#!/usr/bin/env python3
import argparse
import os
import re
import sys

HEADER = '\\documentclass[a4paper]{article}\n\n'\
        '\\author{} %%TODO\n'\
        '\\title{Huiswerk %s, week %d}\n\n'\
        '\\usepackage{enumitem}\n'\
        '\\usepackage[dutch]{babel}\n\n'\
        '\\begin{document}\n\n'\
        '\\maketitle\n'

FOOTER = '\n\\end{document}'

class ExercisesList:
    STYLES = ['\\arabic*.', '(\\alph*)', '\\roman*.']

    def __init__(self, indent=0, style=None):
        self.indent = indent
        self.style = style if style is not None else self.STYLES[self.indent]
        self.exercises = []

    def read(self, lines):
        i = -1
        while i < len(lines) - 1:
            i += 1
            line = lines[i]

            # Single item
            m = re.search(r'^\t{%d}(\d+)$' % self.indent, line)
            if m is not None:
                self.exercises.append(int(m.group(1)))
                continue

            # Range
            m = re.search(r'^\t{%d}(\d+)-(\d+)$' % self.indent, line)
            if m is not None:
                self.exercises += range(int(m.group(1)), int(m.group(2)) + 1)
                continue

            # Style
            m = re.search(r'^\t{%d}(\S.*)$' % self.indent, line)
            if m is not None:
                self.style = m.group(1)
                continue

            # Indent
            if line[:self.indent + 1] == '\t' * (self.indent + 1):
                sublist = ExercisesList(self.indent + 1)
                i += sublist.read(lines[i:]) - 1
                self.exercises.append(sublist)
                continue

            # This line is not for us
            break
        return i

    def to_latex(self):
        latex = []
        indent = '\t' * self.indent * 2
        i = 1

        latex.append(indent + '\\begin{enumerate}')
        if self.style != self.STYLES[self.indent]:
            latex[0] += '[label=%s]' % self.style
        for item in self.exercises:
            if type(item) is ExercisesList:
                latex += item.to_latex()
            else:
                if item != i:
                    latex.append(indent + '\t\\setcounter{enumi%s}{%d}' %
                            ('i' * self.indent, item - 1))
                    i = item
                latex.append(indent + '\t\\item %TODO ' + str(item))
                i += 1
        latex.append(indent + '\\end{enumerate}')
        return latex
            

def parse_args():
    """Parse command line arguments"""
    pars = argparse.ArgumentParser(description='TeX format')

    pars.add_argument(
        '-i', '--input',
        type=argparse.FileType('r'), default=sys.stdin)
    pars.add_argument(
        '-o', '--output',
        type=argparse.FileType('w'), default=sys.stdout)

    pars.add_argument('-c', '--course', type=str, required=True)
    pars.add_argument('-w', '--week', type=int, required=True)

    return pars.parse_args()

def main():
    args = parse_args()

    lines = [line[:-1] for line in args.input.readlines()]

    exercises = ExercisesList()
    exercises.read(lines)

    print(HEADER % (args.course, args.week))
    print('\n'.join(exercises.to_latex()))
    print(FOOTER)

if __name__ == '__main__':
    main()