#include <Arduino.h>

#include <LiquidCrystal_I2C.h>
#include <ESP32Servo.h>

#include <ArduinoJson.h>
#include <HTTPClient.h>
#include <WiFi.h>

#include <ReactESP.h>

#include "time.h"

reactesp::ReactESP app;

/* Miscellaneous constants */
const float flowrate = 61.111f; // mL/s, assuming we're using a 220L/h pump.

/* Proximity sensor related constants */
#define SENSOR_TRIG_PIN 13
#define SENSOR_ECHO_PIN 14
#define DISTANCE 5000

/* Pump related constants */
#define PUMP_PIN 4

/* Display related constants */
#define BAUDRATE 115200

LiquidCrystal_I2C lcd_water(0x26, 16, 2);
LiquidCrystal_I2C lcd_plastic(0x27, 16, 2);

/* Wifi related objects */
WiFiClient client;
HTTPClient http;

/* API related variables */
bool has_api_token = false;
String api_token = "";

/* Global state variables */
int state = 0;             // Current state.
int last_state = 0;        // Previous state.
int start_pressed = 0;     // The moment the system was triggered.
int current_pressed = 0;   // How long it has been triggered.
int end_pressed = 0;       // The moment the system was untriggered.
int hold_time = 0;         // How long the system's been triggered.
int idle_time = 0;         // How long the system was idle.

void start(void) {
	Serial.begin(BAUDRATE);
	pinMode(SENSOR_TRIG_PIN, OUTPUT);
	pinMode(SENSOR_ECHO_PIN, INPUT);

	app.onRepeat(60000, [] () {
		if (!client.connected())
			connect_wifi();
		
		if (!has_api_token)
			has_api_token = authenticate_api();
	});

	app.onTick([] () {
		// Read the sensor input
  	state = readSensorTrigger(DISTANCE);

		// State changed
  	if (state != last_state)
     	update_state();
    else
    	update_counter();

  	// Save state for next loop
  	last_state = state;
	});
}

void loop(void) {
	app.tick();
}

/* Other state functions */
void update_counter() {
  if (state != HIGH)
    return;
  
  // Enable pump
  digitalWrite(PUMP_PIN, HIGH);
  
  current_pressed = millis() - start_pressed;
  
  float volume = current_pressed / 1000.0f * flowrate;
  
  // Update screen with current volume
  show_water_result_screen(volume);
}

void update_state() {
  	// The sensor has just been triggered.
  	if (state == HIGH) {
      	start_pressed = millis();
        idle_time = start_pressed - end_pressed;

      	Serial.print("Idle: ");
      	Serial.print(idle_time);
				Serial.print("\n");

				lcd_water.clear();

	// The sensor has just been untriggered.
	} else {
      	end_pressed = millis();
      	hold_time = end_pressed - start_pressed;

    		Serial.print("Hold: ");
      	Serial.print(hold_time);
				Serial.print("\n");
      
      	// Disable pump
      	digitalWrite(PUMP_PIN, LOW);
      
      	// Testing with 1mL/s
      	float volume = hold_time / 1000.0f * flowrate;
				Serial.print("Flow: ");
      	Serial.print(volume, 3);
				Serial.print("\n");
      
      	// Update screen with final volume
      	show_water_result_screen(volume);
  	}
}

/* Other proximity sensor functions */
long readSensorTrigger(int maxDistance) {
  	digitalWrite(SENSOR_TRIG_PIN, LOW);
  	delayMicroseconds(2);
  
  	// Activate the trigger pin for 10 microseconds
  	digitalWrite(SENSOR_TRIG_PIN, HIGH);
  	delayMicroseconds(10);
  	digitalWrite(SENSOR_TRIG_PIN, LOW);
  	
  	// Read echo
  	long res = pulseIn(SENSOR_ECHO_PIN, HIGH);
  
  	return res <= maxDistance;
}