"""Unit tests for browser_cdp tool.

Uses a tiny in-process ``websockets`` server to simulate a CDP endpoint —
gives real protocol coverage (connect, send, recv, close) without needing
a real Chrome instance.
"""
from __future__ import annotations

import asyncio
import json
import threading
import time
from typing import Any, Dict, List

import pytest

import websockets
from websockets.asyncio.server import serve

from tools import browser_cdp_tool


# ---------------------------------------------------------------------------
# In-process CDP mock server
# ---------------------------------------------------------------------------


class _CDPServer:
    """A tiny CDP-over-WebSocket mock.

    Each client gets a greeting-free stream.  The server replies to each
    inbound request whose ``id`` is set, using the registered handler for
    that method.  If no handler is registered, returns a generic CDP error.
    """

    def __init__(self) -> None:
        self._handlers: Dict[str, Any] = {}
        self._responses: List[Dict[str, Any]] = []
        self._loop: asyncio.AbstractEventLoop | None = None
        self._server: Any = None
        self._thread: threading.Thread | None = None
        self._host = "127.0.0.1"
        self._port = 0

    # --- handler registration --------------------------------------------

    def on(self, method: str, handler):
        """Register a handler ``handler(params, session_id) -> dict or Exception``."""
        self._handlers[method] = handler

    # --- lifecycle -------------------------------------------------------

    def start(self) -> str:
        ready = threading.Event()

        def _run() -> None:
            self._loop = asyncio.new_event_loop()
            asyncio.set_event_loop(self._loop)

            async def _handler(ws):
                try:
                    async for raw in ws:
                        msg = json.loads(raw)
                        call_id = msg.get("id")
                        method = msg.get("method", "")
                        params = msg.get("params", {}) or {}
                        session_id = msg.get("sessionId")
                        self._responses.append(msg)

                        fn = self._handlers.get(method)
                        if fn is None:
                            reply = {
                                "id": call_id,
                                "error": {
                                    "code": -32601,
                                    "message": f"No handler for {method}",
                                },
                            }
                        else:
                            try:
                                result = fn(params, session_id)
                                if isinstance(result, Exception):
                                    raise result
                                reply = {"id": call_id, "result": result}
                            except Exception as exc:
                                reply = {
                                    "id": call_id,
                                    "error": {"code": -1, "message": str(exc)},
                                }
                        if session_id:
                            reply["sessionId"] = session_id
                        await ws.send(json.dumps(reply))
                except websockets.exceptions.ConnectionClosed:
                    pass

            async def _serve() -> None:
                self._server = await serve(_handler, self._host, 0)
                sock = next(iter(self._server.sockets))
                self._port = sock.getsockname()[1]
                ready.set()
                await self._server.wait_closed()

            try:
                self._loop.run_until_complete(_serve())
            finally:
                self._loop.close()

        self._thread = threading.Thread(target=_run, daemon=True)
        self._thread.start()
        if not ready.wait(timeout=5.0):
            raise RuntimeError("CDP mock server failed to start within 5s")
        return f"ws://{self._host}:{self._port}/devtools/browser/mock"

    def stop(self) -> None:
        if self._loop and self._server:
            def _close() -> None:
                self._server.close()

            self._loop.call_soon_threadsafe(_close)
        if self._thread:
            self._thread.join(timeout=3.0)

    def received(self) -> List[Dict[str, Any]]:
        return list(self._responses)


# ---------------------------------------------------------------------------
# Fixtures
# ---------------------------------------------------------------------------


@pytest.fixture
def cdp_server(monkeypatch):
    """Start a CDP mock and route tool resolution to it."""
    server = _CDPServer()
    ws_url = server.start()
    monkeypatch.setattr(
        browser_cdp_tool, "_resolve_cdp_endpoint", lambda: ws_url
    )
    try:
        yield server
    finally:
        server.stop()


# ---------------------------------------------------------------------------
# Input validation
# ---------------------------------------------------------------------------


def test_missing_method_returns_error():
    result = json.loads(browser_cdp_tool.browser_cdp(method=""))
    assert "error" in result
    assert "method" in result["error"].lower()
    assert result.get("cdp_docs") == browser_cdp_tool.CDP_DOCS_URL


def test_non_string_method_returns_error():
    result = json.loads(browser_cdp_tool.browser_cdp(method=123))  # type: ignore[arg-type]
    assert "error" in result
    assert "method" in result["error"].lower()


def test_non_dict_params_returns_error(monkeypatch):
    monkeypatch.setattr(
        browser_cdp_tool, "_resolve_cdp_endpoint", lambda: "ws://localhost:9999"
    )
    result = json.loads(
        browser_cdp_tool.browser_cdp(method="Target.getTargets", params="not-a-dict")  # type: ignore[arg-type]
    )
    assert "error" in result
    assert "object" in result["error"].lower() or "dict" in result["error"].lower()


