/**
 * Tests for AgentSession concurrent prompt guard.
 */

import { afterEach, beforeEach, describe, expect, it } from "bun:test";
import * as fs from "node:fs";
import * as os from "node:os";
import * as path from "node:path";
import { Agent } from "@oh-my-pi/pi-agent-core";
import { type AssistantMessage, getModel } from "@oh-my-pi/pi-ai";
import { AssistantMessageEventStream } from "@oh-my-pi/pi-ai/utils/event-stream";
import { ModelRegistry } from "@oh-my-pi/pi-coding-agent/config/model-registry";
import { Settings } from "@oh-my-pi/pi-coding-agent/config/settings";
import { AgentSession } from "@oh-my-pi/pi-coding-agent/session/agent-session";
import { AuthStorage } from "@oh-my-pi/pi-coding-agent/session/auth-storage";
import { SessionManager } from "@oh-my-pi/pi-coding-agent/session/session-manager";
import { Snowflake } from "@oh-my-pi/pi-utils";

// Mock stream that mimics AssistantMessageEventStream
class MockAssistantStream extends AssistantMessageEventStream {}

function createAssistantMessage(text: string): AssistantMessage {
	return {
		role: "assistant",
		content: [{ type: "text", text }],
		api: "anthropic-messages",
		provider: "anthropic",
		model: "mock",
		usage: {
			input: 0,
			output: 0,
			cacheRead: 0,
			cacheWrite: 0,
			totalTokens: 0,
			cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
		},
		stopReason: "stop",
		timestamp: Date.now(),
	};
}

describe("AgentSession concurrent prompt guard", () => {
	let session: AgentSession;
	let tempDir: string;

	beforeEach(() => {
		tempDir = path.join(os.tmpdir(), `pi-concurrent-test-${Snowflake.next()}`);
		fs.mkdirSync(tempDir, { recursive: true });
	});

	afterEach(async () => {
		if (session) {
			session.dispose();
		}
		if (tempDir && fs.existsSync(tempDir)) {
			fs.rmSync(tempDir, { recursive: true });
		}
	});

	async function createSession() {
		const model = getModel("anthropic", "claude-sonnet-4-5")!;
		let abortSignal: AbortSignal | undefined;

		// Use a stream function that responds to abort
		const agent = new Agent({
			getApiKey: () => "test-key",
			initialState: {
				model,
				systemPrompt: "Test",
				tools: [],
			},
			streamFn: (_model, _context, options) => {
				abortSignal = options?.signal;
				const stream = new MockAssistantStream();
				queueMicrotask(() => {
					stream.push({ type: "start", partial: createAssistantMessage("") });
					const checkAbort = () => {
						if (abortSignal?.aborted) {
							stream.push({ type: "error", reason: "aborted", error: createAssistantMessage("Aborted") });
						} else {
							setTimeout(checkAbort, 5);
						}
					};
					checkAbort();
				});
				return stream;
			},
		});

		const sessionManager = SessionManager.inMemory();
		const settings = Settings.isolated();
		const authStorage = await AuthStorage.create(path.join(tempDir, "testauth.db"));
		const modelRegistry = new ModelRegistry(authStorage, path.join(tempDir, "models.yml"));
		authStorage.setRuntimeApiKey("anthropic", "test-key");

		session = new AgentSession({
			agent,
			sessionManager,
			settings,
			modelRegistry,
		});

		return session;
	}

	it("should throw when prompt() called while streaming", async () => {
		await createSession();

		// Start first prompt (don't await, it will block until abort)
		const firstPrompt = session.prompt("First message");

		// Wait a tick for isStreaming to be set
		await Bun.sleep(10);

		// Verify we're streaming
		expect(session.isStreaming).toBe(true);

		// Second prompt should reject
		await expect(session.prompt("Second message")).rejects.toThrow(
			"Agent is already processing. Specify streamingBehavior ('steer' or 'followUp') to queue the message.",
		);

		// Cleanup
		await session.abort();
		await firstPrompt.catch(() => {}); // Ignore abort error
	});

	it("should allow steer() while streaming", async () => {
		await createSession();

		// Start first prompt
		const firstPrompt = session.prompt("First message");
		await Bun.sleep(10);

		// steer should work while streaming
		expect(() => session.steer("Steering message")).not.toThrow();
		expect(session.queuedMessageCount).toBe(1);

		// Cleanup
		await session.abort();
		await firstPrompt.catch(() => {});
	});

	it("should allow followUp() while streaming", async () => {
		await createSession();

		// Start first prompt
		const firstPrompt = session.prompt("First message");
		await Bun.sleep(10);

		// followUp should work while streaming
		expect(() => session.followUp("Follow-up message")).not.toThrow();
		expect(session.queuedMessageCount).toBe(1);

		// Cleanup
		await session.abort();
		await firstPrompt.catch(() => {});
	});

	it("should allow prompt() after previous completes", async () => {
		// Create session with a stream that completes immediately
		const model = getModel("anthropic", "claude-sonnet-4-5")!;
		const agent = new Agent({
			getApiKey: () => "test-key",
			initialState: {
				model,
				systemPrompt: "Test",
				tools: [],
			},
			streamFn: () => {
				const stream = new MockAssistantStream();
				queueMicrotask(() => {
					stream.push({ type: "start", partial: createAssistantMessage("") });
					stream.push({ type: "done", reason: "stop", message: createAssistantMessage("Done") });
				});
				return stream;
			},
		});

		const sessionManager = SessionManager.inMemory();
		const settings = Settings.isolated();
		const authStorage = await AuthStorage.create(path.join(tempDir, "testauth.db"));
		const modelRegistry = new ModelRegistry(authStorage, path.join(tempDir, "models.yml"));
		authStorage.setRuntimeApiKey("anthropic", "test-key");

		session = new AgentSession({
			agent,
			sessionManager,
			settings,
			modelRegistry,
		});

		// First prompt completes
		await session.prompt("First message");

		// Should not be streaming anymore
		expect(session.isStreaming).toBe(false);

		// Second prompt should work
		await expect(session.prompt("Second message")).resolves.toBeUndefined();
	});
});