/*
 * IoMT Patient Monitoring — ESP32 DevKit V1
 * Module: LD7182 — AI for IoT
 * Board : board-esp32-devkit-v1
 *
 * Pins:
 *   GPIO34 → SpO2 pot       GPIO35 → HR pot
 *   GPIO32 → Systolic pot   GPIO33 → Diastolic pot
 *   GPIO36 → Temp pot
 *   GPIO21 → OLED SDA       GPIO22 → OLED SCL
 *   GPIO25 → Green LED      GPIO26 → Red LED
 *   GPIO17 → Fall button    GPIO18 → Disease button
 *
 * ThingSpeak Fields:
 *   Field 1 → SpO2 (%)
 *   Field 2 → Heart Rate (bpm)
 *   Field 3 → Systolic BP (mmHg)
 *   Field 4 → Diastolic BP (mmHg)
 *   Field 5 → Temperature (°C)
 *   Field 6 → Alert Status  (0 = ALERT, 1 = NORMAL)
 *   Field 7 → Fall Detected (0 = No,    1 = Yes)
 *   Field 8 → Disease Index (0=Normal, 1=Hypertens., 2=Diabetes, 3=Asthma)
 */

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

// ── WiFi ──────────────────────────────────────────────────────
const char* SSID     = "Wokwi-GUEST";   // change for real hardware
const char* PASSWORD = "";

// ── ThingSpeak ────────────────────────────────────────────────
const char* TS_KEY    = "EYOEB444VQDEJ6QV";            // ← Your Write API Key
const char* TS_SERVER = "http://api.thingspeak.com/update";
const unsigned long TS_INTERVAL = 20000;               // 20s (free tier min = 15s)
unsigned long lastUpload = 0;

// ── OLED ────────────────────────────────────────────────────
#define SCREEN_WIDTH  128
#define SCREEN_HEIGHT  64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

// ── Pins ────────────────────────────────────────────────────
#define PIN_SPO2      34
#define PIN_HR        35
#define PIN_SYSTOLIC  32
#define PIN_DIASTOLIC 33
#define PIN_TEMP      36

#define LED_GREEN     25
#define LED_RED       26
#define BTN_FALL      17
#define BTN_DISEASE   18

// ── State ───────────────────────────────────────────────────
int  diseaseIndex   = 0;
bool fallDetected   = false;
bool lastFallBtn    = HIGH;
bool lastDiseaseBtn = HIGH;
unsigned long lastDebounce = 0;

const char* DISEASE_NAMES[] = { "Normal", "Hypertens.", "Diabetes", "Asthma" };

// ── Sensor Readers ──────────────────────────────────────────
float readSpO2()      { return map(analogRead(PIN_SPO2),      0, 4095, 850, 1000) / 10.0f; }
float readHR()        { return (float)map(analogRead(PIN_HR), 0, 4095,  40,  160); }
float readSystolic()  { return (float)map(analogRead(PIN_SYSTOLIC),  0, 4095,  90, 200); }
float readDiastolic() { return (float)map(analogRead(PIN_DIASTOLIC), 0, 4095,  50, 130); }
float readTemp()      { return map(analogRead(PIN_TEMP), 0, 4095, 340, 410) / 10.0f; }

// ── Decision Tree ───────────────────────────────────────────
int classifySpO2Alert(float spO2, float hr, float sys,
                      float dia, float temp,
                      int disease, bool fall) {
  float isHypertension = (disease == 1) ? 1.0f : 0.0f;
  float isDiabetes     = (disease == 2) ? 1.0f : 0.0f;
  float isFall         = fall           ? 1.0f : 0.0f;

  if (spO2 <= 89.55f) {
    if (spO2 <= 89.16f) {
      if (spO2 <= 89.01f) return 0;
      else {
        if (spO2 <= 89.04f) return (spO2 <= 89.03f) ? 0 : 1;
        else return 0;
      }
    } else {
      if (hr <= 77.41f) {
        if (hr <= 67.66f) return (dia <= 85.48f) ? 0 : 1;
        else return (isHypertension <= 0.5f) ? 1 : 0;
      } else {
        if (sys <= 174.06f) return 0;
        else return (isFall <= 0.5f) ? 1 : 0;
      }
    }
  } else {
    if (spO2 <= 89.91f) {
      if (isDiabetes <= 0.5f) return 1;
      else return (sys <= 156.27f) ? 1 : 0;
    } else {
      return 1;
    }
  }
}

// ── ThingSpeak Upload ────────────────────────────────────────
void uploadThingSpeak(float spO2, float hr, float sys,
                      float dia, float temp,
                      int alert, bool fall, int disease) {
  if (WiFi.status() != WL_CONNECTED) {
    Serial.println("[WiFi] Disconnected – skipping upload.");
    return;
  }

  String url = String(TS_SERVER)
    + "?api_key=" + TS_KEY
    + "&field1="  + String(spO2, 1)
    + "&field2="  + String((int)hr)
    + "&field3="  + String((int)sys)
    + "&field4="  + String((int)dia)
    + "&field5="  + String(temp, 1)
    + "&field6="  + String(alert)
    + "&field7="  + String(fall ? 1 : 0)
    + "&field8="  + String(disease);

