#include <WiFi.h>
#include <esp_now.h>
#include <FastLED.h>

// =========================
// LED / Button configuration
// =========================
#define STATUS_LED_PIN 1
#define LED_PIN        6
#define BUTTON_PIN     A0
#define NUM_LEDS       144
#define LED_TYPE       WS2812B
#define COLOR_ORDER    GRB

// =========================
// Brightness
// 70% of 255 = 178.5 -> 179
// =========================
constexpr uint8_t MAX_BRIGHTNESS = 179;

// =========================
// Timing
// =========================
constexpr unsigned long PRINT_INTERVAL = 1000;
constexpr unsigned long DEBOUNCE_TIME  = 50;

// =========================
// LED buffer
// =========================
CRGB leds[NUM_LEDS];

// =========================
// Stored RGB values
// These are the values that are
// currently stored from received packets
// and will be shown on button press
// =========================
uint8_t RED   = 0;
uint8_t GREEN = 0;
uint8_t BLUE  = 0;

// =========================
// Last received packet values
// (for debug / transparency)
// =========================
uint8_t lastRxValue1 = 0;
uint8_t lastRxValue2 = 0;
uint8_t lastRxValue3 = 0;
bool lastRxValid1 = false;
bool lastRxValid2 = false;
bool lastRxValid3 = false;

// =========================
// Receive state / debug
// =========================
bool newPacketReceived = false;
unsigned long packetCounter = 0;
unsigned long lastPrintTime = 0;

// =========================
// Button state
// INPUT_PULLUP:
// released = HIGH
// pressed  = LOW
// =========================
bool lastButtonReading = HIGH;
bool stableButtonState = HIGH;
unsigned long lastDebounceTime = 0;

// =========================
// Data packet from master
// Must match the sender struct exactly
// =========================
struct DataPacket {
  uint8_t valid1;
  uint8_t valid2;
  uint8_t valid3;
  uint8_t value1;
  uint8_t value2;
  uint8_t value3;
};

// =========================
// Status LED blink request
// We only set a flag in callbacks
// and blink later in loop()
// =========================
bool blinkRequest = false;

// =========================
// Helper: print MAC address
// =========================
void printMacAddress(const uint8_t* mac) {
  for (int i = 0; i < 6; i++) {
    if (mac[i] < 16) Serial.print("0");
    Serial.print(mac[i], HEX);
    if (i < 5) Serial.print(":");
  }
  Serial.println();
}

// =========================
// Update LED strip
// =========================
void updateLEDs() {
  fill_solid(leds, NUM_LEDS, CRGB(RED, GREEN, BLUE));
  FastLED.show();
}

// =========================
// Short visual feedback
// =========================
void runStatusBlinkIfRequested() {
  if (!blinkRequest) {
    return;
  }

  blinkRequest = false;

  digitalWrite(STATUS_LED_PIN, HIGH);
  delay(80);
  digitalWrite(STATUS_LED_PIN, LOW);
}

// =========================
// ESP-NOW receive callback
// Keep this short
// =========================
void onDataRecv(const esp_now_recv_info_t *recvInfo, const uint8_t *incomingData, int len) {
  if (len != sizeof(DataPacket)) {
    return;
  }

  DataPacket packet;
  memcpy(&packet, incomingData, sizeof(packet));

  // Save received values for debug
  lastRxValid1 = (packet.valid1 == 1);
  lastRxValid2 = (packet.valid2 == 1);
  lastRxValid3 = (packet.valid3 == 1);

  lastRxValue1 = packet.value1;
  lastRxValue2 = packet.value2;
  lastRxValue3 = packet.value3;

