/*
 * Copyright (C) 2017 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.
 */

#pragma once

#include "config/ConfigKey.h"
#include "config/ConfigListener.h"
#include "frameworks/base/cmds/statsd/src/stats_log_common.pb.h"
#include "packages/PackageInfoListener.h"

#include <binder/IResultReceiver.h>
#include <binder/IShellCallback.h>
#include <gtest/gtest_prod.h>
#include <log/logprint.h>
#include <stdio.h>
#include <utils/RefBase.h>
#include <mutex>
#include <set>
#include <string>
#include <unordered_map>

using namespace std;

namespace android {
namespace os {
namespace statsd {

struct AppData {
    const string packageName;
    int64_t versionCode;

    AppData(const string& a, const int64_t v) : packageName(a), versionCode(v){};
};

// UidMap keeps track of what the corresponding app name (APK name) and version code for every uid
// at any given moment. This map must be updated by StatsCompanionService.
class UidMap : public virtual android::RefBase {
public:
    UidMap();
    ~UidMap();
    static const std::map<std::string, uint32_t> sAidToUidMapping;
    /*
     * All three inputs must be the same size, and the jth element in each array refers to the same
     * tuple, ie. uid[j] corresponds to packageName[j] with versionCode[j].
     */
    void updateMap(const vector<int32_t>& uid, const vector<int64_t>& versionCode,
                   const vector<String16>& packageName);

    void updateApp(const String16& packageName, const int32_t& uid, const int64_t& versionCode);
    void removeApp(const String16& packageName, const int32_t& uid);

    // Returns true if the given uid contains the specified app (eg. com.google.android.gms).
    bool hasApp(int uid, const string& packageName) const;

    // Returns the app names from uid.
    std::set<string> getAppNamesFromUid(const int32_t& uid, bool returnNormalized) const;

    int64_t getAppVersion(int uid, const string& packageName) const;

    // Helper for debugging contents of this uid map. Can be triggered with:
    // adb shell cmd stats print-uid-map
    void printUidMap(FILE* out) const;

    // Commands for indicating to the map that a producer should be notified if an app is updated.
    // This allows the metric producer to distinguish when the same uid or app represents a
    // different version of an app.
    void addListener(wp<PackageInfoListener> producer);
    // Remove the listener from the set of metric producers that subscribe to updates.
    void removeListener(wp<PackageInfoListener> producer);

    // Informs uid map that a config is added/updated. Used for keeping mConfigKeys up to date.
    void OnConfigUpdated(const ConfigKey& key);

    // Informs uid map that a config is removed. Used for keeping mConfigKeys up to date.
    void OnConfigRemoved(const ConfigKey& key);

    void assignIsolatedUid(int isolatedUid, int parentUid);
    void removeIsolatedUid(int isolatedUid, int parentUid);

    // Returns the host uid if it exists. Otherwise, returns the same uid that was passed-in.
    virtual int getHostUidOrSelf(int uid) const;

    // Gets the output. If every config key has received the output, then the output is cleared.
    UidMapping getOutput(const ConfigKey& key);

    // Forces the output to be cleared. We still generate a snapshot based on the current state.
    // This results in extra data uploaded but helps us reconstruct the uid mapping on the server
    // in case we lose a previous upload.
    void clearOutput();

    // Get currently cached value of memory used by UID map.
    size_t getBytesUsed() const;

    std::set<int32_t> getAppUid(const string& package) const;

private:
    std::set<string> getAppNamesFromUidLocked(const int32_t& uid, bool returnNormalized) const;
    string normalizeAppName(const string& appName) const;

    void updateMap(const int64_t& timestamp, const vector<int32_t>& uid,
                   const vector<int64_t>& versionCode, const vector<String16>& packageName);

    void updateApp(const int64_t& timestamp, const String16& packageName, const int32_t& uid,
                   const int64_t& versionCode);
    void removeApp(const int64_t& timestamp, const String16& packageName, const int32_t& uid);

    UidMapping getOutput(const int64_t& timestamp, const ConfigKey& key);

    void getListenerListCopyLocked(std::vector<wp<PackageInfoListener>>* output);

    // TODO: Use shared_mutex for improved read-locking if a library can be found in Android.
    mutable mutex mMutex;
    mutable mutex mIsolatedMutex;

    // Maps uid to application data. This must be multimap since there is a feature in Android for
    // multiple apps to share the same uid.
    std::unordered_multimap<int, AppData> mMap;

    // Maps isolated uid to the parent uid. Any metrics for an isolated uid will instead contribute
    // to the parent uid.
    std::unordered_map<int, int> mIsolatedUidMap;

    // We prepare the output proto as apps are updated, so that we can grab the current output.
    UidMapping mOutput;

    // Metric producers that should be notified if there's an upgrade in any app.
    set<wp<PackageInfoListener>> mSubscribers;

    // Mapping of config keys we're aware of to the epoch time they last received an update. This
    // lets us know it's safe to delete events older than the oldest update. The value is nanosec.
    // Value of -1 denotes this config key has never received an upload.
    std::unordered_map<ConfigKey, int64_t> mLastUpdatePerConfigKey;

    // Returns the minimum value from mConfigKeys.
    int64_t getMinimumTimestampNs();

    // If our current used bytes is above the limit, then we clear out the earliest snapshot. If
    // there are no more snapshots, then we clear out the earliest delta. We repeat the deletions
    // until the memory consumed by mOutput is below the specified limit.
    void ensureBytesUsedBelowLimit();

    // Override used for testing the max memory allowed by uid map. 0 means we use the value
    // specified in StatsdStats.h with the rest of the guardrails.
    size_t maxBytesOverride = 0;

    // Cache the size of mOutput;
    size_t mBytesUsed;

    // Allows unit-test to access private methods.
    FRIEND_TEST(UidMapTest, TestClearingOutput);
    FRIEND_TEST(UidMapTest, TestMemoryComputed);
    FRIEND_TEST(UidMapTest, TestMemoryGuardrail);
};

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