// ESP32 Air Quality Demo for Wokwi
// DHT22 + SSD1306 OLED + NeoPixel + Buzzer + ThingSpeak HTTP upload
// PM2.5 is simulated via Serial: PM=<value> (e.g., PM=160)
//
// Wiring (Wokwi labels):
//   DHT22:  SDA->GPIO19 (esp:19), VCC->3V3, GND->GND
//   OLED  : SDA->GPIO21, SCL->GPIO22, VCC->3V3, GND->GND
//   NeoPx : DIN->GPIO4, VDD->5V, VSS->GND
//   Buzzer: +->GPIO15, - ->GND
//
// ThingSpeak fields: field1=PM2.5, field2=AQI, field3=Temp, field4=Humidity

#include <WiFi.h>
#include <HTTPClient.h>
#include <Adafruit_GFX.h> 
#include <Adafruit_SSD1306.h>
#include <Adafruit_NeoPixel.h>
#include "DHT.h"
#include <Wire.h>

// ---------------- Pins ----------------
#define PIN_DHT     19   // moved off I2C to avoid conflicts
#define PIN_SDA     21
#define PIN_SCL     22
#define PIN_NEOPX   4
#define PIN_BUZZER  15
#define DHTTYPE DHT22

// ---------------- WiFi & ThingSpeak ----------------
const char* WIFI_SSID = "Wokwi-GUEST";
const char* WIFI_PASS = "";
const char* TS_WRITE_KEY = "DQ2AKDGKWOK18H25";

// ---------------- Objects ----------------
Adafruit_SSD1306 display(128, 64, &Wire, -1);
Adafruit_NeoPixel pixels(1, PIN_NEOPX, NEO_GRB + NEO_KHZ800);
DHT dht(PIN_DHT, DHTTYPE);

// ---------------- State ----------------
float pm25 = 12.0; // simulated PM2.5 (µg/m³)
const unsigned long UPLOAD_INTERVAL_MS = 30000; // 30s

// ---------------- Helpers ----------------
int computeAQI_PM25(float c) {
  if (isnan(c)) return -1;
  struct Brk { float Cl; float Ch; int Il; int Ih; };
  Brk bk[] = {
    {0.0, 12.0, 0, 50}, {12.1, 35.4, 51, 100}, {35.5, 55.4, 101,150},
    {55.5,150.4,151,200}, {150.5,250.4,201,300}, {250.5,350.4,301,400},
    {350.5,500.4,401,500}
  };
  for (auto &b : bk) {
    if (c >= b.Cl && c <= b.Ch) {
      return (int)round((b.Ih - b.Il) * (c - b.Cl) / (b.Ch - b.Cl) + b.Il);
    }
  }
  return 500;
}

String aqiCategory(int aqi) {
  if (aqi <= 50)   return "Tot";
  if (aqi <= 100)  return "Trung binh";
  if (aqi <= 150)  return "Nhay cam";
  if (aqi <= 200)  return "Xau";
  if (aqi <= 300)  return "Rat xau";
  return "Nguy hiem";
}

// Detailed advice by AQI band + humidity tweak
String adviceForAsthmaDetailed(int aqi, float T, float H) {
  String msg;
  if (aqi <= 50) {
    msg = "Khong khi tot.";
  } else if (aqi <= 100) {
    msg = "Co the hoat dong binh thuong.";
  } else if (aqi <= 150) {
    msg = "Nhom nhay cam: han che hoat dong ngoai troi.";
  } else if (aqi <= 200) {
    msg = "XAU: Han che ra ngoai; deo N95 khi can; bat may loc.";
  } else if (aqi <= 300) {
    msg = "RAT XAU: O trong nha; dong cua; deo N95 neu buoc ra ngoai; theo doi trieu chung.";
  } else {
    msg = "NGUY HIEM: Tranh ra ngoai; deo N95 bat buoc; dung thuoc cap cuu neu kho tho; lien he y te neu nang.";
  }
  if (!isnan(H)) {
    if (H < 40) msg += " Do am <40% co the kich ung.";
    else if (H > 70) msg += " Do am >70% de kho tho.";
  }
  return msg;
}

// tiny warning icon (triangle + "!") for OLED (monochrome)
void drawWarningIcon(int x, int y) {
  // Triangle outline
  display.drawTriangle(x, y+20, x+10, y, x+20, y+20, SSD1306_WHITE);
  // Exclamation mark
  display.fillRect(x+9, y+6, 2, 8, SSD1306_WHITE);
  display.fillRect(x+9, y+16, 2, 2, SSD1306_WHITE);
}

void setPixel(uint8_t r, uint8_t g, uint8_t b, uint8_t brightness=40) {
  pixels.setBrightness(brightness);
  pixels.setPixelColor(0, pixels.Color(r,g,b));
  pixels.show();
}

