOptions.LaunchCookie;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.Handler;
import android.os.Looper;
import android.os.RemoteException;
import android.util.Log;
import android.window.IRemoteTransition;
import android.window.RemoteTransition;

import com.android.systemui.animation.OriginRemoteTransition.TransitionPlayer;
import com.android.systemui.animation.shared.IOriginTransitions;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Predicate;
import java.util.function.Supplier;

/**
 * A session object that holds origin transition states for starting an activity from an on-screen
 * UI component and smoothly transitioning back from the activity to the same UI component.
 *
 * @hide
 */
public class OriginTransitionSession {
    private static final String TAG = "OriginTransitionSession";
    static final boolean DEBUG = Build.IS_USERDEBUG || Log.isLoggable(TAG, Log.DEBUG);

    @Retention(RetentionPolicy.SOURCE)
    @IntDef(value = {NOT_STARTED, STARTED, CANCELLED})
    private @interface State {}

    @State private static final int NOT_STARTED = 0;
    @State private static final int STARTED = 1;
    @State private static final int CANCELLED = 5;

    private final String mName;
    @Nullable private final IOriginTransitions mOriginTransitions;
    private final Predicate<RemoteTransition> mIntentStarter;
    @Nullable private final IRemoteTransition mEntryTransition;
    @Nullable private final IRemoteTransition mExitTransition;
    private final AtomicInteger mState = new AtomicInteger(NOT_STARTED);

    @Nullable private RemoteTransition mOriginTransition;

    private OriginTransitionSession(
            String name,
            @Nullable IOriginTransitions originTransitions,
            Predicate<RemoteTransition> intentStarter,
            @Nullable IRemoteTransition entryTransition,
            @Nullable IRemoteTransition exitTransition) {
        mName = name;
        mOriginTransitions = originTransitions;
        mIntentStarter = intentStarter;
        mEntryTransition = entryTransition;
        mExitTransition = exitTransition;
        if (hasExitTransition() && !hasEntryTransition()) {
            throw new IllegalArgumentException(
                    "Entry transition must be supplied if you want to play an exit transition!");
        }
    }

    /**
     * Launch the target intent with the supplied entry transition. After this method, the entry
     * transition is expected to receive callbacks. The exit transition will be registered and
     * triggered when the system detects a return from the launched activity to the launching
     * activity.
     */
    public boolean start() {
        if (!mState.compareAndSet(NOT_STARTED, STARTED)) {
            logE("start: illegal state - " + stateToString(mState.get()));
            return false;
        }

        RemoteTransition remoteTransition = null;
        if (hasEntryTransition() && hasExitTransition()) {
            logD("start: starting with entry and exit transition.");
            try {
                remoteTransition =
                        mOriginTransition =
                                mOriginTransitions.makeOriginTransition(
                                        new RemoteTransition(mEntryTransition, mName + "-entry"),
                                        new RemoteTransition(mExitTransition, mName + "-exit"));
            } catch (RemoteException e) {
                logE("Unable to create origin transition!", e);
            }
        } else if (hasEntryTransition()) {
            logD("start: starting with entry transition.");
            remoteTransition = new RemoteTransition(mEntryTransition, mName + "-entry");

        } else {
            logD("start: starting without transition.");
        }
        if (mIntentStarter.test(remoteTransition)) {
            return true;
        } else {
            // Animation is cancelled by intent starter.
            logD("start: cancelled by intent starter!");
            cancel();
            return false;
        }
    }

    /**
     * Cancel the current transition and the registered exit transition if it exists. After this
     * method, this session object can no longer be used. Clients need to create a new session
     * object if they want to launch another intent with origin transition.
     */
    public void cancel() {
        final int lastState = mState.getAndSet(CANCELLED);
        if (lastState == CANCELLED || lastState == NOT_STARTED) {
            return;
        }
        logD("cancel: cancelled transition. Last state: " + stateToString(lastState));
        if (mOriginTransition != null) {
            try {
                mOriginTransitions.cancelOriginTransition(mOriginTransition);
                mOriginTransition = null;
            } catch (RemoteException e) {
                logE("Unable to cancel origin transition!", e);
            }
        }
        if (mEntryTransition instanceof OriginRemoteTransition) {
            ((OriginRemoteTransition) mEntryTransition).cancel();
        }
        if (mExitTransition instanceof OriginRemoteTransition) {
            ((OriginRemoteTransition) mExitTransition).cancel();
        }
    }

    private boolean hasEntryTransition() {
        return mEntryTransition != null;
    }

    private boolean hasExitTransition() {
        return mOriginTransitions != null && mExitTransition != null;
    }

    private void logD(String msg) {
        if (DEBUG) {
            Log.d(TAG, "Session[" + mName + "] - " + msg);
        }
    }

    private void logE(String msg) {
        Log.e(TAG, "Session[" + mName + "] - " + msg);
    }

    private void logE(String msg, Throwable e) {
        Log.e(TAG, "Session[" + mName + "] - " + msg, e);
    }

    private static String stateToString(@State int state) {
        switch (state) {
            case NOT_STARTED:
                return "NOT_STARTED";
            case STARTED:
                return "STARTED";
            case CANCELLED:
                return "CANCELLED";
            default:
                return "UNKNOWN(" + state + ")";
        }
    }

