import os
import threading
import time
import uuid

import pytest
from dotenv import load_dotenv
from openai import AsyncOpenAI
from openai.types.chat.chat_completion_chunk import ChatCompletionChunk

from letta import create_client
from letta.client.streaming import _sse_post
from letta.schemas.embedding_config import EmbeddingConfig
from letta.schemas.enums import MessageStreamStatus
from letta.schemas.llm_config import LLMConfig
from letta.schemas.openai.chat_completion_request import ChatCompletionRequest, UserMessage
from letta.schemas.usage import LettaUsageStatistics

# --- Server Management --- #


def _run_server():
    """Starts the Letta server in a background thread."""
    load_dotenv()
    from letta.server.rest_api.app import start_server

    start_server(debug=True)


@pytest.fixture(scope="session")
def server_url():
    """Ensures a server is running and returns its base URL."""
    url = os.getenv("LETTA_SERVER_URL", "http://localhost:8283")

    if not os.getenv("LETTA_SERVER_URL"):
        thread = threading.Thread(target=_run_server, daemon=True)
        thread.start()
        time.sleep(5)  # Allow server startup time

    return url


# --- Client Setup --- #


@pytest.fixture(scope="session")
def client(server_url):
    """Creates a REST client for testing."""
    client = create_client(base_url=server_url, token=None)
    client.set_default_llm_config(LLMConfig.default_config("gpt-4o-mini"))
    client.set_default_embedding_config(EmbeddingConfig.default_config(provider="openai"))
    yield client


@pytest.fixture(scope="function")
def roll_dice_tool(client):
    def roll_dice():
        """
        Rolls a 6 sided die.

        Returns:
            str: The roll result.
        """
        return "Rolled a 10!"

    tool = client.create_or_update_tool(func=roll_dice)
    # Yield the created tool
    yield tool


@pytest.fixture(scope="function")
def agent(client, roll_dice_tool):
    """Creates an agent and ensures cleanup after tests."""
    agent_state = client.create_agent(name=f"test_client_{uuid.uuid4()}", tool_ids=[roll_dice_tool.id])
    yield agent_state
    client.delete_agent(agent_state.id)


# --- Helper Functions --- #


def _get_chat_request(agent_id, message, stream=True):
    """Returns a chat completion request with streaming enabled."""
    return ChatCompletionRequest(
        model="gpt-4o-mini",
        messages=[UserMessage(content=message)],
        user=agent_id,
        stream=stream,
    )


def _assert_valid_chunk(chunk, idx, chunks):
    """Validates the structure of each streaming chunk."""
    if isinstance(chunk, ChatCompletionChunk):
        assert chunk.choices, "Each ChatCompletionChunk should have at least one choice."

    elif isinstance(chunk, LettaUsageStatistics):
        assert chunk.completion_tokens > 0, "Completion tokens must be > 0."
        assert chunk.prompt_tokens > 0, "Prompt tokens must be > 0."
        assert chunk.total_tokens > 0, "Total tokens must be > 0."
        assert chunk.step_count == 1, "Step count must be 1."

    elif isinstance(chunk, MessageStreamStatus):
        assert chunk == MessageStreamStatus.done, "Stream should end with 'done' status."
        assert idx == len(chunks) - 1, "The last chunk must be 'done'."

    else:
        pytest.fail(f"Unexpected chunk type: {chunk}")


# --- Test Cases --- #


@pytest.mark.parametrize("message", ["Tell me something interesting about bananas."])
def test_chat_completions_streaming(mock_e2b_api_key_none, client, agent, message):
    """Tests chat completion streaming via SSE."""
    request = _get_chat_request(agent.id, message)

    response = _sse_post(
        f"{client.base_url}/openai/{client.api_prefix}/chat/completions", request.model_dump(exclude_none=True), client.headers
    )

    try:
        chunks = list(response)
        assert len(chunks) > 1, "Streaming response did not return enough chunks (may have failed silently)."

        for idx, chunk in enumerate(chunks):
            assert chunk, f"Empty chunk received at index {idx}."
            print(chunk)
            _assert_valid_chunk(chunk, idx, chunks)
    except Exception as e:
        pytest.fail(f"Streaming failed with exception: {e}")


@pytest.mark.asyncio
@pytest.mark.parametrize("message", ["Tell me something interesting about bananas.", "Roll a dice!"])
async def test_chat_completions_streaming_async(client, agent, message):
    """Tests chat completion streaming using the Async OpenAI client."""
    request = _get_chat_request(agent.id, message)

    async_client = AsyncOpenAI(base_url=f"{client.base_url}/openai/{client.api_prefix}", max_retries=0)
    stream = await async_client.chat.completions.create(**request.model_dump(exclude_none=True))

    received_chunks = 0
    try:
        async with stream:
            async for chunk in stream:
                assert isinstance(chunk, ChatCompletionChunk), f"Unexpected chunk type: {type(chunk)}"
                assert chunk.choices, "Each ChatCompletionChunk should have at least one choice."
                assert chunk.choices[0].delta.content, f"Chunk at index 0 has no content: {chunk.model_dump_json(indent=4)}"
                received_chunks += 1
    except Exception as e:
        pytest.fail(f"Streaming failed with exception: {e}")

    assert received_chunks > 1, "No valid streaming chunks were received."