// archy-messh Phase 1 — tri-protocol RX scanner + trippy acid display
// ---------------------------------------------------------------------------
// Target: Heltec WiFi LoRa 32 V3 (ESP32-S3 + single SX1262 + 128x64 SSD1306).
//
// The radio rotates through the Reticulum / meshTastic / meshCore PHY presets
// (RTC), listening in each dwell window and logging every raw packet it
// demodulates. The OLED shows all three networks live — R T C — behind an
// animated acid-house smiley, with per-network activity blips. Received
// Meshtastic packets are decoded on-chip (AES-128-CTR + protobuf).
//
// HONEST HARDWARE NOTE: the single onboard SX1262 can only be tuned to ONE
// PHY at a time (ARCHITECTURE.md §2), so "all three active" is fast time-
// slicing, not literal simultaneity. True concurrent reception needs added
// radios (Phase 2 / Option B). The UI presents all three as armed; the scan
// cycles between them faster than a human notices.
//
// This increment still does NOT decode/bridge/transmit — that is the next
// roadmap step (firmware/README.md). It proves RX + the device UX.
// ---------------------------------------------------------------------------

#include <Arduino.h>
#include <RadioLib.h>
#include <U8g2lib.h>
#include <Wire.h>
#include <math.h>
#include "mbedtls/aes.h"

// --- Heltec V3 SX1262 pin map (from the Heltec V3 schematic) ----------------
static const int PIN_LORA_NSS  = 8;
static const int PIN_LORA_DIO1 = 14;
static const int PIN_LORA_NRST = 12;
static const int PIN_LORA_BUSY = 13;
static const int PIN_LORA_SCK  = 9;
static const int PIN_LORA_MISO = 11;
static const int PIN_LORA_MOSI = 10;
static const float  TCXO_VOLTAGE = 1.8f;
static const int8_t RX_TX_POWER  = 10;

// --- Heltec V3 OLED + power ------------------------------------------------
static const int PIN_OLED_SDA = 17;
static const int PIN_OLED_SCL = 18;
static const int PIN_OLED_RST = 21;
static const int PIN_VEXT     = 36;  // drives Vext rail; LOW = ON (powers OLED)

SX1262 radio = new Module(PIN_LORA_NSS, PIN_LORA_DIO1, PIN_LORA_NRST, PIN_LORA_BUSY);
U8G2_SSD1306_128X64_NONAME_F_HW_I2C oled(U8G2_R0, PIN_OLED_RST, PIN_OLED_SCL, PIN_OLED_SDA);

// --- The three PHY presets (RTC) -------------------------------------------
// Values from docs/ARCHITECTURE.md §1. Items flagged are open questions the
// scan is meant to test against reality.
struct PhyConfig {
  const char* name;
  char        letter;   // R / T / C  for the display
  float       freqMHz;
  float       bwKHz;
  uint8_t     sf;
  uint8_t     cr;       // 4/cr
  uint8_t     syncWord;
  uint16_t    preamble;
};

static const PhyConfig CONFIGS[] = {
  // meshTastic EU868 "LongFast" — confirmed correct (received live packets).
  { "meshtastic", 'T', 869.525f, 250.0f, 11, 5, 0x2b, 16 },
  // MeshCore compiled default PHY; sync word 0x12 is a GUESS (open item §1).
  { "meshcore",   'C', 869.525f, 250.0f, 11, 5, 0x12, 16 },
  // Reticulum has no fixed preset; PLACEHOLDER — set to your RNS RNode config.
  { "reticulum",  'R', 867.200f, 125.0f,  8, 5, 0x12, 16 },
};
static const size_t NUM_CONFIGS = sizeof(CONFIGS) / sizeof(CONFIGS[0]);
static const uint32_t DWELL_MS = 1200;   // faster cycle so all three feel live

