/*
 * 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 com.android.internal.compat;

import static android.text.TextUtils.formatSimple;

import static java.util.Collections.EMPTY_SET;

import android.annotation.IntDef;
import android.util.Log;
import android.util.Slog;

import com.android.internal.annotations.VisibleForTesting;
import com.android.internal.compat.flags.Flags;
import com.android.internal.util.FrameworkStatsLog;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.Collections;
import java.util.HashSet;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;

/**
 * A helper class to report changes to stats log.
 *
 * @hide
 */
public final class ChangeReporter {
    private static final String TAG = "CompatChangeReporter";
    private static final Function<Integer, Set<ChangeReport>> NEW_CHANGE_REPORT_SET =
            uid -> Collections.synchronizedSet(new HashSet<>());
    private int mSource;

    private static final class ChangeReport {
        long mChangeId;
        int mState;

        ChangeReport(long changeId, @State int state) {
            mChangeId = changeId;
            mState = state;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            ChangeReport that = (ChangeReport) o;
            return mChangeId == that.mChangeId
                    && mState == that.mState;
        }

        @Override
        public int hashCode() {
            return Objects.hash(mChangeId, mState);
        }
    }

    // Maps uid to a set of ChangeReports (that were reported for that uid).
    private final ConcurrentHashMap<Integer, Set<ChangeReport>> mReportedChanges;

    // When true will of every time to debug (logcat).
    private boolean mDebugLogAll;

    public ChangeReporter(@Source int source) {
        mSource = source;
        mReportedChanges =  new ConcurrentHashMap<>();
        mDebugLogAll = false;
    }

    /**
     * Report the change to stats log and to the debug log if the change was not previously
     * logged already.
     *
     * @param uid             affected by the change
     * @param changeId        the reported change id
     * @param state           of the reported change - enabled/disabled/only logged
     * @param isLoggableBySdk whether debug logging is allowed for this change based on target
     *                        SDK version. This is combined with other logic to determine whether to
     *                        actually log. If the sdk version does not matter, should be true.
     */
    public void reportChange(int uid, long changeId, int state, boolean isLoggableBySdk) {
        boolean isAlreadyReported =
                checkAndSetIsAlreadyReported(uid, new ChangeReport(changeId, state));
        if (!isAlreadyReported) {
            FrameworkStatsLog.write(FrameworkStatsLog.APP_COMPATIBILITY_CHANGE_REPORTED, uid,
                    changeId, state, mSource);
        }
        if (shouldWriteToDebug(isAlreadyReported, state, isLoggableBySdk)) {
            debugLog(uid, changeId, state);
        }
    }

    /**
     * Report the change to stats log and to the debug log if the change was not previously
     * logged already.
     *
     * @param uid      affected by the change
     * @param changeId the reported change id
     * @param state    of the reported change - enabled/disabled/only logged
     */
    public void reportChange(int uid, long changeId, int state) {
        reportChange(uid, changeId, state, true);
    }

    /**
     * Start logging all the time to logcat.
     */
    public void startDebugLogAll() {
        mDebugLogAll = true;
    }

    /**
     * Stop logging all the time to logcat.
     */
    public void stopDebugLogAll() {
        mDebugLogAll = false;
    }

    /**
     * Returns whether the next report should be logged to FrameworkStatsLog.
     *
     * @param uid      affected by the change
     * @param changeId the reported change id
     * @param state    of the reported change - enabled/disabled/only logged
     * @return true if the report should be logged
     */
    @VisibleForTesting
    boolean shouldWriteToStatsLog(int uid, long changeId, int state) {
        return !isAlreadyReported(uid, new ChangeReport(changeId, state));
    }

    /**
     * Returns whether the next report should be logged to logcat.
     *
     * @param isAlreadyReported is the change already reported
     * @param state             of the reported change - enabled/disabled/only logged
     * @param isLoggableBySdk   whether debug logging is allowed for this change based on target SDK
     *                          version. This is combined with other logic to determine whether to
     *                          actually log. If the sdk version does not matter, should be true.
     * @return true if the report should be logged
     */
    private boolean shouldWriteToDebug(
            boolean isAlreadyReported, int state, boolean isLoggableBySdk) {
        // If log all bit is on, always return true.
        if (mDebugLogAll) return true;
        // If the change has already been reported, do not write.
        if (isAlreadyReported) return false;

        // If the flag is turned off or the TAG's logging is forced to debug level with
        // `adb setprop log.tag.CompatChangeReporter=DEBUG`, write to debug since the above checks
        // have already passed.
        boolean skipLoggingFlag = Flags.skipOldAndDisabledCompatLogging();
        if (!skipLoggingFlag || Log.isLoggable(TAG, Log.DEBUG)) return true;

        // Log if the change is enabled and targets the latest sdk version.
        return isLoggableBySdk && state != STATE_DISABLED;
    }

