from __future__ import annotations

from datetime import UTC, datetime
from typing import Any

import pytest

from cloud.internal_api.models import AssignmentModel
from device.manager import DeviceManager
from driver.base import Driver
from host_agent.mcp_lock import McpBusyTracker
from host_agent.status import AgentStatusTracker
from host_agent.web.mcp import (
    McpDeviceBusyError,
    _call_tool_sync,
    _current_session_id,
    build_mcp_server,
)
from mcp.server.fastmcp import Context
from mcp.shared.context import RequestContext


class _FakeDriver(Driver):
    """Minimal driver. connect/screenshot/tap are exercised; remaining abstract
    methods are stubbed to satisfy Driver's ABC contract."""

    def __init__(self) -> None:
        self.taps: list[tuple[float, float]] = []

    def connect(self) -> None:
        return None

    def disconnect(self) -> None:
        return None

    def screenshot(self) -> bytes:
        return b"fake"

    def tap(self, x: float, y: float) -> None:
        self.taps.append((x, y))

    def long_press(self, x: float, y: float, duration_ms: int = 1200) -> None:
        return None

    def swipe(
        self,
        start_x: float,
        start_y: float,
        end_x: float,
        end_y: float,
        duration_ms: int = 500,
    ) -> None:
        return None

    def swipe_path(self, waypoints: list[tuple[float, float]], duration_ms: int) -> None:
        return None

    def double_tap(self, x: float, y: float, interval_ms: int = 80) -> None:
        return None

    def input(self, text: str) -> None:
        return None

    def launch(self, app_id: str) -> None:
        return None

    def terminate(self, app_id: str) -> None:
        return None

    def tree(self) -> Any:
        return None

    def home(self) -> None:
        return None

    def lock(self) -> None:
        return None

    def unlock(self) -> None:
        return None


def _make_manager_with_device(device_id: str = "phone-1") -> DeviceManager:
    manager = DeviceManager()
    manager.register_device(
        device_id=device_id,
        driver_factory=lambda: _FakeDriver(),
        name=device_id,
    )
    manager.connect(device_id)
    return manager


def test_build_mcp_server_returns_fastmcp_instance() -> None:
    from mcp.server.fastmcp import FastMCP

    manager = _make_manager_with_device()
    tracker = McpBusyTracker()
    status = AgentStatusTracker()
    server = build_mcp_server(
        manager=manager, mcp_busy_tracker=tracker, status_tracker=status
    )
    assert isinstance(server, FastMCP)


def test_call_tool_succeeds_when_device_is_free() -> None:
    manager = _make_manager_with_device()
    tracker = McpBusyTracker()
    status = AgentStatusTracker()
    server = build_mcp_server(
        manager=manager, mcp_busy_tracker=tracker, status_tracker=status
    )
    result = _call_tool_sync(
        server, "take_screenshot", {"device_id": "phone-1"}, session_id="sess-a"
    )
    assert result["ok"] is True
    assert "phone-1" in tracker.busy_device_ids()


def test_call_tool_fails_when_cloud_uses_device() -> None:
    """AgentStatusTracker.current_assignment.device_id matches -> busy."""
    manager = _make_manager_with_device()
    tracker = McpBusyTracker()
    status = AgentStatusTracker()
    status.mark_assignment_started(
        AssignmentModel(
            task_id="t1",
            attempt=1,
            lease_id="l1",
            lease_expires_at=datetime.now(UTC),
            host_id="h1",
            device_id="phone-1",
            goal="cloud task",
        )
    )
    server = build_mcp_server(
        manager=manager, mcp_busy_tracker=tracker, status_tracker=status
    )
    with pytest.raises(McpDeviceBusyError) as exc:
        _call_tool_sync(
            server,
            "take_screenshot",
            {"device_id": "phone-1"},
            session_id="sess-a",
        )
    assert exc.value.device_id == "phone-1"
    assert exc.value.busy_owner == "cloud_assignment"


def test_call_tool_fails_when_another_mcp_session_holds_device() -> None:
    manager = _make_manager_with_device()
    tracker = McpBusyTracker()
    status = AgentStatusTracker()
    # Pre-acquire as a different session.
    tracker.acquire("phone-1", "sess-other")
    server = build_mcp_server(
        manager=manager, mcp_busy_tracker=tracker, status_tracker=status
    )
    with pytest.raises(McpDeviceBusyError) as exc:
        _call_tool_sync(
            server,
            "take_screenshot",
            {"device_id": "phone-1"},
            session_id="sess-a",
        )
    assert exc.value.busy_owner.startswith("mcp_session:")


def test_call_tool_renews_when_same_session_already_holds() -> None:
    manager = _make_manager_with_device()
    tracker = McpBusyTracker()
    status = AgentStatusTracker()
    server = build_mcp_server(
        manager=manager, mcp_busy_tracker=tracker, status_tracker=status
    )
    _call_tool_sync(
        server, "take_screenshot", {"device_id": "phone-1"}, session_id="sess-a"
    )
    # Second call from the same session should succeed.
    result = _call_tool_sync(
        server, "take_screenshot", {"device_id": "phone-1"}, session_id="sess-a"
    )
    assert result["ok"] is True


