#!/usr/bin/env python3

import os.path
from qrcode import make as qrcode_make
import qrcode.image.svg
from svgutils import transform as st
from ch_kreuz import swisscross as get_swisscross
from ch_kreuz import white as get_white
from svgutils.compose import Figure
from chardet import detect


class qr_rechnung():
    data = ''
    error_correction = None

    def __init__(self, data=None, textfile=None):
        if textfile is not None:
            self.set_data_from_textfile(textfile)

    def set_data(self, data):
        self.data = data
        self.data = data.encode('latin-1')

    def set_data_from_textfile(self, textfile):
        with open(textfile, 'rb') as rawdata:
            charenc = detect(rawdata.read())['encoding']
        with open(textfile, 'r', encoding=charenc) as f:
            self.set_data(f.read())

    def write_file(self, filepath, force=False):
        global qrcode
        mode = 'w' if force else 'x'
        try:
            assert force or not os.path.isfile(filepath)
            img = qrcode.make(
                self.data,
                error_correction=qrcode.constants.ERROR_CORRECT_M,
                image_factory=qrcode.image.svg.SvgPathImage
            )
            img.save(filepath)
        except AssertionError:
            print(f"ERROR: Datei {filepath} existiert bereits.")
            return 1

        qrcode = st.fromfile(filepath)
        try:
            assert qrcode.width[-2:] == 'mm'
            qr_scale = 49.5/float(qrcode.width[:-2])
        except AssertionError as e:
            print(f"ERROR: Ein unerwarteter Fall in der Skallierung.")
            print(e)
            return 1

        qrr = Figure(
            '49.5mm', '49.5mm',
            get_white().getroot(),
            qrcode.getroot().scale(qr_scale),
            get_swisscross().getroot()
        )
        qrr.save(filepath)


def help(args):
    return '\n'.join([
        '{0}: Ungültige Eingabe',
        'Aufruf: {0} TEXTDATEI [SVG-ZIELDATEI]',
        ]).format(args[0])


def main(args):
    try:
        textfile = args[1]
    except IndexError:
        print(help(args))
        return 1
    try:
        output_format = 'svg'
        svgfile = args[2]
        if svgfile[-4:] == '.svg':
            pass
        else:
            svgfile += '.svg'
    except IndexError:
        try:
            assert textfile[-4:] == '.txt'
            svgfile = textfile[:-4]+'.svg'
        except AssertionError:
            print(help(args))
            return 1
    try:
        x = qr_rechnung(textfile=textfile)
        x.write_file(svgfile, force=False)
    except (PermissionError, FileNotFoundError) as e:
        print(e)
        return 1
    if output_format == 'svg':
        return 0
    else:
        print(f"ERROR: Unbekanntes Output_format: {output_format}")
        return 1


if __name__ == '__main__':
    import sys
    sys.exit(main(sys.argv))