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

import { existsSync, mkdirSync, rmSync } from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";
import { Agent } from "@mariozechner/pi-agent-core";
import { type AssistantMessage, type AssistantMessageEvent, EventStream, getModel } from "@mariozechner/pi-ai";
import { afterEach, beforeEach, describe, expect, it } from "vitest";
import { AgentSession } from "../src/core/agent-session.js";
import { AuthStorage } from "../src/core/auth-storage.js";
import { ModelRegistry } from "../src/core/model-registry.js";
import { SessionManager } from "../src/core/session-manager.js";
import { SettingsManager } from "../src/core/settings-manager.js";
import { createTestResourceLoader } from "./utilities.js";

// Mock stream that mimics AssistantMessageEventStream
class MockAssistantStream extends EventStream<AssistantMessageEvent, AssistantMessage> {
	constructor() {
		super(
			(event) => event.type === "done" || event.type === "error",
			(event) => {
				if (event.type === "done") return event.message;
				if (event.type === "error") return event.error;
				throw new Error("Unexpected event type");
			},
		);
	}
}

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 = join(tmpdir(), `pi-concurrent-test-${Date.now()}`);
		mkdirSync(tempDir, { recursive: true });
	});

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

	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 settingsManager = SettingsManager.create(tempDir, tempDir);
		const authStorage = AuthStorage.create(join(tempDir, "auth.json"));
		const modelRegistry = new ModelRegistry(authStorage, tempDir);
		// Set a runtime API key so validation passes
		authStorage.setRuntimeApiKey("anthropic", "test-key");

		session = new AgentSession({
			agent,
			sessionManager,
			settingsManager,
			cwd: tempDir,
			modelRegistry,
			resourceLoader: createTestResourceLoader(),
		});

		return session;
	}

	it("should throw when prompt() called while streaming", async () => {
		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 new Promise((resolve) => setTimeout(resolve, 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 () => {
		createSession();

		// Start first prompt
		const firstPrompt = session.prompt("First message");
		await new Promise((resolve) => setTimeout(resolve, 10));

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

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

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

		// Start first prompt
		const firstPrompt = session.prompt("First message");
		await new Promise((resolve) => setTimeout(resolve, 10));

		// followUp should work while streaming
		expect(() => session.followUp("Follow-up message")).not.toThrow();
		expect(session.pendingMessageCount).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 settingsManager = SettingsManager.create(tempDir, tempDir);
		const authStorage = AuthStorage.create(join(tempDir, "auth.json"));
		const modelRegistry = new ModelRegistry(authStorage, tempDir);
		authStorage.setRuntimeApiKey("anthropic", "test-key");

		session = new AgentSession({
			agent,
			sessionManager,
			settingsManager,
			cwd: tempDir,
			modelRegistry,
			resourceLoader: createTestResourceLoader(),
		});

		// 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.not.toThrow();
	});
});