# -*- coding: utf-8 -*-
#
# SPDX-License-Identifier: MIT
"""Common routines for data in glucometers."""

import datetime
import enum
import textwrap

try:
    from typing import Optional, Sequence, Text
except ImportError:
    pass

import attr

class Unit(enum.Enum):
    MG_DL = 'mg/dL'
    MMOL_L = 'mmol/L'

# Constants for meal information
class Meal(enum.Enum):
    NONE = ''
    BEFORE = 'Before Meal'
    AFTER = 'After Meal'

# Constants for measure method
class MeasurementMethod(enum.Enum):
    BLOOD_SAMPLE = 'blood sample'
    CGM = 'CGM' # Continuous Glucose Monitoring
    TIME = 'time'


def convert_glucose_unit(value, from_unit, to_unit):
    # type: (float, Unit, Unit) -> float
    """Convert the given value of glucose level between units.

    Args:
      value: The value of glucose in the current unit
      from_unit: The unit value is currently expressed in
      to_unit: The unit to conver the value to: the other if empty.

    Returns:
      The converted representation of the blood glucose level.
    """
    from_unit = Unit(from_unit)
    to_unit = Unit(to_unit)

    if from_unit == to_unit:
        return value

    if from_unit == Unit.MG_DL:
        return round(value / 18.0, 2)

    return round(value * 18.0, 0)

@attr.s
class GlucoseReading:

    timestamp = attr.ib()  # type: datetime.datetime
    value = attr.ib()  # type: float
    meal = attr.ib(
        default=Meal.NONE, validator=attr.validators.in_(Meal))  # type: Meal
    comment = attr.ib(default='')  # type: Text
    measure_method = attr.ib(
        default=MeasurementMethod.BLOOD_SAMPLE,
        validator=attr.validators.in_(
            MeasurementMethod)) # type: MeasurementMethod

    def get_value_as(self, to_unit):
        # type: (Unit) -> float
        """Returns the reading value as the given unit.

        Args:
          to_unit: (Unit) The unit to return the value to.
        """
        return convert_glucose_unit(self.value, Unit.MG_DL, to_unit)

    def as_csv(self, unit):
        # type: (Unit) -> Text
        """Returns the reading as a formatted comma-separated value string."""
        return '"%s","%.2f","%s","%s","%s"' % (
            self.timestamp, self.get_value_as(unit), self.meal.value,
            self.measure_method.value, self.comment)

@attr.s
class KetoneReading:

    timestamp = attr.ib()  # type: datetime.datetime
    value = attr.ib()  # type: float
    comment = attr.ib(default='')  # type: Text

    def as_csv(self, unit):
        """Returns the reading as a formatted comma-separated value string."""
        del unit  # Unused for Ketone readings.

        return '"%s","%.2f","%s","%s"' % (
            self.timestamp, self.value, MeasurementMethod.BLOOD_SAMPLE.value,
            self.comment)

@attr.s
class TimeAdjustment:
    timestamp = attr.ib()  # type: datetime.datetime
    old_timestamp = attr.ib()  # type: datetime.datetime
    measure_method = attr.ib(
        default=MeasurementMethod.TIME,
        validator=attr.validators.in_(
            MeasurementMethod))  # type: MeasurementMethod

    def as_csv(self, unit):
        del unit
        return '"%s","","%s","%s"' % (
            self.timestamp, self.measure_method.value, self.old_timestamp
        )


@attr.s
class MeterInfo:
    """General information about the meter.

    Attributes:
      model: Human readable model name, chosen by the driver.
      serial_number: Serial number identified for the reader (or N/A if not
        available in the protocol.)
      version_info: List of strings with any version information available about
        the device. It can include hardware and software version.
      native_unit: One of the Unit values to identify the meter native unit.
    """
    model = attr.ib()  # type: Text
    serial_number = attr.ib(default='N/A')  # type: Text
    version_info = attr.ib(default=())  # type: Sequence[Text]
    native_unit = attr.ib(
        default=Unit.MG_DL, validator=attr.validators.in_(Unit))  # type: Unit
    patient_name = attr.ib(default=None)  # type: Optional[Text]

    def __str__(self):
        version_information_string = 'N/A'
        if self.version_info:
            version_information_string = '\n    '.join(
                self.version_info).strip()

        base_output = textwrap.dedent("""\
            {model}
            Serial Number: {serial_number}
            Version Information:
                {version_information_string}
            Native Unit: {native_unit}
        """).format(model=self.model, serial_number=self.serial_number,
                    version_information_string=version_information_string,
                    native_unit=self.native_unit.value)

        if self.patient_name != None:
            base_output += 'Patient Name: {patient_name}\n'.format(
                patient_name=self.patient_name)

        return base_output