"""Shared fixtures: a model snapshot the fingerprint can read without a 9B download."""

from __future__ import annotations

import json
from collections.abc import Callable
from pathlib import Path
from typing import Any

import pytest

ROPE: dict[str, Any] = {
    "rope_type": "yarn",
    "factor": 4.0,
    "original_max_position_embeddings": 262_144,
    "mrope_interleaved": True,
    "mrope_section": [11, 11, 10],
}
TEMPLATE = "{% for message in messages %}{{ message['content'] }}{% endfor %}"


def write_model(model_dir: Path, **config_overrides: Any) -> Path:
    config: dict[str, Any] = {
        "model_type": "qwen3_5",
        "max_position_embeddings": 262_144,
        "partial_rotary_factor": 0.25,
        "rope_parameters": dict(ROPE),
        "chat_template": TEMPLATE,
    }
    config.update(config_overrides)
    model_dir.mkdir(parents=True, exist_ok=True)
    (model_dir / "config.json").write_text(json.dumps(config), encoding="utf-8")
    (model_dir / "tokenizer.json").write_text('{"version": "1.0"}', encoding="utf-8")
    (model_dir / "model.safetensors.index.json").write_text(
        json.dumps({"metadata": {}, "weight_map": {"model-00001.safetensors": "0"}}),
        encoding="utf-8",
    )
    return model_dir


@pytest.fixture
def chat_template() -> str:
    return TEMPLATE


@pytest.fixture
def write_model_fixture() -> Callable[..., Path]:
    return write_model


@pytest.fixture
def model_dir(tmp_path: Path) -> Path:
    return write_model(tmp_path / "model")