#include "SerialBLEInterface.h"
#include <SPIFFS.h>

// FIRMWARE_VERSION is defined in MyMesh.h which may not be in our include
// chain.  If missing, fall back to "unknown" which will safely force a
// bond clear on every boot (conservative but harmless).
#ifndef FIRMWARE_VERSION
#define FIRMWARE_VERSION "unknown"
#endif

// See the following for generating UUIDs:
// https://www.uuidgenerator.net/

#define SERVICE_UUID           "6E400001-B5A3-F393-E0A9-E50E24DCCA9E" // UART service UUID
#define CHARACTERISTIC_UUID_RX "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
#define CHARACTERISTIC_UUID_TX "6E400003-B5A3-F393-E0A9-E50E24DCCA9E"

#define ADVERT_RESTART_DELAY  1000   // millis

void SerialBLEInterface::begin(const char* prefix, char* name, uint32_t pin_code) {
  _pin_code = pin_code;

  if (strcmp(name, "@@MAC") == 0) {
    uint8_t addr[8];
    memset(addr, 0, sizeof(addr));
    esp_efuse_mac_get_default(addr);
    sprintf(name, "%02X%02X%02X%02X%02X%02X",    // modify (IN-OUT param)
          addr[5], addr[4], addr[3], addr[2], addr[1], addr[0]);
  }
  char dev_name[32+16];
  sprintf(dev_name, "%s%s", prefix, name);

  // Create the BLE Device
  BLEDevice::init(dev_name);
  BLEDevice::setSecurityCallbacks(this);
  BLEDevice::setMTU(MAX_FRAME_SIZE);

  // Clear stale BLE bonds when firmware version changes.
  // After a flash, the phone still has old bonding keys cached which causes
  // an authentication error on first connect.  By wiping bonds only when
  // the version string changes, normal reboots keep their pairing intact.
  {
    bool clear_bonds = false;
    File f = SPIFFS.open("/ble_ver", "r");
    if (f) {
      char stored[24] = {0};
      f.readBytes(stored, sizeof(stored) - 1);
      f.close();
      clear_bonds = (strcmp(stored, FIRMWARE_VERSION) != 0);
    } else {
      clear_bonds = true;  // first boot after flash
    }
    if (clear_bonds) {
      int n = esp_ble_get_bond_device_num();
      if (n > 0) {
        esp_ble_bond_dev_t *devs = (esp_ble_bond_dev_t *)malloc(sizeof(esp_ble_bond_dev_t) * n);
        if (devs) {
          esp_ble_get_bond_device_list(&n, devs);
          for (int i = 0; i < n; i++) esp_ble_remove_bond_device(devs[i].bd_addr);
          free(devs);
          BLE_DEBUG_PRINTLN("Cleared %d stale BLE bond(s) (firmware changed)", n);
        }
      }
      File fw = SPIFFS.open("/ble_ver", "w", true);
      if (fw) { fw.print(FIRMWARE_VERSION); fw.close(); }
    }
  }

  BLESecurity  sec;
  sec.setStaticPIN(pin_code);
  sec.setAuthenticationMode(ESP_LE_AUTH_REQ_SC_MITM_BOND);

  BLEDevice::setPower(ESP_PWR_LVL_N3);  // -3 dBm — saves power, plenty for nearby phone

  // Create the BLE Server
  pServer = BLEDevice::createServer();
  pServer->setCallbacks(this);

  // Create the BLE Service
  pService = pServer->createService(SERVICE_UUID);

  // Create a BLE Characteristic
  pTxCharacteristic = pService->createCharacteristic(CHARACTERISTIC_UUID_TX, BLECharacteristic::PROPERTY_READ | BLECharacteristic::PROPERTY_NOTIFY);
  pTxCharacteristic->setAccessPermissions(ESP_GATT_PERM_READ_ENC_MITM);
  pTxCharacteristic->addDescriptor(new BLE2902());

