import fitz  # PyMuPDF
import requests
from io import BytesIO
from concurrent.futures import ThreadPoolExecutor
import os

def extract_page_text(page):
    text = page.get_text()
    return text if text.strip() else None

def parse_pdf_from_url_multithreaded(url, max_workers=None):
    # Automatically detect and use all available CPU cores if max_workers not set
    if max_workers is None:
        max_workers = os.cpu_count() or 8

    res = requests.get(url)
    doc = fitz.open(stream=BytesIO(res.content), filetype="pdf")
    pages = [page for page in doc]
    chunks = [None] * len(pages)
    
    # Process pages in parallel, preserving page order
    with ThreadPoolExecutor(max_workers=max_workers) as executor:
        results = list(executor.map(extract_page_text, pages))
    
    # Keep only non-empty page results, preserving order
    doc.close()
    return [r for r in results if r]

def parse_pdf_from_file_multithreaded(file_path, max_workers=None):
    if max_workers is None:
        max_workers = os.cpu_count() or 8

    try:
        doc = fitz.open(file_path)
        pages = [page for page in doc]
        chunks = [None] * len(pages)
        
        with ThreadPoolExecutor(max_workers=max_workers) as executor:
            results = list(executor.map(extract_page_text, pages))
        doc.close()
        return [r for r in results if r]
    except Exception as e:
        raise Exception(f"Error parsing PDF file {file_path}: {str(e)}")