/*********************************************************************
 This is an example for our nRF52 based Bluefruit LE modules

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 MIT license, check LICENSE for more information
 All text above, and the splash screen below must be included in
 any redistribution
*********************************************************************/

/* This sketch demonstrates the central API() that allows you to connect
 * to multiple peripherals boards (Bluefruit nRF52 in peripheral mode, or
 * any Bluefruit nRF51 boards).
 *
 * One or more Bluefruit boards, configured as a peripheral with the
 * bleuart service running are required for this demo.
 *
 * This sketch will: 
 *  - Read data from the HW serial port (normally USB serial, accessible
 *    via the Serial Monitor for example), and send any incoming data to
 *    all other peripherals connected to the central device.
 *  - Forward any incoming bleuart messages from a peripheral to all of
 *    the other connected devices.
 * 
 * It is recommended to give each peripheral board a distinct name in order
 * to more easily distinguish the individual devices.
 * 
 * Connection Handle Explanation
 * -----------------------------
 * The total number of connections is BLE_MAX_CONN = BLE_PRPH_MAX_CONN + BLE_CENTRAL_MAX_CONN.
 * 
 * The 'connection handle' is an integer number assigned by the SoftDevice
 * (Nordic's proprietary BLE stack). Each connection will receive it's own
 * numeric 'handle' starting from 0 to BLE_MAX_CONN-1, depending on the order
 * of connection(s).
 *
 * - E.g If our Central board connects to a mobile phone first (running as a peripheral),
 *   then afterwards connects to another Bluefruit board running in peripheral mode, then
 *    the connection handle of mobile phone is 0, and the handle for the Bluefruit
 *    board is 1, and so on.
 */

/* LED PATTERNS
 * ------------
 * LED_RED   - Blinks pattern changes based on the number of connections.
 * LED_BLUE  - Blinks constantly when scanning
 */

#include <bluefruit.h>

// Struct containing peripheral info
typedef struct
{
  char name[32];

  uint16_t conn_handle;

  // Each prph need its own bleuart client service
  BLEClientUart bleuart;
} prph_info_t;

/* Peripheral info array (one per peripheral device)
 * 
 * There are 'BLE_CENTRAL_MAX_CONN' central connections, but the
 * the connection handle can be numerically larger (for example if
 * the peripheral role is also used, such as connecting to a mobile
 * device). As such, we need to convert connection handles <-> the array
 * index where appropriate to prevent out of array accesses.
 * 
 * Note: One can simply declares the array with BLE_MAX_CONN and use connection
 * handle as index directly with the expense of SRAM.
 */
prph_info_t prphs[BLE_CENTRAL_MAX_CONN];

// Software Timer for blinking the RED LED
SoftwareTimer blinkTimer;
uint8_t connection_num = 0; // for blink pattern

void setup() 
{
  Serial.begin(115200);
  while ( !Serial ) delay(10);   // for nrf52840 with native usb

  // Initialize blinkTimer for 100 ms and start it
  blinkTimer.begin(100, blink_timer_callback);
  blinkTimer.start();

  Serial.println("Bluefruit52 Central Multi BLEUART Example");
  Serial.println("-----------------------------------------\n");
  
  // Initialize Bluefruit with max concurrent connections as Peripheral = 1, Central = 1
  // SRAM usage required by SoftDevice will increase with number of connections
  Bluefruit.begin(0, 4);

  // Set Name
  Bluefruit.setName("Bluefruit52 Central");
  
  // Init peripheral pool
  for (uint8_t idx=0; idx<BLE_CENTRAL_MAX_CONN; idx++)
  {
    // Invalid all connection handle
    prphs[idx].conn_handle = BLE_CONN_HANDLE_INVALID;
    
    // All of BLE Central Uart Serivce
    prphs[idx].bleuart.begin();
    prphs[idx].bleuart.setRxCallback(bleuart_rx_callback);
  }

  // Callbacks for Central
  Bluefruit.Central.setConnectCallback(connect_callback);
  Bluefruit.Central.setDisconnectCallback(disconnect_callback);

  /* Start Central Scanning
   * - Enable auto scan if disconnected
   * - Interval = 100 ms, window = 80 ms
   * - Filter only accept bleuart service in advertising
   * - Don't use active scan (used to retrieve the optional scan response adv packet)
   * - Start(0) = will scan forever since no timeout is given
   */
  Bluefruit.Scanner.setRxCallback(scan_callback);
  Bluefruit.Scanner.restartOnDisconnect(true);
  Bluefruit.Scanner.setInterval(160, 80);       // in units of 0.625 ms
  Bluefruit.Scanner.filterUuid(BLEUART_UUID_SERVICE);
  Bluefruit.Scanner.useActiveScan(false);       // Don't request scan response data
  Bluefruit.Scanner.start(0);                   // 0 = Don't stop scanning after n seconds
}

/**
 * Callback invoked when scanner picks up an advertising packet
 * @param report Structural advertising data
 */
void scan_callback(ble_gap_evt_adv_report_t* report)
{
  // Since we configure the scanner with filterUuid()
  // Scan callback only invoked for device with bleuart service advertised  
  // Connect to the device with bleuart service in advertising packet
  Bluefruit.Central.connect(report);
}