  BLECharacteristic * pRxCharacteristic = pService->createCharacteristic(CHARACTERISTIC_UUID_RX, BLECharacteristic::PROPERTY_WRITE);
  pRxCharacteristic->setAccessPermissions(ESP_GATT_PERM_WRITE_ENC_MITM);
  pRxCharacteristic->setCallbacks(this);

  pServer->getAdvertising()->addServiceUUID(SERVICE_UUID);
}

// -------- BLESecurityCallbacks methods

uint32_t SerialBLEInterface::onPassKeyRequest() {
  BLE_DEBUG_PRINTLN("onPassKeyRequest()");
  return _pin_code;
}

void SerialBLEInterface::onPassKeyNotify(uint32_t pass_key) {
  BLE_DEBUG_PRINTLN("onPassKeyNotify(%u)", pass_key);
}

bool SerialBLEInterface::onConfirmPIN(uint32_t pass_key) {
  BLE_DEBUG_PRINTLN("onConfirmPIN(%u)", pass_key);
  return true;
}

bool SerialBLEInterface::onSecurityRequest() {
  BLE_DEBUG_PRINTLN("onSecurityRequest()");
  return true;  // allow
}

void SerialBLEInterface::onAuthenticationComplete(esp_ble_auth_cmpl_t cmpl) {
  if (cmpl.success) {
    BLE_DEBUG_PRINTLN(" - SecurityCallback - Authentication Success");
    deviceConnected = true;
  } else {
    BLE_DEBUG_PRINTLN(" - SecurityCallback - Authentication Failure*");

    //pServer->removePeerDevice(pServer->getConnId(), true);
    pServer->disconnect(pServer->getConnId());
    adv_restart_time = millis() + ADVERT_RESTART_DELAY;
  }
}

// -------- BLEServerCallbacks methods

void SerialBLEInterface::onConnect(BLEServer* pServer) {
}

void SerialBLEInterface::onConnect(BLEServer* pServer, esp_ble_gatts_cb_param_t *param) {
  BLE_DEBUG_PRINTLN("onConnect(), conn_id=%d, mtu=%d", param->connect.conn_id, pServer->getPeerMTU(param->connect.conn_id));
  last_conn_id = param->connect.conn_id;
}

void SerialBLEInterface::onMtuChanged(BLEServer* pServer, esp_ble_gatts_cb_param_t* param) {
  BLE_DEBUG_PRINTLN("onMtuChanged(), mtu=%d", pServer->getPeerMTU(param->mtu.conn_id));
}

void SerialBLEInterface::onDisconnect(BLEServer* pServer) {
  BLE_DEBUG_PRINTLN("onDisconnect()");
  if (_isEnabled) {
    adv_restart_time = millis() + ADVERT_RESTART_DELAY;

    // loop() will detect this on next loop, and set deviceConnected to false
  }
}

// -------- BLECharacteristicCallbacks methods

void SerialBLEInterface::onWrite(BLECharacteristic* pCharacteristic, esp_ble_gatts_cb_param_t* param) {
  uint8_t* rxValue = pCharacteristic->getData();
  int len = pCharacteristic->getLength();

  if (len > MAX_FRAME_SIZE) {
    BLE_DEBUG_PRINTLN("ERROR: onWrite(), frame too big, len=%d", len);
  } else if (recv_queue_len >= FRAME_QUEUE_SIZE) {
    BLE_DEBUG_PRINTLN("ERROR: onWrite(), recv_queue is full!");
  } else {
    recv_queue[recv_queue_len].len = len;
    memcpy(recv_queue[recv_queue_len].buf, rxValue, len);
    recv_queue_len++;
  }
}

// ---------- public methods

void SerialBLEInterface::enable() { 
  if (_isEnabled) return;

  _isEnabled = true;
  clearBuffers();

  // Start the service
  pService->start();

  // Start advertising — relaxed interval saves power while waiting for
  // a phone to connect, but stays responsive enough for quick pairing
  pServer->getAdvertising()->setMinInterval(480);   // 480 * 0.625ms = 300ms
  pServer->getAdvertising()->setMaxInterval(960);   // 960 * 0.625ms = 600ms

  pServer->getAdvertising()->start();
  adv_restart_time = 0;
}

void SerialBLEInterface::disable() {
  _isEnabled = false;

