#include <SPI.h>
#include <LoRa.h>

// ==========================================
// PIN DEFINITIONS (Sama dengan Node 2 - ESP8266)
// ==========================================
#define LORA_SS    D8  // NSS/CS
#define LORA_RST   D0  // Reset LoRa
#define LORA_DIO0  D1  // DIO0 / Interrupt
#define BUZZER_PIN D2  // Buzzer
#define LED_PIN    D3  // LED Status

// ==========================================
// PACKET STRUCTURE (MUTLAK SAMA dengan Node 1 & Node 2)
// ==========================================
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;     // RSSI yang diterima Gateway
    float snr_gw;    // SNR yang diterima Gateway
    int rssi_b;      // RSSI yang diterima Node B
    float snr_b;     // SNR yang diterima Node B
} struct_message;

struct_message recvData;

// ==========================================
// SETUP
// ==========================================
void setup() {
  Serial.begin(115200);
  delay(1000); // Jeda extra agar Serial siap
  Serial.println("\n--- LoRa Gateway Starting ---");
  
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(LED_PIN, OUTPUT);
  digitalWrite(BUZZER_PIN, LOW);
  digitalWrite(LED_PIN, LOW);

  // Inisialisasi SPI secara tegas
  SPI.begin();
  LoRa.setPins(LORA_SS, LORA_RST, LORA_DIO0);
  
  if (!LoRa.begin(433E6)) {
    Serial.println("Gagal Inisialisasi LoRa Gateway");
    // Indikator Error: Beep 2x cepat setiap 20 detik
    while (1) {
      for (int i = 0; i < 2; i++) {
        digitalWrite(LED_PIN, HIGH);
        digitalWrite(BUZZER_PIN, HIGH);
        delay(100);
        digitalWrite(LED_PIN, LOW);
        digitalWrite(BUZZER_PIN, LOW);
        delay(100);
      }
      delay(19600); // Jeda hingga mencapai 20 detik total (20000ms - 400ms)
    }
  }
  
  // LED Nyala terus menandakan alat SIAP/READY
  digitalWrite(LED_PIN, HIGH);
  Serial.println("Repeater LoRa (Gateway Perantara) Standby (V2 Piggybacking)");
}

// ==========================================
// LOOP (TANGKAP & PANTULKAN)
// ==========================================
void loop() {
  int packetSize = LoRa.parsePacket();
  
  if (packetSize == sizeof(struct_message)) {
    LoRa.readBytes((uint8_t*)&recvData, sizeof(recvData));

    // 1. CEK IDENTITAS PENGIRIM (Proteksi Broadcast Storm)
    if (recvData.senderId != 3) {
      
      Serial.print("Menerima paket dari Node ");
      Serial.print(recvData.senderId);
      Serial.println(". Memantulkan...");

      // JIKA PAKET DARI NODE 2 (B) - Berarti jalur Balasan (Downlink)
      // Kita suntikkan kualitas sinyal Hop 1 (jalur pulang) ke sini
      if (recvData.senderId == 2) {
          recvData.rssi_gw = LoRa.packetRssi();
          recvData.snr_gw = LoRa.packetSnr();
          Serial.println("Downlink: Menyuntikkan Sinyal dari Node B ke Paket");
      }

      // 2. INDIKATOR SUARA & CAHAYA
      digitalWrite(LED_PIN, LOW);    // Matikan LED sebentar
      digitalWrite(BUZZER_PIN, HIGH); // Bunyikan Buzzer
      delay(50); 
      digitalWrite(BUZZER_PIN, LOW);
      digitalWrite(LED_PIN, HIGH);   // Nyalakan kembali LED (Ready state)

      if (recvData.senderId == 1 && recvData.msgType == 2) {
          struct_message repPong;
          memset(&repPong, 0, sizeof(repPong));
          repPong.msgType = 3; // PONG
          repPong.packetId = 0;
          repPong.totalPackets = 1;
          repPong.senderId = 3; // Identitas Repeater
          strcpy(repPong.text, "REPEATER_READY");
          
          delay(600); // Beri waktu Node A bersiap & Web App merender state awal
          LoRa.beginPacket();
          LoRa.write((uint8_t*)&repPong, sizeof(repPong));
          LoRa.endPacket();
          Serial.println("Mengirim status REPEATER_READY ke Node 1");
      }

      // 3. UBAH IDENTITAS PAKET
      recvData.senderId = 3; 

      // 4. JEDA AMAN UDARA
      // Gunakan delay cepat (50ms) untuk pengiriman data (chunking) agar tidak memakan waktu lama
      // Gunakan delay lama (500ms) untuk PING/PONG agar Web App sempat me-render state UI
      if (recvData.msgType == 0 || recvData.msgType == 1) {
          delay(50);
      } else {
          delay(500); 
      } 

      // 5. PANTULKAN (RE-BROADCAST)
      LoRa.beginPacket();
      LoRa.write((uint8_t*)&recvData, sizeof(recvData));
      LoRa.endPacket();

      Serial.println("Paket sukses dipantulkan ke udara!");
    }
  }
}