  // Update only values that were actually transmitted
  // Missing values keep their previous stored state
  if (packet.valid1) {
    RED = packet.value1;
  }
  if (packet.valid2) {
    GREEN = packet.value2;
  }
  if (packet.valid3) {
    BLUE = packet.value3;
  }

  packetCounter++;
  newPacketReceived = true;
  blinkRequest = true;
}

// =========================
// Button handling
// On button press, show the currently
// stored RGB values on the LED strip
// =========================
void handleButton() {
  bool reading = digitalRead(BUTTON_PIN);

  if (reading != lastButtonReading) {
    lastDebounceTime = millis();
  }

  if ((millis() - lastDebounceTime) > DEBOUNCE_TIME) {
    if (reading != stableButtonState) {
      stableButtonState = reading;

      if (stableButtonState == LOW) {
        Serial.println("Slave button pressed -> showing stored RGB values");
        Serial.print("Applying R: ");
        Serial.print(RED);
        Serial.print(" | G: ");
        Serial.print(GREEN);
        Serial.print(" | B: ");
        Serial.println(BLUE);
        Serial.println();

        updateLEDs();

        digitalWrite(STATUS_LED_PIN, HIGH);
        delay(120);
        digitalWrite(STATUS_LED_PIN, LOW);
        delay(80);
        digitalWrite(STATUS_LED_PIN, HIGH);
        delay(120);
        digitalWrite(STATUS_LED_PIN, LOW);
      }
    }
  }

  lastButtonReading = reading;
}

// =========================
// Periodic serial output
// =========================
void printStatusIfDue() {
  unsigned long now = millis();

  if (now - lastPrintTime < PRINT_INTERVAL) {
    return;
  }

  lastPrintTime = now;

  Serial.print("Stored RGB -> R: ");
  Serial.print(RED);
  Serial.print(" | G: ");
  Serial.print(GREEN);
  Serial.print(" | B: ");
  Serial.print(BLUE);

  Serial.print(" | Last packet #: ");
  Serial.print(packetCounter);

  Serial.print(" | Button raw: ");
  Serial.println(digitalRead(BUTTON_PIN));

  Serial.print("Last RX packet -> ");
  Serial.print("S1: ");
  if (lastRxValid1) Serial.print(lastRxValue1);
  else Serial.print("not transmitted");

  Serial.print(" | S2: ");
  if (lastRxValid2) Serial.print(lastRxValue2);
  else Serial.print("not transmitted");

  Serial.print(" | S3: ");
  if (lastRxValid3) Serial.println(lastRxValue3);
  else Serial.println("not transmitted");

  if (newPacketReceived) {
    Serial.println("New packet has been received and stored.");
    newPacketReceived = false;
  }

  Serial.println();
}

// =========================
// ESP-NOW initialization
// =========================
bool initEspNowReceiver() {
  WiFi.mode(WIFI_STA);
  WiFi.disconnect();

  Serial.print("Receiver STA MAC: ");
  Serial.println(WiFi.macAddress());

  if (esp_now_init() != ESP_OK) {
    Serial.println("ESP-NOW initialization failed");
    return false;
  }

  if (esp_now_register_recv_cb(onDataRecv) != ESP_OK) {
    Serial.println("Failed to register receive callback");
    return false;
  }

  Serial.println("ESP-NOW receiver ready");
  return true;
}

// =========================
// Setup
// =========================
void setup() {
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(STATUS_LED_PIN, OUTPUT);
  digitalWrite(STATUS_LED_PIN, LOW);

  Serial.begin(115200);
  delay(2000);

  Serial.println();
  Serial.println("ESP32-C3 Slave / Receiver");
  Serial.println("ESP-NOW + FastLED");
  Serial.println();

  FastLED.addLeds<LED_TYPE, LED_PIN, COLOR_ORDER>(leds, NUM_LEDS);
  FastLED.setBrightness(MAX_BRIGHTNESS);
  FastLED.clear();
  FastLED.show();

  if (!initEspNowReceiver()) {
    Serial.println("Receiver setup failed. Stopping here.");
    while (true) {
      delay(1000);
    }
  }

  Serial.println();
  Serial.println("System ready.");
  Serial.println("Waiting for packets...");
  Serial.println("Press local button to show currently stored RGB values.");
  Serial.println();
}

// =========================
// Main loop
// =========================
void loop() {
  handleButton();
  runStatusBlinkIfRequested();
  printStatusIfDue();
}