#include <SPI.h>
#include <LoRa.h>
#include <LittleFS.h>      // Memori Permanen
#include <WiFiManager.h>   // Portal Config
#include <ArduinoJson.h>    // Format Data
#include <Ticker.h>        // Kedipan LED Status
#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#include <WiFiClientSecure.h>

// ==========================================
// PIN DEFINITIONS (LoRa SPI & Control)
// ==========================================
#define LORA_SS   D8  // NSS/CS (Tetap di bawah)
#define LORA_RST  D0  // Reset LoRa (Paling Atas)
#define LORA_DIO0 D1  // Interrupt LoRa (Urutan ke-2)
#define BUZZER_PIN D2 // Buzzer (Urutan ke-3)
#define BUTTON_PIN D3 // Pin Reset Button (Urutan ke-4)
#define STATUS_LED_PIN D4 // Pin LED Status (Urutan ke-5)

// ==========================================
// VARIABLES
// ==========================================
char n8n_url[200] = ""; 
bool shouldSaveConfig = false;

typedef struct struct_message {
    char text[220];  // Kapasitas dikurangi untuk 4 variabel sinyal
    int msgType;     // 0=Request, 1=Response, 2=Ping, 3=Pong
    int packetId;    
    int totalPackets;
    int senderId;    // 1=Node1, 2=Node2, 3=Repeater
    int rssi_gw;     // Sinyal Hop 1 (A -> GW)
    float snr_gw;
    int rssi_b;      // Sinyal Hop 2 (GW -> B)
    float snr_b;
} struct_message;

struct_message recvData;
struct_message sendData;
char jsonBufferReq[1024];

volatile bool dataReceived = false;
volatile bool isPingRequested = false;
wl_status_t lastWifiStatus = WL_IDLE_STATUS;
unsigned long lastWifiCheck = 0;
unsigned long lastDisconnectBeep = 0;

// Reset Button Helpers
unsigned long pressStartTime = 0;
bool isPressed = false;

// Status LED Objects
Ticker statusTicker;

// ==========================================
// HELPER FUNCTIONS
// ==========================================
// Buzzer Beep Function
void beep(int count, int durationMs) {
    for(int i=0; i<count; i++) {
        digitalWrite(BUZZER_PIN, HIGH);
        delay(durationMs);
        digitalWrite(BUZZER_PIN, LOW);
        if (i < count-1) delay(100);
    }
}

// Callback Ticker untuk berkedip
void tick() {
  int state = digitalRead(STATUS_LED_PIN); 
  digitalWrite(STATUS_LED_PIN, !state);
}

// Callback WiFiManager saat masuk mode portal
void configModeCallback (WiFiManager *myWiFiManager) {
  Serial.println("Masuk Mode Konfigurasi...");
  Serial.println(WiFi.softAPIP());
  statusTicker.attach(0.1, tick); // Kedip super cepat saat Portal Aktif
}

// Callback Simpan Konfigurasi
void saveConfigCallback () {
  Serial.println("Menerima Konfigurasi Baru...");
  shouldSaveConfig = true;
}

// Load Config dari LittleFS
void loadConfig() {
  if (LittleFS.begin()) {
    if (LittleFS.exists("/config.json")) {
      File configFile = LittleFS.open("/config.json", "r");
      if (configFile) {
        size_t size = configFile.size();
        std::unique_ptr<char[]> buf(new char[size]);
        configFile.readBytes(buf.get(), size);
        DynamicJsonDocument json(1024);
        deserializeJson(json, buf.get());
        strcpy(n8n_url, json["n8n_url"]);
        Serial.print("Config Loaded: "); Serial.println(n8n_url);
      }
    }
  } else {
    Serial.println("Gagal mematikan LittleFS");
  }
}

// Save Config ke LittleFS
void saveConfig() {
  Serial.println("Menyimpan Config ke LittleFS...");
  DynamicJsonDocument json(1024);
  json["n8n_url"] = n8n_url;
  File configFile = LittleFS.open("/config.json", "w");
  if (!configFile) {
    Serial.println("Gagal membuka file config untuk menulis");
  }
  serializeJson(json, configFile);
  configFile.close();
}

// Send Data via LoRa
void sendDataLoRa(struct_message *data) {
  LoRa.beginPacket();
  LoRa.write((uint8_t*)data, sizeof(struct_message));
  LoRa.endPacket();
}

// ==========================================
// SETUP
// ==========================================
void setup() {
  Serial.begin(115200);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(STATUS_LED_PIN, OUTPUT);
  digitalWrite(BUZZER_PIN, LOW);
  digitalWrite(STATUS_LED_PIN, LOW);

