volatile uint32_t inventory = 100;
volatile uint32_t retailCount = 0;
volatile uint32_t onlineCount = 0;

SemaphoreHandle_t xMutexInventory = NULL;
TickType_t timeOut = 1000;

void retailTask(void *pvParam)
{
  while (true)
  {
    if (xSemaphoreTake(xMutexInventory, timeOut) == pdPASS)
    {
      uint32_t inv = inventory;
      for (int i = 0; i < random(1, 10); i++)
        vTaskDelay(pdMS_TO_TICKS(i));

      if (inventory > 0)
      {
        inventory = inv - 1;
        retailCount++;

        xSemaphoreGive(xMutexInventory);
      }
      else
      {
        xSemaphoreGive(xMutexInventory);
        vTaskDelete(NULL);
      }
    }
    vTaskDelay(10);
  }
}

void onlineTask(void *pvParam)
{
  while (true)
  {
    if (xSemaphoreTake(xMutexInventory, timeOut) == pdPASS)
    {
      // 以下实现了带有随机延迟的 inventory减1；
      // 等效为 inventory--； retailCount++；
      uint32_t inv = inventory;
      for (int i; i < random(1, 10); i++)
        vTaskDelay(pdMS_TO_TICKS(i));

      if (inventory > 0)
      {
        inventory = inv - 1;
        onlineCount++;

        xSemaphoreGive(xMutexInventory);
      }
      else
      {
        xSemaphoreGive(xMutexInventory);
        vTaskDelete(NULL);
      }
    }
    vTaskDelay(10); // 老板要求慢一些，客户升级后，可以再加快速度
  }
}

void showTask(void *pvParam)
{
  while (true)
  {
    printf("Inventory: %d\n", inventory);
    printf("  Retail : %d, Online : %d\n", retailCount, onlineCount);

    if (inventory == 0)
    {
      uint32_t totalSales = retailCount + onlineCount;
      printf("\n-----SALES SUMMARY-----\n");
      printf("  Total Sales:  %d\n\n", totalSales);
      printf("  OverSales:  %d\n", 100 - totalSales);
      
      vTaskDelete(NULL);
    }

    vTaskDelay(pdMS_TO_TICKS(100));
  }
}

void setup()
{
  // put your setup code here, to run once:
  Serial.begin(115200);

  xMutexInventory = xSemaphoreCreateMutex();
  if (NULL == xMutexInventory)
  {
    printf("No Enough Ram, Unable to Create Semaphore.");
  }
  else
  {
    xTaskCreate(retailTask, "retailTask Channel", 1024 * 4, NULL, 1, NULL);
    xTaskCreate(onlineTask, "Online Channel", 1024 * 4, NULL, 1, NULL);
    xTaskCreate(showTask, "Display Inventory", 1024 * 4, NULL, 1, NULL);
  }
}

void loop()
{
  // put your main code here, to run repeatedly:
}