"""Fixed-size sliding chunker (default)."""
from __future__ import annotations

from typing import List

from ..core.types import Chunk, Document


def fixed_chunker(doc: Document, chunk_size: int = 600, overlap: int = 100) -> List[Chunk]:
    text = doc.text
    if len(text) <= chunk_size:
        return [Chunk(doc_id=doc.id, chunk_id=f"{doc.id}::0",
                     text=text, start=0, end=len(text),
                     metadata=dict(doc.metadata))]
    chunks: List[Chunk] = []
    i = 0
    idx = 0
    while i < len(text):
        end = min(len(text), i + chunk_size)
        chunks.append(Chunk(
            doc_id=doc.id, chunk_id=f"{doc.id}::{idx}",
            text=text[i:end], start=i, end=end,
            metadata=dict(doc.metadata),
        ))
        idx += 1
        if end == len(text):
            break
        i = end - overlap
    return chunks