#include <array>
#include <cstdint>
#include <stdio.h>
#include <algorithm>

#include "app_networking.hpp"
#include "app_serial.hpp"
#include "app_config.hpp"

#include "freertos/FreeRTOS.h"
#include "freertos/queue.h"
#include "freertos/timers.h"
#include "nvs_flash.h"
#include "driver/uart.h"
#include "esp_log.h"

namespace
{

static const char* LOG_TAG = "App";

TaskHandle_t s_main_task = nullptr;

TimerHandle_t s_timer = nullptr;

QueueSetHandle_t s_queue_set = nullptr;
QueueHandle_t s_esp_now_queue = nullptr;
QueueHandle_t s_uart_queue = nullptr;

void s_sendUartData(std::size_t len)
{
  len = std::clamp<std::size_t>(len, 1, 128);
  ESP_LOGD(LOG_TAG, "Sending %u bytes via UART.", len);

  std::array<std::uint8_t, 128> tx_buffer;
  uart_read_bytes(CONFIG_ESPTNL_UART, tx_buffer.data(), len, 0);

  xTimerStop(s_timer, 0);
  Networking::sendData(tx_buffer, len);
}

std::size_t s_uartBytesWaiting()
{
  std::size_t len = 0;
  uart_get_buffered_data_len(CONFIG_ESPTNL_UART, &len);
  return std::min<std::size_t>(len, 128);
}

[[noreturn]] void s_mainTask(void*)
{
  while (true)
  {
    QueueSetMemberHandle_t queue_select = xQueueSelectFromSet(s_queue_set, portMAX_DELAY);

    ESP_LOGI(LOG_TAG, "Event: %s.", queue_select == s_esp_now_queue ? "ESP-NOW event" : "UART event");

    if (queue_select == s_esp_now_queue)
    {
      Networking::EspNowEvent event;
      xQueueReceive(s_esp_now_queue, &event, 0);

      ESP_LOGD(LOG_TAG, "ESP-NOW event: %u, rx-length: %ull.", event.type, event.rx_length);

      if (event.type == Networking::EspNowEvent::MSG_RECEIVED)
      {
        std::size_t uart_free = 0;
        uart_get_tx_buffer_free_size(CONFIG_ESPTNL_UART, &uart_free);
        if (uart_free >= event.rx_length)
        {
          ESP_LOGD(LOG_TAG, "ESP-NOW event: wrote %ull bytes to UART RX.", uart_free);
          const auto& esp_rx_buffer = Networking::getRxBuffer();
          uart_write_bytes(CONFIG_ESPTNL_UART, esp_rx_buffer.data(), event.rx_length);
        }
        else
        {
          ESP_LOGW(LOG_TAG, "ESP-NOW event: dropped RX data due to full UART RX buffer.");
        }
      }
      else if (event.type == Networking::EspNowEvent::MSG_SEND_COMPLETE)
      {
        ESP_LOGD(LOG_TAG, "ESP-NOW event: TX completed. Checking to send data.");

        const std::size_t bytes_waiting = s_uartBytesWaiting();
        if (s_uartBytesWaiting() >= 128)
        {
          s_sendUartData(bytes_waiting);
        }
      }
    }
    else if (queue_select == s_uart_queue)
    {
      uart_event_t event;
      xQueueReceive(s_uart_queue, &event, 0);

      ESP_LOGD(LOG_TAG, "UART event: %d, size: %u", event.type, event.size);

      if (event.type == UART_DATA)
      {
        const std::size_t recv_size = s_uartBytesWaiting();
        if (recv_size >= 128)
          s_sendUartData(recv_size);
        else
          xTimerReset(s_timer, 0);
      }
      else if (event.type == UART_BUFFER_FULL)
      {
        const std::size_t recv_size = s_uartBytesWaiting();
        s_sendUartData(recv_size);
      }
      else if (event.type == UART_FIFO_OVF)
      {
        ESP_LOGE(LOG_TAG, "UART FIFO overflow. Flushing.");
        Serial::discardRxBuffer(CONFIG_ESPTNL_UART);
      }
    }
    else
    {
      ESP_LOGW(LOG_TAG, "Unknown event type.");
    }
  }
}

void s_cbListenTimeout(TimerHandle_t)
{
  ESP_LOGD(LOG_TAG, "s_cbListenTimeout invoked from timer.");

  const std::size_t bytes_waiting = s_uartBytesWaiting();
  if (bytes_waiting > 0)
    s_sendUartData(bytes_waiting);
}

}// namespace

extern "C" void app_main(void)
{
  ESP_ERROR_CHECK(nvs_flash_init());

  esp_log_level_set("*", esp_log_level_t(CONFIG_LOG_DEFAULT_LEVEL));
  esp_log_level_set(LOG_TAG, Config::appLogLevel());
  esp_log_level_set(Networking::LOG_TAG, Config::appLogLevel());

  ESP_LOGD(LOG_TAG, "Starting main.");

  Networking::setupWifi();
  s_esp_now_queue = Networking::setupEspNow();
  s_uart_queue = Serial::setupSerial(CONFIG_ESPTNL_UART);

  s_timer = xTimerCreate("autosend_timer", pdMS_TO_TICKS(100), false, nullptr, s_cbListenTimeout);

  s_queue_set = xQueueCreateSet(4 + 4);
  xQueueAddToSet(s_esp_now_queue, s_queue_set);
  xQueueAddToSet(s_uart_queue, s_queue_set);

  ESP_LOGI(LOG_TAG, "Setup completed. Sending hello.");

  Networking::sendHello();

  xTaskCreate(s_mainTask, "main_task", 2048, nullptr, 4, &s_main_task);
}