import asyncio
import json
from pathlib import Path
from types import SimpleNamespace
from typing import Any

import pytest

from chat_api.service import ChatProviderError, ChatService
from chat_api.storage import JsonSessionStorage


def completion(
    *,
    content: str | None,
    tool_calls: list[SimpleNamespace] | None = None,
    prompt_tokens: int = 10,
    completion_tokens: int = 2,
) -> SimpleNamespace:
    return SimpleNamespace(
        choices=[
            SimpleNamespace(
                message=SimpleNamespace(content=content, tool_calls=tool_calls)
            )
        ],
        usage=SimpleNamespace(
            prompt_tokens=prompt_tokens,
            completion_tokens=completion_tokens,
            total_tokens=prompt_tokens + completion_tokens,
        ),
    )


def tool_call(call_id: str, name: str, arguments: str) -> SimpleNamespace:
    return SimpleNamespace(
        id=call_id,
        type="function",
        function=SimpleNamespace(name=name, arguments=arguments),
    )


class ScriptedClient:
    def __init__(self, responses: list[SimpleNamespace]) -> None:
        self.responses = responses
        self.calls: list[dict[str, Any]] = []
        self.chat = SimpleNamespace(
            completions=SimpleNamespace(create=self.create)
        )

    async def create(self, **kwargs: Any) -> SimpleNamespace:
        self.calls.append(kwargs)
        return self.responses.pop(0)


def test_agent_executes_tool_and_persists_full_history(tmp_path: Path) -> None:
    async def scenario() -> None:
        provider = ScriptedClient(
            [
                completion(
                    content=None,
                    tool_calls=[
                        tool_call(
                            "call-1",
                            "get_current_time",
                            '{"timezone":"UTC"}',
                        )
                    ],
                ),
                completion(content="当前时间已查询。", prompt_tokens=20, completion_tokens=3),
            ]
        )
        storage = JsonSessionStorage(tmp_path)
        session = await storage.create("Use tools when needed.")
        service = ChatService(storage, provider, "test-model")  # type: ignore[arg-type]

        response = await service.generate_response(session.session_id, "现在几点？")

        assert response.message.content == "当前时间已查询。"
        assert "tool_calls" not in response.message.model_dump()
        assert response.tools_use == ["get_current_time"]
        assert response.usage is not None
        assert response.usage.model_dump() == {
            "prompt_tokens": 30,
            "completion_tokens": 5,
            "total_tokens": 35,
        }
        assert "tools" in provider.calls[0]
        second_messages = provider.calls[1]["messages"]
        assert [message["role"] for message in second_messages] == [
            "system",
            "user",
            "assistant",
            "tool",
        ]
        assert json.loads(second_messages[-1]["content"])["timezone"] == "UTC"

        saved = await storage.read(session.session_id)
        assert [message.role for message in saved.messages] == [
            "user",
            "assistant",
            "tool",
            "assistant",
        ]
        assert saved.messages[1].tool_calls[0].id == "call-1"  # type: ignore[union-attr]
        assert saved.messages[2].tool_call_id == "call-1"  # type: ignore[union-attr]

    asyncio.run(scenario())


def test_agent_executes_multiple_tools_in_order(tmp_path: Path) -> None:
    async def scenario() -> None:
        provider = ScriptedClient(
            [
                completion(
                    content=None,
                    tool_calls=[
                        tool_call(
                            "call-1",
                            "get_current_time",
                            '{"timezone":"UTC"}',
                        ),
                        tool_call(
                            "call-2",
                            "get_current_time",
                            '{"timezone":"Asia/Shanghai"}',
                        ),
                    ],
                ),
                completion(content="完成"),
            ]
        )
        storage = JsonSessionStorage(tmp_path)
        session = await storage.create("system")
        service = ChatService(storage, provider, "test-model")  # type: ignore[arg-type]

        response = await service.generate_response(session.session_id, "计算并查询时间")

        messages = provider.calls[1]["messages"]
        assert [message.get("tool_call_id") for message in messages[-2:]] == [
            "call-1",
            "call-2",
        ]
        assert response.tools_use == ["get_current_time"]

    asyncio.run(scenario())


def test_tool_error_is_returned_to_model(tmp_path: Path) -> None:
    async def scenario() -> None:
        provider = ScriptedClient(
            [
                completion(
                    content=None,
                    tool_calls=[tool_call("bad-1", "get_current_time", "not-json")],
                ),
                completion(content="参数无效。"),
            ]
        )
        storage = JsonSessionStorage(tmp_path)
        session = await storage.create("system")
        service = ChatService(storage, provider, "test-model")  # type: ignore[arg-type]

        await service.generate_response(session.session_id, "test")

        saved = await storage.read(session.session_id)
        tool_message = saved.messages[2]
        assert tool_message.role == "tool"
        assert tool_message.is_error is True  # type: ignore[union-attr]
        assert "invalid_arguments" in tool_message.content

    asyncio.run(scenario())


@pytest.mark.parametrize(
    ("max_rounds", "max_calls", "calls"),
    [
        (
            1,
            10,
            [tool_call("call-1", "get_current_time", '{"timezone":"UTC"}')],
        ),
        (
            5,
            1,
            [
                tool_call("call-1", "get_current_time", '{"timezone":"UTC"}'),
                tool_call(
                    "call-2",
                    "get_current_time",
                    '{"timezone":"Asia/Shanghai"}',
                ),
            ],
        ),
    ],
)
def test_agent_limits_do_not_persist_partial_turn(
    tmp_path: Path,
    max_rounds: int,
    max_calls: int,
    calls: list[SimpleNamespace],
) -> None:
    async def scenario() -> None:
        provider = ScriptedClient([completion(content=None, tool_calls=calls)])
        storage = JsonSessionStorage(tmp_path)
        session = await storage.create("system")
        service = ChatService(
            storage,
            provider,  # type: ignore[arg-type]
            "test-model",
            max_tool_rounds=max_rounds,
            max_tool_calls_per_turn=max_calls,
        )

        with pytest.raises(ChatProviderError):
            await service.generate_response(session.session_id, "test")

        saved = await storage.read(session.session_id)
        assert saved.messages == []

    asyncio.run(scenario())