/*
 * EMF Meter with OLED Display
 * OpenParanormal Project
 *
 * Shows EMF reading on OLED screen with bar graph
 *
 * Hardware:
 * - ESP32 DevKit
 * - 0.96" OLED I2C Display (128x64)
 * - Hall effect sensor or coil
 * - Optional: LEDs for visual alerts
 *
 * Wiring:
 * OLED:
 * VCC → 3.3V
 * GND → GND
 * SCL → GPIO 22
 * SDA → GPIO 21
 *
 * Sensor:
 * VCC → 3.3V
 * GND → GND
 * OUT → GPIO 34
 *
 * Libraries needed:
 * - Adafruit SSD1306
 * - Adafruit GFX
 */

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define SCREEN_ADDRESS 0x3C

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define SENSOR_PIN 34
#define SAMPLES 20

int readings[SAMPLES];
int readIndex = 0;
int total = 0;
int maxReading = 0;

void setup() {
  Serial.begin(115200);

  // Initialize OLED
  if(!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
    Serial.println("OLED init failed!");
    while(1);
  }

  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.println("OpenParanormal");
  display.println("EMF Meter");
  display.println();
  display.println("Initializing...");
  display.display();
  delay(2000);

  pinMode(SENSOR_PIN, INPUT);

  // Initialize readings
  for (int i = 0; i < SAMPLES; i++) {
    readings[i] = 0;
  }
}

void loop() {
  // Read sensor with smoothing
  int rawValue = analogRead(SENSOR_PIN);

  total = total - readings[readIndex];
  readings[readIndex] = rawValue;
  total = total + readings[readIndex];
  readIndex = (readIndex + 1) % SAMPLES;

  int emfValue = total / SAMPLES;

  // Track max for display scaling
  if (emfValue > maxReading) {
    maxReading = emfValue;
  }

  // Slowly decay max
  if (maxReading > 0) {
    maxReading--;
  }

  // Update display
  display.clearDisplay();

  // Title
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.println("EMF Detector");

  // Numeric value
  display.setTextSize(2);
  display.setCursor(0, 12);
  display.print(emfValue);
  display.setTextSize(1);
  display.print(" mG");

  // Bar graph
  int barWidth = map(emfValue, 0, 4095, 0, 128);
  display.fillRect(0, 35, barWidth, 10, SSD1306_WHITE);
  display.drawRect(0, 35, 128, 10, SSD1306_WHITE);

  // Level indicator
  display.setCursor(0, 50);
  if (emfValue < 100) {
    display.print("Level: BASELINE");
  } else if (emfValue < 500) {
    display.print("Level: LOW");
  } else if (emfValue < 1000) {
    display.print("Level: MEDIUM");
  } else if (emfValue < 2000) {
    display.print("Level: HIGH");
  } else {
    display.print("Level: VERY HIGH!");
  }

  display.display();

  delay(100);
}