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

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 Adafruit invests time and resources providing this open source code,
 please support Adafruit and open-source hardware by purchasing
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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 uses the HID Consumer Key API to send the Volume Down
 * key when PIN_SHUTTER is grounded. This will cause your mobile device
 * to capture a photo when you are in the camera app
 */
#include <bluefruit.h>

BLEDis bledis;
BLEHidAdafruit blehid;

#define PIN_SHUTTER   A0

void setup()
{
  pinMode(PIN_SHUTTER, INPUT_PULLUP);

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

  Serial.println("Bluefruit52 HID Camera Shutter Example");
  Serial.println("--------------------------------------\n");

  Serial.println();
  Serial.println("Go to your phone's Bluetooth settings to pair your device");
  Serial.println("then open the camera application");

  Serial.println();
  Serial.printf("Set pin %d to GND to capture a photo\n", PIN_SHUTTER);
  Serial.println();

  Bluefruit.begin();
  // Set max power. Accepted values are: -40, -30, -20, -16, -12, -8, -4, 0, 4
  Bluefruit.setTxPower(4);
  Bluefruit.setName("Bluefruit52");

  // Configure and start DIS (Device Information Service)
  bledis.setManufacturer("Adafruit Industries");
  bledis.setModel("Bluefruit Feather 52");
  bledis.begin();

  /* Start BLE HID
   * Note: Apple requires BLE devices to have a min connection interval >= 20m
   * (The smaller the connection interval the faster we can send data).
   * However, for HID and MIDI device Apple will accept a min connection
   * interval as low as 11.25 ms. Therefore BLEHidAdafruit::begin() will try to
   * set the min and max connection interval to 11.25 ms and 15 ms respectively
   * for the best performance.
   */
  blehid.begin();

  /* Set connection interval (min, max) to your perferred value.
   * Note: It is already set by BLEHidAdafruit::begin() to 11.25ms - 15ms
   * min = 9*1.25=11.25 ms, max = 12*1.25= 15 ms
   */
  /* Bluefruit.setConnInterval(9, 12); */

  // Set up and start advertising
  startAdv();
}

void startAdv(void)
{
  // Advertising packet
  Bluefruit.Advertising.addFlags(BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE);
  Bluefruit.Advertising.addTxPower();
  Bluefruit.Advertising.addAppearance(BLE_APPEARANCE_HID_KEYBOARD);

  // Include BLE HID service
  Bluefruit.Advertising.addService(blehid);

  // There is enough room for the dev name in the advertising packet
  Bluefruit.Advertising.addName();
  
  /* Start Advertising
   * - Enable auto advertising if disconnected
   * - Interval:  fast mode = 20 ms, slow mode = 152.5 ms
   * - Timeout for fast mode is 30 seconds
   * - Start(timeout) with timeout = 0 will advertise forever (until connected)
   * 
   * For recommended advertising interval
   * https://developer.apple.com/library/content/qa/qa1931/_index.html   
   */
  Bluefruit.Advertising.restartOnDisconnect(true);
  Bluefruit.Advertising.setInterval(32, 244);    // in unit of 0.625 ms
  Bluefruit.Advertising.setFastTimeout(30);      // number of seconds in fast mode
  Bluefruit.Advertising.start(0);                // 0 = Don't stop advertising after n seconds  
}

void loop()
{
  // Make sure you are connected and bonded/paired
  if ( Bluefruit.connected() && Bluefruit.connPaired() )
  {
    // Check if pin GND'ed
    if ( digitalRead(PIN_SHUTTER) == 0 )
    {
      // Turn on red LED when we start sending data
      digitalWrite(LED_RED, 1);

      // Send the 'volume down' key press
      // Check BLEHidGeneric.h for a list of valid consumer usage codes
      blehid.consumerKeyPress(HID_USAGE_CONSUMER_VOLUME_DECREMENT);

      // Delay a bit between reports
      delay(10);

      // Send key release
      blehid.consumerKeyRelease();

      // Turn off the red LED
      digitalWrite(LED_RED, 0);

      // Delay to avoid constant capturing
      delay(500);
    }
  }
}