import { beforeEach, describe, expect, it } from "vitest";
import { requestsHandler } from "../requestsHandler"; // Real class
import { MockAdapter } from "./MockAdapter";

describe("Queue Deep Dive (requestsHandler)", () => {
	let mockAdapter: MockAdapter;
	let handler: requestsHandler;

	beforeEach(() => {
		mockAdapter = new MockAdapter();
		// Mock sub-APIs required by requestsHandler
		mockAdapter.mqtt_api = { ensureEndpoint: async () => "endpoint", isConnected: () => true, sendMessage: () => {}, clearIntervals: () => {} } as any;
		mockAdapter.local_api = { isConnected: () => true, sendMessage: () => true, clearLocalDevicedTimeout: () => {} } as any;
		mockAdapter.http_api = { getMatchedLocalKeys: () => new Map([["duid", Buffer.alloc(16)]]) } as any;
		mockAdapter.getDeviceProtocolVersion = async () => "1.0";

		handler = new requestsHandler(mockAdapter as any);
		handler.startupFinished = true; // Bypass startup wait
	});

	it("should respect concurrency limit (10)", async () => {
		const duid = "duid";
		let activeRequests = 0;
		let maxActive = 0;

		// Mock message parser to avoid overhead
		handler.messageParser.buildPayload = async () => "payload";
		handler.messageParser.buildRoborockMessage = async () => Buffer.from("msg");

		const manager = handler["globalManager"];

		// We hijack manager.add to count executions
		const originalAdd = manager.add.bind(manager);

		manager.add = <T>(id: string, _task: (signal: AbortSignal) => Promise<T>, priority?: number): Promise<T> => {
			return originalAdd(id, async () => {
				activeRequests++;
				maxActive = Math.max(maxActive, activeRequests);
				await new Promise(res => setTimeout(res, 20));
				activeRequests--;
				return "ok" as unknown as T;
			}, priority);
		};

		const promises = [];
		for (let i = 0; i < 20; i++) {
			promises.push(handler.sendRequest(duid, "get_status", []));
		}

		// Wait a bit for them to start
		await new Promise(res => setTimeout(res, 10));

		// Concurrency is 10.
		expect(maxActive).to.be.at.most(11); // Allow 1 buffer for timing
		expect(manager.queue.pending).to.be.above(0); // Should have items waiting
	});

	it("should prioritize high-priority requests", async () => {
		// Force concurrency 1 to strictly test priority/serialization
		// Need to import RequestManager class or mock it?
		// RequestManager is not exported from requestsHandler.ts?
		// It is NOT exported.
		// So we cannot instantiate it easily.
		// We can however modify the existing one.
		const manager = handler["globalManager"];
		manager.queue.concurrency = 1;

		const executionOrder: string[] = [];

		// Mock message parser to avoid overhead
		handler.messageParser.buildPayload = async () => "payload";
		handler.messageParser.buildRoborockMessage = async () => Buffer.from("msg");

		// We modify queue behavior to synchronous push to order list
		const originalAdd = manager.add.bind(manager);

		manager.add = <T>(id: string, _task: (signal: AbortSignal) => Promise<T>, priority?: number): Promise<T> => {
			// Identifier hack to trace ordering
			const name = id.includes("blocker") ? "blocker" : (id.includes("low") ? "low" : "high");

			return originalAdd(id, async () => {
				if (name === "blocker") await new Promise(res => setTimeout(res, 50));
				executionOrder.push(name);
				return "ok" as unknown as T;
			}, priority);
		};

		// Block the queue first with a slow task
		// sendRequest generates an ID, so we can't easily control the name unless we mock sendRequest or params?
		// Let's use manager.add directly for this test as we want to test PQueue behavior wrapper in Manager

		// Blocker
		handler["globalManager"].add("req_blocker", async () => {
			await new Promise(res => setTimeout(res, 50));
			executionOrder.push("blocker");
			return "ok";
		}, 0);

		// Low Priority
		handler["globalManager"].add("req_low", async () => {
			executionOrder.push("low");
			return "ok";
		}, 0);

		// High Priority
		handler["globalManager"].add("req_high", async () => {
			executionOrder.push("high");
			return "ok";
		}, 10);

		await manager.onIdle();

		// Expect: blocker (started), then high, then low
		expect(executionOrder).to.deep.equal(["blocker", "high", "low"]);
	});

	it("does not reuse request IDs as local TCP transport message IDs", async () => {
		let payloadRequestId: number | undefined;
		let transportSequenceId: number | undefined;

		mockAdapter.getDeviceProtocolVersion = async () => "L01";
		handler.messageParser.buildPayload = async (_protocol, messageID) => {
			payloadRequestId = messageID;
			return "payload";
		};
		handler.messageParser.buildRoborockMessage = async (_duid, _protocol, _timestamp, _payload, _version, sequenceId) => {
			transportSequenceId = sequenceId;
			return Buffer.from("msg");
		};

		const requestPromise = handler.sendRequest("duid", "get_status", []);
		await new Promise(res => setTimeout(res, 10));

		expect(payloadRequestId).to.equal(301);
		expect(transportSequenceId).to.equal(1);

		handler.resolvePendingRequest(301, ["ok"], 4, "duid", "TCP");
		await expect(requestPromise).resolves.to.deep.equal(["ok"]);
	});
});