# SPDX-License-Identifier: AGPL-3.0-only
# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0

"""Tests for transformers version detection with local checkpoint fallbacks."""

import json
import pytest
from pathlib import Path
from unittest.mock import patch


# ---------------------------------------------------------------------------
# We need to be able to import the module under test.  The studio backend
# uses relative-style imports (``from utils.…``), so we add the backend
# directory to *sys.path* if it is not already there.
# ---------------------------------------------------------------------------
import sys

_BACKEND_DIR = str(Path(__file__).resolve().parent.parent)
if _BACKEND_DIR not in sys.path:
    sys.path.insert(0, _BACKEND_DIR)

# Stub the custom logger before importing the module under test so it
# doesn't fail on the ``from loggers import get_logger`` line.
import types as _types

_loggers_stub = _types.ModuleType("loggers")
_loggers_stub.get_logger = lambda name: __import__("logging").getLogger(name)
sys.modules.setdefault("loggers", _loggers_stub)

from utils.transformers_version import (
    _resolve_base_model,
    _check_tokenizer_config_needs_v5,
    _check_config_needs_550,
    _tokenizer_class_cache,
    _config_needs_550_cache,
    needs_transformers_5,
    get_transformers_tier,
)


# ---------------------------------------------------------------------------
# _resolve_base_model — config.json fallback
# ---------------------------------------------------------------------------


class TestResolveBaseModel:
    """Tests for _resolve_base_model() local config fallbacks."""

    def test_adapter_config_takes_priority(self, tmp_path: Path):
        """adapter_config.json should be preferred over config.json."""
        adapter_cfg = {"base_model_name_or_path": "meta-llama/Llama-3-8B"}
        config_cfg = {"_name_or_path": "different/model"}
        (tmp_path / "adapter_config.json").write_text(json.dumps(adapter_cfg))
        (tmp_path / "config.json").write_text(json.dumps(config_cfg))

        result = _resolve_base_model(str(tmp_path))
        assert result == "meta-llama/Llama-3-8B"

    def test_config_json_fallback_model_name(self, tmp_path: Path):
        """config.json model_name should resolve when no adapter_config."""
        config_cfg = {"model_name": "Qwen/Qwen3.5-9B"}
        (tmp_path / "config.json").write_text(json.dumps(config_cfg))

        result = _resolve_base_model(str(tmp_path))
        assert result == "Qwen/Qwen3.5-9B"

    def test_config_json_fallback_name_or_path(self, tmp_path: Path):
        """config.json _name_or_path should resolve as secondary fallback."""
        config_cfg = {"_name_or_path": "Qwen/Qwen3.5-9B"}
        (tmp_path / "config.json").write_text(json.dumps(config_cfg))

        result = _resolve_base_model(str(tmp_path))
        assert result == "Qwen/Qwen3.5-9B"

    def test_model_name_takes_priority_over_name_or_path(self, tmp_path: Path):
        """model_name should be preferred over _name_or_path."""
        config_cfg = {
            "model_name": "Qwen/Qwen3.5-9B",
            "_name_or_path": "some/other-model",
        }
        (tmp_path / "config.json").write_text(json.dumps(config_cfg))

        result = _resolve_base_model(str(tmp_path))
        assert result == "Qwen/Qwen3.5-9B"

    def test_config_json_skips_self_referencing(self, tmp_path: Path):
        """config.json should be ignored if model_name == the checkpoint path."""
        config_cfg = {"model_name": str(tmp_path)}
        (tmp_path / "config.json").write_text(json.dumps(config_cfg))

        result = _resolve_base_model(str(tmp_path))
        # Should fall through, not return the self-referencing path
        assert result == str(tmp_path)

    def test_no_config_files(self, tmp_path: Path):
        """Returns original name when no config files are present."""
        result = _resolve_base_model(str(tmp_path))
        assert result == str(tmp_path)

    def test_plain_hf_id_passthrough(self):
        """Plain HuggingFace model IDs pass through unchanged."""
        result = _resolve_base_model("meta-llama/Llama-3-8B")
        assert result == "meta-llama/Llama-3-8B"


# ---------------------------------------------------------------------------
# _check_tokenizer_config_needs_v5 — local file check
# ---------------------------------------------------------------------------


class TestCheckTokenizerConfigNeedsV5:
    """Tests for local tokenizer_config.json fallback."""

