/*
 * Copyright (C) 2020 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.
 */

#include "chre/pal/util/wifi_scan_cache.h"

#include <algorithm>
#include <cinttypes>
#include <cstring>

#include "chre/platform/linux/system_time.h"
#include "chre/platform/log.h"
#include "chre/platform/shared/pal_system_api.h"
#include "chre/util/fixed_size_vector.h"
#include "chre/util/macros.h"
#include "chre/util/nanoapp/wifi.h"
#include "chre/util/optional.h"
#include "chre/util/time.h"
#include "chre_api/chre/common.h"
#include "gtest/gtest.h"

using chre::Milliseconds;
using chre::Nanoseconds;
using chre::Seconds;
using chre::platform_linux::clearMonotonicTimeOverride;
using chre::platform_linux::overrideMonotonicTime;

namespace {

/************************************************
 *  Prototypes
 ***********************************************/
void chreWifiScanResponseCallback(bool pending, uint8_t errorCode);
void chreWifiScanEventCallback(struct chreWifiScanEvent *event);

struct WifiScanResponse {
  bool pending;
  uint8_t errorCode;
};

/************************************************
 *  Global variables
 ***********************************************/
const chrePalWifiCallbacks gChreWifiPalCallbacks = {
    .scanResponseCallback = chreWifiScanResponseCallback,
    .scanEventCallback = chreWifiScanEventCallback,
};

using InputVec = std::vector<chreWifiScanResult>;
using ResultVec = chre::FixedSizeVector<chreWifiScanResult,
                                        CHRE_PAL_WIFI_SCAN_CACHE_CAPACITY>;

chre::Optional<WifiScanResponse> gWifiScanResponse;
ResultVec gWifiScanResultList;
chre::Optional<chreWifiScanEvent> gExpectedWifiScanEvent;
bool gWifiScanEventCompleted;

/************************************************
 *  Test class
 ***********************************************/
class WifiScanCacheTests : public ::testing::Test {
 protected:
  void SetUp() override {
    clearTestState();
    EXPECT_TRUE(chreWifiScanCacheInit(&chre::gChrePalSystemApi,
                                      &gChreWifiPalCallbacks));
  }

  void TearDown() override {
    chreWifiScanCacheDeinit();
    clearMonotonicTimeOverride();
  }

  void clearTestState() {
    gExpectedWifiScanEvent.reset();
    gWifiScanResponse.reset();
    while (!gWifiScanResultList.empty()) {
      gWifiScanResultList.pop_back();
    }
  }
};

/************************************************
 *  Private functions
 ***********************************************/
void chreWifiScanResponseCallback(bool pending, uint8_t errorCode) {
  WifiScanResponse response = {
      .pending = pending,
      .errorCode = errorCode,
  };
  gWifiScanResponse = response;
}

void chreWifiScanEventCallback(struct chreWifiScanEvent *event) {
  ASSERT_TRUE(gExpectedWifiScanEvent.has_value());
  EXPECT_EQ(event->version, gExpectedWifiScanEvent->version);
  EXPECT_EQ(event->scanType, gExpectedWifiScanEvent->scanType);
  EXPECT_EQ(event->ssidSetSize, gExpectedWifiScanEvent->ssidSetSize);
  ASSERT_EQ(event->scannedFreqListLen,
            gExpectedWifiScanEvent->scannedFreqListLen);
  if (event->scannedFreqListLen > 0) {
    ASSERT_NE(event->scannedFreqList, nullptr);
    EXPECT_EQ(
        memcmp(gExpectedWifiScanEvent->scannedFreqList, event->scannedFreqList,
               event->scannedFreqListLen * sizeof(uint32_t)),
        0);
  }

