#include "stm32l0xx_hal.h"

static unsigned int MAX_TICKS = 3000;

/* Private variables */
GPIO_InitTypeDef GPIO_InitStruct = {0};

/* Function prototypes */
void SystemClock_Config(void);
static void MX_GPIO_Init(void);

int main(void) {
  HAL_Init();           // Initialize HAL library
  SystemClock_Config(); // Configure system clock
  MX_GPIO_Init();       // Initialize GPIO

  // Add timer tracking variables
  uint32_t pressStartTime = 0;
  GPIO_PinState previousButtonState = GPIO_PIN_SET; // Initialize as "not pressed"

  while (1) {
    // Read current button state
    GPIO_PinState currentButtonState = HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_5);

    if (currentButtonState == GPIO_PIN_RESET) { // Button is pressed
      // Detect rising edge (transition from not pressed to pressed)
      if (previousButtonState == GPIO_PIN_SET) {
        pressStartTime = HAL_GetTick(); // Record press start time
      }

      // Keep LED on only for first 3 seconds of press
      if ((HAL_GetTick() - pressStartTime) < MAX_TICKS) {
        HAL_GPIO_WritePin(GPIOB, GPIO_PIN_4, GPIO_PIN_SET);
      } else {
        HAL_GPIO_WritePin(GPIOB, GPIO_PIN_4, GPIO_PIN_RESET);
      }
    } else { // Button is released
      HAL_GPIO_WritePin(GPIOB, GPIO_PIN_4, GPIO_PIN_RESET);
    }

    // Update previous button state
    previousButtonState = currentButtonState;
  }
}

static void MX_GPIO_Init(void) {
  __HAL_RCC_GPIOB_CLK_ENABLE();  // Enable GPIOB clock

  // Configure LED pin (PB4) as output
  GPIO_InitStruct.Pin = GPIO_PIN_4;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;  // Push-pull output
  GPIO_InitStruct.Pull = GPIO_NOPULL;          // No pull-up/pull-down
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW; // Low speed
  HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

  // Configure button pin (PB5) as input with pull-up resistor
  GPIO_InitStruct.Pin = GPIO_PIN_5;
  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;      // Input mode
  GPIO_InitStruct.Pull = GPIO_PULLUP;          // Internal pull-up resistor
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW; // Low speed
  HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

  // Initialize LED to be off
  HAL_GPIO_WritePin(GPIOB, GPIO_PIN_4, GPIO_PIN_RESET);
}