/*
 * Copyright (C) 2025 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.server.healthconnect.onboarding;

import static android.health.connect.HealthConnectOnboardingState.ONBOARDING_BANNER_STATE_HIDE;
import static android.health.connect.HealthConnectOnboardingState.ONBOARDING_BANNER_STATE_ONE_APP_CONNECTED;
import static android.health.connect.HealthConnectOnboardingState.ONBOARDING_BANNER_STATE_ZERO_APPS_CONNECTED;

import android.content.Context;
import android.content.pm.PackageInfo;
import android.health.connect.Constants;
import android.health.connect.HealthConnectOnboardingState;
import android.health.connect.internal.datatypes.AppInfoInternal;
import android.os.UserHandle;
import android.util.Slog;

import androidx.annotation.NonNull;

import com.android.healthfitness.flags.Flags;
import com.android.internal.annotations.VisibleForTesting;
import com.android.server.healthconnect.common.accesslog.AccessLogsHelper;
import com.android.server.healthconnect.common.metadata.AppInfoHelper;
import com.android.server.healthconnect.common.preferences.PreferenceHelper;
import com.android.server.healthconnect.permission.HealthConnectPermissionHelper;
import com.android.server.healthconnect.permission.PackageInfoUtils;

import java.time.Duration;
import java.time.Instant;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 * Sends the appropriate notification based on the onboarding state, and returns the current
 * onboarding state of user to the caller.
 *
 * @hide
 */
public final class OnboardingStateManager {
    private static final String TAG = OnboardingStateManager.class.getSimpleName();

    @VisibleForTesting
    static final String ONBOARDING_STATE_PREFERENCE_KEY_PREFIX = "onboarding_state_";

    private final Context mContext;
    private final PreferenceHelper mPreferenceHelper;
    private final ReentrantReadWriteLock mStatesLock = new ReentrantReadWriteLock(true);
    private final Set<StateChangedListener> mStateChangedListeners = new CopyOnWriteArraySet<>();
    private final HealthConnectPermissionHelper mHealthConnectPermissionHelper;
    private final PackageInfoUtils mPackageInfoUtils;
    private final AppInfoHelper mAppInfoHelper;
    private final AccessLogsHelper mAccessLogsHelper;

    private UserHandle mUserHandle;

    public OnboardingStateManager(
            Context context,
            PreferenceHelper preferenceHelper,
            HealthConnectPermissionHelper healthConnectPermissionHelper,
            PackageInfoUtils packageInfoUtils,
            AppInfoHelper appInfoHelper,
            AccessLogsHelper accessLogsHelper,
            UserHandle userHandle) {
        mContext = context;
        mPreferenceHelper = preferenceHelper;
        mHealthConnectPermissionHelper = healthConnectPermissionHelper;
        mPackageInfoUtils = packageInfoUtils;
        mAppInfoHelper = appInfoHelper;
        mAccessLogsHelper = accessLogsHelper;
        mUserHandle = userHandle;
    }

    /** Re-initialize this class instance with the new user */
    public void setupForUser(UserHandle userHandle) {
        mStatesLock.writeLock().lock();
        try {
            mUserHandle = userHandle;
        } finally {
            mStatesLock.writeLock().unlock();
        }
    }

    /** Registers {@link StateChangedListener} for observing onboarding state changes. */
    public void addStateChangedListener(StateChangedListener listener) {
        mStatesLock.writeLock().lock();
        try {
            mStateChangedListeners.add(listener);
        } finally {
            mStatesLock.writeLock().unlock();
        }
    }

    /** Returns the current onboarding state. */
    @HealthConnectOnboardingState.OnboardingState
    @VisibleForTesting
    int getOnboardingState() {
        mStatesLock.readLock().lock();
        try {
            String onboardingStateStr =
                    mPreferenceHelper.getPreference(getOnboardingStatePreferenceKey());
            if (Objects.isNull(onboardingStateStr)) {
                return ONBOARDING_BANNER_STATE_HIDE;
            }
            return Integer.parseInt(onboardingStateStr);
        } finally {
            mStatesLock.readLock().unlock();
        }
    }

    /**
     * Evaluates the current onboarding state, updates the value in storage, and returns the current
     * state.
     */
    @HealthConnectOnboardingState.OnboardingState
    public int updateAndGetOnboardingState() {
        return updateAndGetOnboardingState(false);
    }

    /**
     * Evaluates the current onboarding state, updates the value in storage, and returns the current
     * state.
     */
    @HealthConnectOnboardingState.OnboardingState
    public int updateAndGetOnboardingState(boolean bypassInstallTime) {
        if (!Flags.onboarding()) {
            return ONBOARDING_BANNER_STATE_HIDE;
        }

        int onboardingState = evaluateCurrentOnboardingState(bypassInstallTime);
        updateOnboardingState(onboardingState);
        return onboardingState;
    }

    /** Updates the onboarding state. */
    private void updateOnboardingState(@HealthConnectOnboardingState.OnboardingState int state) {
        if (state == getOnboardingState()) {
            if (Constants.DEBUG) {
                Slog.d(TAG, "The new state same as the current state.");
            }
            return;
        }
        updateOnboardingStateGuarded(state);
        updateListeners(state);
    }

    @HealthConnectOnboardingState.OnboardingState
    private int evaluateCurrentOnboardingState(boolean bypassInstallTime) {
        List<PackageInfo> compatibleFitnessApps = getCompatibleFitnessApps();

        if (compatibleFitnessApps.isEmpty()) {
            return ONBOARDING_BANNER_STATE_HIDE;
        }