  // Mulai kedipan lambat (sedang mencari WiFi)
  statusTicker.attach(0.6, tick);

  // 1. Baca Konfigurasi Tersimpan
  loadConfig();

  // 2. Setup WiFiManager
  WiFiManager wm;
  wm.setSaveConfigCallback(saveConfigCallback);
  wm.setAPCallback(configModeCallback);
  
  // Tambahkan Input Custom untuk URL n8n
  WiFiManagerParameter custom_n8n_url("n8n", "N8N Webhook URL", n8n_url, 199);
  wm.addParameter(&custom_n8n_url);

  // Suara tanda portal siap
  beep(1, 300);

  // Start Portal (Hotspot: Stunting-Gateway-Config)
  if (!wm.autoConnect("Stunting-Gateway-Config")) {
    Serial.println("Gagal konek WiFi.");
    delay(3000);
    ESP.restart();
  }

  // Ambil nilai dari portal
  strcpy(n8n_url, custom_n8n_url.getValue());

  // Matikan Ticker setelah konek
  statusTicker.detach();

  // Simpan jika user mengubah nilainya
  if (shouldSaveConfig) {
    saveConfig();
    beep(2, 100); 
  }

  Serial.println("Connected to WiFi!");
  digitalWrite(STATUS_LED_PIN, HIGH); // LED Nyala Diam (Sukses)
  Serial.print("IP: "); Serial.println(WiFi.localIP());
  Serial.print("N8N URL: "); Serial.println(n8n_url);
  beep(1, 100); 

  // Setup LoRa
  LoRa.setPins(LORA_SS, LORA_RST, LORA_DIO0);
  if (!LoRa.begin(433E6)) { 
    Serial.println("Error initializing LoRa");
    while (1) { delay(1000); }
  }
  
  Serial.println("Gateway LoRa Ready (V2 Piggybacking)");
  lastWifiStatus = WiFi.status();
}

// ==========================================
// LOOP
// ==========================================
void loop() {
  // --- 1. RESET BUTTON MONITORING (D4) ---
  if (digitalRead(BUTTON_PIN) == LOW) {
    if (!isPressed) { isPressed = true; pressStartTime = millis(); }
    unsigned long pressDuration = millis() - pressStartTime;
    
    if (pressDuration > 2000) { digitalWrite(BUZZER_PIN, (millis() / 200) % 2); } // Bunyi alarm pelan

    if (pressDuration >= 5000) {
      Serial.println("!!!!!!! FACTORY RESET TRIGGERED !!!!!!!");
      beep(1, 2000); // Beep panjang tanda sukses reset
      
      WiFiManager wm;
      wm.resetSettings(); // Hapus WiFi
      LittleFS.format();  // Hapus Config n8n
      
      ESP.restart();
    }
  } else {
    if (isPressed) { isPressed = false; digitalWrite(BUZZER_PIN, LOW); }
  }

  // --- 2. WIFI STATUS MONITORING ---
  wl_status_t currentStatus = WiFi.status();
  if (currentStatus != lastWifiStatus) {
      if (currentStatus == WL_CONNECTED) {
          Serial.println("WiFi Reconnected!");
          digitalWrite(STATUS_LED_PIN, HIGH);
          beep(2, 100);
      } else {
          Serial.println("WiFi Disconnected");
      }
      lastWifiStatus = currentStatus;
  }

  // Alarm WiFi Offline (Setiap 10s)
  if (currentStatus != WL_CONNECTED) {
      digitalWrite(STATUS_LED_PIN, LOW); // Lampu Mati jika Offline
      if (millis() - lastDisconnectBeep > 10000) {
          lastDisconnectBeep = millis();
          beep(1, 400); 
          Serial.println("Status: Offline...");
      }
  }

  // --- 3. LORA RECEIVE LOGIC ---
  int packetSize = LoRa.parsePacket();
  if (packetSize == sizeof(struct_message)) {
    uint8_t buffer[sizeof(struct_message)];
    int i = 0;
    while (LoRa.available() && i < sizeof(struct_message)) {
      buffer[i] = LoRa.read();
      i++;
    }
    memcpy(&recvData, buffer, sizeof(struct_message));
    recvData.text[219] = '\0'; // ensure null termination (kapasitas diubah ke 220)
    
