#include <Arduino.h>
#include <LiquidCrystal_I2C.h>

#define TRIG_PIN    D0
#define ECHO_PIN    D1
#define KEY_LIGHT   D2
#define KEY_TH      D3
#define KEY_TOGGLE  D5
#define LED_PIN     D4

LiquidCrystal_I2C lcd(0x27, 16, 2);

int simLightVal = 500;
int threshold   = 500;
int dist = 0;
bool hasPerson = false;

unsigned long keyLightPressTime = 0;
bool keyLightPressed = false;
unsigned long keyThPressTime = 0;
bool keyThPressed = false;

int readDistance() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  long time = pulseIn(ECHO_PIN, HIGH, 30000);
  return time * 0.034 / 2;
}

void setup() {
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(KEY_LIGHT, INPUT_PULLUP);
  pinMode(KEY_TH, INPUT_PULLUP);
  pinMode(KEY_TOGGLE, INPUT_PULLUP);
  pinMode(LED_PIN, OUTPUT);
  
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0,0);
  lcd.print("Light:500");
  lcd.setCursor(0,1);
  lcd.print("Th:500 P:N OFF");
  delay(1000);
}

void loop() {
  // 光照按键（保留显示功能）
  if (digitalRead(KEY_LIGHT) == LOW) {
    if (!keyLightPressed) {
      keyLightPressed = true;
      keyLightPressTime = millis();
    }
    if (millis() - keyLightPressTime > 400) {
      simLightVal -= 50;
      if (simLightVal < 0) simLightVal = 0;
      delay(150);
    }
  } else {
    if (keyLightPressed) {
      if (millis() - keyLightPressTime <= 400) {
        simLightVal += 50;
        if (simLightVal > 1023) simLightVal = 1023;
      }
      keyLightPressed = false;
    }
  }

  // 阈值按键（保留）
  if (digitalRead(KEY_TH) == LOW) {
    if (!keyThPressed) {
      keyThPressed = true;
      keyThPressTime = millis();
    }
    if (millis() - keyThPressTime > 400) {
      threshold -= 50;
      if (threshold < 0) threshold = 0;
      delay(150);
    }
  } else {
    if (keyThPressed) {
      if (millis() - keyThPressTime <= 400) {
        threshold += 50;
        if (threshold > 1023) threshold = 1023;
      }
      keyThPressed = false;
    }
  }

  // ====================== 超声波人体检测 ======================
  dist = readDistance();
  hasPerson = (dist > 0 && dist <= 200);  // 200cm内有人

  // ====================== 核心逻辑：有人亮、无人灭 ======================
  if (hasPerson) {
    digitalWrite(LED_PIN, HIGH);  // 有人 → 亮
  } else {
    digitalWrite(LED_PIN, LOW);   // 无人 → 灭
  }

  // ====================== LCD 显示 ======================
  lcd.setCursor(0,0);
  lcd.print("Light:");
  lcd.print(simLightVal);
  lcd.print("    ");

  lcd.setCursor(0,1);
  lcd.print("Th:");
  lcd.print(threshold);
  lcd.print(" P:");
  lcd.print(hasPerson ? "Y" : "N");

  if (hasPerson) {
    lcd.print(" ON ");
  } else {
    lcd.print(" OFF");
  }

  delay(30);
}