// Device identity — this single name is what the bridge will present on ALL
// three networks once the participation/TX layer lands, so a message addressed
// to "Reticutasticore" on Meshtastic, MeshCore or Reticulum reaches this device:
//   - Meshtastic: User.long_name = DEVICE_NAME, short_name = DEVICE_SHORT (<=4)
//   - MeshCore:   advertised contact name = DEVICE_NAME
//   - Reticulum:  LXMF delivery display_name = DEVICE_NAME
// (RX-only today; the constants exist now so TX inherits them with no churn.)
static const char* DEVICE_NAME  = "Reticutasticore";
static const char* DEVICE_SHORT = "RTC";

// --- Runtime stats ----------------------------------------------------------
struct NetStat {
  uint32_t pkts = 0;
  int16_t  lastRssi = 0;
  bool     seen = false;
  uint32_t lastRxMs = 0;   // for the RX activity blip
};
static NetStat  stats[NUM_CONFIGS];
static int      activeIdx = 0;
static uint32_t totalPkts = 0;
static uint32_t dwellStart = 0;
static uint32_t frame = 0;

// Last decoded human-readable event, shown along the bottom of the display.
static char     lastMsg[40] = {0};
static char     lastMsgNet = ' ';
static uint32_t lastMsgMs = 0;

// --- RX interrupt -----------------------------------------------------------
static volatile bool rxFlag = false;
ICACHE_RAM_ATTR static void onDio1() { rxFlag = true; }

static bool applyConfig(const PhyConfig& c) {
  radio.standby();
  bool ok = true;
  ok &= radio.setFrequency(c.freqMHz)       == RADIOLIB_ERR_NONE;
  ok &= radio.setBandwidth(c.bwKHz)         == RADIOLIB_ERR_NONE;
  ok &= radio.setSpreadingFactor(c.sf)      == RADIOLIB_ERR_NONE;
  ok &= radio.setCodingRate(c.cr)           == RADIOLIB_ERR_NONE;
  ok &= radio.setSyncWord(c.syncWord)       == RADIOLIB_ERR_NONE;
  ok &= radio.setPreambleLength(c.preamble) == RADIOLIB_ERR_NONE;
  if (!ok) return false;
  return radio.startReceive() == RADIOLIB_ERR_NONE;
}

// --- On-chip Meshtastic decode ---------------------------------------------
// Default-channel ("LongFast") packets use AES-128-CTR with a PUBLIC key.
// Validated offline against real captured packets (firmware/tools/
// meshtastic_decode.py). Wire format: 16-byte header + encrypted Data protobuf.
static const uint8_t MT_KEY[16] = {
  0xd4, 0xf1, 0xbb, 0x3a, 0x20, 0x29, 0x07, 0x59,
  0xf0, 0xbc, 0xff, 0xab, 0xcf, 0x4e, 0x69, 0x01};

static uint32_t readVarint(const uint8_t* b, size_t len, size_t& i) {
  uint32_t v = 0; int shift = 0;
  while (i < len) {
    uint8_t c = b[i++];
    v |= (uint32_t)(c & 0x7f) << shift; shift += 7;
    if (!(c & 0x80)) break;
  }
  return v;
}

// Decode a Meshtastic packet into a short human string (text, or node name for
// NodeInfo). Returns false if not decodable / not an interesting type.
static bool decodeMeshtastic(const uint8_t* pkt, size_t len, char* out, size_t outsz) {
  if (len <= 16) return false;
  uint32_t sender, pid;
  memcpy(&sender, pkt + 4, 4);
  memcpy(&pid, pkt + 8, 4);

  // CTR nonce = packetId (8 LE, high 4 zero) + fromNode (4 LE) + extraNonce (4 = 0)
  uint8_t nonce[16]; memset(nonce, 0, 16);
  memcpy(nonce + 0, &pid, 4);
  memcpy(nonce + 8, &sender, 4);

  size_t plen = len - 16;
  if (plen > 240) return false;
  uint8_t plain[240];
  mbedtls_aes_context aes; mbedtls_aes_init(&aes);
  mbedtls_aes_setkey_enc(&aes, MT_KEY, 128);
  size_t nc_off = 0; uint8_t stream[16]; memset(stream, 0, 16);
  mbedtls_aes_crypt_ctr(&aes, plen, &nc_off, nonce, stream, pkt + 16, plain);
  mbedtls_aes_free(&aes);

