from typing import List, Optional
from langchain.schema import Document
from config import CHUNK_OVERLAP


def clean_text(text: str) -> str:
    """
    Remove NUL (0x00) characters from a string.

    :param text: The original text with potential NUL characters.
    :return: Cleaned text without NUL characters.
    """
    return text.replace("\x00", "")


def process_documents(documents: List[Document]) -> str:
    processed_text = ""
    last_page: Optional[int] = None
    doc_basename = ""

    for doc in documents:
        if "source" in doc.metadata:
            doc_basename = doc.metadata["source"].split("/")[-1]
            break

    processed_text += f"{doc_basename}\n"

    for doc in documents:
        current_page = doc.metadata.get("page")
        if current_page and current_page != last_page:
            processed_text += f"\n# PAGE {doc.metadata['page']}\n\n"
            last_page = current_page

        new_content = doc.page_content
        if processed_text.endswith(new_content[:CHUNK_OVERLAP]):
            processed_text += new_content[CHUNK_OVERLAP:]
        else:
            processed_text += new_content

    return processed_text.strip()