/*
 * Copyright 2018 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.intentresolver.model;

import android.app.usage.UsageStatsManager;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.os.BadParcelableException;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.os.UserHandle;
import android.util.Log;

import androidx.annotation.Nullable;

import com.android.intentresolver.ResolvedComponentInfo;
import com.android.intentresolver.ResolverActivity;
import com.android.intentresolver.ResolverListController;
import com.android.intentresolver.chooser.TargetInfo;
import com.android.intentresolver.logging.EventLog;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Used to sort resolved activities in {@link ResolverListController}.
 *
 * @hide
 */
public abstract class AbstractResolverComparator implements Comparator<ResolvedComponentInfo> {

    private static final int NUM_OF_TOP_ANNOTATIONS_TO_USE = 3;
    private static final boolean DEBUG = true;
    private static final String TAG = "AbstractResolverComp";

    protected Runnable mAfterCompute;
    protected final Map<UserHandle, PackageManager> mPmMap = new HashMap<>();
    protected final Map<UserHandle, UsageStatsManager> mUsmMap = new HashMap<>();
    protected String[] mAnnotations;
    protected String mContentType;
    protected final ComponentName mPromoteToFirst;

    // True if the current share is a link.
    private final boolean mHttp;

    // message types
    static final int RANKER_SERVICE_RESULT = 0;
    static final int RANKER_RESULT_TIMEOUT = 1;

    // timeout for establishing connections with a ResolverRankerService, collecting features and
    // predicting ranking scores.
    private static final int WATCHDOG_TIMEOUT_MILLIS = 500;

    private final Comparator<ResolveInfo> mAzComparator;
    private EventLog mEventLog;

    protected final Handler mHandler = new Handler(Looper.getMainLooper()) {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case RANKER_SERVICE_RESULT:
                    if (DEBUG) {
                        Log.d(TAG, "RANKER_SERVICE_RESULT");
                    }
                    if (mHandler.hasMessages(RANKER_RESULT_TIMEOUT)) {
                        handleResultMessage(msg);
                        mHandler.removeMessages(RANKER_RESULT_TIMEOUT);
                        afterCompute();
                    }
                    break;

                case RANKER_RESULT_TIMEOUT:
                    if (DEBUG) {
                        Log.d(TAG, "RANKER_RESULT_TIMEOUT; unbinding services");
                    }
                    mHandler.removeMessages(RANKER_SERVICE_RESULT);
                    afterCompute();
                    if (mEventLog != null) {
                        mEventLog.logSharesheetAppShareRankingTimeout();
                    }
                    break;

                default:
                    super.handleMessage(msg);
            }
        }
    };

    /**
     * Constructor to initialize the comparator.
     * @param launchedFromContext the activity calling this comparator
     * @param intent original intent
     * @param resolvedActivityUserSpaceList refers to the userSpace(s) used by the comparator for
     *                                      fetching activity stats and recording activity
     *                                      selection. The latter could be different from the
     *                                      userSpace provided by context.
     * @param promoteToFirst a component to be moved to the front of the app list if it's being
     *                       ranked. Unlike pinned apps, this cannot be modified by the user.
     */
    public AbstractResolverComparator(
            Context launchedFromContext,
            Intent intent,
            List<UserHandle> resolvedActivityUserSpaceList,
            @Nullable ComponentName promoteToFirst) {
        String scheme = intent.getScheme();
        mHttp = "http".equals(scheme) || "https".equals(scheme);
        mContentType = intent.getType();
        getContentAnnotations(intent);
        for (UserHandle user : resolvedActivityUserSpaceList) {
            Context userContext = launchedFromContext.createContextAsUser(user, 0);
            mPmMap.put(user, userContext.getPackageManager());
            mUsmMap.put(
                    user,
                    (UsageStatsManager) userContext.getSystemService(Context.USAGE_STATS_SERVICE));
        }
        mAzComparator = new ResolveInfoAzInfoComparator(launchedFromContext);
        mPromoteToFirst = promoteToFirst;
    }

    // get annotations of content from intent.
    private void getContentAnnotations(Intent intent) {
        try {
            ArrayList<String> annotations = intent.getStringArrayListExtra(
                    Intent.EXTRA_CONTENT_ANNOTATIONS);
            if (annotations != null) {
                int size = annotations.size();
                if (size > NUM_OF_TOP_ANNOTATIONS_TO_USE) {
                    size = NUM_OF_TOP_ANNOTATIONS_TO_USE;
                }
                mAnnotations = new String[size];
                for (int i = 0; i < size; i++) {
                    mAnnotations[i] = annotations.get(i);
                }
            }
        } catch (BadParcelableException e) {
            Log.i(TAG, "Couldn't unparcel intent annotations. Ignoring.");
            mAnnotations = new String[0];
        }
    }

    public void setCallBack(Runnable afterCompute) {
        mAfterCompute = afterCompute;
    }

    void setEventLog(EventLog eventLog) {
        mEventLog = eventLog;
    }

    EventLog getEventLog() {
        return mEventLog;
    }

    protected final void afterCompute() {
        final Runnable afterCompute = mAfterCompute;
        if (afterCompute != null) {
            afterCompute.run();
        }
    }