  // Data protobuf: field 1 = portnum (varint), field 2 = payload (bytes)
  size_t i = 0; uint8_t port = 0; const uint8_t* payload = nullptr; size_t payLen = 0;
  while (i < plen) {
    uint8_t tag = plain[i++]; uint8_t field = tag >> 3, wt = tag & 7;
    if (wt == 0) { uint32_t v = readVarint(plain, plen, i); if (field == 1) port = (uint8_t)v; }
    else if (wt == 2) { uint32_t l = readVarint(plain, plen, i);
                        if (field == 2) { payload = plain + i; payLen = l; } i += l; }
    else break;
  }
  if (!payload) return false;

  if (port == 1) {  // TEXT_MESSAGE_APP
    size_t n = payLen < outsz - 1 ? payLen : outsz - 1;
    memcpy(out, payload, n); out[n] = 0;
    return true;
  }
  if (port == 4) {  // NODEINFO_APP -> User protobuf; field 3 = shortName
    size_t j = 0; const uint8_t* sn = nullptr; size_t snl = 0;
    while (j < payLen) {
      uint8_t tag = payload[j++]; uint8_t f = tag >> 3, w = tag & 7;
      if (w == 2) { uint32_t l = readVarint(payload, payLen, j);
                    if (f == 3) { sn = payload + j; snl = l; } j += l; }
      else if (w == 0) { readVarint(payload, payLen, j); }
      else break;
    }
    if (sn) { size_t n = snl < outsz - 1 ? snl : outsz - 1;
              memcpy(out, sn, n); out[n] = 0; return true; }
  }
  return false;
}

static void drainPacket() {
  size_t len = radio.getPacketLength();
  uint8_t buf[256];
  if (len > sizeof(buf)) len = sizeof(buf);
  int state = radio.readData(buf, len);
  if (state != RADIOLIB_ERR_NONE) {
    Serial.printf("  [%s] RX error state=%d\n", CONFIGS[activeIdx].name, state);
    return;
  }
  NetStat& s = stats[activeIdx];
  s.pkts++; s.seen = true; s.lastRssi = (int16_t)radio.getRSSI(); s.lastRxMs = millis();
  totalPkts++;
  Serial.printf("  [%s] PACKET len=%u rssi=%ddBm snr=%.1fdB : ",
                CONFIGS[activeIdx].name, (unsigned)len, s.lastRssi, radio.getSNR());
  for (size_t i = 0; i < len; i++) Serial.printf("%02x", buf[i]);
  Serial.println();

  // meshTastic packets we can decode on-chip today.
  if (CONFIGS[activeIdx].letter == 'T') {
    char msg[40];
    if (decodeMeshtastic(buf, len, msg, sizeof(msg))) {
      strncpy(lastMsg, msg, sizeof(lastMsg) - 1); lastMsg[sizeof(lastMsg) - 1] = 0;
      lastMsgNet = 'T'; lastMsgMs = millis();
      Serial.printf("      decoded[T]: %s\n", msg);
    }
  }
}

// --- The trippy acid display ------------------------------------------------
// Left: an acid-house smiley wobbling inside expanding psychedelic rings.
// Right: "RMC" and the three network rows with live counts + RX blips.
static void drawAcidSmiley(int cx, int cy) {
  // expanding ripple rings (the trip)
  for (int k = 0; k < 3; k++) {
    int r = (int)((frame * 2 + k * 13) % 42);
    if (r > 3) oled.drawCircle(cx, cy, r, U8G2_DRAW_ALL);
  }
  // face: filled disc, eyes + smile cut back out in background colour
  oled.setDrawColor(1);
  oled.drawDisc(cx, cy, 18, U8G2_DRAW_ALL);
  oled.setDrawColor(0);
  oled.drawBox(cx - 8, cy - 8, 3, 7);   // left eye
  oled.drawBox(cx + 5, cy - 8, 3, 7);   // right eye
  for (int dx = -10; dx <= 10; dx++) {   // grinning acid smile
    int dy = 4 + (100 - dx * dx) / 22;   // corners up, dips in the middle
    oled.drawPixel(cx + dx, cy + dy);
    oled.drawPixel(cx + dx, cy + dy + 1);
  }
  oled.setDrawColor(1);
}

