#!/usr/bin/env python3
import requests
import os

from bs4 import BeautifulSoup
from argparse import ArgumentParser


class DVIDSParser:
    def __init__(self, url, output):
        self._url = url
        self._output = output

    def go(self):
        years = self.get_years()
        for y in years:
            pages = self.get_pages_count(y)
            for page in range(pages):
                url = f'{self._url}?issueYearDropDown={y}&sortOptions=DESC&page={page+1}'
                r = requests.get(url)
                html = BeautifulSoup(r.text, 'html.parser')

                for pub in html.select('.publication-item'):
                    title = pub.select_one('div:not(.uk-row) > p:not(.issue-downloads):not(.issue-hits)').text.strip()
                    pdf_id = os.path.basename(pub.select_one('a')['href'])
                    pdf_url = f'https://media-cdn.dvidshub.net/pubs/pdf_{pdf_id}.pdf'
                    filename = f'{title} ({pdf_id}).pdf'
                    self.save(pdf_url, filename)
                    print(f'[{y}/{page}/{pdf_id}] {title} OK')

    def get_pages_count(self, year: int) -> int:
        url = f'{self._url}/page/999/?issueYearDropDown={year}&sortOptions=DESC'
        r = requests.get(url)
        html = BeautifulSoup(r.text, 'html.parser')
        return int(html.select_one('li.uk-active > span').text)

    def get_years(self) -> list[int]:
        r = requests.get(self._url)
        html = BeautifulSoup(r.text, 'html.parser')
        return list(map(lambda opt: int(opt['value']), html.select_one('#issueYearDropDown').select('option')))

    def save(self, url, filename):
        streamed_response = requests.get(url, stream=True)
        with open(os.path.join(self._output, filename), 'wb') as file:
            for chunk in streamed_response.iter_content(chunk_size=1024):
                if chunk:  # filter out keep-alive new chunks
                    file.write(chunk)


if __name__ == '__main__':
    parser = ArgumentParser()
    parser.add_argument('--collection-url', type=str, required=True)
    # parser.add_argument('--pages', type=int, default=1)
    parser.add_argument('--output-directory', type=str, required=True,
                        help='Directory where to save files. If does not exist, it will be created')
    args = parser.parse_args()

    if os.path.exists(args.output_directory) and not os.path.isdir(args.output_directory):
        raise OSError('specified path is not a directory')
    elif not os.path.exists(args.output_directory):
        os.makedirs(args.output_directory)

    p = DVIDSParser(url=args.collection_url,
                    output=args.output_directory)
    p.go()