/*
 * 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 DEBUG true  // STOPSHIP if true
#include "Log.h"

#include "stats_util.h"

#include "StateTracker.h"

namespace android {
namespace os {
namespace statsd {

StateTracker::StateTracker(const int32_t atomId, const util::StateAtomFieldOptions& stateAtomInfo)
    : mAtomId(atomId),
      mStateField(getSimpleMatcher(atomId, stateAtomInfo.exclusiveField)),
      mNested(stateAtomInfo.nested) {
    // create matcher for each primary field
    for (const auto& primaryField : stateAtomInfo.primaryFields) {
        if (primaryField == util::FIRST_UID_IN_CHAIN) {
            Matcher matcher = getFirstUidMatcher(atomId);
            mPrimaryFields.push_back(matcher);
        } else {
            Matcher matcher = getSimpleMatcher(atomId, primaryField);
            mPrimaryFields.push_back(matcher);
        }
    }

    if (stateAtomInfo.defaultState != util::UNSET_VALUE) {
        mDefaultState = stateAtomInfo.defaultState;
    }

    if (stateAtomInfo.resetState != util::UNSET_VALUE) {
        mResetState = stateAtomInfo.resetState;
    }
}

void StateTracker::onLogEvent(const LogEvent& event) {
    int64_t eventTimeNs = event.GetElapsedTimestampNs();

    // Parse event for primary field values i.e. primary key.
    HashableDimensionKey primaryKey;
    if (mPrimaryFields.size() > 0) {
        if (!filterValues(mPrimaryFields, event.getValues(), &primaryKey) ||
            primaryKey.getValues().size() != mPrimaryFields.size()) {
            ALOGE("StateTracker error extracting primary key from log event.");
            handleReset(eventTimeNs);
            return;
        }
    } else {
        // Use an empty HashableDimensionKey if atom has no primary fields.
        primaryKey = DEFAULT_DIMENSION_KEY;
    }

    // Parse event for state value.
    FieldValue stateValue;
    if (!filterValues(mStateField, event.getValues(), &stateValue) ||
        stateValue.mValue.getType() != INT) {
        ALOGE("StateTracker error extracting state from log event. Type: %d",
              stateValue.mValue.getType());
        handlePartialReset(eventTimeNs, primaryKey);
        return;
    }

    int32_t state = stateValue.mValue.int_value;
    if (state == mResetState) {
        VLOG("StateTracker Reset state: %s", stateValue.mValue.toString().c_str());
        handleReset(eventTimeNs);
        return;
    }

    // Track and update state.
    int32_t oldState = 0;
    int32_t newState = 0;
    updateState(primaryKey, state, &oldState, &newState);

    // Notify all listeners if state has changed.
    if (oldState != newState) {
        VLOG("StateTracker updated state");
        for (auto listener : mListeners) {
            auto sListener = listener.promote();  // safe access to wp<>
            if (sListener != nullptr) {
                sListener->onStateChanged(eventTimeNs, mAtomId, primaryKey, oldState, newState);
            }
        }
    } else {
        VLOG("StateTracker NO updated state");
    }
}

void StateTracker::registerListener(wp<StateListener> listener) {
    mListeners.insert(listener);
}

void StateTracker::unregisterListener(wp<StateListener> listener) {
    mListeners.erase(listener);
}

bool StateTracker::getStateValue(const HashableDimensionKey& queryKey, FieldValue* output) const {
    output->mField = mStateField.mMatcher;

    // Check that the query key has the correct number of primary fields.
    if (queryKey.getValues().size() == mPrimaryFields.size()) {
        auto it = mStateMap.find(queryKey);
        if (it != mStateMap.end()) {
            output->mValue = it->second.state;
            return true;
        }
    } else if (queryKey.getValues().size() > mPrimaryFields.size()) {
        ALOGE("StateTracker query key size %zu > primary key size %zu is illegal",
              queryKey.getValues().size(), mPrimaryFields.size());
    } else {
        ALOGE("StateTracker query key size %zu < primary key size %zu is not supported",
              queryKey.getValues().size(), mPrimaryFields.size());
    }

    // Set the state value to default state if:
    // - query key size is incorrect
    // - query key is not found in state map
    output->mValue = mDefaultState;
    return false;
}

void StateTracker::handleReset(const int64_t eventTimeNs) {
    VLOG("StateTracker handle reset");
    for (const auto pair : mStateMap) {
        for (auto l : mListeners) {
            auto sl = l.promote();
            if (sl != nullptr) {
                sl->onStateChanged(eventTimeNs, mAtomId, pair.first, pair.second.state,
                                   mDefaultState);
            }
        }
    }
    mStateMap.clear();
}

void StateTracker::handlePartialReset(const int64_t eventTimeNs,
                                      const HashableDimensionKey& primaryKey) {
    VLOG("StateTracker handle partial reset");
    if (mStateMap.find(primaryKey) != mStateMap.end()) {
        for (auto l : mListeners) {
            auto sl = l.promote();
            if (sl != nullptr) {
                sl->onStateChanged(eventTimeNs, mAtomId, primaryKey,
                                   mStateMap.find(primaryKey)->second.state, mDefaultState);
            }
        }
        mStateMap.erase(primaryKey);
    }
}

void StateTracker::updateState(const HashableDimensionKey& primaryKey, const int32_t eventState,
                               int32_t* oldState, int32_t* newState) {
    // get old state (either current state in map or default state)
    auto it = mStateMap.find(primaryKey);
    if (it != mStateMap.end()) {
        *oldState = it->second.state;
    } else {
        *oldState = mDefaultState;
    }

    // Update state map for non-nested counting case.
    // Every state event triggers a state overwrite.
    if (!mNested) {
        if (eventState == mDefaultState) {
            // remove (key, state) pair if state returns to default state
            VLOG("\t StateTracker changed to default state")
            mStateMap.erase(primaryKey);
        } else {
            mStateMap[primaryKey].state = eventState;
            mStateMap[primaryKey].count = 1;
        }
        *newState = eventState;
        return;
    }

    // Update state map for nested counting case.
    //
    // Nested counting is only allowed for binary state events such as ON/OFF or
    // ACQUIRE/RELEASE. For example, WakelockStateChanged might have the state
    // events: ON, ON, OFF. The state will still be ON until we see the same
    // number of OFF events as ON events.
    //
    // In atoms.proto, a state atom with nested counting enabled
    // must only have 2 states and one of the states must be the default state.
    it = mStateMap.find(primaryKey);
    if (it != mStateMap.end()) {
        *newState = it->second.state;
        if (eventState == it->second.state) {
            it->second.count++;
        } else if (eventState == mDefaultState) {
            if ((--it->second.count) == 0) {
                mStateMap.erase(primaryKey);
                *newState = mDefaultState;
            }
        } else {
            ALOGE("StateTracker Nest counting state has a third state instead of the binary state "
                  "limit.");
            return;
        }
    } else {
        if (eventState != mDefaultState) {
            mStateMap[primaryKey].state = eventState;
            mStateMap[primaryKey].count = 1;
        }
        *newState = eventState;
    }
}

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