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

void IRAM_ATTR button_isr_handler(void* arg);

#define BUTTON_PIN 4  // Button connected to GPIO4

// Global flags for ISR
bool button_event = false; //This becomes true after an interrupt is called, which occurs after a button press or release. When this flag is true, it means we can proceed with the code which allows us to print a falling or rising edge. (JI)
bool fallingEdge = false; //Boolean variable to determine if the edge is falling or rising. Becomes true after an interrupt. (JI)

void app_main() {
    // Configuring GPIO as input
    gpio_set_direction(BUTTON_PIN, GPIO_MODE_INPUT);
    gpio_set_pull_mode(BUTTON_PIN, GPIO_PULLUP_ONLY);

    // Setting interrupt on FALLING edge (button press)
    gpio_set_intr_type(BUTTON_PIN, GPIO_INTR_ANYEDGE); //Changed NEGEDGE to ANYEDGE, because we want to capture the moment it falls and the moment it rises. (JI)

    // Install ISR service (interrupt handling)
    gpio_install_isr_service(0);

    // Attaching ISR handler to BUTTON_PIN
    gpio_isr_handler_add(BUTTON_PIN, button_isr_handler, NULL);

    while (1) { //The if statements below can only be accessed after an interrupt is called, which occurs on a button press or release. (JI)
        if (button_event) {  //Translation: If an interrupt was called (button press or release), proceed with the code below. The interrupt function makes this variable true. (JI)
            button_event = false;  // Reset flag
            
            //This 'if/else' code block is only reached if an interrupt was called, and the interrupt can only be called on a button press or release. (JI)
            if (fallingEdge) { //If this variable is true, then the button was pressed, which means it's falling edge since this an active low circuit. (JI)
                printf("Falling Edge\n");
            } else {
                printf("Rising Edge\n"); //If the variable is false, then it means the button was released and it's a rising edge. (JI)
        }                                //The interrupt runs through its function on button press and button release. (JI)
            }

        printf("Main loop running...\n"); //This block of code will continuously run if no button is pressed. (JI)
        vTaskDelay(pdMS_TO_TICKS(500));  // loop continues running
    }
}

// Interrupt Service Routine (ISR)
void IRAM_ATTR button_isr_handler(void* arg) {
    int button_state = gpio_get_level(BUTTON_PIN); //This function is called on button press and release to read the value of button_pin and store the value into button_state. (JI)
    fallingEdge = (button_state == 0); //If the button is pressed, then button_state becomes true. It feeds a '1' into the 'fallingEdge' variable. The inverse is true on button release. (JI)
    button_event = true; //We set this value to true so we can enter the "button_event" if-statement, which is the part of the code which determines if it's a falling or rising edge. (JI)
}