def test_list_devices_uses_display_status() -> None:
    """Connected-but-idle devices report as 'connected', not 'busy'."""
    manager = _make_manager_with_device()
    tracker = McpBusyTracker()
    status = AgentStatusTracker()
    server = build_mcp_server(
        manager=manager, mcp_busy_tracker=tracker, status_tracker=status
    )
    result = _call_tool_sync(server, "list_devices", {}, session_id="sess-a")
    assert isinstance(result, list)
    assert result[0]["status"] == "connected"


def test_unknown_device_returns_semantic_error_dict() -> None:
    """take_screenshot against an unknown device returns the api-errors semantic
    error dict (``ok=False, error="device not found"``) rather than raising.

    Note: this test adapts the brief's exception-assertion semantics to the
    actual behavior of ``call_with_semantic_errors`` in ``api/errors.py`` —
    the brief's expectation that an exception is raised here is incorrect for
    the current handler implementation."""
    manager = _make_manager_with_device()
    tracker = McpBusyTracker()
    status = AgentStatusTracker()
    server = build_mcp_server(
        manager=manager, mcp_busy_tracker=tracker, status_tracker=status
    )
    result = _call_tool_sync(
        server,
        "take_screenshot",
        {"device_id": "does-not-exist"},
        session_id="sess-a",
    )
    assert isinstance(result, dict)
    assert result["ok"] is False
    assert "device" in result["error"].lower()


def test_manager_required_for_build_mcp_server() -> None:
    """Reinforces D12 — build_mcp_server requires manager as keyword-only."""
    import inspect

    sig = inspect.signature(build_mcp_server)
    assert sig.parameters["manager"].kind == inspect.Parameter.KEYWORD_ONLY


def _fake_ctx(session_obj: object) -> Context:
    """Build a Context whose ``session`` attribute returns ``session_obj``.

    Context's ``session`` is a property backed by ``request_context.session``;
    we construct a minimal ``RequestContext`` and set it as the private
    ``_request_context`` field. The pydantic public API doesn't expose a
    setter for ``session``, so we use ``object.__setattr__`` on the private
    backing field.
    """
    ctx = Context.model_construct()
    request_ctx = RequestContext(
        request_id="req-test",
        meta=None,
        session=session_obj,
        lifespan_context=None,
    )
    object.__setattr__(ctx, "_request_context", request_ctx)
    return ctx


def test_current_session_id_is_stable_across_calls_same_session() -> None:
    """Production-path identity: two tool calls from the same MCP session
    must yield the same session_id so the busy tracker can renew the lease.

    This exercises the ``Context.session`` code path (NOT the
    ``_TEST_SESSION_ID`` fallback used by ``_call_tool_sync``)."""
    sentinel_session = object()
    ctx = _fake_ctx(sentinel_session)
    first = _current_session_id(ctx)
    second = _current_session_id(ctx)
    assert first == second
    assert first.startswith("mcp_session:")
    # Object identity of the underlying ServerSession is the key — verifies
    # we use id(ctx.session) rather than e.g. ctx.request_id.
    assert first == f"mcp_session:{id(sentinel_session)}"


def test_current_session_id_differs_across_sessions() -> None:
    """Two different MCP sessions (distinct ServerSession objects) must
    produce distinct session_ids so the busy tracker can isolate them."""
    sess_a = object()
    sess_b = object()
    assert _current_session_id(_fake_ctx(sess_a)) != _current_session_id(
        _fake_ctx(sess_b)
    )


def test_current_session_id_falls_back_when_no_context() -> None:
    """When no Context is available (e.g. outside a FastMCP request lifecycle,
    or via ``_call_tool_sync`` which omits the ctx kwarg), the test
    contextvars override provides the session_id."""
    token = None
    try:
        from host_agent.web import mcp as mcp_mod

        token = mcp_mod._TEST_SESSION_ID.set("test-session-xyz")
        assert _current_session_id(None) == "test-session-xyz"
    finally:
        if token is not None:
            from host_agent.web import mcp as mcp_mod

            mcp_mod._TEST_SESSION_ID.reset(token)


def test_wrapped_tool_accepts_context_kwarg() -> None:
    """The wrapper registered on FastMCP must declare a ``ctx`` parameter so
    FastMCP injects the live Context (and ``tool.context_kwarg`` is set to
    ``"ctx"``). Without this, FastMCP never injects context and we fall
    back to the empty test default — the production bug this PR fixes."""
    manager = _make_manager_with_device()
    tracker = McpBusyTracker()
    status = AgentStatusTracker()
    server = build_mcp_server(
        manager=manager, mcp_busy_tracker=tracker, status_tracker=status
    )
    tool_manager = server._tool_manager  # type: ignore[attr-defined]
    tool = tool_manager.get_tool("take_screenshot")
    assert tool is not None
    assert tool.context_kwarg == "ctx"