#include <Arduino.h>
#include <SPI.h>
#include <Wire.h>
#include <RadioLib.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// =========================
// LoRa pins - LilyGO T3S3 SX1262
// =========================
static const int PIN_LORA_SCK  = 5;
static const int PIN_LORA_MISO = 3;
static const int PIN_LORA_MOSI = 6;
static const int PIN_LORA_CS   = 7;
static const int PIN_LORA_RST  = 8;
static const int PIN_LORA_DIO1 = 33;
static const int PIN_LORA_BUSY = 34;

// =========================
// Button - LilyGO T3S3
// BOOT button usually GPIO0, active low
// =========================
static const int PIN_BUTTON = 0;

// =========================
// OLED pins - LilyGO T3S3 OLED
// =========================
static const int OLED_SDA = 18;
static const int OLED_SCL = 17;
static const int OLED_ADDR = 0x3C;
static const int SCREEN_WIDTH = 128;
static const int SCREEN_HEIGHT = 64;

// =========================
// ACTIVE PROFILE - Shelly / custom LoRa
// =========================
static const float LORA_FREQ_MHZ      = 865.000;
static const float LORA_BW_KHZ        = 125.0;
static const uint8_t LORA_SF          = 12;
static const uint8_t LORA_CR          = 5;
static const uint8_t LORA_SYNC_WORD   = 0x12;
static const int8_t  LORA_TX_POWER    = 10;
static const uint16_t LORA_PREAMBLE   = 10;
static const float LORA_TCXO_VOLTAGE  = 1.6;
static const bool LORA_USE_LDO        = false;
static const bool LORA_USE_CRC        = false;
static const bool LORA_EXPLICIT_HDR   = true;

// =========================
// Protocol
// =========================
static const String DEVICE_ID = "MG64738";
static const String CMD_ON    = "ON";
static const String CMD_OFF   = "OF";

// =========================
// Objects
// =========================
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
SX1262 radio = new Module(PIN_LORA_CS, PIN_LORA_DIO1, PIN_LORA_RST, PIN_LORA_BUSY);

// =========================
// Runtime state
// =========================
bool outputState = true;       // start with ON
bool lastButtonState = HIGH;
unsigned long lastDebounceMs = 0;
unsigned long txCount = 0;
int lastTxState = 0;

static const unsigned long DEBOUNCE_MS = 60;

// =========================
// Helpers
// =========================
String formatCR(uint8_t cr) {
  return "4/" + String(cr);
}

String formatHexByte(uint8_t value) {
  char buf[5];
  snprintf(buf, sizeof(buf), "%02X", value);
  return String(buf);
}

String currentPayload() {
  return DEVICE_ID + "|" + (outputState ? CMD_ON : CMD_OFF);
}

void drawLine(int x, int y, const String& text) {
  display.setCursor(x, y);
  display.print(text);
}

void drawStatusScreen(const String& status) {
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);

  drawLine(0, 0, "LoRa Button TX");
  drawLine(88, 0, String(txCount) + " tx");

  drawLine(0, 10, "F:" + String(LORA_FREQ_MHZ, 3));
  drawLine(0, 20, "BW:" + String(LORA_BW_KHZ, 1) + " SF:" + String(LORA_SF));
  drawLine(0, 30, "CR:" + formatCR(LORA_CR) + " SW:0x" + formatHexByte(LORA_SYNC_WORD));

  drawLine(0, 42, status);
  drawLine(0, 54, currentPayload());

  display.display();
}

void drawErrorScreen(const String& title, int code) {
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);

  drawLine(0, 0, title);
  drawLine(0, 12, "code: " + String(code));

  display.display();
}

void sendCurrentState() {
  String payload = currentPayload();

  drawStatusScreen("Sending...");

  Serial.print("TX: ");
  Serial.println(payload);

  int state = radio.transmit(payload);
  lastTxState = state;

  if (state == RADIOLIB_ERR_NONE) {
    txCount++;

    Serial.println("TX OK");
    drawStatusScreen(outputState ? "Sent ON" : "Sent OF");
  } else {
    Serial.print("TX failed, code ");
    Serial.println(state);
    drawStatusScreen("TX failed: " + String(state));
  }
}

void setup() {
  Serial.begin(115200);
  delay(1500);

  pinMode(PIN_BUTTON, INPUT_PULLUP);

  Wire.begin(OLED_SDA, OLED_SCL);

  if (!display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR)) {
    Serial.println("OLED init failed");
    while (true) delay(1000);
  }

  drawStatusScreen("Booting...");

  SPI.begin(PIN_LORA_SCK, PIN_LORA_MISO, PIN_LORA_MOSI, PIN_LORA_CS);

  Serial.println();
  Serial.println("Starting LoRa button sender...");

  int state = radio.begin(
    LORA_FREQ_MHZ,
    LORA_BW_KHZ,
    LORA_SF,
    LORA_CR,
    LORA_SYNC_WORD,
    LORA_TX_POWER,
    LORA_PREAMBLE,
    LORA_TCXO_VOLTAGE,
    LORA_USE_LDO
  );

  if (state != RADIOLIB_ERR_NONE) {
    Serial.print("radio.begin failed, code ");
    Serial.println(state);
    drawErrorScreen("LoRa init failed", state);
    while (true) delay(1000);
  }

  if (LORA_EXPLICIT_HDR) {
    state = radio.explicitHeader();
  } else {
    state = radio.implicitHeader(LORA_PREAMBLE);
  }

  if (state != RADIOLIB_ERR_NONE) {
    Serial.print("header mode failed, code ");
    Serial.println(state);
    drawErrorScreen("Header config failed", state);
    while (true) delay(1000);
  }

  state = radio.setCRC(LORA_USE_CRC);

  if (state != RADIOLIB_ERR_NONE) {
    Serial.print("CRC config failed, code ");
    Serial.println(state);
    drawErrorScreen("CRC config failed", state);
    while (true) delay(1000);
  }

  drawStatusScreen("Ready");

  sendCurrentState();   // first send = MG64738|ON
}

void loop() {
  bool buttonState = digitalRead(PIN_BUTTON);

  if (buttonState != lastButtonState) {
    lastDebounceMs = millis();
    lastButtonState = buttonState;
  }

  if ((millis() - lastDebounceMs) > DEBOUNCE_MS) {
    static bool pressHandled = false;

    if (buttonState == LOW && !pressHandled) {
      pressHandled = true;

      outputState = !outputState;
      sendCurrentState();
    }

    if (buttonState == HIGH) {
      pressHandled = false;
    }
  }
}