#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/gpio.h"
#include "driver/adc.h"
#include "math.h"

#define LED_PIN GPIO_NUM_2  // Using GPIO2 for the LED
#define LDR_PIN GPIO_NUM_32 // LDR_PIN to gpio pin 32
#define LDR_ADC_CHANNEL ADC1_CHANNEL_4 // LDR_ADC_CHANNEL

#define AVG_WINDOW 10
#define SENSOR_THRESHOLD 500

//TODO9: Adjust Task to blink an LED at 1 Hz (1000 ms period: 500 ms ON, 500 ms OFF);
//Consider supressing the output
void heartbeat_task(void *pvParameters) {
    int heartbeatState = 0;
    TickType_t currentTime = pdTICKS_TO_MS( xTaskGetTickCount() );

    while (1) {
        currentTime = pdTICKS_TO_MS( xTaskGetTickCount() );
        gpio_set_level(LED_PIN, heartbeatState);  
        heartbeatState = !heartbeatState;  
        
        printf("Heart %s @ Time %lu\n", heartbeatState ? "Systole" : "Diastole", currentTime);
        vTaskDelay(pdMS_TO_TICKS(500)); 
       
    }
    vTaskDelete(NULL); // We'll never get here; tasks run forever
}

//TODO10: Task to print a message every 1000 ms (1 seconds)
void vitals_task(void *pvParameters) {
    TickType_t currentTime = pdTICKS_TO_MS( xTaskGetTickCount() );
    TickType_t previousTime = 0;
    while (1) {
        previousTime = currentTime;
        currentTime = pdTICKS_TO_MS( xTaskGetTickCount() );
        
        // Prints a periodic message based on a thematic area. Output a timestamp (ms) and period (ms)
        printf("Patient's heart is beating | time = %lu ms\n",currentTime);
        vTaskDelay(pdMS_TO_TICKS(1000)); // Delay for 1000 ms
    }
    vTaskDelete(NULL); // We'll never get here; tasks run forever
}

//TODO11: Create new task for sensor reading every 500ms
// simulates a photoplethysmography (PPG) senor that measures heart rate
void PPG_task(void *pvParameters) {
    //TODO110 Configure ADC (12-bit width, 0-3.3V range with 11dB attenuation)
    adc1_config_width(ADC_WIDTH_BIT_12);
    adc1_config_channel_atten(LDR_ADC_CHANNEL, ADC_ATTEN_DB_11); //could be ADC_ATTEN_DB_11


    // Variables to compute LUX
    float raw;
    float Vmeasure = 0.;
    float Rmeasure = 0.;
    float lux = 0.;
    // Variables for moving average
    int luxreadings[AVG_WINDOW] = {0};
    int idx = 0;
    float sum = 0;

    //TODO11a consider where AVG_WINDOW is defined, it could be here, or global value 
    //int AVG_WINDOW = 10;
    //int SENSOR_THRESHOLD = 500;

    //See TODO 99
    // Pre-fill the readings array with an initial sample to avoid startup anomaly
    for(int i = 0; i < AVG_WINDOW; ++i) {
        raw =  adc1_get_raw(LDR_ADC_CHANNEL);
        Vmeasure = (raw/4096)*3.3; //TODO11b correct this with the equation seen earlier
        Rmeasure = (10000*Vmeasure)/(3.3-Vmeasure); //TODO11c correct this with the equation seen earlier
        lux = pow((50*1000*pow(10, 0.7))/Rmeasure, (1/0.7)); //TODO11d correct this with the equation seen earlier
        luxreadings[i] = lux;
        sum += luxreadings[i];
    }

    const TickType_t periodTicks = pdMS_TO_TICKS(500); // e.g. 500 ms period
    TickType_t lastWakeTime = xTaskGetTickCount(); // initialize last wake time

    while (1) {
        // Read current sensor value
        raw = adc1_get_raw(LDR_ADC_CHANNEL);
        //printf("**raw **: Sensor %d\n", raw);