  EXPECT_EQ(event->radioChainPref, gExpectedWifiScanEvent->radioChainPref);
  EXPECT_EQ(event->eventIndex, gExpectedWifiScanEvent->eventIndex);
  gExpectedWifiScanEvent->eventIndex++;

  for (uint8_t i = 0; i < event->resultCount; i++) {
    const chreWifiScanResult &result = event->results[i];
    gWifiScanResultList.push_back(result);
  }

  if (gWifiScanResultList.size() == event->resultTotal) {
    gWifiScanEventCompleted = true;
  }

  chreWifiScanCacheReleaseScanEvent(event);
}

void beginDefaultWifiCache(const uint32_t *scannedFreqList,
                           uint16_t scannedFreqListLen,
                           bool scanRequestedByChre = true) {
  chreWifiScanEvent event;
  memset(&event, 0, sizeof(chreWifiScanEvent));
  event.version = CHRE_WIFI_SCAN_EVENT_VERSION;
  event.scanType = CHRE_WIFI_SCAN_TYPE_ACTIVE;
  event.scannedFreqList = scannedFreqList;
  event.scannedFreqListLen = scannedFreqListLen;
  event.radioChainPref = CHRE_WIFI_RADIO_CHAIN_PREF_DEFAULT;
  gExpectedWifiScanEvent = event;

  chreWifiScanCacheScanEventBegin(
      static_cast<enum chreWifiScanType>(gExpectedWifiScanEvent->scanType),
      gExpectedWifiScanEvent->ssidSetSize,
      gExpectedWifiScanEvent->scannedFreqList,
      gExpectedWifiScanEvent->scannedFreqListLen,
      gExpectedWifiScanEvent->radioChainPref, scanRequestedByChre);
}

void resultSpecifiedWifiCacheTest(size_t numEvents, InputVec &inputResults,
                                  ResultVec &expectedResults,
                                  const uint32_t *scannedFreqList,
                                  uint16_t scannedFreqListLen,
                                  bool scanRequestedByChre = true,
                                  bool scanMonitoringEnabled = false) {
  gWifiScanEventCompleted = false;
  beginDefaultWifiCache(scannedFreqList, scannedFreqListLen,
                        scanRequestedByChre);

  for (size_t i = 0; i < numEvents; i++) {
    chreWifiScanCacheScanEventAdd(&inputResults[i]);
  }

  chreWifiScanCacheScanEventEnd(CHRE_ERROR_NONE);

  if (scanRequestedByChre) {
    EXPECT_TRUE(gWifiScanResponse.has_value());
    EXPECT_EQ(gWifiScanResponse->pending, true);
    ASSERT_EQ(gWifiScanResponse->errorCode, CHRE_ERROR_NONE);
  } else {
    EXPECT_FALSE(gWifiScanResponse.has_value());
  }

  size_t numEventsExpected = 0;
  if (scanRequestedByChre || scanMonitoringEnabled) {
    numEventsExpected = std::min(
        numEvents, static_cast<size_t>(CHRE_PAL_WIFI_SCAN_CACHE_CAPACITY));
    ASSERT_TRUE(gWifiScanEventCompleted);
  }

  ASSERT_EQ(gWifiScanResultList.size(), numEventsExpected);
  for (size_t i = 0; i < gWifiScanResultList.size(); i++) {
    // ageMs is not known apriori
    expectedResults[i].ageMs = gWifiScanResultList[i].ageMs;
    EXPECT_EQ(memcmp(&gWifiScanResultList[i], &expectedResults[i],
                     sizeof(chreWifiScanResult)),
              0);
  }
}

void cacheDefaultWifiCacheTest(size_t numEvents,
                               const uint32_t *scannedFreqList,
                               uint16_t scannedFreqListLen,
                               bool scanRequestedByChre = true,
                               bool scanMonitoringEnabled = false) {
  InputVec inputResults;
  ResultVec expectedResults;

