import os
import yaml
import requests
from pathlib import Path
from langchain.document_loaders import PyPDFLoader

def get_pdf_from_url(arxiv_id: str, save_dir: str) -> str:
    """
    Downloads a PDF from arXiv given an ID, unless already downloaded.

    Returns:
        str: Path to the downloaded (or existing) PDF.
    """
    os.makedirs(save_dir, exist_ok=True)
    pdf_path = os.path.join(save_dir, f"{arxiv_id}.pdf")

    if os.path.exists(pdf_path):
        # print(f"[cache] PDF already exists: {pdf_path}")
        return pdf_path

    url = f"https://arxiv.org/pdf/{arxiv_id}.pdf"

    response = requests.get(url)
    response.raise_for_status()

    with open(pdf_path, "wb") as f:
        f.write(response.content)

def load_config(config_path: str="./configs/pipeline.yaml") -> dict:
    """
    Load a YAML configuration file and return its contents as a dictionary.

    Args:
        config_path (str): The path to the YAML configuration file.

    Returns:
        dict: The contents of the configuration file.
    """
    config_path = Path(config_path)
    if not config_path.exists():
        raise FileNotFoundError(f"Configuration file {config_path} does not exist.")

    with open(config_path, 'r') as file:
        config = yaml.safe_load(file)

    return config

def extract_text_from_pdf(pdf_path: str) -> str:
    """
    Extract text from a PDF file.

    Args:
        pdf_path (str): The path to the PDF file.

    Returns:
        str: The extracted text from the PDF.
    """
    loader = PyPDFLoader(pdf_path)
    documents = loader.load()
    
    return documents