        // Compute LUX
        Vmeasure = (raw/4096)*3.3; //TODO11e correct this with the equation seen earlier
        Rmeasure = (10000*Vmeasure)/(3.3-Vmeasure); //TODO11f correct this with the equation seen earlier
        lux = pow((50*1000*pow(10, 0.7))/Rmeasure, (1/0.7)); //TODO11g correct this with the equation seen earlier
       
        // Update moving average buffer 
        sum -= luxreadings[idx];       // remove oldest value from sum
        
        luxreadings[idx] = lux;        // place new reading
        sum += lux;                 // add new value to sum
        idx = (idx + 1) % AVG_WINDOW;
        int avg = sum / AVG_WINDOW; // compute average

        //TODO11h Check threshold and print alert if exceeded or below based on context
        if (avg >= SENSOR_THRESHOLD) {
            printf("**Alert**: Heart rate %d BPM exceeds threshold %d BPM!\n", avg, SENSOR_THRESHOLD);
        } else {
          //TODO11i
          printf("Heart rate %d BPM is within normal range.\n", avg);

        }
        //TODO11j: Print out time period [to help with answering Eng/Analysis quetionst (hint check Application Solution #1 )
        //https://wokwi.com/projects/430683087703949313
        printf("PPG Task ran at tick %lu with period %lu\n", xTaskGetTickCount(), periodTicks);
        //TODO11k Replace vTaskDelay with vTaskDelayUntil with parameters &lastWakeTime and periodTicks
        vTaskDelayUntil(&lastWakeTime, periodTicks);

    }
}


void app_main() {
    // Initialize LED GPIO     
    gpio_reset_pin(LED_PIN);
    gpio_set_direction(LED_PIN, GPIO_MODE_OUTPUT);
    // Initialize LDR PIN as INPUT 
    gpio_reset_pin(LDR_PIN);
    gpio_set_direction(LDR_PIN, GPIO_MODE_INPUT);

    // Set ADC1's resolution 
    adc1_config_width(ADC_WIDTH_BIT_12);

    // Set the the input channel to 11 DB Attenuation
    adc1_config_channel_atten(LDR_ADC_CHANNEL, ADC_ATTEN_DB_11);

    // Instantiate/ Create tasks: 
    // . pointer to task function, 
    // . descriptive name, [has a max length; located in the FREERTOS_CONFIG.H]
    // . stack depth, 
    // . parameters [optional] = NULL 
    // . priority [0 = low], 
    // . pointer referencing this created task [optional] = NULL
    // Learn more here https://www.freertos.org/Documentation/02-Kernel/04-API-references/01-Task-creation/01-xTaskCreate
    
    // TODO7: Pin tasks to core 1    
    // Convert these xTaskCreate function calls to  xTaskCreatePinnedToCore() function calls
    // The new function takes one more parameter at the end (0 or 1);
    // pin all your tasks to core 1 
    
    // This is a special (custom) espressif FreeRTOS function
    // . pointer to task function, 
    // . descriptive name, [has a max length; located in the FREERTOS_CONFIG.H]
    // . stack depth, 
    // . parameters [optional] = NULL 
    // . priority [0 = low], 
    // . pointer referencing this created task [optional] = NULL
    // . core [0,1] to pin task too 
    // https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/system/freertos_additions.html#_CPPv423xTaskCreatePinnedToCore14TaskFunction_tPCKcK8uint32_tPCv11UBaseType_tPC12TaskHandle_tK10BaseType_t
    xTaskCreatePinnedToCore(heartbeat_task, "LED", 2048, NULL, 1, NULL, 1);
    xTaskCreatePinnedToCore(vitals_task, "STATUS", 2048, NULL, 2, NULL, 1);

    // TODO8: Make sure everything still works as expected before moving on to TODO9 (above).

    //TODO12 Add in new Sensor task; make sure it has the correct priority to preempt 
    //the other two tasks.
    xTaskCreatePinnedToCore(PPG_task, "SENSOR", 4096, NULL, 3, NULL, 1);

    //TODO13: Make sure the output is working as expected and move on to the engineering
    //and analysis part of the application. You may need to make modifications for experiments. 
    //Make sure you can return back to the working version!
}