import ustruct

class SensorBase:

	def read16(self, register):
		data = self.i2c.readfrom_mem(self.address, register, 2)
		return ustruct.unpack('<H', data)[0]

	def read_temp(self, register):
		temp = self.read16(register);
		# apply measurement resolution (0.02 degrees per LSB)
		temp *= .02;
		# Kelvin to Celcius
		temp -= 273.15;
		return temp;

	def read_ambient_temp(self):
		return self.read_temp(self._REGISTER_TA)

	def read_object_temp(self):
		return self.read_temp(self._REGISTER_TOBJ1)

	def read_object2_temp(self):
		if self.dual_zone:
			return self.read_temp(self._REGISTER_TOBJ2)
		else:
			raise RuntimeError("Device only has one thermopile")

	@property
	def ambient_temp(self):
		return self.read_ambient_temp()

	@property
	def object_temp(self):
		return self.read_object_temp()

	@property
	def object2_temp(self):
		return self.read_object2_temp()

class MLX90614(SensorBase):

	_REGISTER_TA = 0x06
	_REGISTER_TOBJ1 = 0x07
	_REGISTER_TOBJ2 = 0x08

	def __init__(self, i2c, address=0x5a):
		self.i2c = i2c
		self.address = address
		_config1 = i2c.readfrom_mem(address, 0x25, 2)
		_dz = ustruct.unpack('<H', _config1)[0] & (1<<6)
		self.dual_zone = True if _dz else False

class MLX90615(SensorBase):

	_REGISTER_TA = 0x26
	_REGISTER_TOBJ1 = 0x27

	def __init__(self, i2c, address=0x5b):
		self.i2c = i2c
		self.address = address
		self.dual_zone = False