// Buzzer using tone()
void beep(int freq, int ms){
  tone(PIN_BUZZER, freq, ms);
  delay(ms + 10);
  noTone(PIN_BUZZER);
}

void handleSerialPM() {
  static String buf;
  while (Serial.available()) {
    char c = Serial.read();
    if (c=='\n' || c=='\r') {
      if (buf.startsWith("PM=")) {
        float v = buf.substring(3).toFloat();
        if (v>=0 && v<=1000) {
          pm25 = v;
          Serial.printf("[OK] PM2.5 set to %.1f ug/m3\n", pm25);
        } else {
          Serial.println("[ERR] PM must be 0..1000");
        }
      } else if (buf=="HELP") {
        Serial.println("Commands:");
        Serial.println("  PM=<value>   set PM2.5 in ug/m3 (0..1000)");
      }
      buf = "";
    } else {
      buf += c;
    }
  }
}

void connectWiFi() {
  if (WiFi.status() == WL_CONNECTED) return;
  Serial.printf("Connecting to WiFi: %s\n", WIFI_SSID);
  WiFi.mode(WIFI_STA);
  WiFi.begin(WIFI_SSID, WIFI_PASS);
  unsigned long t0 = millis();
  while (WiFi.status() != WL_CONNECTED && millis() - t0 < 15000) {
    delay(500);
    Serial.print(".");
  }
  if (WiFi.status() == WL_CONNECTED) {
    Serial.printf("\nWiFi connected. IP: %s\n", WiFi.localIP().toString().c_str());
  } else {
    Serial.println("\nWiFi connect failed.");
  }
}

void uploadThingSpeak(float pm25, int aqi, float t, float h) {
  if (WiFi.status() != WL_CONNECTED) {
    connectWiFi();
    if (WiFi.status() != WL_CONNECTED) return;
  }
  HTTPClient http;
  String url = String("https://api.thingspeak.com/update?api_key=") + TS_WRITE_KEY +
               "&field1=" + String(pm25,1) +
               "&field2=" + String(aqi) +
               "&field3=" + String(t,1) +
               "&field4=" + String(h,1);
  http.begin(url);
  int code = http.GET();
  if (code > 0) {
    String payload = http.getString();
    Serial.printf("[ThingSpeak] HTTP %d, response: %s\n", code, payload.c_str());
  } else {
    Serial.printf("[ThingSpeak] HTTP error: %d\n", code);
  }
  http.end();
}

void setup() {
  Serial.begin(115200);
  Serial.println("ESP32 – Air Quality + ThingSpeak Demo");
  Serial.println("Type PM=<value> to simulate PM2.5 (e.g., PM=160).");

  Wire.begin(PIN_SDA, PIN_SCL);

  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println("[WARN] SSD1306 not found.");
  } else {
    display.clearDisplay();
    display.setTextSize(1);
    display.setTextColor(SSD1306_WHITE);
  }

  dht.begin();
  pixels.begin();
  setPixel(0,0,0,0);

  pinMode(PIN_BUZZER, OUTPUT);
  digitalWrite(PIN_BUZZER, LOW);

  connectWiFi();
}

void loop() {
  handleSerialPM();

  float temp = dht.readTemperature();
  float humid = dht.readHumidity();
  if (isnan(temp))  temp  = 0;
  if (isnan(humid)) humid = 0;

  int aqi = computeAQI_PM25(pm25);

  // OLED with detailed advice + icon
  if (display.width() > 0) {
    String cat = aqiCategory(aqi);
    String adv = adviceForAsthmaDetailed(aqi, temp, humid);

    display.clearDisplay();
    display.setCursor(0,0);
    display.setTextSize(1);
    display.println("Air Quality Monitor");

    display.print("PM2.5: "); display.print(pm25,1); display.println(" ug/m3");
    display.print("AQI  : "); display.print(aqi); display.print(" ("); display.print(cat); display.println(")");
    display.print("T: "); display.print(temp,1); display.print("C  H: "); display.print(humid,0); display.println("%");

    if (aqi >= 151) {
      display.setTextSize(2);
      display.println("CANH BAO");
      display.setTextSize(1);
      drawWarningIcon(104, 0); // top-right corner
    } else {
      display.println("Trang thai on dinh.");
    }

    // Wrap advice into 2 lines (~21 chars/line)
    for (int i = 0; i < adv.length() && i < 42; i += 21) {
      int end = i + 21; if (end > adv.length()) end = adv.length();
      display.println(adv.substring(i, end));
    }

    display.display();
  }

  // LED color by AQI
  if (aqi <= 50)        setPixel(0, 180, 0);
  else if (aqi <= 100)  setPixel(200, 120, 0);
  else if (aqi <= 150)  setPixel(255, 80, 0);
  else if (aqi <= 300)  setPixel(200, 0, 0);       // red for unhealthy & very unhealthy
  else                  setPixel(200, 0, 200);     // magenta for hazardous

  // Beep pattern by severity every 10s
  static unsigned long lastBeep = 0;
  unsigned long now = millis();
  if (aqi >= 151 && now - lastBeep > 10000) {
    int n = (aqi > 300) ? 4 : (aqi > 200) ? 3 : 2;
    for (int i=0; i<n; ++i) { beep(2000, 150); delay(120); }
    lastBeep = now;
  }

  // Upload to ThingSpeak every 30 seconds
  static unsigned long lastUpload = 0;
  if (now - lastUpload >= UPLOAD_INTERVAL_MS) {
    uploadThingSpeak(pm25, aqi, temp, humid);
    lastUpload = now;
  }

  delay(500);
}