/*
 * Copyright (C) 2019 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.content.om;

import static com.android.internal.util.Preconditions.checkNotNull;

import android.annotation.IntDef;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.content.Context;
import android.os.Bundle;
import android.os.Parcel;
import android.os.Parcelable;
import android.os.UserHandle;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;

/**
 * Container for a batch of requests to the OverlayManagerService.
 *
 * Transactions are created using a builder interface. Example usage:
 *
 * final OverlayManager om = ctx.getSystemService(OverlayManager.class);
 * final OverlayManagerTransaction t = new OverlayManagerTransaction.Builder()
 *     .setEnabled(...)
 *     .setEnabled(...)
 *     .build();
 * om.commit(t);
 *
 * @hide
 */
public class OverlayManagerTransaction
        implements Iterable<OverlayManagerTransaction.Request>, Parcelable {
    // TODO: remove @hide from this class when OverlayManager is added to the
    // SDK, but keep OverlayManagerTransaction.Request @hidden
    private final List<Request> mRequests;

    OverlayManagerTransaction(@NonNull final List<Request> requests) {
        checkNotNull(requests);
        if (requests.contains(null)) {
            throw new IllegalArgumentException("null request");
        }
        mRequests = requests;
    }

    private OverlayManagerTransaction(@NonNull final Parcel source) {
        final int size = source.readInt();
        mRequests = new ArrayList<>(size);
        for (int i = 0; i < size; i++) {
            final int request = source.readInt();
            final OverlayIdentifier overlay = source.readParcelable(null);
            final int userId = source.readInt();
            final Bundle extras = source.readBundle(null);
            mRequests.add(new Request(request, overlay, userId, extras));
        }
    }

    @Override
    public Iterator<Request> iterator() {
        return mRequests.iterator();
    }

    @Override
    public String toString() {
        return String.format("OverlayManagerTransaction { mRequests = %s }", mRequests);
    }

    /**
     * A single unit of the transaction, such as a request to enable an
     * overlay, or to disable an overlay.
     *
     * @hide
     */
    public static class Request {
        @IntDef(prefix = "TYPE_", value = {
                TYPE_SET_ENABLED,
                TYPE_SET_DISABLED,
        })
        @Retention(RetentionPolicy.SOURCE)
        @interface RequestType {}

        public static final int TYPE_SET_ENABLED = 0;
        public static final int TYPE_SET_DISABLED = 1;
        public static final int TYPE_REGISTER_FABRICATED = 2;
        public static final int TYPE_UNREGISTER_FABRICATED = 3;

        public static final String BUNDLE_FABRICATED_OVERLAY = "fabricated_overlay";

        @RequestType
        public final int type;
        @NonNull
        public final OverlayIdentifier overlay;
        public final int userId;
        @Nullable
        public final Bundle extras;

        public Request(@RequestType final int type, @NonNull final OverlayIdentifier overlay,
                final int userId) {
            this(type, overlay, userId, null /* extras */);
        }

        public Request(@RequestType final int type, @NonNull final OverlayIdentifier overlay,
                final int userId, @Nullable Bundle extras) {
            this.type = type;
            this.overlay = overlay;
            this.userId = userId;
            this.extras = extras;
        }

        @Override
        public String toString() {
            return String.format(Locale.US, "Request{type=0x%02x (%s), overlay=%s, userId=%d}",
                    type, typeToString(), overlay, userId);
        }

        /**
         * Translate the request type into a human readable string. Only
         * intended for debugging.
         *
         * @hide
         */
        public String typeToString() {
            switch (type) {
                case TYPE_SET_ENABLED: return "TYPE_SET_ENABLED";
                case TYPE_SET_DISABLED: return "TYPE_SET_DISABLED";
                case TYPE_REGISTER_FABRICATED: return "TYPE_REGISTER_FABRICATED";
                case TYPE_UNREGISTER_FABRICATED: return "TYPE_UNREGISTER_FABRICATED";
                default: return String.format("TYPE_UNKNOWN (0x%02x)", type);
            }
        }
    }