  // Generate a default set of input and expected results if not specified
  chreWifiScanResult result = {};
  for (uint64_t i = 0; i < numEvents; i++) {
    result.rssi = static_cast<int8_t>(i);
    memcpy(result.bssid, &i, sizeof(result.bssid));
    inputResults.push_back(result);

    if (!expectedResults.full()) {
      expectedResults.push_back(result);
    } else {
      int8_t minRssi = result.rssi;
      int minIdx = -1;
      for (uint64_t idx = 0; idx < expectedResults.size(); idx++) {
        if (expectedResults[idx].rssi < minRssi) {
          minRssi = expectedResults[idx].rssi;
          minIdx = idx;
        }
      }
      if (minIdx != -1) {
        expectedResults[minIdx] = result;
      }
    }
  }

  resultSpecifiedWifiCacheTest(numEvents, inputResults, expectedResults,
                               scannedFreqList, scannedFreqListLen,
                               scanRequestedByChre, scanMonitoringEnabled);
}

void testCacheDispatch(size_t numEvents, uint32_t maxScanAgeMs,
                       bool expectSuccess) {
  cacheDefaultWifiCacheTest(numEvents, nullptr /* scannedFreqList */,
                            0 /* scannedFreqListLen */);

  gExpectedWifiScanEvent->eventIndex = 0;
  gWifiScanResponse.reset();
  while (!gWifiScanResultList.empty()) {
    gWifiScanResultList.pop_back();
  }

  struct chreWifiScanParams params = {
      .scanType = CHRE_WIFI_SCAN_TYPE_NO_PREFERENCE,
      .maxScanAgeMs = maxScanAgeMs,
      .frequencyListLen = 0,
      .frequencyList = nullptr,
      .ssidListLen = 0,
      .ssidList = nullptr,
      .radioChainPref = CHRE_WIFI_RADIO_CHAIN_PREF_DEFAULT,
      .channelSet = CHRE_WIFI_CHANNEL_SET_NON_DFS,
  };
  EXPECT_EQ(chreWifiScanCacheDispatchFromCache(&params), expectSuccess);

  EXPECT_EQ(gWifiScanResponse.has_value(), expectSuccess);
  if (expectSuccess) {
    EXPECT_TRUE(gWifiScanResponse->pending);
    EXPECT_EQ(gWifiScanResponse->errorCode, CHRE_ERROR_NONE);
  }

  EXPECT_EQ(gWifiScanResultList.size(), expectSuccess ? numEvents : 0);
}

}  // anonymous namespace

/************************************************
 *  Tests
 ***********************************************/
TEST_F(WifiScanCacheTests, SingleWifiResultTest) {
  cacheDefaultWifiCacheTest(1 /* numEvents */, nullptr /* scannedFreqList */,
                            0 /* scannedFreqListLen */);
}

TEST_F(WifiScanCacheTests, MultiWifiResultTest) {
  cacheDefaultWifiCacheTest(
      CHRE_PAL_WIFI_SCAN_CACHE_MAX_RESULT_COUNT + 1 /* numEvents */,
      nullptr /* scannedFreqList */, 0 /* scannedFreqListLen */);
}

TEST_F(WifiScanCacheTests, WifiResultOverflowTest) {
  cacheDefaultWifiCacheTest(
      CHRE_PAL_WIFI_SCAN_CACHE_CAPACITY + 42 /* numEvents */,
      nullptr /* scannedFreqList */, 0 /* scannedFreqListLen */);
}

TEST_F(WifiScanCacheTests, WeakestRssiNotAddedToFullCacheTest) {
  size_t numEvents = CHRE_PAL_WIFI_SCAN_CACHE_CAPACITY + 1;
  InputVec inputResults;
  ResultVec expectedResults;

  chreWifiScanResult result = {};
  result.rssi = -20;
  uint64_t i;
  for (i = 0; i < CHRE_PAL_WIFI_SCAN_CACHE_CAPACITY; i++) {
    memcpy(result.bssid, &i, sizeof(result.bssid));
    inputResults.push_back(result);
    expectedResults.push_back(result);
  }

  result.rssi = -21;
  memcpy(result.bssid, &i, sizeof(result.bssid));
  inputResults.push_back(result);

  resultSpecifiedWifiCacheTest(numEvents, inputResults, expectedResults,
                               nullptr /* scannedFreqList */,
                               0 /* scannedFreqListLen */);
}

