class uPySensor:
    def __init__(self):
        dummy=''

    def sleep_ms(self, delay):
        from time import sleep_ms
        sleep_ms(delay)


class BME280(uPySensor):
    import bme280
    BME280_ADDRESS = 0x76

    def __init__(self, i2c):
        self.i2c = i2c
        self.handle = self.bme280.BME280(i2c=self.i2c)

    def update_sensor(self):
        t, p, h = self.handle.values
        self.temperature = float(t[:-1])
        self.pressure = float(p[:-3])
        self.humidity = float(h[:-1])

    def read_tempC(self):
        self.update_sensor()
        return self.temperature

    def read_hum(self):
        self.update_sensor()
        return self.humidity

    def read_pressure(self):
        self.update_sensor()
        return self.pressure

class DS18B20(uPySensor):
    def __init__(self, onewire):
        from ds18x20 import DS18X20
        self.bus=onewire
        self.bus_filter=DS18X20(self.bus)
        if len(self.bus_filter.scan()) == 0: raise IOError("No DS18B20 sensors found on OneWire bus")
        self.sensor=self.bus_filter.scan()[0]

    def read_tempC(self):
        self.bus_filter.convert_temp()
        self.sleep_ms(300)
        return self.bus_filter.read_temp(self.sensor)

class LM75A(uPySensor):
    LM75A_ADDRESS = 0x48

    def __init__(self, i2c):
        self.i2c = i2c

    def readbyte(self):
        return self.i2c.readfrom(self.LM75A_ADDRESS, 1)

    def readbytes(self, num):
        return self.i2c.readfrom(self.LM75A_ADDRESS, num)

    def read_tempC(self):
        import math
        data = self.readbytes(2)
        return float("%d.%d" % (int(data[0]), math.floor(int(data[1])/23)))

class SHT21(uPySensor):
    SOFT_RESET = 0xfe
    SHT21_ADDRESS = 0x40
    TRIG_TEMP_NO_HOLD = 0xf3
    TRIG_HUM_NO_HOLD = 0xf5

    def writebyte(self, byte):
        self.i2c.writeto(self.SHT21_ADDRESS, bytearray([byte]))

    def readbyte(self):
        return self.i2c.readfrom(self.SHT21_ADDRESS, 1)

    def readbytes(self, num):
        return self.i2c.readfrom(self.SHT21_ADDRESS, num)

    def __init__(self, i2c):
        self.i2c = i2c
        self.writebyte(self.SOFT_RESET)
        self.sleep_ms(15)

    def read_tempC(self):
        self.writebyte(self.TRIG_TEMP_NO_HOLD)
        self.sleep_ms(250)
        data = self.readbytes(2)
        return self._buffer_to_tempC(data)

    def read_hum(self):
        self.writebyte(self.TRIG_HUM_NO_HOLD)
        self.sleep_ms(250)
        data = self.readbytes(2)
        return self._buffer_to_hum(data)

    def _buffer_to_tempC(self, buf):
        unadj = (buf[0] << 8) + buf[1]
        unadj *= 175.72
        unadj /= 1 << 16
        unadj -= 46.85
        return unadj

    def _buffer_to_hum(self, buf):
        unadj = (buf[0] << 8) + buf[1]
        unadj *= 125
        unadj /= 1 << 16
        unadj -= 6
        return unadj

    def close(self):
        self.i2c.close()

    def __enter__(self):
        return self

    def __exit__(self, type, value, traceback):
        self.close()