Class: Simms::Packet

Inherits:
Object
  • Object
show all
Defined in:
lib/simms/packet.rb

Constant Summary collapse

ACTION_BEACON =

Action type constants

0x35

Class Method Summary collapse

Class Method Details

.parse(timestamp, data_packet, raise_on_unknown = false) ⇒ Object

Parses an incoming packet, extracts its enclosed beacon data, instantiates the correct beacon class, and returns it. Raises exceptions on malformed data. If beacon type is unknown, raises an exception if raise_on_unknown is set to true. Otherwise, unknown beacons are returned as nil.



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# File 'lib/simms/packet.rb', line 11

def self.parse(timestamp, data_packet, raise_on_unknown = false)
  # Parse the string into hex pair bytes for the mesh packet
  mesh_data = Bytes.new(data_packet)
  
  # Extract the bytes for the embedded beacon data
  beacon_data = mesh_data[34..-1]
  
  # Verify data
  if mesh_data.empty? || beacon_data.empty?
    raise "Malformed packet - missing segments"
  end
  unless mesh_data.uint16(32) == beacon_data.count
    raise "Malformed packet - length field (#{mesh_data.uint16(32)}) does not match data length (#{beacon_data.count})"
  end
  
  # Parse timestamp - always UTC time
  timestamp = Time.utc(*(timestamp.split(/[\- \:]/)))
  
  # Get key variables from packet
  uuid = mesh_data.slice(6,6).data.join('-')
  group = beacon_data.uint16(0)
  command = beacon_data.uint8(2)
  action = beacon_data.uint8(3)
  
  # Instantiate beacon instance (assuming it's a beacon action!)
  klass = Simms::Beacon.class_for(group, command) if action == ACTION_BEACON
  if klass
    # Create the beacon, then set all the meta-info we have about it
    beacon = klass.new(beacon_data)
    beacon.command_group_id = group
    beacon.device_command_id = command
    beacon.timestamp = timestamp
    beacon.uuid = uuid
    beacon
    
  else        
    raise "Unable to find beacon class for group #{group} and command #{command}" if raise_on_unknown
    nil
  end
end