#  SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
#  SPDX-License-Identifier: Apache-2.0

"""Unit tests for vLLM processor components.

Tests for the tool-stripping behaviour of _prepare_request when
tool_choice='none' and the exclude_tools_when_tool_choice_none flag.
"""

import pytest
from transformers import AutoTokenizer

from dynamo.frontend.prepost import _prepare_request

MODEL = "Qwen/Qwen3-0.6B"

TOOL_REQUEST = {
    "model": MODEL,
    "messages": [{"role": "user", "content": "Hello"}],
    "tools": [
        {
            "type": "function",
            "function": {
                "name": "get_weather",
                "description": "Get weather",
                "parameters": {
                    "type": "object",
                    "properties": {"city": {"type": "string"}},
                },
            },
        }
    ],
}


@pytest.fixture(scope="module")
def tokenizer():
    return AutoTokenizer.from_pretrained(MODEL)


# ---------------------------------------------------------------------------
# _prepare_request: tool_choice=none tool-stripping
# ---------------------------------------------------------------------------


class TestPrepareRequestToolStripping:
    """Test that _prepare_request strips/keeps tools based on the flag."""

    def test_tool_choice_none_strips_tools_from_template(self, tokenizer):
        """When exclude flag is on and tool_choice=none, tools are excluded from template kwargs."""
        _, _, _, _, chat_params = _prepare_request(
            {**TOOL_REQUEST, "tool_choice": "none"},
            tokenizer=tokenizer,
            tool_parser_class=None,
            exclude_tools_when_tool_choice_none=True,
        )
        assert (
            chat_params.chat_template_kwargs["tools"] is None
        ), "tool_choice=none with exclude flag should strip tools from template"

    def test_tool_choice_none_keeps_tools_when_flag_off(self, tokenizer):
        """When exclude flag is off, tool_choice=none still includes tools in template kwargs."""
        _, _, _, _, chat_params = _prepare_request(
            {**TOOL_REQUEST, "tool_choice": "none"},
            tokenizer=tokenizer,
            tool_parser_class=None,
            exclude_tools_when_tool_choice_none=False,
        )
        tools = chat_params.chat_template_kwargs["tools"]
        assert (
            tools is not None and len(tools) == 1
        ), "tool_choice=none with flag off should keep tools in template"

    def test_tool_choice_auto_keeps_tools(self, tokenizer):
        """tool_choice=auto should always include tools regardless of flag."""
        _, _, _, _, chat_params = _prepare_request(
            {**TOOL_REQUEST, "tool_choice": "auto"},
            tokenizer=tokenizer,
            tool_parser_class=None,
            exclude_tools_when_tool_choice_none=True,
        )
        tools = chat_params.chat_template_kwargs["tools"]
        assert (
            tools is not None and len(tools) == 1
        ), "tool_choice=auto should keep tools in template"

    def test_tool_choice_required_keeps_tools(self, tokenizer):
        """tool_choice=required should always include tools regardless of flag."""
        _, _, _, _, chat_params = _prepare_request(
            {**TOOL_REQUEST, "tool_choice": "required"},
            tokenizer=tokenizer,
            tool_parser_class=None,
            exclude_tools_when_tool_choice_none=True,
        )
        tools = chat_params.chat_template_kwargs["tools"]
        assert (
            tools is not None and len(tools) == 1
        ), "tool_choice=required should keep tools in template"

    def test_no_tools_in_request(self, tokenizer):
        """Request without tools should produce None tools in template kwargs."""
        _, _, _, _, chat_params = _prepare_request(
            {"model": MODEL, "messages": [{"role": "user", "content": "Hello"}]},
            tokenizer=tokenizer,
            tool_parser_class=None,
            exclude_tools_when_tool_choice_none=True,
        )
        assert (
            chat_params.chat_template_kwargs["tools"] is None
        ), "No tools in request should produce None tools in template"
