/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2024 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/

#include "main.h"  // Includes the HAL (Hardware Abstraction Layer) library definitions for STM32.

uint8_t button;  // Variable to hold the button state (pressed or not).

// Function prototypes
void SystemClock_Config(void);       // Configures the system clock to set up the microcontroller's clock frequency.
static void MX_GPIO_Init(void);      // Configures the GPIO peripherals (pins for the button and LEDs).

int main(void) {
  button = 0;  // Initialize the button variable to 0 (indicating not pressed).

  HAL_Init();  // Initializes the HAL Library. This sets up the MCU, including the SysTick timer for delays.
  SystemClock_Config();  // Configures the clock system for proper timing.
  MX_GPIO_Init();  // Initializes GPIO pins for input (button) and output (LEDs).

  while (1) {  // Infinite loop: Keeps the microcontroller running continuously.
    // Read the state of the button connected to GPIO pin PC7.
    button = HAL_GPIO_ReadPin(GPIOC, GPIO_PIN_7);  

    if (button == 0) {  // If the button is pressed (logic 0 due to pull-down configuration):
      HAL_GPIO_WritePin(GPIOA, GPIO_PIN_1, GPIO_PIN_SET);   // Turn ON LED2 (PA1).
      HAL_GPIO_WritePin(GPIOA, GPIO_PIN_0, GPIO_PIN_RESET); // Turn OFF LED1 (PA0).
    } else {  // If the button is not pressed (logic HIGH):
      HAL_GPIO_WritePin(GPIOA, GPIO_PIN_1, GPIO_PIN_RESET); // Turn OFF LED2 (PA1).

      // Implement the SOS Morse code pattern on LED1 (PA0).
      // SOS pattern consists of three short flashes, three long flashes, and three short flashes.

      // Three short flashes
      for (int i = 0; i < 3; i++) {
        HAL_GPIO_WritePin(GPIOA, GPIO_PIN_0, GPIO_PIN_SET);  // Turn ON LED1.
        HAL_Delay(200);  // Short ON delay (200ms).
        HAL_GPIO_WritePin(GPIOA, GPIO_PIN_0, GPIO_PIN_RESET); // Turn OFF LED1.
        HAL_Delay(200);  // Short OFF delay (200ms).
      }

      // Three long flashes
      for (int i = 0; i < 3; i++) {
        HAL_GPIO_WritePin(GPIOA, GPIO_PIN_0, GPIO_PIN_SET);  // Turn ON LED1.
        HAL_Delay(600);  // Long ON delay (600ms).
        HAL_GPIO_WritePin(GPIOA, GPIO_PIN_0, GPIO_PIN_RESET); // Turn OFF LED1.
        HAL_Delay(200);  // Short OFF delay (200ms).
      }

      // Three short flashes
      for (int i = 0; i < 3; i++) {
        HAL_GPIO_WritePin(GPIOA, GPIO_PIN_0, GPIO_PIN_SET);  // Turn ON LED1.
        HAL_Delay(200);  // Short ON delay (200ms).
        HAL_GPIO_WritePin(GPIOA, GPIO_PIN_0, GPIO_PIN_RESET); // Turn OFF LED1.
        HAL_Delay(200);  // Short OFF delay (200ms).
      }

      HAL_Delay(1000);  // Pause for 1 second before repeating the SOS sequence.
    }
  }
}

void SystemClock_Config(void) {
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};  // Configures the internal high-speed oscillator (HSI).
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};  // Sets up the clock source and dividers.

  // Enable the High-Speed Internal Oscillator (HSI) and configure it as the clock source.
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;  // Enable HSI.
  RCC_OscInitStruct.HSIDiv = RCC_HSI_DIV1;  // No clock division.
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;

  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) {
    while (1);  // Error handling: Stay in an infinite loop if configuration fails.
  }

  // Configure the clock source and dividers for the system clock, AHB, and APB buses.
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_PCLK1;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;  // Use HSI as the system clock source.
  RCC_ClkInitStruct.SYSCLKDivider = RCC_SYSCLK_DIV1;      // No division for system clock.
  RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV1;        // No division for AHB clock.
  RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV1;       // No division for APB1 clock.

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK) {
    while (1);  // Error handling: Stay in an infinite loop if configuration fails.
  }
}

static void MX_GPIO_Init(void) {
  GPIO_InitTypeDef GPIO_InitStruct = {0};  // Structure to configure GPIO pins.

  // Enable GPIOC and GPIOA clocks.
  __HAL_RCC_GPIOC_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();

  // Reset output pins PA0 and PA1 (LEDs OFF initially).
  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_0 | GPIO_PIN_1, GPIO_PIN_RESET);

  // Configure GPIO pins PA0 and PA1 as output pins for LEDs.
  GPIO_InitStruct.Pin = GPIO_PIN_0 | GPIO_PIN_1;  // Select pins PA0 and PA1.
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;     // Configure as push-pull output.
  GPIO_InitStruct.Pull = GPIO_NOPULL;            // No pull-up or pull-down resistors.
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;   // Low speed to minimize power consumption.
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);        // Apply configuration to GPIOA.

  // Configure GPIO pin PC7 as input pin for the button.
  GPIO_InitStruct.Pin = GPIO_PIN_7;              // Select pin PC7.
  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;        // Configure as input.
  GPIO_InitStruct.Pull = GPIO_PULLDOWN;          // Enable pull-down resistor for stable LOW state.
  HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);        // Apply configuration to GPIOC.
}