    /**
     * Builder class for OverlayManagerTransaction objects.
     *
     * @hide
     */
    public static class Builder {
        private final List<Request> mRequests = new ArrayList<>();

        /**
         * Request that an overlay package be enabled and change its loading
         * order to the last package to be loaded, or disabled
         *
         * If the caller has the correct permissions, it is always possible to
         * disable an overlay. Due to technical and security reasons it may not
         * always be possible to enable an overlay, for instance if the overlay
         * does not successfully overlay any target resources due to
         * overlayable policy restrictions.
         *
         * An enabled overlay is a part of target package's resources, i.e. it will
         * be part of any lookups performed via {@link android.content.res.Resources}
         * and {@link android.content.res.AssetManager}. A disabled overlay will no
         * longer affect the resources of the target package. If the target is
         * currently running, its outdated resources will be replaced by new ones.
         *
         * @param overlay The name of the overlay package.
         * @param enable true to enable the overlay, false to disable it.
         * @return this Builder object, so you can chain additional requests
         */
        public Builder setEnabled(@NonNull OverlayIdentifier overlay, boolean enable) {
            return setEnabled(overlay, enable, UserHandle.myUserId());
        }

        /**
         * @hide
         */
        public Builder setEnabled(@NonNull OverlayIdentifier overlay, boolean enable, int userId) {
            checkNotNull(overlay);
            @Request.RequestType final int type =
                enable ? Request.TYPE_SET_ENABLED : Request.TYPE_SET_DISABLED;
            mRequests.add(new Request(type, overlay, userId));
            return this;
        }

        /**
         * Registers the fabricated overlay with the overlay manager so it can be enabled and
         * disabled for any user.
         *
         * The fabricated overlay is initialized in a disabled state. If an overlay is re-registered
         * the existing overlay will be replaced by the newly registered overlay and the enabled
         * state of the overlay will be left unchanged if the target package and target overlayable
         * have not changed.
         *
         * @param overlay the overlay to register with the overlay manager
         *
         * @hide
         */
        public Builder registerFabricatedOverlay(@NonNull FabricatedOverlay overlay) {
            final Bundle extras = new Bundle();
            extras.putParcelable(Request.BUNDLE_FABRICATED_OVERLAY, overlay.mOverlay);
            mRequests.add(new Request(Request.TYPE_REGISTER_FABRICATED, overlay.getIdentifier(),
                    UserHandle.USER_ALL, extras));
            return this;
        }

        /**
         * Disables and removes the overlay from the overlay manager for all users.
         *
         * @param overlay the overlay to disable and remove
         *
         * @hide
         */
        public Builder unregisterFabricatedOverlay(@NonNull OverlayIdentifier overlay) {
            mRequests.add(new Request(Request.TYPE_UNREGISTER_FABRICATED, overlay,
                    UserHandle.USER_ALL));
            return this;
        }

        /**
         * Create a new transaction out of the requests added so far. Execute
         * the transaction by calling OverlayManager#commit.
         *
         * @see OverlayManager#commit
         * @return a new transaction
         */
        public OverlayManagerTransaction build() {
            return new OverlayManagerTransaction(mRequests);
        }
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        final int size = mRequests.size();
        dest.writeInt(size);
        for (int i = 0; i < size; i++) {
            final Request req = mRequests.get(i);
            dest.writeInt(req.type);
            dest.writeParcelable(req.overlay, flags);
            dest.writeInt(req.userId);
            dest.writeBundle(req.extras);
        }
    }

    public static final Parcelable.Creator<OverlayManagerTransaction> CREATOR =
            new Parcelable.Creator<OverlayManagerTransaction>() {

        @Override
        public OverlayManagerTransaction createFromParcel(Parcel source) {
            return new OverlayManagerTransaction(source);
        }

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