/**
 * End-to-end contract: a host started with both link variants marks view-link
 * guests read-only in `welcome` and refuses their mutating frames, while
 * full-link guests keep prompt/abort/agent-cmd capability. Runs over an
 * in-process relay + fake WebSocket transport (no real sockets, no handshake
 * or polling latency) that speaks the documented relay forwarding contract,
 * with real AES-GCM sealing — only the TUI context and the network transport
 * are stubbed. One host/relay boots once and is reused; guest frames ride the
 * in-memory transport, so the suite stays fast and time-independent.
 */
import { afterAll, afterEach, beforeAll, describe, expect, it } from "bun:test";
import { importRoomKey } from "@oh-my-pi/pi-coding-agent/collab/crypto";
import { CollabHost } from "@oh-my-pi/pi-coding-agent/collab/host";
import {
	COLLAB_PROTO,
	type CollabFrame,
	parseCollabLink,
	rewriteEnvelopePeer,
	unpackEnvelope,
} from "@oh-my-pi/pi-coding-agent/collab/protocol";
import { CollabSocket } from "@oh-my-pi/pi-coding-agent/collab/relay-client";
import type { InteractiveModeContext } from "@oh-my-pi/pi-coding-agent/modes/types";

// ── In-memory transport ────────────────────────────────────────────────────
// FakeWebSocket + InMemoryRelay replace the real Bun.serve relay and loopback
// WebSocket. They mirror the production relay's forwarding contract exactly
// (4-byte peerId envelope routing, peer-joined/peer-left control frames) but
// deliver every frame on a microtask with zero network or timer latency. Real
// CollabSocket / CollabHost run unchanged on top, so sealing, enveloping, the
// hello→welcome handshake, and read-only enforcement are all exercised.

/** Active relay the fake transport routes through; set for the lifetime of this file. */
let activeRelay: InMemoryRelay | null = null;

class FakeWebSocket {
	static readonly CONNECTING = 0;
	static readonly OPEN = 1;
	static readonly CLOSING = 2;
	static readonly CLOSED = 3;

	binaryType = "blob";
	readyState: number = FakeWebSocket.CONNECTING;
	readonly role: "host" | "guest";
	peerId = 0;
	onopen: (() => void) | null = null;
	onmessage: ((event: { data: unknown }) => void) | null = null;
	onerror: (() => void) | null = null;
	onclose: ((event: { code: number; reason: string }) => void) | null = null;
	readonly #relay: InMemoryRelay;

	constructor(url: string) {
		const relay = activeRelay;
		if (!relay) throw new Error("FakeWebSocket: no active in-memory relay");
		this.#relay = relay;
		this.role = new URL(url).searchParams.get("role") === "host" ? "host" : "guest";
		queueMicrotask(() => {
			if (this.readyState !== FakeWebSocket.CONNECTING) return;
			this.readyState = FakeWebSocket.OPEN;
			relay.connect(this);
			this.onopen?.();
		});
	}

	send(data: Uint8Array): void {
		if (this.readyState !== FakeWebSocket.OPEN) return;
		// Snapshot: the relay rewrites the peerId in place, and the sender may
		// reuse the buffer once send() returns.
		const bytes = new Uint8Array(data);
		queueMicrotask(() => this.#relay.forward(this, bytes));
	}

	close(_code?: number): void {
		if (this.readyState === FakeWebSocket.CLOSED) return;
		this.readyState = FakeWebSocket.CLOSED;
		this.#relay.disconnect(this);
		queueMicrotask(() => this.onclose?.({ code: 1000, reason: "closed" }));
	}

	/** Relay → this socket: a binary frame, delivered as ArrayBuffer (binaryType "arraybuffer"). */
	deliver(bytes: Uint8Array): void {
		if (this.readyState !== FakeWebSocket.OPEN) return;
		const copy = new Uint8Array(bytes);
		queueMicrotask(() => this.onmessage?.({ data: copy.buffer }));
	}

	/** Relay → this socket: a JSON control message. */
	deliverControl(json: string): void {
		if (this.readyState !== FakeWebSocket.OPEN) return;
		queueMicrotask(() => this.onmessage?.({ data: json }));
	}
}

/** Single-room in-memory relay mirroring the production forwarding contract. */
class InMemoryRelay {
	#host: FakeWebSocket | null = null;
	readonly #guests = new Map<number, FakeWebSocket>();
	#nextPeerId = 1;

	connect(ws: FakeWebSocket): void {
		if (ws.role === "host") {
			this.#host = ws;
			return;
		}
		ws.peerId = this.#nextPeerId++;
		this.#guests.set(ws.peerId, ws);
		this.#host?.deliverControl(JSON.stringify({ t: "peer-joined", peer: ws.peerId }));
	}

	forward(from: FakeWebSocket, bytes: Uint8Array): void {
		if (from.role === "host") {
			const envelope = unpackEnvelope(bytes);
			if (!envelope) return;
			if (envelope.peerId === 0) {
				for (const guest of this.#guests.values()) guest.deliver(bytes);
			} else {
				this.#guests.get(envelope.peerId)?.deliver(bytes);
			}
			return;
		}
		rewriteEnvelopePeer(bytes, from.peerId);
		this.#host?.deliver(bytes);
	}

	disconnect(ws: FakeWebSocket): void {
		if (ws.role === "host") {
			if (this.#host === ws) this.#host = null;
			return;
		}
		this.#guests.delete(ws.peerId);
		this.#host?.deliverControl(JSON.stringify({ t: "peer-left", peer: ws.peerId }));
	}
}

interface HostHarness {
	ctx: InteractiveModeContext;
	prompts: { from?: string }[];
	aborts: { count: number };
	/** Resolves on the next promptCustomMessage call — no polling. */
	nextPrompt(): Promise<{ from?: string }>;
}