# ---------------------------------------------------------------------------
# Endpoint resolution
# ---------------------------------------------------------------------------


def test_no_endpoint_returns_helpful_error(monkeypatch):
    monkeypatch.setattr(browser_cdp_tool, "_resolve_cdp_endpoint", lambda: "")
    result = json.loads(browser_cdp_tool.browser_cdp(method="Target.getTargets"))
    assert "error" in result
    assert "/browser connect" in result["error"]
    assert result.get("cdp_docs") == browser_cdp_tool.CDP_DOCS_URL


def test_non_ws_endpoint_returns_error(monkeypatch):
    monkeypatch.setattr(
        browser_cdp_tool, "_resolve_cdp_endpoint", lambda: "http://localhost:9222"
    )
    result = json.loads(browser_cdp_tool.browser_cdp(method="Target.getTargets"))
    assert "error" in result
    assert "WebSocket" in result["error"]


def test_websockets_missing_returns_error(monkeypatch):
    monkeypatch.setattr(browser_cdp_tool, "_WS_AVAILABLE", False)
    result = json.loads(browser_cdp_tool.browser_cdp(method="Target.getTargets"))
    assert "error" in result
    assert "websockets" in result["error"].lower()


# ---------------------------------------------------------------------------
# Happy-path: browser-level call
# ---------------------------------------------------------------------------


def test_browser_level_success(cdp_server):
    cdp_server.on(
        "Target.getTargets",
        lambda params, sid: {
            "targetInfos": [
                {"targetId": "A", "type": "page", "title": "Tab 1", "url": "about:blank"},
                {"targetId": "B", "type": "page", "title": "Tab 2", "url": "https://a.test"},
            ]
        },
    )
    result = json.loads(browser_cdp_tool.browser_cdp(method="Target.getTargets"))
    assert result["success"] is True
    assert result["method"] == "Target.getTargets"
    assert "target_id" not in result
    assert len(result["result"]["targetInfos"]) == 2
    # Verify the server actually received exactly one call (no extra traffic)
    calls = cdp_server.received()
    assert len(calls) == 1
    assert calls[0]["method"] == "Target.getTargets"
    assert "sessionId" not in calls[0]


def test_empty_params_sends_empty_object(cdp_server):
    cdp_server.on("Browser.getVersion", lambda params, sid: {"product": "Mock/1.0"})
    json.loads(browser_cdp_tool.browser_cdp(method="Browser.getVersion"))
    assert cdp_server.received()[0]["params"] == {}


# ---------------------------------------------------------------------------
# Happy-path: target-attached call
# ---------------------------------------------------------------------------


def test_target_attach_then_call(cdp_server):
    cdp_server.on(
        "Target.attachToTarget",
        lambda params, sid: {"sessionId": f"sess-{params['targetId']}"},
    )
    cdp_server.on(
        "Runtime.evaluate",
        lambda params, sid: {
            "result": {"type": "string", "value": f"evaluated[{sid}]"},
        },
    )
    result = json.loads(
        browser_cdp_tool.browser_cdp(
            method="Runtime.evaluate",
            params={"expression": "document.title", "returnByValue": True},
            target_id="tab-A",
        )
    )
    assert result["success"] is True
    assert result["target_id"] == "tab-A"
    assert result["result"]["result"]["value"] == "evaluated[sess-tab-A]"

    calls = cdp_server.received()
    # First call: attach
    assert calls[0]["method"] == "Target.attachToTarget"
    assert calls[0]["params"] == {"targetId": "tab-A", "flatten": True}
    # Second call: dispatched method on the session
    assert calls[1]["method"] == "Runtime.evaluate"
    assert calls[1]["sessionId"] == "sess-tab-A"


