import pytest
import json
import httpx
from typing import List, AsyncGenerator

from app.services import inject_tools_into_prompt, parse_llm_response_from_content, process_chat_request
from app.models import ChatMessage, Tool, ResponseMessage, ToolCall, ToolCallFunction, IncomingRequest
from app.core.config import Settings
from app.database import get_latest_log_entry

# --- Mocks for simulating httpx responses ---

@pytest.fixture
def mock_settings() -> Settings:
    """Provides mock settings for tests."""
    return Settings(
        REAL_LLM_API_URL="http://fake-llm-api.com/chat",
        REAL_LLM_API_KEY="fake-key"
    )

class MockAsyncClient:
    """Mocks the httpx.AsyncClient to simulate LLM responses."""
    def __init__(self, response_chunks: List[str]):
        self._response_chunks = response_chunks

    async def __aenter__(self):
        return self

    async def __aexit__(self, exc_type, exc_val, exc_tb):
        pass

    def stream(self, method, url, headers, json, timeout):
        return MockStreamResponse(self._response_chunks)

class MockStreamResponse:
    """Mocks the httpx.Response object for streaming."""
    def __init__(self, chunks: List[str], status_code: int = 200):
        self._chunks = chunks
        self._status_code = status_code

    async def __aenter__(self):
        return self

    async def __aexit__(self, exc_type, exc_val, exc_tb):
        pass

    def raise_for_status(self):
        if self._status_code != 200:
            raise httpx.HTTPStatusError("Error", request=None, response=httpx.Response(self._status_code))

    async def aiter_bytes(self) -> AsyncGenerator[bytes, None]:
        for chunk in self._chunks:
            yield chunk.encode('utf-8')

# --- End Mocks ---


def test_inject_tools_into_prompt():
    """
    Tests that `inject_tools_into_prompt` correctly adds a system message
    with tool definitions to the message list.
    """
    # 1. Fetch the latest request from the database
    latest_entry = get_latest_log_entry()
    assert latest_entry is not None
    client_request_data = json.loads(latest_entry["client_request"])

    # 2. Parse the data into Pydantic models
    incoming_request = IncomingRequest.model_validate(client_request_data)

    # 3. Call the function to be tested
    modified_messages = inject_tools_into_prompt(incoming_request.messages, incoming_request.tools)

    # 4. Assert the results
    assert len(modified_messages) == len(incoming_request.messages) + 1

    # Check that the first message is the new system prompt
    system_prompt = modified_messages[0]
    assert system_prompt.role == "system"
    assert "You are a helpful assistant with access to a set of tools." in system_prompt.content

    # Check that the tool definitions are in the system prompt
    for tool in incoming_request.tools:
        assert tool.function.name in system_prompt.content

def test_parse_llm_response_from_content():
    """
    Tests that `parse_llm_response_from_content` correctly parses a raw LLM
    text response containing a { and extracts the `ResponseMessage`.
    """
    # Sample raw text from an LLM
    # Note: Since tags are { and }, we use double braces {{...}} where
    # the outer { and } are tags, and the inner { and } are JSON
    llm_text = """
Some text from the model.
{{
  "name": "shell",
  "arguments": {
    "command": ["echo", "Hello from the tool!"]
  }
}}
"""

    # Call the function
    response_message = parse_llm_response_from_content(llm_text)

    # Assertions
    assert response_message.content == "Some text from the model."
    assert response_message.tool_calls is not None
    assert len(response_message.tool_calls) == 1

    tool_call = response_message.tool_calls[0]
    assert isinstance(tool_call, ToolCall)
    assert tool_call.function.name == "shell"

    # The arguments are a JSON string, so we parse it for detailed checking
    arguments = json.loads(tool_call.function.arguments)
    assert arguments["command"] == ["echo", "Hello from the tool!"]


@pytest.mark.anyio
async def test_process_chat_request_with_tool_call(monkeypatch, mock_settings):
    """
    Tests that `process_chat_request` can correctly parse a tool call from a
    simulated real LLM streaming response.
    """
    # 1. Define the simulated SSE stream from the LLM
    # Using double braces for tool call tags
    sse_chunks = [
        'data: {"choices": [{"delta": {"content": "Okay, I will run that shell command."}}], "object": "chat.completion.chunk"}\n\n',
        'data: {"choices": [{"delta": {"content": "{{\\n  \\"name\\": \\"shell\\",\\n  \\"arguments\\": {\\n    \\"command\\": [\\"ls\\", \\"-l\\"]\\n  }\\n}}\\n"}}], "object": "chat.completion.chunk"}\n\n',
        'data: [DONE]\n\n'
    ]

    # 2. Mock the httpx.AsyncClient
    def mock_async_client(*args, **kwargs):
        return MockAsyncClient(response_chunks=sse_chunks)

    monkeypatch.setattr(httpx, "AsyncClient", mock_async_client)

    # 3. Prepare the input for process_chat_request
    messages = [ChatMessage(role="user", content="List the files.")]
    tools = [Tool(type="function", function={"name": "shell", "description": "Run a shell command.", "parameters": {}})]
    log_id = 1 # Dummy log ID for the test

    # 4. Call the function
    request_messages = inject_tools_into_prompt(messages, tools)
    response_message = await process_chat_request(request_messages, mock_settings, log_id)

    # 5. Assert the response is parsed correctly
    assert response_message.content is not None
    assert response_message.content.strip() == "Okay, I will run that shell command."
    assert response_message.tool_calls is not None
    assert len(response_message.tool_calls) == 1

    tool_call = response_message.tool_calls[0]
    assert tool_call.function.name == "shell"

    arguments = json.loads(tool_call.function.arguments)
    assert arguments["command"] == ["ls", "-l"]