1  # The MIT License (MIT)
  2  #
  3  # Copyright (c) 2020 Scott Shawcroft for Adafruit Industries LLC
  4  #
  5  # Permission is hereby granted, free of charge, to any person obtaining a copy
  6  # of this software and associated documentation files (the "Software"), to deal
  7  # in the Software without restriction, including without limitation the rights
  8  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  9  # copies of the Software, and to permit persons to whom the Software is
 10  # furnished to do so, subject to the following conditions:
 11  #
 12  # The above copyright notice and this permission notice shall be included in
 13  # all copies or substantial portions of the Software.
 14  #
 15  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 16  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 17  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 18  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 19  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 20  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 21  # THE SOFTWARE.
 22  """
 23  `adafruit_ble_eddystone`
 24  ================================================================================
 25  
 26  CircuitPython BLE library for Google's open "physical web" Eddystone.
 27  
 28  Documented by Google here: https://github.com/google/eddystone
 29  
 30  """
 31  
 32  import struct
 33  
 34  from adafruit_ble.advertising import Advertisement
 35  from adafruit_ble.advertising.standard import ServiceList, ServiceData
 36  from adafruit_ble.uuid import StandardUUID
 37  
 38  __version__ = "0.0.0-auto.0"
 39  __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_BLE_Eddystone.git"
 40  
 41  
 42  class _EddystoneService:
 43      """Placeholder service. Not implemented."""
 44  
 45      # pylint: disable=too-few-public-methods
 46      uuid = StandardUUID(0xFEAA)
 47  
 48  
 49  class _EddystoneFrame(ServiceData):
 50      """Top level advertising data field that adds the field type to bytearrays set."""
 51  
 52      def __init__(self):
 53          super().__init__(_EddystoneService)
 54  
 55      def __get__(self, obj, cls):
 56          if obj is None:
 57              return self
 58          return super().__get__(obj, cls)[1:]
 59  
 60      def __set__(self, obj, value):
 61          # ServiceData requires a bytearray.
 62          return super().__set__(obj, bytearray(obj.frame_type) + value)
 63  
 64  
 65  class EddystoneFrameBytes:
 66      """Extracts and manipulates a byte range from an EddystoneAdvertisement. For library use only.
 67  
 68         If length is None, then the byte range must be at the end of the frame.
 69      """
 70  
 71      def __init__(self, *, length=None, offset=0):
 72          self._length = length
 73          self._offset = offset
 74  
 75      def __get__(self, obj, cls):
 76          if obj is None:
 77              return self
 78          if self._length is not None:
 79              return obj.eddystone_frame[self._offset : self._offset + self._length]
 80          return obj.eddystone_frame[self._offset :]
 81  
 82      def __set__(self, obj, value):
 83          if self._length is not None:
 84              if self._length != len(value):
 85                  raise ValueError("Value length does not match")
 86              obj.eddystone_frame[self._offset : self._offset + self._length] = value
 87          else:
 88              obj.eddystone_frame = obj.eddystone_frame[: self._offset] + value
 89  
 90  
 91  class EddystoneFrameStruct(EddystoneFrameBytes):
 92      """Packs and unpacks a single value from a byte range. For library use only."""
 93  
 94      def __init__(self, fmt, *, offset=0):
 95          self._format = fmt
 96          super().__init__(offset=offset, length=struct.calcsize(self._format))
 97  
 98      def __get__(self, obj, cls):
 99          if obj is None:
100              return self
101          return struct.unpack(self._format, super().__get__(obj, cls))[0]
102  
103      def __set__(self, obj, value):
104          super().__set__(obj, struct.pack(self._format, value))
105  
106  
107  class EddystoneAdvertisement(Advertisement):
108      """Top level Eddystone advertisement that manages frame type. For library use only."""
109  
110      # Subclasses must provide `match_prefixes`.
111      services = ServiceList(standard_services=[0x03], vendor_services=[0x07])
112      eddystone_frame = _EddystoneFrame()
113  
114      def __init__(self, *, minimum_size=None):
115          super().__init__()
116          self.services.append(_EddystoneService)
117          self.connectable = False
118          self.flags.general_discovery = True
119          self.flags.le_only = True
120          # self.frame_type is defined by the subclass.
121          if not self.eddystone_frame:
122              self.eddystone_frame = bytearray(minimum_size)
123  
124      def __str__(self):
125          parts = []
126          for attr in dir(self.__class__):
127              attribute_instance = getattr(self.__class__, attr)
128              if issubclass(attribute_instance.__class__, EddystoneFrameBytes):
129                  value = getattr(self, attr)
130                  if value is not None:
131                      if isinstance(value, memoryview):
132                          value = bytes(value)
133                      parts.append("{}={}".format(attr, repr(value)))
134          return "<{} {} >".format(self.__class__.__name__, " ".join(parts))