/**
 * Callback invoked when an connection is established
 * @param conn_handle
 */
void connect_callback(uint16_t conn_handle)
{
  // Find an available ID to use
  int id  = findConnHandle(BLE_CONN_HANDLE_INVALID);

  // Eeek: Exceeded the number of connections !!!
  if ( id < 0 ) return;
  
  prph_info_t* peer = &prphs[id];
  peer->conn_handle = conn_handle;
  
  Bluefruit.Gap.getPeerName(conn_handle, peer->name, 32);

  Serial.print("Connected to ");
  Serial.println(peer->name);

  Serial.print("Discovering BLE UART service ... ");

  if ( peer->bleuart.discover(conn_handle) )
  {
    Serial.println("Found it");
    Serial.println("Enabling TXD characteristic's CCCD notify bit");
    peer->bleuart.enableTXD();

    Serial.println("Continue scanning for more peripherals");
    Bluefruit.Scanner.start(0);

    Serial.println("Enter some text in the Serial Monitor to send it to all connected peripherals:");
  } else
  {
    Serial.println("Found ... NOTHING!");

    // disconect since we couldn't find bleuart service
    Bluefruit.Central.disconnect(conn_handle);
  }  

  connection_num++;
}

/**
 * Callback invoked when a connection is dropped
 * @param conn_handle
 * @param reason is a BLE_HCI_STATUS_CODE which can be found in ble_hci.h
 * https://github.com/adafruit/Adafruit_nRF52_Arduino/blob/master/cores/nRF5/nordic/softdevice/s140_nrf52_6.1.1_API/include/ble_hci.h
 */
void disconnect_callback(uint16_t conn_handle, uint8_t reason)
{
  (void) conn_handle;
  (void) reason;

  connection_num--;

  // Mark the ID as invalid
  int id  = findConnHandle(conn_handle);

  // Non-existant connection, something went wrong, DBG !!!
  if ( id < 0 ) return;

  // Mark conn handle as invalid
  prphs[id].conn_handle = BLE_CONN_HANDLE_INVALID;

  Serial.print(prphs[id].name);
  Serial.println(" disconnected!");
}

/**
 * Callback invoked when BLE UART data is received
 * @param uart_svc Reference object to the service where the data 
 * arrived.
 */
void bleuart_rx_callback(BLEClientUart& uart_svc)
{
  // uart_svc is prphs[conn_handle].bleuart
  uint16_t conn_handle = uart_svc.connHandle();

  int id = findConnHandle(conn_handle);
  prph_info_t* peer = &prphs[id];
  
  // Print sender's name
  Serial.printf("[From %s]: ", peer->name);

  // Read then forward to all peripherals
  while ( uart_svc.available() )
  {
    // default MTU with an extra byte for string terminator
    char buf[20+1] = { 0 };
    
    if ( uart_svc.read(buf,sizeof(buf)-1) )
    {
      Serial.println(buf);
      sendAll(buf);
    }
  }
}

/**
 * Helper function to send a string to all connected peripherals
 */
void sendAll(const char* str)
{
  Serial.print("[Send to All]: ");
  Serial.println(str);
  
  for(uint8_t id=0; id < BLE_CENTRAL_MAX_CONN; id++)
  {
    prph_info_t* peer = &prphs[id];

    if ( peer->bleuart.discovered() )
    {
      peer->bleuart.print(str);
    }
  }
}

void loop()
{
  // First check if we are connected to any peripherals
  if ( Bluefruit.Central.connected() )
  {
    // default MTU with an extra byte for string terminator
    char buf[20+1] = { 0 };
    
    // Read from HW Serial (normally USB Serial) and send to all peripherals
    if ( Serial.readBytes(buf, sizeof(buf)-1) )
    {
      sendAll(buf);
    }
  }
}

/**
 * Find the connection handle in the peripheral array
 * @param conn_handle Connection handle
 * @return array index if found, otherwise -1
 */
int findConnHandle(uint16_t conn_handle)
{
  for(int id=0; id<BLE_CENTRAL_MAX_CONN; id++)
  {
    if (conn_handle == prphs[id].conn_handle)
    {
      return id;
    }
  }

  return -1;  
}

/**
 * Software Timer callback is invoked via a built-in FreeRTOS thread with
 * minimal stack size. Therefore it should be as simple as possible. If
 * a periodically heavy task is needed, please use Scheduler.startLoop() to
 * create a dedicated task for it.
 * 
 * More information http://www.freertos.org/RTOS-software-timer.html
 */
void blink_timer_callback(TimerHandle_t xTimerID)
{
  (void) xTimerID;

  // Period of sequence is 10 times (1 second). 
  // RED LED will toggle first 2*n times (on/off) and remain off for the rest of period
  // Where n = number of connection
  static uint8_t count = 0;

  if ( count < 2*connection_num ) digitalToggle(LED_RED);
  if ( count % 2 && digitalRead(LED_RED)) digitalWrite(LED_RED, LOW); // issue #98

  count++;
  if (count >= 10) count = 0;
}