    def setup_method(self):
        _tokenizer_class_cache.clear()

    def test_local_tokenizer_config_v5(self, tmp_path: Path):
        """Local tokenizer_config.json with v5 tokenizer should return True."""
        tc = {"tokenizer_class": "TokenizersBackend"}
        (tmp_path / "tokenizer_config.json").write_text(json.dumps(tc))

        result = _check_tokenizer_config_needs_v5(str(tmp_path))
        assert result is True

    def test_local_tokenizer_config_v4(self, tmp_path: Path):
        """Local tokenizer_config.json with standard tokenizer should return False."""
        tc = {"tokenizer_class": "LlamaTokenizerFast"}
        (tmp_path / "tokenizer_config.json").write_text(json.dumps(tc))

        result = _check_tokenizer_config_needs_v5(str(tmp_path))
        assert result is False

    def test_local_file_skips_network(self, tmp_path: Path):
        """When local file exists, no network request should be made."""
        tc = {"tokenizer_class": "LlamaTokenizerFast"}
        (tmp_path / "tokenizer_config.json").write_text(json.dumps(tc))

        with patch("urllib.request.urlopen") as mock_urlopen:
            result = _check_tokenizer_config_needs_v5(str(tmp_path))
            mock_urlopen.assert_not_called()
        assert result is False

    def test_result_is_cached(self, tmp_path: Path):
        """Subsequent calls should use the cache."""
        tc = {"tokenizer_class": "TokenizersBackend"}
        (tmp_path / "tokenizer_config.json").write_text(json.dumps(tc))

        key = str(tmp_path)
        _check_tokenizer_config_needs_v5(key)
        assert key in _tokenizer_class_cache
        assert _tokenizer_class_cache[key] is True


# ---------------------------------------------------------------------------
# needs_transformers_5 — integration-level
# ---------------------------------------------------------------------------


class TestNeedsTransformers5:
    """Integration tests for the top-level needs_transformers_5() function."""

    def setup_method(self):
        _tokenizer_class_cache.clear()

    def test_qwen35_substring(self):
        assert needs_transformers_5("Qwen/Qwen3.5-9B") is True

    def test_qwen3_30b_a3b_substring(self):
        assert needs_transformers_5("Qwen/Qwen3-30B-A3B-Instruct-2507") is True

    def test_ministral_substring(self):
        assert needs_transformers_5("mistralai/Ministral-3-8B-Instruct-2512") is True

    def test_llama_does_not_need_v5(self):
        """Standard models should not trigger v5."""
        # Patch network call to avoid real fetch
        with patch(
            "utils.transformers_version._check_tokenizer_config_needs_v5",
            return_value = False,
        ):
            assert needs_transformers_5("meta-llama/Llama-3-8B") is False

    def test_local_checkpoint_resolved_via_config(self, tmp_path: Path):
        """A local checkpoint with config.json pointing to Qwen3.5 should need v5."""
        config_cfg = {"model_name": "Qwen/Qwen3.5-9B"}
        (tmp_path / "config.json").write_text(json.dumps(config_cfg))

        # _resolve_base_model is called by ensure_transformers_version,
        # but needs_transformers_5 just does substring matching.
        # We test the full resolution chain here:
        resolved = _resolve_base_model(str(tmp_path))
        assert needs_transformers_5(resolved) is True


# ---------------------------------------------------------------------------
# _check_config_needs_550 — config.json architecture/model_type check
# ---------------------------------------------------------------------------


class TestCheckConfigNeeds550:
    """Tests for _check_config_needs_550() local config.json checks."""

    def setup_method(self):
        _config_needs_550_cache.clear()

    def test_gemma4_architecture(self, tmp_path: Path):
        """config.json with Gemma4ForConditionalGeneration should return True."""
        cfg = {
            "architectures": ["Gemma4ForConditionalGeneration"],
            "model_type": "gemma4",
        }
        (tmp_path / "config.json").write_text(json.dumps(cfg))

        assert _check_config_needs_550(str(tmp_path)) is True

    def test_gemma4_model_type_only(self, tmp_path: Path):
        """config.json with model_type=gemma4 (no architectures) should return True."""
        cfg = {"model_type": "gemma4"}
        (tmp_path / "config.json").write_text(json.dumps(cfg))