// Periodic freak-out: the face becomes a spinning striped ball with wide-open
// googly eyes and a gaping mouth.
static void drawAcidSmileyFreaky(int cx, int cy) {
  const int R = 18;
  oled.setDrawColor(1);
  oled.drawDisc(cx, cy, R, U8G2_DRAW_ALL);
  // rotating stripes carved into the ball (the spin)
  float th = frame * 0.35f;
  float c = cosf(th), s = sinf(th);
  oled.setDrawColor(0);
  for (int off = -R; off <= R; off += 4) {
    float px = cx - s * off, py = cy + c * off;
    oled.drawLine((int)(px - c * R), (int)(py - s * R),
                  (int)(px + c * R), (int)(py + s * R));
  }
  oled.setDrawColor(1);
  oled.drawCircle(cx, cy, R, U8G2_DRAW_ALL);   // crisp rim
  // wide-open googly eyes: white halo -> dark iris -> white pupil highlight,
  // so they read against the striped ball (a plain white disc would vanish)
  for (int sgn = -1; sgn <= 1; sgn += 2) {
    int ex = cx + sgn * 7;
    oled.setDrawColor(1); oled.drawDisc(ex, cy - 6, 4, U8G2_DRAW_ALL);  // halo
    oled.setDrawColor(0); oled.drawDisc(ex, cy - 6, 3, U8G2_DRAW_ALL);  // iris
    oled.setDrawColor(1); oled.drawDisc(ex, cy - 6, 1, U8G2_DRAW_ALL);  // pupil
  }
  // gaping mouth: white ring around a dark O
  oled.setDrawColor(1); oled.drawDisc(cx, cy + 7, 5, U8G2_DRAW_ALL);
  oled.setDrawColor(0); oled.drawDisc(cx, cy + 7, 3, U8G2_DRAW_ALL);
  oled.setDrawColor(1);
}

static void drawMarchingBorder() {
  for (int x = 0; x < 128; x++) {
    if (((x + frame) & 3) == 0) { oled.drawPixel(x, 0); oled.drawPixel(x, 63); }
  }
  for (int y = 0; y < 64; y++) {
    if (((y + frame) & 3) == 0) { oled.drawPixel(0, y); oled.drawPixel(127, y); }
  }
}

static const PhyConfig* configByLetter(char L) {
  for (size_t i = 0; i < NUM_CONFIGS; i++) if (CONFIGS[i].letter == L) return &CONFIGS[i];
  return nullptr;
}
static int indexByLetter(char L) {
  for (size_t i = 0; i < NUM_CONFIGS; i++) if (CONFIGS[i].letter == L) return (int)i;
  return -1;
}

static void drawUI() {
  oled.clearBuffer();

  // Every ~9s the smiley freaks out (spins, stripes, eyes + mouth open) for ~2.5s.
  bool freaky = (millis() % 9000) < 2500;
  if (freaky) drawAcidSmileyFreaky(31, 33);
  else        drawAcidSmiley(31, 33);
  drawMarchingBorder();

  // "RTC" punk header on the right
  oled.setFont(u8g2_font_bubble_tr);
  const char* rtc = "RTC";
  int rw = oled.getStrWidth(rtc);
  int rx = 64 + (64 - rw) / 2;
  if ((frame / 10) & 1) {                 // strobe invert
    oled.drawBox(64, 0, 64, 22);
    oled.setDrawColor(0); oled.drawStr(rx, 19, rtc); oled.setDrawColor(1);
  } else {
    oled.drawStr(rx, 19, rtc);
  }

