from math import floor
from os import getenv
from typing import List

from xdg import BaseDirectory

def first_defined_argument(*args):
    return next((item for item in args if item is not None), None)
first = first_defined_argument

class Environment(object):
    """
    This is where all of the configuration options (should) live.

    Please review the class variables for available configuration
    options through their respective environment variables.
    """

    ARCHIVE = getenv('ARCHIVE_DIR', BaseDirectory.save_data_path(__package__))
    ARCHIVE_SUFFIX_LENGTH = int(getenv('SUFFIX_LENGTH', 6))
    ALLOWED_SENDERS = [
        num for num in getenv('ALLOWED_SENDERS', '').split(',') if num
    ]

    MESSAGE_FORMAT = getenv('MESSAGE_FORMAT', '{message}')

    PRINT_COMMAND = getenv('PRINT_COMMAND', 'lp')
    PRINTER_NAME = getenv('PRINTER_NAME', None)
    PRINT_JOB_TIMEOUT = int(getenv('PRINT_JOB_TIMEOUT', 5)) # seconds

    CPI = int(getenv('CPI', 10))
    LPI = int(getenv('LPI', 6))
    TEXT_SCALE = float(getenv('TEXT_SCALE', 1.0))

    # Set in points; each point is 1/72 inch or 0.35mm.
    MARGINS = getenv('MARGINS', None)
    MARGIN_SIDES = first(getenv('MARGIN_SIDES', None), MARGINS)
    MARGIN_TOP = first(getenv('MARGIN_TOP', None), MARGINS)
    MARGIN_BOTTOM = first(getenv('MARGIN_BOTTOM', None), MARGINS)
    MARGIN_LEFT = first(getenv('MARGIN_LEFT', None), MARGIN_SIDES, MARGINS)
    MARGIN_RIGHT = first(getenv('MARGIN_RIGHT', None), MARGIN_SIDES, MARGINS)

    def print_command(self, file_to_print=None) -> List[str]:
        command = [self.PRINT_COMMAND]

        if self.PRINTER_NAME is not None:
            command.append(
                "-d {}".format(self.PRINTER_NAME))

        if self.TEXT_SCALE is not 1.0:
            # Scale horizontally
            cpi = floor(self.CPI*(1/self.TEXT_SCALE))
            command.append(
                "-o cpi={}".format(cpi))

            # Scale vertically
            lpi = floor(self.LPI*(1/self.TEXT_SCALE))
            command.append(
                "-o lpi={}".format(lpi))

        if self.MARGIN_TOP is not None:
            command.append(
                "-o page-top={}".format(self.MARGIN_TOP))

        if self.MARGIN_BOTTOM is not None:
            command.append(
                "-o page-bottom={}".format(self.MARGIN_BOTTOM))

        if self.MARGIN_LEFT is not None:
            command.append(
                "-o page-left={}".format(self.MARGIN_LEFT))

        if self.MARGIN_RIGHT is not None:
            command.append(
                "-o page-right={}".format(self.MARGIN_RIGHT))

        if file_to_print is not None:
            command.append(file_to_print)

        return command