  HTTPClient http;
  http.begin(url);
  int resp = http.GET();
  http.end();

  if (resp > 0) Serial.printf("[ThingSpeak] Entry: %d\n", resp);
  else          Serial.printf("[ThingSpeak] Error: %d\n", resp);
}

// ── WiFi Connect ─────────────────────────────────────────────
void connectWiFi() {
  Serial.printf("[WiFi] Connecting to: %s\n", SSID);
  WiFi.begin(SSID, PASSWORD);
  int attempts = 0;
  while (WiFi.status() != WL_CONNECTED && attempts < 20) {
    delay(500); Serial.print("."); attempts++;
  }
  if (WiFi.status() == WL_CONNECTED) {
    Serial.printf("\n[WiFi] Connected. IP: %s\n", WiFi.localIP().toString().c_str());
  } else {
    Serial.println("\n[WiFi] Failed – running offline.");
  }
}

// ── Setup ───────────────────────────────────────────────────
void setup() {
  Serial.begin(115200);
  delay(300);

  pinMode(LED_GREEN, OUTPUT); digitalWrite(LED_GREEN, LOW);
  pinMode(LED_RED,   OUTPUT); digitalWrite(LED_RED,   LOW);
  pinMode(BTN_FALL,    INPUT_PULLUP);
  pinMode(BTN_DISEASE, INPUT_PULLUP);

  Wire.begin(21, 22);
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println("OLED failed"); while (1);
  }

  display.clearDisplay();
  display.setTextSize(1); display.setTextColor(WHITE);
  display.setCursor(15, 5);  display.println("LD7182 - AI for IoT");
  display.setCursor(20, 18); display.println("IoMT Monitor v2.0");
  display.setCursor(25, 31); display.println("+ ThingSpeak");
  display.setCursor(30, 44); display.println("Starting...");
  display.display();
  delay(1500);

  connectWiFi();
  Serial.println("=== IoMT Monitor Ready ===");
}

// ── Loop ────────────────────────────────────────────────────
void loop() {
  unsigned long now = millis();

  // Fall button toggle
  bool fb = digitalRead(BTN_FALL);
  if (fb == LOW && lastFallBtn == HIGH && (now - lastDebounce) > 250) {
    fallDetected = !fallDetected;
    lastDebounce = now;
    Serial.print("Fall: "); Serial.println(fallDetected ? "ON" : "OFF");
  }
  lastFallBtn = fb;

  // Disease cycle button
  bool db = digitalRead(BTN_DISEASE);
  if (db == LOW && lastDiseaseBtn == HIGH && (now - lastDebounce) > 250) {
    diseaseIndex = (diseaseIndex + 1) % 4;
    lastDebounce = now;
    Serial.print("Disease: "); Serial.println(DISEASE_NAMES[diseaseIndex]);
  }
  lastDiseaseBtn = db;

  // Read sensors
  float spO2 = readSpO2();
  float hr   = readHR();
  float sys  = readSystolic();
  float dia  = readDiastolic();
  float temp = readTemp();

  // Run decision tree
  int result = classifySpO2Alert(spO2, hr, sys, dia, temp,
                                 diseaseIndex, fallDetected);

  // Drive LEDs
  digitalWrite(LED_GREEN, (result == 1) ? HIGH : LOW);
  digitalWrite(LED_RED,   (result == 0) ? HIGH : LOW);

  // ThingSpeak upload every TS_INTERVAL ms
  if (now - lastUpload >= TS_INTERVAL) {
    lastUpload = now;
    uploadThingSpeak(spO2, hr, sys, dia, temp,
                     result, fallDetected, diseaseIndex);
  }

  // Update OLED
  display.clearDisplay();
  display.setTextSize(1); display.setTextColor(WHITE);

  display.setCursor(0, 0);  display.println("=== IoMT Monitor ===");
  display.setCursor(0, 12); display.print("SpO2: "); display.print(spO2, 1); display.println(" %");
  display.setCursor(0, 22); display.print("HR: "); display.print((int)hr);
  display.print(" bpm  T:"); display.print(temp, 1); display.println("C");
  display.setCursor(0, 32); display.print("BP: "); display.print((int)sys);
  display.print("/"); display.print((int)dia); display.println(" mmHg");
  display.setCursor(0, 42); display.print("Dx:"); display.print(DISEASE_NAMES[diseaseIndex]);
  display.print(" Fall:"); display.println(fallDetected ? "YES" : "NO");
  display.drawFastHLine(0, 52, 128, WHITE);
  display.setCursor(0, 55);
  display.println(result == 0 ? "!! SpO2 ALERT: LOW !!" : "   STATUS: NORMAL   ");
  display.display();

  // Serial log
  Serial.printf("SpO2=%.1f HR=%.0f SYS=%.0f DIA=%.0f T=%.1f => %s\n",
                spO2, hr, sys, dia, temp, result == 0 ? "ALERT" : "NORMAL");

  delay(800);
}