        assert _check_config_needs_550(str(tmp_path)) is True

    def test_llama_architecture(self, tmp_path: Path):
        """config.json with LlamaForCausalLM should return False."""
        cfg = {"architectures": ["LlamaForCausalLM"], "model_type": "llama"}
        (tmp_path / "config.json").write_text(json.dumps(cfg))

        assert _check_config_needs_550(str(tmp_path)) is False

    def test_no_config_json(self, tmp_path: Path):
        """Missing config.json should return False (fail-open)."""
        # Patch network call to avoid real fetch
        with patch("urllib.request.urlopen") as mock_urlopen:
            mock_urlopen.side_effect = Exception("no network")
            assert _check_config_needs_550(str(tmp_path)) is False

    def test_result_is_cached(self, tmp_path: Path):
        """Subsequent calls should use the cache."""
        cfg = {"architectures": ["Gemma4ForConditionalGeneration"]}
        (tmp_path / "config.json").write_text(json.dumps(cfg))

        key = str(tmp_path)
        _check_config_needs_550(key)
        assert key in _config_needs_550_cache
        assert _config_needs_550_cache[key] is True

    def test_local_file_skips_network(self, tmp_path: Path):
        """When local config.json exists, no network request should be made."""
        cfg = {"architectures": ["LlamaForCausalLM"]}
        (tmp_path / "config.json").write_text(json.dumps(cfg))

        with patch("urllib.request.urlopen") as mock_urlopen:
            _check_config_needs_550(str(tmp_path))
            mock_urlopen.assert_not_called()


# ---------------------------------------------------------------------------
# get_transformers_tier — tier detection
# ---------------------------------------------------------------------------


class TestGetTransformersTier:
    """Tests for get_transformers_tier() tiered version detection."""

    def setup_method(self):
        _tokenizer_class_cache.clear()
        _config_needs_550_cache.clear()

    def test_gemma4_substring_returns_550(self):
        assert get_transformers_tier("google/gemma-4-E2B-it") == "550"

    def test_gemma4_alt_substring_returns_550(self):
        assert get_transformers_tier("unsloth/gemma4-E4B-it") == "550"

    def test_gemma4_config_json_returns_550(self, tmp_path: Path):
        """Local checkpoint with Gemma4 architecture → 550."""
        cfg = {
            "architectures": ["Gemma4ForConditionalGeneration"],
            "model_type": "gemma4",
        }
        (tmp_path / "config.json").write_text(json.dumps(cfg))

        assert get_transformers_tier(str(tmp_path)) == "550"

    def test_qwen35_returns_530(self):
        with patch(
            "utils.transformers_version._check_config_needs_550",
            return_value = False,
        ):
            assert get_transformers_tier("Qwen/Qwen3.5-9B") == "530"

    def test_ministral_returns_530(self):
        with patch(
            "utils.transformers_version._check_config_needs_550",
            return_value = False,
        ):
            assert (
                get_transformers_tier("mistralai/Ministral-3-8B-Instruct-2512") == "530"
            )

    def test_llama_returns_default(self):
        with (
            patch(
                "utils.transformers_version._check_config_needs_550",
                return_value = False,
            ),
            patch(
                "utils.transformers_version._check_tokenizer_config_needs_v5",
                return_value = False,
            ),
        ):
            assert get_transformers_tier("meta-llama/Llama-3-8B") == "default"

    def test_550_checked_before_530(self):
        """Ensure 5.5.0 is checked first — a model matching both should get 550."""
        # This shouldn't happen in practice, but verifies priority
        assert get_transformers_tier("gemma-4-model") == "550"

    def test_needs_transformers_5_compat(self):
        """needs_transformers_5 should return True for both 530 and 550 models."""
        assert needs_transformers_5("google/gemma-4-E2B-it") is True
        with patch(
            "utils.transformers_version._check_config_needs_550",
            return_value = False,
        ):
            assert needs_transformers_5("Qwen/Qwen3.5-9B") is True
        with (
            patch(
                "utils.transformers_version._check_config_needs_550",
                return_value = False,
            ),
            patch(
                "utils.transformers_version._check_tokenizer_config_needs_v5",
                return_value = False,
            ),
        ):
            assert needs_transformers_5("meta-llama/Llama-3-8B") is False