    // STRICT ROUTING: HANYA terima data dari Node Perantara (Repeater / ID 3)
    // Abaikan jika data datang langsung dari Node 1 atau pantulan Node 2 sendiri
    if (recvData.senderId != 3) return;
    
    if (recvData.msgType == 0) { // DATA REQUEST
        if (recvData.packetId == 0) {
            memset(jsonBufferReq, 0, sizeof(jsonBufferReq));
        }
        
        int currentLen = strlen(jsonBufferReq);
        int spaceLeft = sizeof(jsonBufferReq) - currentLen - 1;
        if (spaceLeft > 0) {
            strncat(jsonBufferReq, recvData.text, spaceLeft);
        }

        if (recvData.packetId == recvData.totalPackets - 1) {
            // Menangkap RSSI dan SNR Hop 2 di Node B ini
            recvData.rssi_b = LoRa.packetRssi();
            recvData.snr_b = LoRa.packetSnr();
            
            dataReceived = true;
            beep(1, 50); 
        }
    } else if (recvData.msgType == 2) {
        isPingRequested = true; 
        beep(1, 40); 
    }
  }

  // --- 4. HANDLE PING (UI CHECK) ---
  if (isPingRequested) {
      isPingRequested = false;
      sendData.msgType = 3; 
      sendData.packetId = 0;
      sendData.totalPackets = 1;
      sendData.senderId = 2;

      if (WiFi.status() != WL_CONNECTED) {
          strcpy(sendData.text, "WIFI_ERROR");
      } else if (strlen(n8n_url) < 10) {
          strcpy(sendData.text, "N8N_ERROR"); // Belum diatur
      } else {
          // Cukup pastikan WiFi terhubung dan URL N8N Tersetting.
          // JANGAN lakukan POST ke webhook n8n agar tidak mengirim eksekusi palsu (ghost trigger)
          strcpy(sendData.text, "READY");
      }
      sendDataLoRa(&sendData);
  }

  // --- 5. HANDLE DATA (SEND TO n8n) ---
  if (dataReceived) {
      dataReceived = false; 
      Serial.println("Forwarding to n8n...");
      
      // Inject RSSI dan SNR ke dalam JSON Payload sebelum dikirim
      String payloadReq = String(jsonBufferReq);
      int lastBrace = payloadReq.lastIndexOf('}');
      if (lastBrace != -1) {
          payloadReq.remove(lastBrace);
          payloadReq += ",\"rssi_b\":" + String(recvData.rssi_b) + 
                        ",\"snr_b\":" + String(recvData.snr_b) + "}";
      }

      if (WiFi.status() == WL_CONNECTED && strlen(n8n_url) > 10) {
          WiFiClientSecure client;
          client.setInsecure(); 
          HTTPClient http;
          
          if (http.begin(client, n8n_url)) { 
              http.setTimeout(30000);
              http.addHeader("Content-Type", "application/json");
              int httpCode = -1;
              int retryCount = 0;
              
              while (retryCount < 3) {
                  httpCode = http.POST(payloadReq); // Kirim Payload yang sudah ada titipan RSSI
                  if (httpCode > 0) break;
                  retryCount++;
                  delay(1500); 
              }

              String payload = "{}";
              if (httpCode > 0) {
                  payload = http.getString();
                  Serial.print("n8n RESPONSE: ");
                  Serial.println(payload);
                  beep(2, 100); 
              } else {
                  payload = "{\"status\":\"ERROR\",\"status_gizi\":\"error\",\"ai_narrative\":\"Gagal koneksi n8n.\"}";
                  beep(1, 1000); 
              }
              http.end();
              
              // CHUNKING LORA
              int payloadLen = payload.length();
              int chunkSize = 215; // Disesuaikan dengan kapasitas struct_message baru
              int totalPackets = (payloadLen + chunkSize - 1) / chunkSize;
              for(int i=0; i<totalPackets; i++) {
                  memset(&sendData, 0, sizeof(struct_message));
                  sendData.msgType = 1; // RESPONSE
                  sendData.packetId = i;
                  sendData.totalPackets = totalPackets;
                  sendData.senderId = 2;
                  int startIdx = i * chunkSize;
                  String chunk = payload.substring(startIdx, startIdx + chunkSize);
                  strncpy(sendData.text, chunk.c_str(), 219); 
                  sendDataLoRa(&sendData);
                  
                  if (i < totalPackets - 1) {
                      delay(400); // Beri jeda 400ms agar Repeater sempat memantulkan chunk sebelumnya
                  }
              }
          }
      } else {
          beep(3, 200); 
          String err = "{\"status_gizi\":\"offline\",\"ai_narrative\":\"Gateway Belum Siap.\"}";
          memset(&sendData, 0, sizeof(struct_message));
          sendData.msgType = 1;
          sendData.packetId = 0;
          sendData.totalPackets = 1;
          sendData.senderId = 2; // Node 2
          strncpy(sendData.text, err.c_str(), 219);
          sendDataLoRa(&sendData);
      }
  }
}