from pathlib import Path

from backend.database.schemas import Chunk


DOC_LANGUAGES = {"markdown", "text", "yaml", "json", "env"}


def fallback_chunk_file(path: Path, repo_root: Path, repo_id: str, language: str) -> list[Chunk]:
    text = path.read_text(encoding="utf-8", errors="ignore")
    chunk_size = 700
    overlap = 80 if language in DOC_LANGUAGES else 20
    return split_text_into_chunks(text, path, repo_root, repo_id, language, chunk_size, overlap)


def split_text_into_chunks(
    text: str,
    path: Path,
    repo_root: Path,
    repo_id: str,
    language: str,
    chunk_size: int,
    overlap: int,
) -> list[Chunk]:
    words = text.split()
    lines = text.splitlines()
    rel = path.relative_to(repo_root).as_posix()
    if not words:
        return [
            Chunk(
                id=f"{repo_id}:{rel}:1",
                repo_id=repo_id,
                path=rel,
                language=language,
                start_line=1,
                end_line=max(1, len(lines)),
                content=text,
            )
        ]

    chunks: list[Chunk] = []
    step = max(1, chunk_size - overlap)
    for index, start in enumerate(range(0, len(words), step), start=1):
        window = words[start : start + chunk_size]
        content = " ".join(window)
        start_line = _estimate_line_for_word(text, start)
        end_line = _estimate_line_for_word(text, min(start + len(window), len(words)))
        chunks.append(
            Chunk(
                id=f"{repo_id}:{rel}:fallback:{index}",
                repo_id=repo_id,
                path=rel,
                language=language,
                symbol=f"chunk_{index}",
                kind="text" if language in DOC_LANGUAGES else "module",
                start_line=start_line,
                end_line=max(start_line, end_line),
                content=content,
            )
        )
    return chunks


def _estimate_line_for_word(text: str, word_index: int) -> int:
    if word_index <= 0:
        return 1
    seen = 0
    for line_number, line in enumerate(text.splitlines(), start=1):
        seen += len(line.split())
        if seen >= word_index:
            return line_number
    return max(1, len(text.splitlines()))