from gpiozero import InternalDevice
import os

class GPUTemperature(InternalDevice):
    """
    Extends :class:`InternalDevice` to provide a device which is active when
    the GPU temperature exceeds the *threshold* value.
    Modified from :class:`CPUTemperature`

    :param str sensor_command:
        The command from which to read the temperature. This defaults to the
        run `vcgencmd measure_temp`. Whatever message return is specified is
        expected to contain a single line containing the
        temperature in degrees celsius.

    :param float min_temp:
        The temperature at which :attr:`value` will read 0.0. This defaults to
        0.0.

    :param float max_temp:
        The temperature at which :attr:`value` will read 1.0. This defaults to
        100.0.

    :param float threshold:
        The temperature above which the device will be considered "active".
        This defaults to 80.0.
    """
    def __init__(self, sensor_command='vcgencmd measure_temp', min_temp=0.0,
            max_temp=100.0, threshold=80.0):
        self.sensor_command = sensor_command
        super(GPUTemperature, self).__init__()
        self.min_temp = min_temp
        self.max_temp = max_temp
        self.threshold = threshold
        self._fire_events()

    def __repr__(self):
        return '<gpiozero.GPUTemperature temperature=%.2f>' % self.temperature

    @property
    def temperature(self):
        """
        Returns the current GPU temperature in degrees celsius.
        """
        with os.popen(self.sensor_command) as f:
            return float(f.readline().replace('temp=','').replace("'C\n",'').strip())

    @property
    def value(self):
        """
        Returns the current GPU temperature as a value between 0.0
        (representing the *min_temp* value) and 1.0 (representing the
        *max_temp* value). These default to 0.0 and 100.0 respectively, hence
        :attr:`value` is :attr:`temperature` divided by 100 by default.
        """
        temp_range = self.max_temp - self.min_temp
        return (self.temperature - self.min_temp) / temp_range

    @property
    def is_active(self):
        """
        Returns ``True`` when the GPU :attr:`temperature` exceeds the
        :attr:`threshold`.
        """
        return self.temperature > self.threshold