"""Project-level chunking defaults and validation."""
from __future__ import annotations

from dataclasses import dataclass


DEFAULT_CHUNK_SIZE = 512
DEFAULT_CHUNK_OVERLAP = 64


@dataclass(frozen=True)
class ChunkConfig:
    size: int
    overlap: int


def resolve_chunk_config(
    *,
    chunk_size: int | None = None,
    chunk_overlap: int | None = None,
) -> ChunkConfig:
    size = DEFAULT_CHUNK_SIZE if chunk_size is None else chunk_size
    overlap = DEFAULT_CHUNK_OVERLAP if chunk_overlap is None else chunk_overlap
    if size <= 0:
        raise ValueError("chunk_size must be greater than zero")
    if overlap < 0:
        raise ValueError("chunk_overlap cannot be negative")
    if overlap >= size:
        raise ValueError("chunk_overlap must be smaller than chunk_size")
    return ChunkConfig(size=size, overlap=overlap)