TEST_F(WifiScanCacheTests, WeakestRssiReplacedAtEndOfFullCacheTest) {
  size_t numEvents = CHRE_PAL_WIFI_SCAN_CACHE_CAPACITY + 1;
  InputVec inputResults;
  ResultVec expectedResults;

  chreWifiScanResult result = {};
  result.rssi = -20;
  uint64_t i;
  for (i = 0; i < CHRE_PAL_WIFI_SCAN_CACHE_CAPACITY - 1; i++) {
    memcpy(result.bssid, &i, sizeof(result.bssid));
    inputResults.push_back(result);
    expectedResults.push_back(result);
  }

  result.rssi = -21;
  memcpy(result.bssid, &i, sizeof(result.bssid));
  i++;
  inputResults.push_back(result);

  result.rssi = -19;
  memcpy(result.bssid, &i, sizeof(result.bssid));
  i++;
  inputResults.push_back(result);
  expectedResults.push_back(result);

  resultSpecifiedWifiCacheTest(numEvents, inputResults, expectedResults,
                               nullptr /* scannedFreqList */,
                               0 /* scannedFreqListLen */);
}

TEST_F(WifiScanCacheTests, EmptyWifiResultTest) {
  cacheDefaultWifiCacheTest(0 /* numEvents */, nullptr /* scannedFreqList */,
                            0 /* scannedFreqListLen */);
}

TEST_F(WifiScanCacheTests, FailedWifiCacheTest) {
  beginDefaultWifiCache(nullptr /* scannedFreqList */,
                        0 /* scannedFreqListLen */);

  chreWifiScanCacheScanEventEnd(CHRE_ERROR);

  EXPECT_TRUE(gWifiScanResponse.has_value());
  EXPECT_FALSE(gWifiScanResponse->pending);
  EXPECT_EQ(gWifiScanResponse->errorCode, CHRE_ERROR);

  EXPECT_EQ(gWifiScanResultList.size(), 0);
}

TEST_F(WifiScanCacheTests, FrequencyListTest) {
  const uint32_t freqList[2] = {5210, 5240};
  cacheDefaultWifiCacheTest(1 /* numEvents */, freqList, ARRAY_SIZE(freqList));
}

TEST_F(WifiScanCacheTests, InvalidFrequencyListTest) {
  beginDefaultWifiCache(nullptr /* scannedFreqList */,
                        1 /* scannedFreqListLen */);

  EXPECT_TRUE(gWifiScanResponse.has_value());
  EXPECT_FALSE(gWifiScanResponse->pending);
  EXPECT_EQ(gWifiScanResponse->errorCode, CHRE_ERROR_INVALID_ARGUMENT);

  EXPECT_EQ(gWifiScanResultList.size(), 0);
}

TEST_F(WifiScanCacheTests, SequentialWifiResultTest) {
  cacheDefaultWifiCacheTest(1 /* numEvents */, nullptr /* scannedFreqList */,
                            0 /* scannedFreqListLen */);

  clearTestState();
  cacheDefaultWifiCacheTest(1 /* numEvents */, nullptr /* scannedFreqList */,
                            0 /* scannedFreqListLen */);
}

TEST_F(WifiScanCacheTests, ScanMonitorDisabledTest) {
  cacheDefaultWifiCacheTest(1 /* numEvents */, nullptr /* scannedFreqList */,
                            0 /* scannedFreqListLen */,
                            false /* scanRequestedByChre */,
                            false /* scanMonitoringEnabled */);
}

