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

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

def parse_pdf_from_url_multithreaded(url, max_workers=2, chunk_size=1):
    """
    Download PDF from URL, extract text in parallel, optionally chunk pages.
    """
    res = requests.get(url)
    with fitz.open(stream=BytesIO(res.content), filetype="pdf") as doc:
        num_pages = len(doc)
        pages = list(doc)
        # Step 1: Parallel text extraction
        with ThreadPoolExecutor(max_workers=max_workers) as executor:
            texts = list(executor.map(_extract_text, pages))
        # Step 2: Optional chunking
        if chunk_size > 1:
            chunks = []
            for i in range(0, len(texts), chunk_size):
                chunk = ' '.join([t for t in texts[i:i+chunk_size] if t])
                if chunk:
                    chunks.append(chunk)
            return chunks
        # Default: return one chunk per page
        return [t for t in texts if t]

def parse_pdf_from_file_multithreaded(file_path, max_workers=2, chunk_size=1):
    """
    Parse a local PDF file, extract text in parallel, optionally chunk pages.
    """
    with fitz.open(file_path) as doc:
        num_pages = len(doc)
        pages = list(doc)
        # Step 1: Parallel text extraction
        with ThreadPoolExecutor(max_workers=max_workers) as executor:
            texts = list(executor.map(_extract_text, pages))
        # Step 2: Optional chunking
        if chunk_size > 1:
            chunks = []
            for i in range(0, len(texts), chunk_size):
                chunk = ' '.join([t for t in texts[i:i+chunk_size] if t])
                if chunk:
                    chunks.append(chunk)
            return chunks
        return [t for t in texts if t]