"""Module that creates barcode image from product UPC from database.

generate_barcode uses elaphe library to create barcode from 12 or
13 digit number and Pillow to create image with created barcode.
"""

import os

from elaphe.ean import Ean13
from elaphe.upc import UpcA
from oto import response
from salessheets import config
from salessheets.connectors import loggly
from salessheets.constants import barcode
from salessheets.constants import errors

logger = loggly.get_current_logger()


def generate_barcode(
        upc, scale=barcode.DEFAULT_SCALE,
        margin=barcode.DEFAULT_MARGIN, options=None):
    """
    Main function, that generate barcode from product upc.

    If product has 12 digit upc it generates UPC-A-type barcode.
    If product has 13 digit upc it generates EAN-13 barcode.
    If it has other length return error.

    Args:
        upc (str): upc of product which should become a barcode.
        scale (int): scale of barcode, impact on size of image.
        margin (int): margin of barcode in image.
        options (dict): dict of options for elaphe generating.

    Returns:
        Response: Response with barcode data of error message.

    """
    upc = str(upc)
    barcode_path = os.path.join(
        config.PDF_RENDERING_DIR, barcode.BARCODES_DIRECTORY)
    if not os.path.exists(barcode_path):
        os.makedirs(barcode_path)
    barcode_file = os.path.join(barcode_path, '{upc}.png'.format(upc=upc))
    render_options = {
        barcode.INCLUDE_TEXT: barcode.DEFAULT_INCLUDE_TEXT
    }
    validated_barcode = validate_barcode_data(upc)
    if not validated_barcode:
        return validated_barcode
    if options:
        render_options.update(options)
    if len(upc) == 12:
        barcode_renderer = UpcA()
        barcode_type = barcode.UPC_A
    else:
        barcode_renderer = Ean13()
        barcode_type = barcode.EAN_13
    brcd_img = barcode_renderer.render(
        upc, options=render_options,
        scale=scale, margin=margin)
    barcode_data = {
        barcode.BARCODE_TYPE: barcode_type,
        barcode.BARCODE: barcode_file
    }
    try:
        brcd_img.save(barcode_file)
    except OSError as e:
        return response.create_error_response(
            code=errors.ERROR_BARCODE_GENERATING_CODE,
            message=e)
    return response.Response(message=barcode_data)


def validate_barcode_data(upc):
    """
    Validation of upc for barcode, it should be 12-digit or 13-digit number.

    Args:
        upc (str): upc of product which should become a barcode.

    Returns:
        Response: Response with barcode validation data.
    """
    if not upc.isdigit():
        return response.create_error_response(
            code=errors.ERROR_BARCODE_IS_NOT_NUMERIC,
            message=errors.ERROR_INVALID_BARCODE_MESSAGE
        )
    if len(upc) not in [12, 13]:
        return response.create_error_response(
            code=errors.ERROR_BARCODE_INVALID_LENGTH,
            message=errors.ERROR_INVALID_BARCODE_MESSAGE
        )
    return response.Response()