    /**
     * Returns whether the next report should be logged to logcat.
     *
     * @param uid         affected by the change
     * @param changeId    the reported change id
     * @param state       of the reported change - enabled/disabled/only logged
     *
     * @return true if the report should be logged
     */
    @VisibleForTesting
    boolean shouldWriteToDebug(int uid, long changeId, int state) {
        return shouldWriteToDebug(uid, changeId, state, true);
    }

    /**
     * Returns whether the next report should be logged to logcat.
     *
     * @param uid               affected by the change
     * @param changeId          the reported change id
     * @param state             of the reported change - enabled/disabled/only logged
     * @param isLoggableBySdk   whether debug logging is allowed for this change based on target SDK
     *                          version. This is combined with other logic to determine whether to
     *                          actually log. If the sdk version does not matter, should be true.
     * @return true if the report should be logged
     */
    @VisibleForTesting
    boolean shouldWriteToDebug(int uid, long changeId, int state, boolean isLoggableBySdk) {
        return shouldWriteToDebug(
                isAlreadyReported(uid, new ChangeReport(changeId, state)), state, isLoggableBySdk);
    }

    /**
     * Return if change has been reported. Also mark change as reported if not.
     *
     * @param uid affected by the change
     * @param changeReport change reported to be checked and marked as reported.
     *
     * @return true if change has been reported, and vice versa.
     */
    private boolean checkAndSetIsAlreadyReported(int uid, ChangeReport changeReport) {
        boolean isAlreadyReported = isAlreadyReported(uid, changeReport);
        if (!isAlreadyReported) {
            markAsReported(uid, changeReport);
        }
        return isAlreadyReported;
    }

    private boolean isAlreadyReported(int uid, ChangeReport report) {
        return mReportedChanges.getOrDefault(uid, EMPTY_SET).contains(report);
    }

    private void markAsReported(int uid, ChangeReport report) {
        mReportedChanges.computeIfAbsent(uid, NEW_CHANGE_REPORT_SET).add(report);
    }

    /**
     * Clears the saved information about a given uid. Requests to report uid again will be reported
     * regardless to the past reports.
     *
     * <p> Only intended to be called from PlatformCompat.
     *
     * @param uid to reset
     */
    public void resetReportedChanges(int uid) {
        mReportedChanges.remove(uid);
    }

    private void debugLog(int uid, long changeId, int state) {
        String message = formatSimple("Compat change id reported: %d; UID %d; state: %s", changeId,
                uid, stateToString(state));
        if (mSource == SOURCE_SYSTEM_SERVER) {
            Slog.d(TAG, message);
        } else {
            Log.d(TAG, message);
        }
    }

    /**
     * Transforms {@link #ChangeReporter.State} enum to a string.
     *
     * @param state to transform
     * @return a string representing the state
     */
    private static String stateToString(@State int state) {
        switch (state) {
            case STATE_LOGGED:
                return "LOGGED";
            case STATE_ENABLED:
                return "ENABLED";
            case STATE_DISABLED:
                return "DISABLED";
            default:
                return "UNKNOWN";
        }
    }

    /** These values should be kept in sync with those in atoms.proto */
    public static final int STATE_UNKNOWN_STATE =
                    FrameworkStatsLog.APP_COMPATIBILITY_CHANGE_REPORTED__STATE__UNKNOWN_STATE;
    public static final int STATE_ENABLED =
                    FrameworkStatsLog.APP_COMPATIBILITY_CHANGE_REPORTED__STATE__ENABLED;
    public static final int STATE_DISABLED =
                    FrameworkStatsLog.APP_COMPATIBILITY_CHANGE_REPORTED__STATE__DISABLED;
    public static final int STATE_LOGGED =
                    FrameworkStatsLog.APP_COMPATIBILITY_CHANGE_REPORTED__STATE__LOGGED;
    public static final int SOURCE_UNKNOWN_SOURCE =
                    FrameworkStatsLog.APP_COMPATIBILITY_CHANGE_REPORTED__SOURCE__UNKNOWN_SOURCE;
    public static final int SOURCE_APP_PROCESS =
                    FrameworkStatsLog.APP_COMPATIBILITY_CHANGE_REPORTED__SOURCE__APP_PROCESS;
    public static final int SOURCE_SYSTEM_SERVER =
                    FrameworkStatsLog.APP_COMPATIBILITY_CHANGE_REPORTED__SOURCE__SYSTEM_SERVER;

    @Retention(RetentionPolicy.SOURCE)
    @IntDef(prefix = { "STATE_" }, value = {
            STATE_UNKNOWN_STATE,
            STATE_ENABLED,
            STATE_DISABLED,
            STATE_LOGGED
    })
    public @interface State {
    }

    @Retention(RetentionPolicy.SOURCE)
    @IntDef(prefix = { "SOURCE_" }, value = {
            SOURCE_UNKNOWN_SOURCE,
            SOURCE_APP_PROCESS,
            SOURCE_SYSTEM_SERVER
    })
    public @interface Source {
    }
}