        // compatible but not connected apps are potential candidates
        List<PackageInfo> potentialCandidates =
                compatibleFitnessApps.stream().filter(app -> !isConnected(app)).toList();

        if (potentialCandidates.isEmpty()) {
            return ONBOARDING_BANNER_STATE_HIDE;
        }

        long connectedFitnessAppsCount = compatibleFitnessApps.size() - potentialCandidates.size();
        if (connectedFitnessAppsCount >= 2) {
            return ONBOARDING_BANNER_STATE_HIDE;
        }

        long candidateAppsCount =
                potentialCandidates.stream()
                        .filter(app -> !hasBeenUsed(app))
                        .filter(
                                app -> {
                                    if (!bypassInstallTime) {
                                        return installed7DaysAgo(app);
                                    } else {
                                        return true;
                                    }
                                })
                        .count();
        if (connectedFitnessAppsCount == 0 && candidateAppsCount >= 2) {
            return ONBOARDING_BANNER_STATE_ZERO_APPS_CONNECTED;
        }
        if (connectedFitnessAppsCount == 1 && candidateAppsCount >= 1) {
            return ONBOARDING_BANNER_STATE_ONE_APP_CONNECTED;
        }

        return ONBOARDING_BANNER_STATE_HIDE;
    }

    @NonNull
    private List<PackageInfo> getCompatibleFitnessApps() {
        return mPackageInfoUtils
                .getPackagesCompatibleWithHealthConnect(mContext, mUserHandle)
                .stream()
                .filter(info -> !isSystemApp(info.packageName))
                .filter(this::hasFitnessPerm)
                .toList();
    }

    private boolean isConnected(PackageInfo app) {
        return mHealthConnectPermissionHelper.hasGrantedFitnessPermission(app);
    }

    private boolean hasFitnessPerm(PackageInfo app) {
        return mHealthConnectPermissionHelper.isRequestingFitnessPermission(app);
    }

    // TODO(b/421165586): Consider using ApplicationInfo.FLAG_SYSTEM
    private boolean isSystemApp(String packageName) {
        return mHealthConnectPermissionHelper.hasNonUserSensitiveHealthPermission(
                packageName, mUserHandle, mContext);
    }

    private boolean hasDeniedFitnessPerm(PackageInfo app) {
        return mHealthConnectPermissionHelper.hasDeniedFitnessPermission(app, mUserHandle);
    }

    private boolean hasBeenUsed(PackageInfo app) {
        if (hasDeniedFitnessPerm(app)) {
            return true;
        }

        AppInfoInternal appInfo = mAppInfoHelper.getAppInfoMap().get(app.packageName);
        if (appInfo == null) {
            return false;
        }

        // We don't need to filter these - they are created only for fitness data
        Set<Integer> recordTypesUsed = appInfo.getRecordTypesUsed();
        boolean hasData = recordTypesUsed != null && !recordTypesUsed.isEmpty();
        boolean hasAccessLog =
                mAccessLogsHelper.queryAccessLogs(mUserHandle).stream()
                        .filter(log -> !log.getRecordTypes().isEmpty())
                        .anyMatch(log -> log.getPackageName().equals(app.packageName));
        return hasData || hasAccessLog;
    }

    private boolean installed7DaysAgo(PackageInfo app) {
        Instant installTime = Instant.ofEpochMilli(app.firstInstallTime);
        Instant aWeekAgo = Instant.now().minus(Duration.ofDays(7));
        return installTime.isBefore(aWeekAgo);
    }

    /** Atomically updates the onboarding state. */
    private void updateOnboardingStateGuarded(
            @HealthConnectOnboardingState.OnboardingState int state) {
        switch (state) {
            case ONBOARDING_BANNER_STATE_ZERO_APPS_CONNECTED,
            ONBOARDING_BANNER_STATE_ONE_APP_CONNECTED,
            ONBOARDING_BANNER_STATE_HIDE:
                updateOnboardingStatePreference(state);
                return;
            default:
                throw new IllegalArgumentException(
                        "Cannot update onboarding state. Unknown state: " + state);
        }
    }

    /** Updates the onboarding state preference and the timeout reached preferences. */
    private void updateOnboardingStatePreference(
            @HealthConnectOnboardingState.OnboardingState int onboardingState) {
        mStatesLock.writeLock().lock();
        try {
            mPreferenceHelper.insertOrReplacePreference(
                    getOnboardingStatePreferenceKey(), String.valueOf(onboardingState));

        } finally {
            mStatesLock.writeLock().unlock();
        }
    }

    private String getOnboardingStatePreferenceKey() {
        return ONBOARDING_STATE_PREFERENCE_KEY_PREFIX + mUserHandle.getIdentifier();
    }

    private void updateListeners(
            @HealthConnectOnboardingState.OnboardingState int onboardingState) {
        for (StateChangedListener listener : mStateChangedListeners) {
            listener.onChanged(onboardingState);
        }
    }

    /**
     * A listener for observing onboarding state changes.
     *
     * @see OnboardingStateManager#addStateChangedListener(StateChangedListener)
     */
    public interface StateChangedListener {

        /**
         * Called on every onboarding state change.
         *
         * @param state the new onboarding state.
         */
        void onChanged(@HealthConnectOnboardingState.OnboardingState int state);
    }
}