"""Direct-handler tests for the auto-derived `server/discover` handler.

These call the registered handler via the public `Server.get_request_handler`
accessor without spinning up a `ServerRunner` or any transport, so they verify
the handler's contract in isolation from the dispatch pipeline.
"""

import importlib.metadata
from typing import Any, cast

import pytest

from mcp import types
from mcp.server import Server, ServerRequestContext
from mcp.shared.version import MODERN_PROTOCOL_VERSIONS

# `Server._handle_discover` ignores its `ctx` argument entirely (it derives the
# result from server state), so a sentinel keeps the call site type-correct
# without dragging session machinery into a unit test.
_UNUSED_CTX = cast("ServerRequestContext[Any]", None)


async def _discover(server: Server[Any]) -> types.DiscoverResult:
    entry = server.get_request_handler("server/discover")
    assert entry is not None
    result = await entry.handler(_UNUSED_CTX, types.RequestParams())
    assert isinstance(result, types.DiscoverResult)
    return result


def test_registered_by_default() -> None:
    """SDK-defined: a bare `Server` registers a `server/discover` handler out of
    the box, typed for the base `RequestParams`."""
    server = Server("test-server")
    entry = server.get_request_handler("server/discover")
    assert entry is not None
    assert entry.params_type is types.RequestParams


@pytest.mark.anyio
async def test_supported_versions_is_modern_set() -> None:
    """`supportedVersions` is exactly the modern envelope set, not the full
    legacy-compat list (D-008)."""
    result = await _discover(Server("test-server"))
    assert result.supported_versions == list(MODERN_PROTOCOL_VERSIONS)


@pytest.mark.anyio
async def test_server_info_reflects_constructor_fields() -> None:
    """SDK-defined: `serverInfo` is built field-for-field from the `Server`
    constructor arguments."""
    icons = [types.Icon(src="https://example.test/icon.png")]
    server = Server(
        "info-server",
        version="9.9.9",
        title="Info Server",
        description="A server for testing discover.",
        website_url="https://example.test",
        icons=icons,
    )
    result = await _discover(server)
    assert result.server_info == types.Implementation(
        name="info-server",
        version="9.9.9",
        title="Info Server",
        description="A server for testing discover.",
        website_url="https://example.test",
        icons=icons,
    )


@pytest.mark.anyio
async def test_server_info_version_falls_back_to_package() -> None:
    """SDK-defined: when no explicit version is supplied, `serverInfo.version`
    falls back to the installed `mcp` package version."""
    result = await _discover(Server("unversioned"))
    assert result.server_info.version == importlib.metadata.version("mcp")


@pytest.mark.anyio
async def test_instructions_threaded_through() -> None:
    """SDK-defined: the `instructions` constructor argument is passed through
    verbatim, defaulting to `None` when omitted."""
    server = Server("inst-server", instructions="Read the docs first.")
    result = await _discover(server)
    assert result.instructions == "Read the docs first."

    bare = await _discover(Server("bare"))
    assert bare.instructions is None


@pytest.mark.anyio
async def test_capabilities_derived_from_registered_handlers() -> None:
    """SDK-defined: capabilities are computed at handler call time from the
    live registry, so post-construction `add_request_handler` calls are
    reflected."""

    async def list_tools(
        ctx: ServerRequestContext[Any], params: types.PaginatedRequestParams | None
    ) -> types.ListToolsResult:
        raise NotImplementedError

    async def list_prompts(
        ctx: ServerRequestContext[Any], params: types.PaginatedRequestParams | None
    ) -> types.ListPromptsResult:
        raise NotImplementedError

    server = Server("cap-server", on_list_tools=list_tools)

    before = await _discover(server)
    assert before.capabilities.tools is not None
    assert before.capabilities.prompts is None

    server.add_request_handler("prompts/list", types.PaginatedRequestParams, list_prompts)

    after = await _discover(server)
    assert after.capabilities.tools is not None
    assert after.capabilities.prompts is not None


@pytest.mark.anyio
async def test_discover_result_defaults_to_immediately_stale_private_cache() -> None:
    """SDK-defined: `DiscoverResult` is cacheable; the auto-derived handler
    relies on the model defaults (immediately-stale, private)."""
    result = await _discover(Server("cache-server"))
    assert result.ttl_ms == 0
    assert result.cache_scope == "private"


@pytest.mark.anyio
async def test_overridable_via_add_request_handler() -> None:
    """SDK-defined: a custom `server/discover` handler registered via
    `add_request_handler` replaces the auto-derived default wholesale."""
    server = Server("custom-server", version="1.0.0")
    custom = types.DiscoverResult(
        supported_versions=list(MODERN_PROTOCOL_VERSIONS),
        capabilities=types.ServerCapabilities(),
        server_info=types.Implementation(name="custom-server", version="1.0.0"),
        instructions="overridden",
        ttl_ms=60_000,
        cache_scope="public",
    )

    async def custom_discover(
        ctx: ServerRequestContext[Any], params: types.RequestParams | None
    ) -> types.DiscoverResult:
        return custom

    server.add_request_handler("server/discover", types.RequestParams, custom_discover)
    result = await _discover(server)
    assert result is custom