#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <stm32l0xx_hal.h>

#define LED_PORT                GPIOB
#define LED_PIN                 GPIO_PIN_3
#define LED_PORT_CLK_ENABLE     __HAL_RCC_GPIOB_CLK_ENABLE

#define VCP_TX_Pin              GPIO_PIN_2
#define VCP_RX_Pin              GPIO_PIN_15

#define STDOUT_FILENO 1
#define STDERR_FILENO 2

UART_HandleTypeDef huart2;

void SystemClock_Config(void);
static void MX_USART2_UART_Init(void);
void initGPIO(void);
void My_Error_Handler(void);
int _write(int file, uint8_t *ptr, int len);

void osSystickHandler(void)
{
    if ((HAL_GetTick() % 500) == 0)
    {
        HAL_GPIO_TogglePin(LED_PORT, LED_PIN);
    }
}

void initGPIO(void)
{
    GPIO_InitTypeDef GPIO_Config;
    LED_PORT_CLK_ENABLE();
    GPIO_Config.Pin = LED_PIN;
    GPIO_Config.Mode = GPIO_MODE_OUTPUT_PP;
    GPIO_Config.Pull = GPIO_NOPULL;
    GPIO_Config.Speed = GPIO_SPEED_FREQ_HIGH;
    HAL_GPIO_Init(LED_PORT, &GPIO_Config);
}

int main(void)
{
    HAL_Init();
    SystemClock_Config();
    initGPIO();
    MX_USART2_UART_Init();

    printf("Hello, %s!\n", "Wokwi");

    HAL_GPIO_TogglePin(LED_PORT, LED_PIN);

    while (1);

    return 0;
}

void SystemClock_Config(void)
{
    RCC_OscInitTypeDef RCC_OscInitStruct = {0};
    RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
    RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};

    __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
    RCC_OscInitStruct.HSIState = RCC_HSI_ON;
    RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
    RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
    RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
    RCC_OscInitStruct.PLL.PLLMUL = RCC_PLLMUL_4;
    RCC_OscInitStruct.PLL.PLLDIV = RCC_PLLDIV_2;
    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
    {
        My_Error_Handler();
    }

    RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_SYSCLK
                                  | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2;
    RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
    RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
    RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
    RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

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

    PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART2;
    PeriphClkInit.Usart2ClockSelection = RCC_USART2CLKSOURCE_PCLK1;
    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
    {
        My_Error_Handler();
    }
}

static void MX_USART2_UART_Init(void)
{
    __HAL_RCC_GPIOA_CLK_ENABLE();

    GPIO_InitTypeDef GPIO_InitStruct = {0};
    GPIO_InitStruct.Pin = VCP_TX_Pin | VCP_RX_Pin;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF4_USART2;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

    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.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
    if (HAL_UART_Init(&huart2) != HAL_OK)
    {
        My_Error_Handler();
    }

    __HAL_RCC_USART2_CLK_ENABLE();
}

void My_Error_Handler(void)
{
    while (1)
    {
        HAL_GPIO_TogglePin(LED_PORT, LED_PIN);
        HAL_Delay(500); 
    }
}


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

        default:
            return -1;
    }
    return len;
}