TEST_F(WifiScanCacheTests, ScanMonitorEnabledTest) {
  chreWifiScanCacheConfigureScanMonitor(true /* enable */);
  cacheDefaultWifiCacheTest(1 /* numEvents */, nullptr /* scannedFreqList */,
                            0 /* scannedFreqListLen */,
                            false /* scanRequestedByChre */,
                            true /* scanMonitoringEnabled */);
}

TEST_F(WifiScanCacheTests, ScanMonitorEnableDisableTest) {
  chreWifiScanCacheConfigureScanMonitor(true /* enable */);
  cacheDefaultWifiCacheTest(1 /* numEvents */, nullptr /* scannedFreqList */,
                            0 /* scannedFreqListLen */,
                            false /* scanRequestedByChre */,
                            true /* scanMonitoringEnabled */);

  clearTestState();
  chreWifiScanCacheConfigureScanMonitor(false /* enable */);
  cacheDefaultWifiCacheTest(1 /* numEvents */, nullptr /* scannedFreqList */,
                            0 /* scannedFreqListLen */,
                            false /* scanRequestedByChre */,
                            false /* scanMonitoringEnabled */);
}

TEST_F(WifiScanCacheTests, CacheDispatchTest) {
  testCacheDispatch(1 /* numEvents */, 5000 /* maxScanAgeMs */,
                    true /* expectSuccess */);
}

TEST_F(WifiScanCacheTests, ZeroMaxScanAgeCacheDispatchTest) {
  testCacheDispatch(1 /* numEvents */, 0 /* maxScanAgeMs */,
                    false /* expectSuccess */);
}

TEST_F(WifiScanCacheTests, DuplicateScanResultTest) {
  beginDefaultWifiCache(nullptr /* scannedFreqList */,
                        0 /* scannedFreqListLen */,
                        true /* scanRequestedByChre */);

  chreWifiScanResult result = {};
  result.rssi = -98;
  result.primaryChannel = 5270;
  std::string sampleSsid = "Test ssid";
  memcpy(result.ssid, sampleSsid.c_str(), sampleSsid.length());
  result.ssidLen = sampleSsid.length();
  std::string sampleBssid = "12:34:56:78:9a:bc";
  memcpy(result.bssid, sampleBssid.c_str(), sampleBssid.length());
  chreWifiScanResult result2 = {};
  result2.rssi = -98;
  result2.primaryChannel = 5270;
  std::string sampleSsid2 = "Test ssid 2";
  memcpy(result2.ssid, sampleSsid2.c_str(), sampleSsid2.length());
  result2.ssidLen = sampleSsid2.length();
  std::string sampleBssid2 = "34:56:78:9a:bc:de";
  memcpy(result2.bssid, sampleBssid2.c_str(), sampleBssid2.length());

  chreWifiScanCacheScanEventAdd(&result);
  chreWifiScanCacheScanEventAdd(&result2);
  chreWifiScanCacheScanEventAdd(&result);

  chreWifiScanCacheScanEventEnd(CHRE_ERROR_NONE);

  EXPECT_TRUE(gWifiScanResponse.has_value());
  EXPECT_EQ(gWifiScanResponse->pending, true);
  ASSERT_EQ(gWifiScanResponse->errorCode, CHRE_ERROR_NONE);

  ASSERT_EQ(gWifiScanResultList.size(), 2);
  result.ageMs = gWifiScanResultList[0].ageMs;
  EXPECT_EQ(
      memcmp(&gWifiScanResultList[0], &result, sizeof(chreWifiScanResult)), 0);
  result2.ageMs = gWifiScanResultList[1].ageMs;
  EXPECT_EQ(
      memcmp(&gWifiScanResultList[1], &result2, sizeof(chreWifiScanResult)), 0);
}

TEST_F(WifiScanCacheTests, IncomingRequestDuringCachePopulationTest) {
  beginDefaultWifiCache(nullptr /* scannedFreqList */,
                        0 /* scannedFreqListLen */,
                        false /* scanRequestedByChre */);

  chreWifiScanResult result = {};
  chreWifiScanCacheScanEventAdd(&result);