  // three network rows, in R T C order
  const char order[3] = {'R', 'T', 'C'};
  oled.setFont(u8g2_font_6x10_tf);
  uint32_t now = millis();
  for (int r = 0; r < 3; r++) {
    int idx = indexByLetter(order[r]);
    if (idx < 0) continue;
    const NetStat& s = stats[idx];
    int y = 32 + r * 11;                   // baseline (below the taller header)
    bool active = (idx == activeIdx);
    if (active) oled.drawFrame(64, y - 9, 64, 11);
    char line[24];
    if (s.seen) snprintf(line, sizeof(line), "%c %4lu", order[r], (unsigned long)s.pkts);
    else        snprintf(line, sizeof(line), "%c   --", order[r]);
    oled.drawStr(67, y, line);
    // RX activity blip (filled when a packet landed in the last 400ms)
    bool blip = s.seen && (now - s.lastRxMs < 400);
    if (blip) oled.drawDisc(121, y - 4, 3, U8G2_DRAW_ALL);
    else      oled.drawCircle(121, y - 4, 3, U8G2_DRAW_ALL);
  }

  // last decoded event along the bottom of the right column
  if (lastMsg[0]) {
    oled.setFont(u8g2_font_4x6_tf);
    char line[24];
    snprintf(line, sizeof(line), "%c:%s", lastMsgNet, lastMsg);
    line[15] = 0;  // truncate to fit the ~60px column
    oled.drawStr(66, 62, line);
  }

  oled.sendBuffer();
}

void setup() {
  Serial.begin(115200);
  uint32_t t0 = millis();
  while (!Serial && millis() - t0 < 2000) { }

  Serial.println("\n=== archy-messh Phase 1 — RTC scanner + acid display ===");

  // Power the OLED rail, then reset the panel, then bring up U8g2.
  pinMode(PIN_VEXT, OUTPUT); digitalWrite(PIN_VEXT, LOW); delay(60);
  pinMode(PIN_OLED_RST, OUTPUT);
  digitalWrite(PIN_OLED_RST, LOW);  delay(20);
  digitalWrite(PIN_OLED_RST, HIGH); delay(20);
  oled.begin();
  oled.setBusClock(400000);

  // Boot splash: the device identity, shared across all three networks.
  oled.clearBuffer();
  drawAcidSmiley(64, 24);
  oled.setFont(u8g2_font_6x10_tf);
  int nw = oled.getStrWidth(DEVICE_NAME);
  oled.drawStr((128 - nw) / 2, 52, DEVICE_NAME);
  oled.setFont(u8g2_font_5x8_tf);
  const char* sub = "R T C  bridge";
  int sw = oled.getStrWidth(sub);
  oled.drawStr((128 - sw) / 2, 62, sub);
  oled.sendBuffer();
  Serial.printf("Device identity (all networks): %s / %s\n", DEVICE_NAME, DEVICE_SHORT);
  delay(2200);

  SPI.begin(PIN_LORA_SCK, PIN_LORA_MISO, PIN_LORA_MOSI, PIN_LORA_NSS);
  const PhyConfig& first = CONFIGS[0];
  int state = radio.begin(first.freqMHz, first.bwKHz, first.sf, first.cr,
                          first.syncWord, RX_TX_POWER, first.preamble, TCXO_VOLTAGE);
  Serial.printf("radio.begin -> %d %s\n", state, state == RADIOLIB_ERR_NONE ? "(OK)" : "(ERR)");
  if (state != RADIOLIB_ERR_NONE) {
    Serial.println("!! SX1262 init failed — check wiring/TCXO. Halting.");
    while (true) { drawUI(); frame++; delay(60); }  // still show the trip
  }
  radio.setDio2AsRfSwitch(true);
  radio.setDio1Action(onDio1);

  activeIdx = 0;
  applyConfig(CONFIGS[0]);
  dwellStart = millis();
}

void loop() {
  // Non-blocking scan: rotate the radio when the dwell window elapses, so the
  // display keeps animating smoothly the whole time.
  if (millis() - dwellStart >= DWELL_MS) {
    activeIdx = (activeIdx + 1) % NUM_CONFIGS;
    applyConfig(CONFIGS[activeIdx]);
    dwellStart = millis();
  }
  if (rxFlag) {
    rxFlag = false;
    drainPacket();
    radio.startReceive();
  }
  drawUI();
  frame++;
  delay(45);   // ~20 fps
}