import re
import hashlib
from pathlib import Path
from typing import Any

from langchain_core.documents import Document


def clean_text(text: str) -> str:
    text = text.replace("\u00a0", " ")
    text = re.sub(r"\s+", " ", text).strip()
    return text


def build_chunks_from_folder(
    folder_path: str,
) -> list[Document]:

    folder = Path(folder_path)

    if not folder.exists() or not folder.is_dir():
        raise ValueError(f"Invalid folder path: {folder_path}")

    all_chunks: list[Document] = []

    for file_path in folder.glob("*.txt"):
        doc_text = file_path.read_text(encoding="utf-8")

        if not doc_text.strip():
            continue

        metadata: dict[str, Any] = {
            "source": file_path.name,
        }   

        doc_text = clean_text(doc_text)
        chunk = Document(
            id=hashlib.md5(file_path.name.encode()).hexdigest(),
            page_content=doc_text,
            metadata={**metadata,}
        )

        all_chunks.append(chunk)

    return all_chunks