#include "main.h"
#include <stdio.h>
#include <string.h>

/* =========================================================
   HANDLES
   ========================================================= */

ADC_HandleTypeDef hadc1;
TIM_HandleTypeDef htim2;
UART_HandleTypeDef huart1;


/* =========================================================
   FUNCTION PROTOTYPES
   ========================================================= */

void SystemClock_Config(void);

static void MX_GPIO_Init(void);
static void MX_ADC1_Init(void);
static void MX_TIM2_Init(void);
static void MX_USART1_UART_Init(void);

void Error_Handler(void);

int main(void)
{
    /* HAL initialization */
    HAL_Init();

    /* Configure system clock */
    SystemClock_Config();

    /* Initialize peripherals */
    MX_GPIO_Init();
    MX_ADC1_Init();
    MX_TIM2_Init();
    MX_USART1_UART_Init();


    /* =====================================================
       VARIABLES
       ===================================================== */

    char msg[100];

    uint32_t adc_value = 0;

    GPIO_PinState current_status;
    GPIO_PinState last_status = GPIO_PIN_RESET;


    /* =====================================================
       START PWM
       ===================================================== */

    HAL_TIM_PWM_Start(&htim2, TIM_CHANNEL_1);

    /*
     * Initial PWM duty cycle = 0
     */
    __HAL_TIM_SET_COMPARE(&htim2, TIM_CHANNEL_1, 0);


    /* =====================================================
       SEND START MESSAGE
       ===================================================== */

    sprintf(msg, "System Started\r\n");

    HAL_UART_Transmit(
        &huart1,
        (uint8_t *)msg,
        strlen(msg),
        100
    );


    /* =====================================================
       MAIN LOOP
       ===================================================== */

    while (1)
    {

        /* =================================================
           1. READ PIR SENSOR
           PA1
           ================================================= */

        current_status =
            HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_1);


        /* =================================================
           2. CHECK PIR STATUS CHANGE
           ================================================= */

        if (current_status != last_status)
        {

            if (current_status == GPIO_PIN_SET)
            {
                /*
                 * PIR HIGH
                 * Motion detected
                 */

                sprintf(
                    msg,
                    "ALERT: Motion Detected!\r\n"
                );
            }
            else
            {
                /*
                 * PIR LOW
                 * No motion
                 */

                sprintf(
                    msg,
                    "STATUS: Area Clear.\r\n"
                );
            }


            /* Send message through UART */

            HAL_UART_Transmit(
                &huart1,
                (uint8_t *)msg,
                strlen(msg),
                100
            );


            /* Update previous state */

            last_status = current_status;
        }


        /* =================================================
           3. READ ADC
           PA5 = ADC1_IN5
           ================================================= */

        HAL_ADC_Start(&hadc1);


        if (HAL_ADC_PollForConversion(
                &hadc1,
                100) == HAL_OK)
        {
            adc_value =
                HAL_ADC_GetValue(&hadc1);
        }


        HAL_ADC_Stop(&hadc1);


        /* =================================================
           4. ADC VALUE → PWM
           ================================================= */

        /*
         * ADC:
         *
         * 0       → 0
         * 4095    → 4095
         *
         * PWM:
         *
         * 0       → 0%
         * 4095    → 100%
         */

        __HAL_TIM_SET_COMPARE(
            &htim2,
            TIM_CHANNEL_1,
            adc_value
        );


        /* =================================================
           5. SMALL DELAY
           ================================================= */

        HAL_Delay(100);
    }
}


/* =========================================================
   SYSTEM CLOCK CONFIGURATION
   ========================================================= */

void SystemClock_Config(void)
{
    RCC_OscInitTypeDef RCC_OscInitStruct = {0};

    RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};


    /* HSE + PLL */

    RCC_OscInitStruct.OscillatorType =
        RCC_OSCILLATORTYPE_HSE;

    RCC_OscInitStruct.HSEState =
        RCC_HSE_ON;

    RCC_OscInitStruct.HSEPredivValue =
        RCC_HSE_PREDIV_DIV1;

    RCC_OscInitStruct.HSIState =
        RCC_HSI_ON;


    /* PLL */

    RCC_OscInitStruct.PLL.PLLState =
        RCC_PLL_ON;

    RCC_OscInitStruct.PLL.PLLSource =
        RCC_PLLSOURCE_HSE;

    RCC_OscInitStruct.PLL.PLLMUL =
        RCC_PLL_MUL9;


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


    /* Clock configuration */

    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_DIV2;

    RCC_ClkInitStruct.APB2CLKDivider =
        RCC_HCLK_DIV1;


    if (HAL_RCC_ClockConfig(
            &RCC_ClkInitStruct,
            FLASH_LATENCY_2) != HAL_OK)
    {
        Error_Handler();
    }
}


/* =========================================================
   ADC1 CONFIGURATION
   PA5 = ADC1_IN5
   ========================================================= */

static void MX_ADC1_Init(void)
{
    ADC_ChannelConfTypeDef sConfig = {0};


    /* ADC instance */

    hadc1.Instance = ADC1;


