import { afterEach, describe, expect, it, vi } from "bun:test";
import type { ModelRegistry } from "../../src/config/model-registry";
import { Settings } from "../../src/config/settings";
import type { LoadExtensionsResult } from "../../src/extensibility/extensions/types";
import type { CreateAgentSessionResult } from "../../src/sdk";
import * as sdkModule from "../../src/sdk";
import type { AgentSession, AgentSessionEvent, PromptOptions } from "../../src/session/agent-session";
import { runSubprocess } from "../../src/task/executor";
import type { AgentDefinition } from "../../src/task/types";
import { EventBus } from "../../src/utils/event-bus";

/**
 * Contract: when `task.maxRuntimeMs` is set, a subagent whose inference call
 * never resolves (provider stream hang the watchdog couldn't catch) MUST be
 * aborted within ~maxRuntimeMs and surface a clear "runtime limit exceeded"
 * reason — not a generic "Cancelled by caller" — so on-call engineers don't
 * mistake it for a user cancellation.
 *
 * Without this defense, the executor's `await session.waitForIdle()` waits
 * indefinitely (see session 019e2b4d-fa25-7000-a725-955278e9b293, subagent 7,
 * which stayed silent for ~2 hours).
 */

interface HangingSessionHandle {
	session: AgentSession;
	abortCalls: () => number;
}

function createHangingSession(): HangingSessionHandle {
	let abortCount = 0;
	const { promise: hang, resolve: releaseHang } = Promise.withResolvers<void>();
	const session: Partial<AgentSession> = {
		state: { messages: [] } as never,
		agent: { state: { systemPrompt: ["test"] } } as never,
		extensionRunner: undefined as never,
		sessionManager: {
			appendSessionInit: () => {},
		} as never,
		getActiveToolNames: () => ["read", "yield"],
		setActiveToolsByName: async (_names: string[]) => {},
		subscribe: (_listener: (event: AgentSessionEvent) => void) => () => {},
		prompt: async (_text: string, _options?: PromptOptions) => {
			await hang;
		},
		waitForIdle: async () => {
			await hang;
		},
		getLastAssistantMessage: () => undefined,
		abort: async () => {
			abortCount += 1;
			releaseHang();
		},
		dispose: async () => {},
	};
	return {
		session: session as AgentSession,
		abortCalls: () => abortCount,
	};
}

function mockCreateAgentSession(session: AgentSession) {
	return vi.spyOn(sdkModule, "createAgentSession").mockResolvedValue({
		session,
		extensionsResult: {} as unknown as LoadExtensionsResult,
		setToolUIContext: () => {},
		eventBus: new EventBus(),
	} satisfies CreateAgentSessionResult);
}

describe("runSubprocess wall clock (task.maxRuntimeMs)", () => {
	afterEach(() => {
		vi.restoreAllMocks();
	});

	const baseAgent: AgentDefinition = {
		name: "task",
		description: "test",
		systemPrompt: "test",
		source: "bundled",
	};

	const baseOptions = {
		cwd: "/tmp",
		agent: baseAgent,
		task: "do work",
		index: 0,
		id: "subagent-walltime",
		modelRegistry: { refresh: async () => {} } as unknown as ModelRegistry,
		enableLsp: false,
	};

	it("aborts a stalled subagent and surfaces a runtime-limit reason", async () => {
		const settings = Settings.isolated({ "task.maxRuntimeMs": 50 });
		const handle = createHangingSession();
		mockCreateAgentSession(handle.session);

		const startedAt = Date.now();
		const result = await runSubprocess({
			...baseOptions,
			id: "subagent-timeout",
			settings,
		});
		const elapsedMs = Date.now() - startedAt;

		expect(result.aborted).toBe(true);
		expect(result.exitCode).toBe(1);
		expect(result.abortReason).toContain("runtime limit exceeded");
		expect(result.abortReason).toContain("task.maxRuntimeMs=50");
		expect(handle.abortCalls()).toBeGreaterThanOrEqual(1);
		// Sanity: must finish in roughly the configured window (allow generous slack
		// for CI; the contract is "doesn't hang for hours", not "exactly 50 ms").
		expect(elapsedMs).toBeLessThan(10_000);
	});

	it("does not abort early when the runtime budget is unlimited", async () => {
		// Stub session resolves immediately to a no-op yield so we don't actually
		// hang; we only need to assert that NO timeout fires when maxRuntimeMs=0.
		const settings = Settings.isolated({ "task.maxRuntimeMs": 0 });
		const fastSession: Partial<AgentSession> = {
			state: { messages: [] } as never,
			agent: { state: { systemPrompt: ["test"] } } as never,
			extensionRunner: undefined as never,
			sessionManager: { appendSessionInit: () => {} } as never,
			getActiveToolNames: () => ["read", "yield"],
			setActiveToolsByName: async () => {},
			subscribe: (listener: (event: AgentSessionEvent) => void) => {
				// Fire a synthetic yield on the next tick to drive runSubprocess to
				// completion without depending on the real agent loop.
				queueMicrotask(() => {
					listener({
						type: "tool_execution_end",
						toolCallId: "tool-fast",
						toolName: "yield",
						result: {
							content: [{ type: "text", text: "Result submitted." }],
							details: { status: "success", data: { ok: true } },
						},
						isError: false,
					} as AgentSessionEvent);
				});
				return () => {};
			},
			prompt: async () => {},
			waitForIdle: async () => {},
			getLastAssistantMessage: () => undefined,
			abort: async () => {},
			dispose: async () => {},
		};
		mockCreateAgentSession(fastSession as AgentSession);

		const result = await runSubprocess({
			...baseOptions,
			id: "subagent-no-limit",
			settings,
		});

		expect(result.aborted).toBe(false);
		expect(result.abortReason).toBeUndefined();
	});
});