#!/usr/bin/env python3

import json
import itertools
import textwrap
from pathlib import Path
from argparse import ArgumentParser

import requests
from bs4 import BeautifulSoup


ROOT_DIR           = Path(__file__).resolve().parent
LANGUAGES_FILENAME = ROOT_DIR / 'languages.json'
URL_FORMAT         = 'http://projecteuler.net/problem={index}'
LINE_WRAP          = 89
PROBLEM_PADDING    = 3

class Problem:
    def __init__(self, index: int, language: dict):
        self.index = index
        self.language = language

    def fetch(self):
        url = URL_FORMAT.format(index=self.index)
        print(f"Fetching problem {self.index} at {url}")
        data = requests.get(url)
        soup = BeautifulSoup(data.text, 'html.parser')
        data = soup.find('div', {'id': 'content'})
        self.title     = data.h2.text
        self.sub_title = data.h3.text
        self.content   = soup.find('div', {'class': 'problem_content'}).text
        print(self)
        return self

    def write(self):
        file_name = f'{self.index:03}-{self._slug}.{self.language["extension"]}'
        file_path = ROOT_DIR / self.language['name'] / file_name
        if file_path.exists():
            raise FileExistsError(f'{file_path} already exists')
        file_path.parent.mkdir(exist_ok=True)
        with open(file_path, 'w') as file:
            file.write(str(self))
        return self

    def __str__(self) -> str:
        title     = self.title.strip()
        sub_title = self.sub_title.strip()
        content   = self.content.strip()

        content_lines = []
        for line in content.splitlines():
            content_lines.extend(textwrap.wrap(line, width=LINE_WRAP))

        lines = [title, sub_title, "", *content_lines]
        lines = [self.language['comment']['prefix'] + line for line in lines]
        lines.insert(0, self.language['comment']['top'])
        lines.append(self.language['comment']['bottom'])
        lines.extend(itertools.repeat("", PROBLEM_PADDING))
        return '\n'.join(lines)

    @property
    def _slug(self) -> str:
        title = self.title.lower().replace(' ', '_')
        title = [c for c in title if c.isalnum() or c == '_']
        return ''.join(title)


def main():
    with open(LANGUAGES_FILENAME, 'r') as file:
        languages = json.load(file)
    parser = ArgumentParser(description='Project Euler problem file generator')
    parser.add_argument(
        'language',
        metavar='LANGUAGE',
        choices=languages,
        help='file programming language',
    )
    parser.add_argument(
        'indices',
        metavar='INDEX',
        nargs='+',
        type=int,
        help='Project Euler problems index',
    )
    args = parser.parse_args()
    for index in args.indices:
        language = languages[args.language]
        language['name'] = args.language
        Problem(index, language).fetch().write()


if __name__ == '__main__':
    main()