    /**
     * A builder to build a {@link OriginTransitionSession}.
     *
     * @hide
     */
    public static class Builder {
        private final Context mContext;
        @Nullable private final IOriginTransitions mOriginTransitions;
        @Nullable private Supplier<IRemoteTransition> mEntryTransitionSupplier;
        @Nullable private Supplier<IRemoteTransition> mExitTransitionSupplier;
        private Handler mHandler = new Handler(Looper.getMainLooper());
        private String mName;
        @Nullable private Predicate<RemoteTransition> mIntentStarter;

        /** Create a builder that only supports entry transition. */
        public Builder(Context context) {
            this(context, /* originTransitions= */ null);
        }

        /** Create a builder that supports both entry and return transition. */
        public Builder(Context context, @Nullable IOriginTransitions originTransitions) {
            mContext = context;
            mOriginTransitions = originTransitions;
            mName = context.getPackageName();
        }

        /** Specify a name that is used in logging. */
        public Builder withName(String name) {
            mName = name;
            return this;
        }

        /** Specify an intent that will be launched when the session started. */
        public Builder withIntent(Intent intent) {
            return withIntentStarter(
                    transition -> {
                        mContext.startActivity(
                                intent, createDefaultActivityOptions(transition).toBundle());
                        return true;
                    });
        }

        /** Specify a pending intent that will be launched when the session started. */
        public Builder withPendingIntent(PendingIntent pendingIntent) {
            return withIntentStarter(
                    transition -> {
                        try {
                            pendingIntent.send(createDefaultActivityOptions(transition).toBundle());
                            return true;
                        } catch (PendingIntent.CanceledException e) {
                            Log.e(TAG, "Failed to launch pending intent!", e);
                            return false;
                        }
                    });
        }

        private static ActivityOptions createDefaultActivityOptions(
                @Nullable RemoteTransition transition) {
            ActivityOptions options =
                    transition == null
                            ? ActivityOptions.makeBasic()
                            : ActivityOptions.makeRemoteTransition(transition);
            LaunchCookie cookie = new LaunchCookie();
            options.setLaunchCookie(cookie);
            return options;
        }

        /**
         * Specify an intent starter function that will be called to start an activity. The function
         * accepts an optional {@link RemoteTransition} object which can be used to create an {@link
         * ActivityOptions} for the activity launch. The function can also return a {@code false}
         * result to cancel the session.
         *
         * <p>Note: it's encouraged to use {@link #withIntent(Intent)} or {@link
         * #withPendingIntent(PendingIntent)} instead of this method. Use it only if the default
         * activity launch code doesn't satisfy your requirement.
         */
        public Builder withIntentStarter(Predicate<RemoteTransition> intentStarter) {
            mIntentStarter = intentStarter;
            return this;
        }

        /** Add an entry transition to the builder. */
        public Builder withEntryTransition(IRemoteTransition transition) {
            mEntryTransitionSupplier = () -> transition;
            return this;
        }

        /** Add an origin entry transition to the builder. */
        public Builder withEntryTransition(
                UIComponent entryOrigin, TransitionPlayer entryPlayer, long entryDuration) {
            mEntryTransitionSupplier =
                    () ->
                            new OriginRemoteTransition(
                                    mContext,
                                    /* isEntry= */ true,
                                    entryOrigin,
                                    entryPlayer,
                                    entryDuration,
                                    mHandler);
            return this;
        }

        /** Add an exit transition to the builder. */
        public Builder withExitTransition(IRemoteTransition transition) {
            mExitTransitionSupplier = () -> transition;
            return this;
        }

        /** Add an origin exit transition to the builder. */
        public Builder withExitTransition(
                UIComponent exitTarget, TransitionPlayer exitPlayer, long exitDuration) {
            mExitTransitionSupplier =
                    () ->
                            new OriginRemoteTransition(
                                    mContext,
                                    /* isEntry= */ false,
                                    exitTarget,
                                    exitPlayer,
                                    exitDuration,
                                    mHandler);
            return this;
        }

        /** Supply a handler where transition callbacks will run. */
        public Builder withHandler(Handler handler) {
            mHandler = handler;
            return this;
        }

        /** Build an {@link OriginTransitionSession}. */
        public OriginTransitionSession build() {
            if (mIntentStarter == null) {
                throw new IllegalArgumentException("No intent, pending intent, or intent starter!");
            }
            return new OriginTransitionSession(
                    mName,
                    mOriginTransitions,
                    mIntentStarter,
                    mEntryTransitionSupplier == null ? null : mEntryTransitionSupplier.get(),
                    mExitTransitionSupplier == null ? null : mExitTransitionSupplier.get());
        }
    }
}