#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <stm32c0xx_hal.h>

UART_HandleTypeDef huart2;

void SystemClock_Config(void);
static void MX_USART2_UART_Init(void);
static void MX_GPIO_Init(void);

int main(void) {
  HAL_Init();
  SystemClock_Config();

  MX_GPIO_Init();
  MX_USART2_UART_Init();

  printf("Switch RGD Led: [RED/GREEN/BLUE].\n");
  char received[6];
  while (1) {
    if (HAL_UART_Receive(&huart2, (uint8_t *)received, 5, HAL_MAX_DELAY) == HAL_OK) {
      if (strncmp(received, "RED", 3) == 0) {
        HAL_GPIO_WritePin(GPIOB, GPIO_PIN_4, GPIO_PIN_RESET); // RED pin
        HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, GPIO_PIN_SET); // BLUE pin
        HAL_GPIO_WritePin(GPIOB, GPIO_PIN_3, GPIO_PIN_SET); // GREEN pin
        printf("Set RED\n");
      }
      if (strncmp(received, "BLUE", 4) == 0) {
        HAL_GPIO_WritePin(GPIOB, GPIO_PIN_4, GPIO_PIN_SET); // RED pin
        HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, GPIO_PIN_RESET); // BLUE pin
        HAL_GPIO_WritePin(GPIOB, GPIO_PIN_3, GPIO_PIN_SET); // GREEN pin
        printf("Set BLUE\n");
      }
      if (strncmp(received, "GREEN", 5) == 0) {
        HAL_GPIO_WritePin(GPIOB, GPIO_PIN_4, GPIO_PIN_SET); // RED pin
        HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, GPIO_PIN_SET); // BLUE pin
        HAL_GPIO_WritePin(GPIOB, GPIO_PIN_3, GPIO_PIN_RESET); // GREEN pin
        printf("Set GREEN\n");
      }
    }
  }
  return 0;
}

/**
    @brief System Clock Configuration
    @retval None
*/
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  /** Initializes the RCC Oscillators according to the specified parameters
    in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSIDiv = RCC_HSI_DIV1;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;

  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
    Error_Handler();
  }

  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK|RCC_CLOCKTYPE_PCLK1;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
  RCC_ClkInitStruct.SYSCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK) {
    Error_Handler();
  }
}

/**
    @brief USART2 Initialization Function
    @param None
    @retval None
*/
static void MX_USART2_UART_Init(void) { 
  huart2.Instance = USART2;
  huart2.Init.BaudRate = 115200;
  huart2.Init.WordLength = UART_WORDLENGTH_8B;
  huart2.Init.StopBits = UART_STOPBITS_1;
  huart2.Init.Parity = UART_PARITY_NONE;
  huart2.Init.Mode = UART_MODE_TX_RX;
  huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart2.Init.OverSampling = UART_OVERSAMPLING_16;
  huart2.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart2.Init.ClockPrescaler = UART_PRESCALER_DIV1;
  huart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;

  if (HAL_UART_Init(&huart2) != HAL_OK) {
    Error_Handler();
  }
}

static void MX_GPIO_Init(void) {
  GPIO_InitTypeDef GPIO_InitStruct = {0};

  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_GPIOB_CLK_ENABLE();

  /*Configure GPIO pin : PA3 */
  GPIO_InitStruct.Pin = GPIO_PIN_3;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

  /*Configure GPIO pins : PB3 PB4 */
  GPIO_InitStruct.Pin = GPIO_PIN_1|GPIO_PIN_3|GPIO_PIN_4;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

  // PA2     ------> USART2_TX
  // PA5     ------> USART2_RX
  GPIO_InitStruct.Pin = GPIO_PIN_2|GPIO_PIN_5;
  GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  GPIO_InitStruct.Alternate = GPIO_AF1_USART2;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
}

void Error_Handler(void) {
  /* User can add his own implementation to report the HAL error return state */
}

// The following makes printf() write to USART2:

#define STDOUT_FILENO   1
#define STDERR_FILENO   2

int _write(int file, uint8_t *ptr, int len) {
  switch (file) {
    case STDOUT_FILENO: HAL_UART_Transmit(&huart2, ptr, len, HAL_MAX_DELAY); break;
    case STDERR_FILENO: HAL_UART_Transmit(&huart2, ptr, len, HAL_MAX_DELAY); break;
    default: return -1;
  }

  return len;
}