# ---------------------------------------------------------------------------
# CDP error responses
# ---------------------------------------------------------------------------


def test_cdp_method_error_returns_tool_error(cdp_server):
    # No handler registered -> server returns CDP error
    result = json.loads(
        browser_cdp_tool.browser_cdp(method="NonExistent.method")
    )
    assert "error" in result
    assert "CDP error" in result["error"]
    assert result.get("method") == "NonExistent.method"


def test_attach_failure_returns_tool_error(cdp_server):
    # Target.attachToTarget has no handler -> server errors on attach
    result = json.loads(
        browser_cdp_tool.browser_cdp(
            method="Runtime.evaluate",
            params={"expression": "1+1"},
            target_id="missing",
        )
    )
    assert "error" in result
    assert "Target.attachToTarget" in result["error"]


# ---------------------------------------------------------------------------
# Timeouts
# ---------------------------------------------------------------------------


def test_timeout_when_server_never_replies(cdp_server):
    # Register a handler that blocks forever
    def slow(params, sid):
        time.sleep(10)
        return {}

    cdp_server.on("Page.slowMethod", slow)
    result = json.loads(
        browser_cdp_tool.browser_cdp(
            method="Page.slowMethod", timeout=0.5
        )
    )
    assert "error" in result
    assert "tim" in result["error"].lower()


# ---------------------------------------------------------------------------
# Timeout clamping
# ---------------------------------------------------------------------------


def test_timeout_clamped_above_max(cdp_server):
    cdp_server.on("Browser.getVersion", lambda p, s: {"product": "ok"})
    # timeout=10_000 should be clamped to 300 but still succeed
    result = json.loads(
        browser_cdp_tool.browser_cdp(method="Browser.getVersion", timeout=10_000)
    )
    assert result["success"] is True


def test_invalid_timeout_falls_back_to_default(cdp_server):
    cdp_server.on("Browser.getVersion", lambda p, s: {"product": "ok"})
    result = json.loads(
        browser_cdp_tool.browser_cdp(method="Browser.getVersion", timeout="nope")  # type: ignore[arg-type]
    )
    assert result["success"] is True


# ---------------------------------------------------------------------------
# Registry integration
# ---------------------------------------------------------------------------


def test_registered_in_browser_toolset():
    from tools.registry import registry

    entry = registry.get_entry("browser_cdp")
    assert entry is not None
    # browser_cdp lives in its own toolset so its stricter check_fn
    # (requires reachable CDP endpoint) doesn't gate the whole browser
    # toolset — see commit 96b0f3700.
    assert entry.toolset == "browser-cdp"
    assert entry.schema["name"] == "browser_cdp"
    assert entry.schema["parameters"]["required"] == ["method"]
    assert "Chrome DevTools Protocol" in entry.schema["description"]
    assert browser_cdp_tool.CDP_DOCS_URL in entry.schema["description"]


def test_dispatch_through_registry(cdp_server):
    from tools.registry import registry

    cdp_server.on("Target.getTargets", lambda p, s: {"targetInfos": []})
    raw = registry.dispatch(
        "browser_cdp", {"method": "Target.getTargets"}, task_id="t1"
    )
    result = json.loads(raw)
    assert result["success"] is True
    assert result["method"] == "Target.getTargets"


# ---------------------------------------------------------------------------
# check_fn gating
# ---------------------------------------------------------------------------


def test_check_fn_false_when_no_cdp_url(monkeypatch):
    """Gate closes when no CDP URL is set — even if the browser toolset is
    otherwise configured."""
    import tools.browser_tool as bt

    monkeypatch.setattr(bt, "check_browser_requirements", lambda: True)
    monkeypatch.setattr(bt, "_get_cdp_override", lambda: "")
    assert browser_cdp_tool._browser_cdp_check() is False


def test_check_fn_true_when_cdp_url_set(monkeypatch):
    """Gate opens as soon as a CDP URL is resolvable."""
    import tools.browser_tool as bt

    monkeypatch.setattr(bt, "check_browser_requirements", lambda: True)
    monkeypatch.setattr(
        bt, "_get_cdp_override", lambda: "ws://localhost:9222/devtools/browser/x"
    )
    assert browser_cdp_tool._browser_cdp_check() is True


def test_check_fn_false_when_browser_requirements_fail(monkeypatch):
    """Even with a CDP URL, gate closes if the overall browser toolset is
    unavailable (e.g. agent-browser not installed)."""
    import tools.browser_tool as bt

    monkeypatch.setattr(bt, "check_browser_requirements", lambda: False)
    monkeypatch.setattr(
        bt, "_get_cdp_override", lambda: "ws://localhost:9222/devtools/browser/x"
    )
    assert browser_cdp_tool._browser_cdp_check() is False