"""Tests for Phase 3: brief agent WS frame + REST fallback.

Coverage:
  - run_home_brief streams non-empty text (mocked _run_single_agent_stream)
  - run_project_brief with bogus UUID → WS returns stream_end with error, no crash
  - _build_read_tools uses read-only subset only (no mutating tools)
  - POST /chat/brief home mode returns {response: "..."}
  - POST /chat/brief project mode with invalid UUID → 422
"""

from __future__ import annotations

import uuid
from collections.abc import AsyncGenerator
from typing import Any
from unittest.mock import AsyncMock, patch

import pytest

from tests.conftest import TEST_USER_IDS, auth_header


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------

_USER_ID = TEST_USER_IDS["pro"]
_EMPTY_CONTEXT: dict[str, Any] = {"core_memory": {}}


async def _fake_token_stream(*_args, **_kwargs) -> AsyncGenerator[tuple[str, Any], None]:
    """Fake _run_single_agent_stream that yields two token events."""
    yield ("token", "Hello")
    yield ("token", " world")


# ---------------------------------------------------------------------------
# Unit: run_home_brief streams non-empty text
# ---------------------------------------------------------------------------

@pytest.mark.asyncio
async def test_run_home_brief_streams_text():
    with patch(
        "app.core.brief_agent._run_single_agent_stream",
        side_effect=_fake_token_stream,
    ):
        from app.core.brief_agent import run_home_brief

        chunks: list[str] = []
        async for event_type, data in run_home_brief(_USER_ID, _EMPTY_CONTEXT):
            if event_type == "token":
                chunks.append(str(data))

    assert "".join(chunks) == "Hello world"


# ---------------------------------------------------------------------------
# Unit: run_project_brief streams text with valid UUID
# ---------------------------------------------------------------------------

@pytest.mark.asyncio
async def test_run_project_brief_streams_text():
    project_id = str(uuid.uuid4())
    with patch(
        "app.core.brief_agent._run_single_agent_stream",
        side_effect=_fake_token_stream,
    ):
        from app.core.brief_agent import run_project_brief

        chunks: list[str] = []
        async for event_type, data in run_project_brief(_USER_ID, project_id, _EMPTY_CONTEXT):
            if event_type == "token":
                chunks.append(str(data))

    assert "".join(chunks) == "Hello world"


# ---------------------------------------------------------------------------
# Unit: _build_read_tools uses read-only subset (no write tools)
# ---------------------------------------------------------------------------

def test_build_read_tools_read_only_subset():
    from app.agents.note_agent import NOTE_READ_TOOLS
    from app.agents.project_agent import PROJECT_READ_TOOLS
    from app.agents.task_agent import TASK_READ_TOOLS
    from app.agents.timeline_agent import TIMELINE_READ_TOOLS
    from app.core.brief_agent import _build_read_tools

    tools = _build_read_tools(_USER_ID, None)
    tool_names = {getattr(t, "name", None) or getattr(t, "__name__", str(t)) for t in tools}

    # Read-only exports must be present.
    for read_list in (TASK_READ_TOOLS, PROJECT_READ_TOOLS, TIMELINE_READ_TOOLS, NOTE_READ_TOOLS):
        for t in read_list:
            name = getattr(t, "name", None) or getattr(t, "__name__", str(t))
            assert name in tool_names, f"Read tool {name!r} missing from _build_read_tools"

    # No mutating tools (e.g. create_task, update_task, delete_task).
    mutating = {"create_task", "update_task", "delete_task", "create_project",
                "update_project", "delete_project", "create_note", "update_note",
                "delete_note", "memory_add", "memory_update", "memory_delete"}
    overlap = tool_names & mutating
    assert not overlap, f"Mutating tools in brief read-only subset: {overlap}"


# ---------------------------------------------------------------------------
# Integration: POST /chat/brief — home mode
# ---------------------------------------------------------------------------

@pytest.fixture(autouse=True)
def _override_db(db_session):
    from app.db import get_session
    from app.main import app

    async def _gen():
        yield db_session

    app.dependency_overrides[get_session] = _gen
    yield
    app.dependency_overrides.pop(get_session, None)


@pytest.mark.asyncio
async def test_rest_brief_home_returns_response(client):
    async def _fake_home_brief(user_id, context):
        yield ("token", "Today looks light.")

    with (
        patch("app.api.routes.chat.run_home_brief", side_effect=_fake_home_brief),
        patch(
            "app.api.routes.chat.MemoryMiddleware.enrich_context",
            new=AsyncMock(return_value={}),
        ),
    ):
        res = client.post(
            "/api/v1/chat/brief",
            json={"mode": "home"},
            headers=auth_header("pro"),
        )

    assert res.status_code == 200
    data = res.json()
    assert data["response"] == "Today looks light."


@pytest.mark.asyncio
async def test_rest_brief_project_invalid_uuid_returns_422(client):
    res = client.post(
        "/api/v1/chat/brief",
        json={"mode": "project", "project_id": "not-a-uuid"},
        headers=auth_header("pro"),
    )
    assert res.status_code == 422


@pytest.mark.asyncio
async def test_rest_brief_project_missing_uuid_returns_422(client):
    res = client.post(
        "/api/v1/chat/brief",
        json={"mode": "project"},
        headers=auth_header("pro"),
    )
    assert res.status_code == 422