/*
 * VALIS Node Firmware — ESP32-C3
 * Variable Arrived Location In Superposition
 *
 * Proof of concept: Meilong scatter protocol over serial.
 * Phase 1: Pi sends message via serial, ESP32 scrambles into 3 XOR shares,
 *          outputs each share on separate "channels" (simulated via tagged serial output).
 *          Pi collects shares and reassembles.
 *
 * Phase 2 (with coupling hardware): inject shares onto power line via DAC/ADC.
 *
 * "It's a walkie-talkie with math."
 */

#include <Arduino.h>
#include <ArduinoJson.h>

#define LED_PIN 8
#define MAX_MSG_LEN 256

// === MEILONG PROTOCOL ===

void scramble(const uint8_t* data, size_t len, uint8_t* s1, uint8_t* s2, uint8_t* s3) {
  // Generate two random shares, XOR to create third
  for (size_t i = 0; i < len; i++) {
    s1[i] = (uint8_t)random(256);
    s2[i] = (uint8_t)random(256);
    s3[i] = data[i] ^ s1[i] ^ s2[i];
  }
}

void reassemble(const uint8_t* s1, const uint8_t* s2, const uint8_t* s3, size_t len, uint8_t* out) {
  for (size_t i = 0; i < len; i++) {
    out[i] = s1[i] ^ s2[i] ^ s3[i];
  }
}

// === BASE64 (minimal for share transport) ===

static const char b64chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

String toBase64(const uint8_t* data, size_t len) {
  String out = "";
  for (size_t i = 0; i < len; i += 3) {
    uint32_t n = ((uint32_t)data[i]) << 16;
    if (i + 1 < len) n |= ((uint32_t)data[i + 1]) << 8;
    if (i + 2 < len) n |= data[i + 2];
    out += b64chars[(n >> 18) & 0x3F];
    out += b64chars[(n >> 12) & 0x3F];
    out += (i + 1 < len) ? b64chars[(n >> 6) & 0x3F] : '=';
    out += (i + 2 < len) ? b64chars[n & 0x3F] : '=';
  }
  return out;
}

// === LED FEEDBACK ===

void blinkLED(int times, int delayMs) {
  for (int i = 0; i < times; i++) {
    digitalWrite(LED_PIN, HIGH);
    delay(delayMs);
    digitalWrite(LED_PIN, LOW);
    delay(delayMs);
  }
}

void setLED(bool on) {
  digitalWrite(LED_PIN, on ? HIGH : LOW);
}

// === NODE STATE ===

enum NodeMode {
  MODE_IDLE,
  MODE_SCATTER,
  MODE_COLLECT,
  MODE_RELAY
};

NodeMode currentMode = MODE_IDLE;
String nodeId = "";
unsigned long lastHeartbeat = 0;

// === SERIAL PROTOCOL ===
// Commands from Pi:
//   {"cmd":"scatter","msg":"hello world"}     — scramble and output 3 shares
//   {"cmd":"collect","s1":"...","s2":"...","s3":"..."}  — reassemble from 3 shares
//   {"cmd":"ping"}                             — heartbeat check
//   {"cmd":"id"}                               — report node ID
//
// Responses to Pi:
//   {"type":"share","index":0,"data":"base64...","hop":"uuid"}
//   {"type":"share","index":1,"data":"base64...","hop":"uuid"}
//   {"type":"share","index":2,"data":"base64...","hop":"uuid"}
//   {"type":"assembled","msg":"hello world","hop":"uuid"}
//   {"type":"pong","id":"node-xxxx","uptime":12345}

String serialBuffer = "";

void processCommand(const String& json) {
  JsonDocument doc;
  DeserializationError err = deserializeJson(doc, json);
  if (err) {
    Serial.println("{\"type\":\"error\",\"msg\":\"bad json\"}");
    return;
  }

  const char* cmd = doc["cmd"];
  if (!cmd) return;

  // === PING ===
  if (strcmp(cmd, "ping") == 0) {
    JsonDocument resp;
    resp["type"] = "pong";
    resp["id"] = nodeId;
    resp["uptime"] = millis() / 1000;
    resp["mode"] = currentMode;
    serializeJson(resp, Serial);
    Serial.println();
    blinkLED(1, 50);
    return;
  }

