// ============================================================
//  UNIVERSAL ESP32 Zone Firmware v4 — EcoSense IoT System
//  3 DEDICATED POTENTIOMETERS per board:
//    Pin 32 → PM2.5 sensor (dedicated)
//    Pin 34 → CO2  sensor  (dedicated)
//    Pin 35 → Zone-specific sensor (SO2/O3/NH3/CO)
//    Pin 4  → DHT22 (Temp + Humidity)
//    Pin 13 → LED   (Actuator)
//  Zone auto-detected via last hex digit of MAC address
//  Dashboard control: zones/<id>/control  → {"state":"ON"|"OFF"}
//  Threshold updates: zones/<id>/threshold → {"pm25":50,"co2":600,"spec":9}
// ============================================================
#include <WiFi.h>
#include <PubSubClient.h>
#include <ArduinoJson.h>
#include <DHT.h>

#define MQTT_BUFFER 512
#define DHTPIN      4
#define DHTTYPE     DHT22
#define PM25_PIN    32   // Dedicated PM2.5 potentiometer
#define CO2_PIN     34   // Dedicated CO2  potentiometer
#define SPEC_PIN    35   // Zone-specific sensor potentiometer
#define ACT_PIN     13   // LED actuator

const char* SSID   = "Wokwi-GUEST";
const char* PASS   = "";
const char* BROKER = "broker.emqx.io";
const int   PORT   = 1883;

struct Zone {
    const char* id;
    const char* name;
    const char* location;
    int   pm25Lo,  pm25Hi;
    int   co2Lo,   co2Hi;
    int   specLo,  specHi;
    const char* specKey;
    const char* specLabel;
    const char* specUnit;
    float pm25ThreshDefault;
    float co2ThreshDefault;
    float specThreshDefault;
    const char* actuator;
};

const Zone ZONES[5] = {
  { "residential","Residential","RK Puram",
    0,80, 400,700, 0,20, "co","MQ135 CO","ppm",
    50.0, 600.0, 9.0, "Ventilation Fans" },
  { "industrial","Industrial","Anand Vihar",
    30,150, 600,2000, 0,300, "so2","SO2 Sensor","ug/m3",
    75.0, 1000.0, 125.0, "Air Scrubbers" },
  { "commercial","Commercial","ITO",
    0,100, 400,900, 0,250, "o3","O3 Ozone","ug/m3",
    50.0, 700.0, 100.0, "Air Purifiers" },
  { "agriculture","Agricultural","Narela",
    0,60, 400,1200, 0,100, "nh3","NH3 MQ137","ppm",
    40.0, 600.0, 25.0, "Mist Sprayers" },
  { "construction","Construction","Rohini",
    0,300, 400,650, 0,100, "co","MQ7 CO","ppm",
    150.0, 600.0, 35.0, "Water Sprinklers" }
};

// ── Runtime state ──────────────────────────────────────────
int         zoneId = 0;
const Zone* Z      = nullptr;
char clientId[64], dataTopic[40], ctrlTopic[40], threshTopic[40];

// Thresholds (mutable by MQTT from dashboard)
float pm25Threshold;
float co2Threshold;
float specThreshold;

DHT          dht(DHTPIN, DHTTYPE);
WiFiClient   net;
PubSubClient mqtt(net);

unsigned long lastMsg        = 0;
bool          manualOverride = false;
unsigned long overrideStart  = 0;
const long    OVERRIDE_DUR   = 30000;  // 30 s manual override window

// ───────────────────────────────────────────────────────────
void updateZone() {
    Z = &ZONES[zoneId];

    // Reset thresholds to defaults on zone change
    pm25Threshold = Z->pm25ThreshDefault;
    co2Threshold  = Z->co2ThreshDefault;
    specThreshold = Z->specThreshDefault;

    uint64_t chipId = ESP.getEfuseMac();
    uint32_t macLow = chipId & 0xFFFFFFFF;
    snprintf(clientId,   sizeof(clientId),   "esp32_%s_%08X", Z->id, macLow);
    snprintf(dataTopic,  sizeof(dataTopic),  "zones/%s/data",      Z->id);
    snprintf(ctrlTopic,  sizeof(ctrlTopic),  "zones/%s/control",   Z->id);
    snprintf(threshTopic,sizeof(threshTopic),"zones/%s/threshold", Z->id);

    Serial.println("\n╔══════════════════════════════════╗");
    Serial.printf( "║  ACTIVE ZONE : %-17s ║\n", Z->name);
    Serial.printf( "║  Location    : %-17s ║\n", Z->location);
    Serial.printf( "║  Actuator    : %-17s ║\n", Z->actuator);
    Serial.println("╚══════════════════════════════════╝\n");
    Serial.printf("[THRESH] PM2.5=%.1f  CO2=%.1f  %s=%.1f\n",
                  pm25Threshold, co2Threshold, Z->specLabel, specThreshold);
}

// ── WiFi ───────────────────────────────────────────────────
void connectWiFi() {
    WiFi.begin(SSID, PASS);
    Serial.print("WiFi connecting");
    while(WiFi.status() != WL_CONNECTED){ delay(400); Serial.print("."); }
    Serial.println(" ✓  IP=" + WiFi.localIP().toString());
}

// ── MQTT callback ──────────────────────────────────────────
void onMessage(char* topic, byte* payload, unsigned int len) {
    String msg;
    for(unsigned int i = 0; i < len; i++) msg += (char)payload[i];

    StaticJsonDocument<256> doc;
    if(deserializeJson(doc, msg)) return;   // parse error → ignore