  BLE_DEBUG_PRINTLN("SerialBLEInterface::disable");

  pServer->getAdvertising()->stop();
  pServer->disconnect(last_conn_id);
  pService->stop();
  oldDeviceConnected = deviceConnected = false;
  adv_restart_time = 0;
}

size_t SerialBLEInterface::writeFrame(const uint8_t src[], size_t len) {
  if (len > MAX_FRAME_SIZE) {
    BLE_DEBUG_PRINTLN("writeFrame(), frame too big, len=%d", len);
    return 0;
  }

  if (deviceConnected && len > 0) {
    if (send_queue_len >= FRAME_QUEUE_SIZE) {
      BLE_DEBUG_PRINTLN("writeFrame(), send_queue is full!");
      return 0;
    }

    send_queue[send_queue_len].len = len;  // add to send queue
    memcpy(send_queue[send_queue_len].buf, src, len);
    send_queue_len++;

    return len;
  }
  return 0;
}

#define  BLE_WRITE_MIN_INTERVAL   60

bool SerialBLEInterface::isWriteBusy() const {
  return millis() < _last_write + BLE_WRITE_MIN_INTERVAL;   // still too soon to start another write?
}

size_t SerialBLEInterface::checkRecvFrame(uint8_t dest[]) {
  if (send_queue_len > 0   // first, check send queue
    && millis() >= _last_write + BLE_WRITE_MIN_INTERVAL    // space the writes apart
  ) {
    _last_write = millis();
    pTxCharacteristic->setValue(send_queue[0].buf, send_queue[0].len);
    pTxCharacteristic->notify();

    BLE_DEBUG_PRINTLN("writeBytes: sz=%d, hdr=%d", (uint32_t)send_queue[0].len, (uint32_t) send_queue[0].buf[0]);

    send_queue_len--;
    for (int i = 0; i < send_queue_len; i++) {   // delete top item from queue
      send_queue[i] = send_queue[i + 1];
    }
  }

  if (recv_queue_len > 0) {   // check recv queue
    size_t len = recv_queue[0].len;   // take from top of queue
    memcpy(dest, recv_queue[0].buf, len);

    BLE_DEBUG_PRINTLN("readBytes: sz=%d, hdr=%d", len, (uint32_t) dest[0]);

    recv_queue_len--;
    for (int i = 0; i < recv_queue_len; i++) {   // delete top item from queue
      recv_queue[i] = recv_queue[i + 1];
    }
    return len;
  }

  if (pServer->getConnectedCount() == 0)  deviceConnected = false;

  if (deviceConnected != oldDeviceConnected) {
    if (!deviceConnected) {    // disconnecting
      clearBuffers();

      BLE_DEBUG_PRINTLN("SerialBLEInterface -> disconnecting...");

      pServer->getAdvertising()->setMinInterval(480);
      pServer->getAdvertising()->setMaxInterval(960);

      adv_restart_time = millis() + ADVERT_RESTART_DELAY;
    } else {
      BLE_DEBUG_PRINTLN("SerialBLEInterface -> stopping advertising");
      BLE_DEBUG_PRINTLN("SerialBLEInterface -> connecting...");
      // connecting
      // do stuff here on connecting
      pServer->getAdvertising()->stop();
      adv_restart_time = 0;
    }
    oldDeviceConnected = deviceConnected;
  }

  if (adv_restart_time && millis() >= adv_restart_time) {
    if (pServer->getConnectedCount() == 0) {
      BLE_DEBUG_PRINTLN("SerialBLEInterface -> re-starting advertising");
      pServer->getAdvertising()->start();  // re-Start advertising
    }
    adv_restart_time = 0;
  }
  return 0;
}

bool SerialBLEInterface::isConnected() const {
  return deviceConnected;  //pServer != NULL && pServer->getConnectedCount() > 0;
}