"""
Chunking utilities for the RAG agent.

Uses RecursiveCharacterTextSplitter from LangChain with chunk_size=500 and overlap=100.
"""
import os
from pathlib import Path
from typing import List

from langchain_text_splitters import RecursiveCharacterTextSplitter

# Default splitter configuration
CHUNK_SIZE = 500
OVERLAP = 100

splitter = RecursiveCharacterTextSplitter(chunk_size=CHUNK_SIZE, chunk_overlap=OVERLAP)

def split_text(text: str) -> List[str]:
    """Split a large string into chunks.

    Parameters
    ----------
    text: str
        The raw document content.

    Returns
    -------
    List[str]
        A list of chunk strings.
    """
    return splitter.split_text(text)

# Helper to read all files from a directory and split them

def load_and_split(directory: Path) -> List[tuple]:
    """Load text files from *directory* and split into chunks.

    Returns a list of tuples (chunk, metadata).
    Metadata contains the source file path.
    """
    chunks = []
    for file_path in directory.rglob("*.txt"):
        content = file_path.read_text(encoding="utf-8")
        for chunk in split_text(content):
            chunks.append((chunk, {"source": str(file_path)}))
    return chunks