  // An incoming request should upgrade the cache to a CHRE requested scan
  // event.
  chreWifiScanParams params = {
      .scanType = CHRE_WIFI_SCAN_TYPE_ACTIVE,
      .maxScanAgeMs = 5000,
      .frequencyListLen = 0,
      .frequencyList = nullptr,
      .ssidListLen = 0,
      .ssidList = nullptr,
      .radioChainPref = CHRE_WIFI_RADIO_CHAIN_PREF_DEFAULT,
      .channelSet = CHRE_WIFI_CHANNEL_SET_NON_DFS,
  };
  EXPECT_TRUE(chreWifiScanCacheDispatchFromCache(&params));

  // We shouldn't get the scan response until cache population is complete.
  EXPECT_FALSE(gWifiScanResponse.has_value());

  result.bssid[0] = 1;
  chreWifiScanCacheScanEventAdd(&result);
  chreWifiScanCacheScanEventEnd(CHRE_ERROR_NONE);

  // CHRE should get the full cache result.
  EXPECT_TRUE(gWifiScanResponse.has_value());
  EXPECT_EQ(gWifiScanResponse->pending, true);
  EXPECT_EQ(gWifiScanResponse->errorCode, CHRE_ERROR_NONE);
  EXPECT_EQ(gWifiScanResultList.size(), 2);
}

TEST_F(WifiScanCacheTests, AgeCalculatedCorrectly) {
  constexpr auto kStartTime = Seconds(4);
  overrideMonotonicTime(kStartTime);
  beginDefaultWifiCache(nullptr /* scannedFreqList */,
                        0 /* scannedFreqListLen */);

  overrideMonotonicTime(kStartTime + Milliseconds(100));
  chreWifiScanResult result = {};
  chreWifiScanCacheScanEventAdd(&result);

  overrideMonotonicTime(kStartTime + Milliseconds(500));
  chreWifiScanCacheScanEventEnd(CHRE_ERROR_NONE);

  ASSERT_EQ(gWifiScanResultList.size(), 1);
  EXPECT_EQ(gWifiScanResultList[0].ageMs, 500 - 100);
}

TEST_F(WifiScanCacheTests, AgeLongUptime) {
  constexpr auto kStartTime = Seconds(60 * 60 * 24 * 50);  // 50 days
  overrideMonotonicTime(kStartTime);
  beginDefaultWifiCache(nullptr /* scannedFreqList */,
                        0 /* scannedFreqListLen */);

  overrideMonotonicTime(kStartTime + Milliseconds(500));
  chreWifiScanResult result = {};
  chreWifiScanCacheScanEventAdd(&result);

  overrideMonotonicTime(kStartTime + Milliseconds(4000));
  chreWifiScanCacheScanEventEnd(CHRE_ERROR_NONE);

  ASSERT_EQ(gWifiScanResultList.size(), 1);
  EXPECT_EQ(gWifiScanResultList[0].ageMs, 4000 - 500);
}

TEST_F(WifiScanCacheTests, AgeAvoidsUnderflow) {
  constexpr auto kStartTime = Seconds(30);
  constexpr auto kEndTime = kStartTime + Seconds(5);
  overrideMonotonicTime(kStartTime);
  beginDefaultWifiCache(nullptr /* scannedFreqList */,
                        0 /* scannedFreqListLen */);

  overrideMonotonicTime(Nanoseconds(0));
  chreWifiScanResult result = {};
  chreWifiScanCacheScanEventAdd(&result);

  overrideMonotonicTime(kEndTime);
  chreWifiScanCacheScanEventEnd(CHRE_ERROR_NONE);

  ASSERT_EQ(gWifiScanResultList.size(), 1);
  EXPECT_LT(gWifiScanResultList[0].ageMs,
            Milliseconds(kEndTime - kStartTime).getMilliseconds());
}