  // === ID ===
  if (strcmp(cmd, "id") == 0) {
    JsonDocument resp;
    resp["type"] = "identity";
    resp["id"] = nodeId;
    resp["chip"] = "ESP32-C3";
    resp["protocol"] = "VALIS/Meilong";
    resp["version"] = "0.1";
    serializeJson(resp, Serial);
    Serial.println();
    return;
  }

  // === SCATTER (Meilong scramble) ===
  if (strcmp(cmd, "scatter") == 0) {
    const char* msg = doc["msg"];
    if (!msg) {
      Serial.println("{\"type\":\"error\",\"msg\":\"no message\"}");
      return;
    }

    setLED(true);
    currentMode = MODE_SCATTER;

    size_t len = strlen(msg);
    if (len > MAX_MSG_LEN) len = MAX_MSG_LEN;

    uint8_t s1[MAX_MSG_LEN], s2[MAX_MSG_LEN], s3[MAX_MSG_LEN];
    scramble((const uint8_t*)msg, len, s1, s2, s3);

    // Generate hop ID
    String hopId = String(random(100000, 999999));

    // Output each share with a staggered delay (simulating different routes)
    uint8_t* shares[] = {s1, s2, s3};
    const char* routes[] = {"alpha", "beta", "gamma"};

    for (int i = 0; i < 3; i++) {
      delay(100 + random(400));  // staggered — different "routes" take different time

      JsonDocument shareDoc;
      shareDoc["type"] = "share";
      shareDoc["index"] = i;
      shareDoc["route"] = routes[i];
      shareDoc["data"] = toBase64(shares[i], len);
      shareDoc["hop"] = hopId;
      shareDoc["len"] = len;
      serializeJson(shareDoc, Serial);
      Serial.println();

      blinkLED(1, 30);
    }

    // Confirm scatter complete
    JsonDocument done;
    done["type"] = "scattered";
    done["hop"] = hopId;
    done["shares"] = 3;
    done["msg_len"] = len;
    done["note"] = "the dragon sleeps between the nodes";
    serializeJson(done, Serial);
    Serial.println();

    currentMode = MODE_IDLE;
    setLED(false);
    return;
  }

  // === HEARTBEAT ===
  Serial.println("{\"type\":\"error\",\"msg\":\"unknown command\"}");
}

// === SETUP ===

void setup() {
  Serial.begin(115200);
  pinMode(LED_PIN, OUTPUT);

  // Generate node ID from chip MAC
  uint64_t mac = ESP.getEfuseMac();
  nodeId = "valis-" + String((uint32_t)(mac >> 24), HEX);

  // Seed random from analog noise
  randomSeed(analogRead(0) ^ micros());

  delay(1000);

  // Boot announcement
  JsonDocument boot;
  boot["type"] = "boot";
  boot["id"] = nodeId;
  boot["protocol"] = "VALIS/Meilong";
  boot["version"] = "0.1";
  boot["chip"] = "ESP32-C3";
  boot["msg"] = "node online — the dragon stirs";
  serializeJson(boot, Serial);
  Serial.println();

  blinkLED(3, 100);
}

// === LOOP ===

void loop() {
  // Read serial input
  while (Serial.available()) {
    char c = Serial.read();
    if (c == '\n' || c == '\r') {
      if (serialBuffer.length() > 0) {
        processCommand(serialBuffer);
        serialBuffer = "";
      }
    } else {
      serialBuffer += c;
      if (serialBuffer.length() > 1024) {
        serialBuffer = "";  // overflow protection
      }
    }
  }

  // Periodic heartbeat (every 30s)
  if (millis() - lastHeartbeat > 30000) {
    lastHeartbeat = millis();
    JsonDocument hb;
    hb["type"] = "heartbeat";
    hb["id"] = nodeId;
    hb["uptime"] = millis() / 1000;
    hb["mode"] = currentMode;
    serializeJson(hb, Serial);
    Serial.println();
  }
}