"""Local filesystem helpers."""

from __future__ import annotations

import re
from pathlib import Path

from .exceptions import ValidationError

_REPO_ID_RE = re.compile(r"^[a-zA-Z0-9_.\-]+/[a-zA-Z0-9_.\-]+$")
_VERSION_RE = re.compile(r"^v?\d+\.\d+\.\d+([.\-].+)?$")


def validate_model_dir(path: Path) -> Path:
    if not path.exists():
        raise ValidationError(
            f"Model directory does not exist: {path}",
            suggestion="Pass the correct --model path.",
        )
    if not path.is_dir():
        raise ValidationError(
            f"--model must be a directory, got a file: {path}",
            suggestion="Point --model to the directory containing your model files.",
        )
    files = list(path.iterdir())
    if not files:
        raise ValidationError(
            f"Model directory is empty: {path}",
            suggestion="Make sure training has completed and the output directory is correct.",
        )
    return path


def validate_version(version: str) -> str:
    if not _VERSION_RE.match(version):
        raise ValidationError(
            f"Invalid version string: {version!r}",
            suggestion="Use semantic versioning like v1.2.0 or 1.2.0.",
        )
    return version


def validate_repo_id(repo_id: str, label: str = "repo") -> str:
    if not _REPO_ID_RE.match(repo_id):
        raise ValidationError(
            f"Invalid {label} ID: {repo_id!r}",
            suggestion="Repo IDs must be in 'owner/name' format.",
        )
    return repo_id