    /* ADC configuration */

    hadc1.Init.ScanConvMode =
        ADC_SCAN_DISABLE;

    hadc1.Init.ContinuousConvMode =
        DISABLE;

    hadc1.Init.DiscontinuousConvMode =
        DISABLE;

    hadc1.Init.ExternalTrigConv =
        ADC_SOFTWARE_START;

    hadc1.Init.DataAlign =
        ADC_DATAALIGN_RIGHT;

    hadc1.Init.NbrOfConversion =
        1;


    if (HAL_ADC_Init(&hadc1) != HAL_OK)
    {
        Error_Handler();
    }


    /* =====================================================
       PA5 = ADC CHANNEL 5
       ===================================================== */

    sConfig.Channel =
        ADC_CHANNEL_5;

    sConfig.Rank =
        ADC_REGULAR_RANK_1;

    sConfig.SamplingTime =
        ADC_SAMPLETIME_239CYCLES_5;


    if (HAL_ADC_ConfigChannel(
            &hadc1,
            &sConfig) != HAL_OK)
    {
        Error_Handler();
    }
}


/* =========================================================
   TIM2 PWM CONFIGURATION
   PA0 = TIM2_CH1
   ========================================================= */

static void MX_TIM2_Init(void)
{
    TIM_ClockConfigTypeDef sClockSourceConfig = {0};

    TIM_OC_InitTypeDef sConfigOC = {0};


    /* Timer instance */

    htim2.Instance = TIM2;


    /*
     * Timer clock = 72 MHz
     *
     * Prescaler = 17
     *
     * Timer frequency:
     *
     * 72 MHz / (17 + 1)
     *
     * = 4 MHz
     *
     * ARR = 4095
     *
     * PWM frequency:
     *
     * 4 MHz / 4096
     *
     * ≈ 976.56 Hz
     */


    htim2.Init.Prescaler = 17;

    htim2.Init.CounterMode =
        TIM_COUNTERMODE_UP;

    htim2.Init.Period = 4095;

    htim2.Init.ClockDivision =
        TIM_CLOCKDIVISION_DIV1;

    htim2.Init.AutoReloadPreload =
        TIM_AUTORELOAD_PRELOAD_DISABLE;


    if (HAL_TIM_Base_Init(&htim2) != HAL_OK)
    {
        Error_Handler();
    }


    /* Internal clock */

    sClockSourceConfig.ClockSource =
        TIM_CLOCKSOURCE_INTERNAL;


    if (HAL_TIM_ConfigClockSource(
            &htim2,
            &sClockSourceConfig) != HAL_OK)
    {
        Error_Handler();
    }


    /* PWM initialization */

    if (HAL_TIM_PWM_Init(&htim2) != HAL_OK)
    {
        Error_Handler();
    }


    /* =====================================================
       PWM CHANNEL 1
       ===================================================== */

    sConfigOC.OCMode =
        TIM_OCMODE_PWM1;

    sConfigOC.Pulse =
        0;

    sConfigOC.OCPolarity =
        TIM_OCPOLARITY_HIGH;

    sConfigOC.OCFastMode =
        TIM_OCFAST_DISABLE;


    if (HAL_TIM_PWM_ConfigChannel(
            &htim2,
            &sConfigOC,
            TIM_CHANNEL_1) != HAL_OK)
    {
        Error_Handler();
    }
}


/* =========================================================
   USART1 CONFIGURATION
   ========================================================= */

static void MX_USART1_UART_Init(void)
{
    huart1.Instance = USART1;


    huart1.Init.BaudRate =
        9600;

    huart1.Init.WordLength =
        UART_WORDLENGTH_8B;

    huart1.Init.StopBits =
        UART_STOPBITS_1;

    huart1.Init.Parity =
        UART_PARITY_NONE;

    huart1.Init.Mode =
        UART_MODE_TX_RX;

    huart1.Init.HwFlowCtl =
        UART_HWCONTROL_NONE;

    huart1.Init.OverSampling =
        UART_OVERSAMPLING_16;


    if (HAL_UART_Init(&huart1) != HAL_OK)
    {
        Error_Handler();
    }
}


/* =========================================================
   GPIO CONFIGURATION
   ========================================================= */

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


    /* Enable GPIOA clock */

    __HAL_RCC_GPIOA_CLK_ENABLE();


    /* =====================================================
       PA1 = PIR SENSOR
       ===================================================== */

    GPIO_InitStruct.Pin =
        GPIO_PIN_1;

    GPIO_InitStruct.Mode =
        GPIO_MODE_INPUT;

    GPIO_InitStruct.Pull =
        GPIO_NOPULL;

    GPIO_InitStruct.Speed =
        GPIO_SPEED_FREQ_LOW;


    HAL_GPIO_Init(
        GPIOA,
        &GPIO_InitStruct
    );


    /* =====================================================
       PA5 = ADC INPUT
       ===================================================== */

    GPIO_InitStruct.Pin =
        GPIO_PIN_5;

    GPIO_InitStruct.Mode =
        GPIO_MODE_ANALOG;

    GPIO_InitStruct.Pull =
        GPIO_NOPULL;


    HAL_GPIO_Init(
        GPIOA,
        &GPIO_InitStruct
    );


    /* =====================================================
       PA0 = TIM2_CH1 PWM OUTPUT
       ===================================================== */

    GPIO_InitStruct.Pin =
        GPIO_PIN_0;

    GPIO_InitStruct.Mode =
        GPIO_MODE_AF_PP;

    GPIO_InitStruct.Pull =
        GPIO_NOPULL;

    GPIO_InitStruct.Speed =
        GPIO_SPEED_FREQ_HIGH;


    HAL_GPIO_Init(
        GPIOA,
        &GPIO_InitStruct
    );
}


/* =========================================================
   ERROR HANDLER
   ========================================================= */

void Error_Handler(void)
{
    __disable_irq();

    while (1)
    {
    }
}