# -----------------------------------------------------------------------------
# Author: Jiawei Liu
# Date: 2024-11-22
# -----------------------------------------------------------------------------
'''
To run: 
`python BalticWay/download_script/download.py`
'''

import requests
from requests.adapters import HTTPAdapter
from tqdm import tqdm
from bs4 import BeautifulSoup
from urllib.parse import urljoin
from urllib3.util.retry import Retry
from pathlib import Path


def build_session(
    max_retries: int = 3,
    backoff_factor: int = 2,
    session: requests.Session = None
) -> requests.Session:
    """
    Build a requests session with retries

    Args:
        max_retries (int, optional): Number of retries. Defaults to 3.
        backoff_factor (int, optional): Backoff factor. Defaults to 2.
        session (requests.Session, optional): Session object. Defaults to None.
    """
    session = session or requests.Session()
    adapter = HTTPAdapter(max_retries=Retry(total=max_retries, backoff_factor=backoff_factor))
    session.mount("http://", adapter)
    session.mount("https://", adapter)
    session.headers.update({
        "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.3"
    })

    return session


def main():
    base_url = "https://www.math.olympiaadid.ut.ee/eng/html/?id=bw"

    output_dir = Path(__file__).parent.parent / "raw"
    output_dir.mkdir(parents=True, exist_ok=True)

    req_session = build_session()

    resp = req_session.get(base_url)
    soup = BeautifulSoup(resp.text, "html.parser")

    year_list_eles = soup.find("td", class_="leht").find_all("a", class_="siseviit")

    for year_ele in tqdm(year_list_eles):
        problem_with_solution_link_ele = year_ele.find(lambda tag: tag.name == "a" and "solutions:" in tag.parent.text.lower())
        problem_link_ele = year_ele.find(lambda tag: tag.name == "a" and "problems:" in tag.parent.text.lower())

        if problem_with_solution_link_ele:
            pdf_url = urljoin(base_url, problem_with_solution_link_ele["href"])
        elif problem_link_ele:
            pdf_url = urljoin(base_url, problem_link_ele["href"])
        else:
            continue

        output_file = output_dir / f"en-{pdf_url.split('/')[-1]}"
        if output_file.exists():
            continue

        resp = req_session.get(pdf_url)

        if resp.status_code != 200:
            print(f"Failed to download {pdf_url}")
            continue

        output_file.write_bytes(resp.content)


if __name__ == "__main__":
    main()