    @Override
    public final int compare(ResolvedComponentInfo lhsp, ResolvedComponentInfo rhsp) {
        final ResolveInfo lhs = lhsp.getResolveInfoAt(0);
        final ResolveInfo rhs = rhsp.getResolveInfoAt(0);

        // We want to put the one targeted to another user at the end of the dialog.
        if (lhs.targetUserId != UserHandle.USER_CURRENT) {
            return rhs.targetUserId != UserHandle.USER_CURRENT ? 0 : 1;
        }
        if (rhs.targetUserId != UserHandle.USER_CURRENT) {
            return -1;
        }

        if (mPromoteToFirst != null) {
            // A single component can be cemented to the front of the list. If it is seen, let it
            // always get priority.
            if (mPromoteToFirst.equals(lhs.activityInfo.getComponentName())) {
                return -1;
            } else if (mPromoteToFirst.equals(rhs.activityInfo.getComponentName())) {
                return 1;
            }
        }

        if (mHttp) {
            final boolean lhsSpecific = isSpecificUriMatch(lhs.match);
            final boolean rhsSpecific = isSpecificUriMatch(rhs.match);
            if (lhsSpecific != rhsSpecific) {
                return lhsSpecific ? -1 : 1;
            }
        }

        final boolean lPinned = lhsp.isPinned();
        final boolean rPinned = rhsp.isPinned();

        // Pinned items always receive priority.
        if (lPinned && !rPinned) {
            return -1;
        } else if (!lPinned && rPinned) {
            return 1;
        } else if (lPinned && rPinned) {
            // If both items are pinned, resolve the tie alphabetically.
            return mAzComparator.compare(lhsp.getResolveInfoAt(0), rhsp.getResolveInfoAt(0));
        }

        return compare(lhs, rhs);
    }

    /** Determine whether a given match result is considered "specific" in our application. */
    public static final boolean isSpecificUriMatch(int match) {
        match = (match & IntentFilter.MATCH_CATEGORY_MASK);
        return match >= IntentFilter.MATCH_CATEGORY_HOST
                && match <= IntentFilter.MATCH_CATEGORY_PATH;
    }

    /**
     * Delegated to when used as a {@link Comparator<ResolvedComponentInfo>} if there is not a
     * special case. The {@link ResolveInfo ResolveInfos} are the first {@link ResolveInfo} in
     * {@link ResolvedComponentInfo#getResolveInfoAt(int)} from the parameters of {@link
     * #compare(ResolvedComponentInfo, ResolvedComponentInfo)}
     */
    public abstract int compare(ResolveInfo lhs, ResolveInfo rhs);

    /**
     * Computes features for each target. This will be called before calls to {@link
     * #getScore(TargetInfo)} or {@link #compare(ResolveInfo, ResolveInfo)}, in order to prepare the
     * comparator for those calls. Note that {@link #getScore(TargetInfo)} uses {@link
     * ComponentName}, so the implementation will have to be prepared to identify a {@link
     * ResolvedComponentInfo} by {@link ComponentName}. {@link #beforeCompute()} will be called
     * before doing any computing.
     */
    public final void compute(List<ResolvedComponentInfo> targets) {
        beforeCompute();
        doCompute(targets);
    }

    /** Implementation of compute called after {@link #beforeCompute()}. */
    public abstract void doCompute(List<ResolvedComponentInfo> targets);

    /**
     * Returns the score that was calculated for the corresponding {@link ResolvedComponentInfo}
     * when {@link #compute(List)} was called before this.
     */
    public abstract float getScore(TargetInfo targetInfo);

    /** Handles result message sent to mHandler. */
    public abstract void handleResultMessage(Message message);

    /**
     * Reports to UsageStats what was chosen.
     */
    public void updateChooserCounts(String packageName, UserHandle user, String action) {
        if (mUsmMap.containsKey(user)) {
            mUsmMap.get(user).reportChooserSelection(
                    packageName,
                    user.getIdentifier(),
                    mContentType,
                    mAnnotations,
                    action);
        }
    }

    /**
     * Updates the model used to rank the componentNames.
     *
     * <p>Default implementation does nothing, as we could have simple model that does not train
     * online.
     *
     * * @param targetInfo the target that the user clicked.
     */
    public void updateModel(TargetInfo targetInfo) {
    }

    /** Called before {@link #doCompute(List)}. Sets up 500ms timeout. */
    void beforeCompute() {
        if (DEBUG) Log.d(TAG, "Setting watchdog timer for " + WATCHDOG_TIMEOUT_MILLIS + "ms");
        if (mHandler == null) {
            Log.d(TAG, "Error: Handler is Null; Needs to be initialized.");
            return;
        }
        mHandler.sendEmptyMessageDelayed(RANKER_RESULT_TIMEOUT, WATCHDOG_TIMEOUT_MILLIS);
    }

    /**
     * Called when the {@link ResolverActivity} is destroyed. This calls {@link #afterCompute()}. If
     * this call needs to happen at a different time during destroy, the method should be
     * overridden.
     */
    public void destroy() {
        mHandler.removeMessages(RANKER_SERVICE_RESULT);
        mHandler.removeMessages(RANKER_RESULT_TIMEOUT);
        afterCompute();
        mAfterCompute = null;
    }

}