/*
 * 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.
 */

#define STATSD_DEBUG false  // STOPSHIP if true
#include "Log.h"

#include "StateManager.h"

#include <private/android_filesystem_config.h>
#include <statslog_statsd.h>

#include <unordered_set>

namespace android {
namespace os {
namespace statsd {

StateManager::StateManager()
    : mAllowedPkg({
              "com.android.systemui",
      }) {
}

StateManager& StateManager::getInstance() {
    static StateManager sStateManager;
    return sStateManager;
}

void StateManager::clear() {
    mStateTrackers.clear();
}

void StateManager::onLogEvent(const LogEvent& event) {
    // Only process state events from uids in AID_* and packages that are whitelisted in
    // mAllowedPkg.
    // Allowlisted AIDs are AID_ROOT and all AIDs in [1000, 2000) which is [AID_SYSTEM, AID_SHELL)
    if (event.GetUid() == AID_ROOT ||
        (event.GetUid() >= AID_SYSTEM && event.GetUid() < AID_SHELL) ||
        mAllowedLogSources.find(event.GetUid()) != mAllowedLogSources.end()) {
        const int tagId = event.GetTagId();
        if (tagId == util::STATS_SOCKET_LOSS_REPORTED) {
            // Hard coded logic to handle socket loss info to highlight metric corruption reason
            const std::optional<SocketLossInfo>& lossInfo = toSocketLossInfo(event);
            if (lossInfo) {
                handleSocketLossInfo(*lossInfo);
            }
        } else {
            auto stateTrackersForEvent = mStateTrackers.find(tagId);
            if (stateTrackersForEvent != mStateTrackers.end()) {
                stateTrackersForEvent->second->onLogEvent(event);
            }
        }
    }
}

void StateManager::handleSocketLossInfo(const SocketLossInfo& socketLossInfo) {
    // socketLossInfo stores atomId per UID - to eliminate duplicates using set
    const std::unordered_set<int> uniqueLostAtomIds(socketLossInfo.atomIds.begin(),
                                                    socketLossInfo.atomIds.end());

    // pass lost atom id to all relevant metrics
    for (const auto lostAtomId : uniqueLostAtomIds) {
        onLogEventLost(lostAtomId, DATA_CORRUPTED_SOCKET_LOSS);
    }
}

bool StateManager::onLogEventLost(int32_t lostAtomId, DataCorruptedReason reason) {
    auto stateTrackersIt = mStateTrackers.find(lostAtomId);
    if (stateTrackersIt != mStateTrackers.end()) {
        stateTrackersIt->second->onLogEventLost(reason);
        return true;
    }
    return false;
}

void StateManager::registerListener(const int32_t atomId, const wp<StateListener>& listener) {
    // Check if state tracker already exists.
    if (mStateTrackers.find(atomId) == mStateTrackers.end()) {
        mStateTrackers[atomId] = new StateTracker(atomId);
    }
    mStateTrackers[atomId]->registerListener(listener);
}

void StateManager::unregisterListener(const int32_t atomId, const wp<StateListener>& listener) {
    std::unique_lock<std::mutex> lock(mMutex);

    // Hold the sp<> until the lock is released so that ~StateTracker() is
    // not called while the lock is held.
    sp<StateTracker> toRemove;

    // Unregister listener from correct StateTracker
    auto it = mStateTrackers.find(atomId);
    if (it != mStateTrackers.end()) {
        it->second->unregisterListener(listener);

        // Remove the StateTracker if it has no listeners
        if (it->second->getListenersCount() == 0) {
            toRemove = it->second;
            mStateTrackers.erase(it);
        }
    } else {
        ALOGE("StateManager cannot unregister listener, StateTracker for atom %d does not exist",
              atomId);
    }
    lock.unlock();
}

bool StateManager::getStateValue(const int32_t atomId, const HashableDimensionKey& key,
                                 FieldValue* output) const {
    auto it = mStateTrackers.find(atomId);
    if (it != mStateTrackers.end()) {
        return it->second->getStateValue(key, output);
    }
    ALOGE("StateManager cannot get state value, no StateTracker for atom %d", atomId);
    return false;
}

void StateManager::updateLogSources(const sp<UidMap>& uidMap) {
    mAllowedLogSources.clear();
    for (const auto& pkg : mAllowedPkg) {
        auto uids = uidMap->getAppUid(pkg);
        mAllowedLogSources.insert(uids.begin(), uids.end());
    }
}

void StateManager::notifyAppChanged(const string& apk, const sp<UidMap>& uidMap) {
    if (mAllowedPkg.find(apk) != mAllowedPkg.end()) {
        updateLogSources(uidMap);
    }
}

void StateManager::addAllAtomIds(LogEventFilter::AtomIdSet& allIds) const {
    for (const auto& stateTracker : mStateTrackers) {
        allIds.insert(stateTracker.first);
    }
}

}  // namespace statsd
}  // namespace os
}  // namespace android