    // ── Actuator control ─────────────────────────
    if(String(topic) == String(ctrlTopic)) {
        const char* s = doc["state"];
        if(s) {
            bool on = strcmp(s,"ON") == 0;
            digitalWrite(ACT_PIN, on ? HIGH : LOW);
            manualOverride = true;
            overrideStart  = millis();
            Serial.println(on
                ? "🟢 MANUAL → " + String(Z->actuator) + " ON"
                : "⛔ MANUAL → " + String(Z->actuator) + " OFF");
        }
    }

    // ── Threshold update from dashboard ──────────
    if(String(topic) == String(threshTopic)) {
        bool changed = false;
        if(doc.containsKey("pm25")) { pm25Threshold = doc["pm25"].as<float>(); changed = true; }
        if(doc.containsKey("co2"))  { co2Threshold  = doc["co2"].as<float>();  changed = true; }
        if(doc.containsKey("spec")) { specThreshold = doc["spec"].as<float>(); changed = true; }
        if(changed) {
            Serial.printf("[THRESH UPDATE] PM2.5=%.1f  CO2=%.1f  %s=%.1f\n",
                          pm25Threshold, co2Threshold, Z->specLabel, specThreshold);
        }
    }
}

// ── MQTT reconnect ────────────────────────────────────────
void ensureConnected() {
    while(!mqtt.connected()) {
        Serial.print("MQTT reconnecting...");
        if(mqtt.connect(clientId)) {
            Serial.println(" ✓");
            mqtt.subscribe(ctrlTopic);
            mqtt.subscribe(threshTopic);
        } else {
            Serial.printf(" ✗ (rc=%d) retry in 5s\n", mqtt.state());
            delay(5000);
        }
    }
}

// ───────────────────────────────────────────────────────────
void setup() {
    Serial.begin(115200);
    delay(200);

    // Derive zone from last nibble of MAC
    WiFi.mode(WIFI_STA);
    String mac   = WiFi.macAddress();
    char   last  = mac.charAt(mac.length() - 1);
    zoneId = (last >= '0' && last <= '9') ? (last - '0') : (toupper(last) - 'A' + 10);
    if(zoneId < 0 || zoneId >= 5) zoneId = 0;

    updateZone();
    pinMode(ACT_PIN, OUTPUT);
    dht.begin();
    connectWiFi();
    mqtt.setServer(BROKER, PORT);
    mqtt.setBufferSize(MQTT_BUFFER);
    mqtt.setCallback(onMessage);
    randomSeed(analogRead(0));
}

// ───────────────────────────────────────────────────────────
void loop() {
    ensureConnected();
    mqtt.loop();

    if(millis() - lastMsg >= 5000) {
        lastMsg = millis();

        // ── Read sensors ──────────────────────────────────
        float temp = dht.readTemperature();
        float hum  = dht.readHumidity();
        if(isnan(temp)) temp = 28.0f + zoneId * 1.5f;
        if(isnan(hum))  hum  = 60.0f - zoneId * 4.0f;

        // Each sensor has its own dedicated potentiometer
        float pm25 = map(analogRead(PM25_PIN), 0, 4095, Z->pm25Lo, Z->pm25Hi);
        float co2  = map(analogRead(CO2_PIN),  0, 4095, Z->co2Lo,  Z->co2Hi);
        float spec = map(analogRead(SPEC_PIN), 0, 4095, Z->specLo, Z->specHi);

        // ── Build JSON payload ────────────────────────────
        StaticJsonDocument<256> doc;
        doc["pm25"]        = round(pm25 * 10) / 10.0;
        doc["co2"]         = round(co2  * 10) / 10.0;
        doc["temperature"] = round(temp * 10) / 10.0;
        doc["humidity"]    = round(hum  * 10) / 10.0;
        doc[Z->specKey]    = round(spec * 10) / 10.0;
        doc["zone"]        = Z->id;
        // Include current thresholds so dashboard can sync on reconnect
        doc["thr_pm25"]    = pm25Threshold;
        doc["thr_co2"]     = co2Threshold;
        doc["thr_spec"]    = specThreshold;

        char buf[350];
        serializeJson(doc, buf);
        mqtt.publish(dataTopic, buf);

        Serial.printf("[%s] PM2.5=%.1f(thr:%.0f) CO2=%.1f(thr:%.0f) %s=%.1f(thr:%.0f) T=%.1f H=%.1f\n",
                      Z->id, pm25, pm25Threshold, co2, co2Threshold,
                      Z->specLabel, spec, specThreshold, temp, hum);

        // ── Threshold check & actuator logic ─────────────
        bool alert = (pm25 > pm25Threshold) ||
                     (co2  > co2Threshold)  ||
                     (spec > specThreshold);

        // Manual override expires after OVERRIDE_DUR ms
        if(manualOverride && (millis() - overrideStart > OVERRIDE_DUR)) {
            manualOverride = false;
            Serial.println("🔄 Auto-mode resumed");
        }

        if(!manualOverride) {
            digitalWrite(ACT_PIN, alert ? HIGH : LOW);
            if(alert) {
                Serial.println("🚨 THRESHOLD EXCEEDED → " + String(Z->actuator) + " ACTIVATED");
                // Report which sensor triggered
                if(pm25 > pm25Threshold) Serial.printf("   PM2.5 %.1f > %.1f\n", pm25, pm25Threshold);
                if(co2  > co2Threshold)  Serial.printf("   CO2   %.1f > %.1f\n", co2,  co2Threshold);
                if(spec > specThreshold) Serial.printf("   %s %.1f > %.1f\n", Z->specLabel, spec, specThreshold);
            }
        }
    }
}