"""Tests distillation preparation helpers."""

from __future__ import annotations

import json
from pathlib import Path

from maris_core.training.distill import distill


def test_distill_writes_plan_and_readme(tmp_path: Path) -> None:
    teacher_dir = tmp_path / "teacher"
    student_dir = tmp_path / "student"
    teacher_dir.mkdir()
    student_dir.mkdir()
    (teacher_dir / "config.json").write_text("{}", encoding="utf-8")

    output_dir = tmp_path / "distilled"
    distill(str(teacher_dir), str(student_dir), str(output_dir))

    manifest = json.loads((output_dir / "distillation-plan.json").read_text(encoding="utf-8"))
    assert manifest["status"] == "prepared"
    assert manifest["teacher"]["is_local_path"] is True
    assert manifest["teacher"]["config_exists"] is True
    assert manifest["student"]["config_exists"] is False
    assert (output_dir / "README.md").is_file()


def test_distill_rejects_empty_teacher_model(tmp_path: Path) -> None:
    try:
        distill("   ", "student", str(tmp_path / "distilled"))
    except ValueError as exc:
        assert "teacher_model" in str(exc)
    else:
        raise AssertionError("distill() should reject an empty teacher model reference")