/** Minimal InteractiveModeContext double: only the members CollabHost touches. */
function makeHostContext(): HostHarness {
	const prompts: { from?: string }[] = [];
	const aborts = { count: 0 };
	const promptWaiters: ((details: { from?: string }) => void)[] = [];
	const ctx = {
		settings: { get: () => "" },
		sessionManager: {
			getSessionId: () => "sess-1",
			getCwd: () => "/tmp",
			snapshotForReplication: () => ({
				header: { type: "session", id: "sess-1", timestamp: new Date().toISOString(), cwd: "/tmp" },
				entries: [],
			}),
			onEntryAppended: undefined,
		},
		session: {
			isStreaming: false,
			queuedMessageCount: 0,
			sessionName: "test",
			model: undefined,
			thinkingLevel: undefined,
			subscribe: () => () => {},
			emitNotice: () => {},
			promptCustomMessage: (message: { details?: { from?: string } }) => {
				const details = message.details ?? {};
				prompts.push(details);
				for (const waiter of promptWaiters.splice(0)) waiter(details);
				return Promise.resolve();
			},
			abort: () => {
				aborts.count++;
				return Promise.resolve();
			},
		},
		eventBus: undefined,
		statusLine: {
			setCollabStatus: () => {},
			invalidate: () => {},
			getCachedContextBreakdown: () => ({ usedTokens: 0, contextWindow: 0 }),
		},
		ui: { requestRender: () => {} },
		showStatus: () => {},
		collabHost: undefined,
	} as unknown as InteractiveModeContext;
	const nextPrompt = (): Promise<{ from?: string }> => {
		const { promise, resolve } = Promise.withResolvers<{ from?: string }>();
		promptWaiters.push(resolve);
		return promise;
	};
	return { ctx, prompts, aborts, nextPrompt };
}

interface TestGuest {
	socket: CollabSocket;
	nextFrame(): Promise<CollabFrame>;
}

/**
 * Frames the test harness skips: the host's debounced broadcasts (state,
 * agents, entry, event, bus) and the per-peer snapshot-chunk train that
 * follows every welcome. They interleave nondeterministically with the
 * directed welcome/error frames these tests actually assert on.
 */
const FILTERED_FRAME_TYPES: Record<string, true> = {
	state: true,
	agents: true,
	entry: true,
	event: true,
	bus: true,
	"snapshot-chunk": true,
};

/**
 * Raw guest speaking the wire protocol directly. `writeToken` overrides the link's token (e.g. forged).
 * Broadcast frames interleave nondeterministically with directed replies (the post-hello state
 * broadcast races the first prompt's error reply), so `nextFrame` drops them and yields only the
 * welcome/error frames these tests assert on.
 */
async function joinAsGuest(link: string, name: string, writeTokenOverride?: string): Promise<TestGuest> {
	const parsed = parseCollabLink(link);
	if ("error" in parsed) throw new Error(parsed.error);
	const writeToken =
		writeTokenOverride ?? (parsed.writeToken ? Buffer.from(parsed.writeToken).toString("base64url") : undefined);
	const key = await importRoomKey(parsed.key);
	const socket = new CollabSocket({ wsUrl: parsed.wsUrl, role: "guest", key });
	const queue: CollabFrame[] = [];
	const waiters: ((frame: CollabFrame) => void)[] = [];
	socket.onFrame = frame => {
		if (FILTERED_FRAME_TYPES[frame.t]) return;
		const waiter = waiters.shift();
		if (waiter) waiter(frame);
		else queue.push(frame);
	};
	socket.onOpen = () => socket.send({ t: "hello", proto: COLLAB_PROTO, name, writeToken });
	socket.connect();
	const nextFrame = (): Promise<CollabFrame> => {
		const queued = queue.shift();
		if (queued) return Promise.resolve(queued);
		const { promise, resolve } = Promise.withResolvers<CollabFrame>();
		waiters.push(resolve);
		return promise;
	};
	return { socket, nextFrame };
}

// ── Shared host/relay, booted once ──────────────────────────────────────────
// Booting the relay + host and connecting the host socket is the only heavy
// step; it is identical across all three tests (none mutate host config), so it
// runs once. Per-test guest state is reset in afterEach.

const RealWebSocket = globalThis.WebSocket;
const guestCleanups: (() => void)[] = [];
let harness: HostHarness;
let host: CollabHost;

beforeAll(async () => {
	globalThis.WebSocket = FakeWebSocket as unknown as typeof WebSocket;
	activeRelay = new InMemoryRelay();
	harness = makeHostContext();
	host = new CollabHost(harness.ctx);
	// Port is irrelevant: the fake transport routes by the `role` query param.
	await host.start("ws://localhost:8787");
});

afterEach(() => {
	for (const cleanup of guestCleanups.splice(0).reverse()) cleanup();
	harness.prompts.length = 0;
	harness.aborts.count = 0;
});

afterAll(async () => {
	// Restore the real transport first so the global is clean even if stop() throws;
	// the host's socket holds its own FakeWebSocket/relay refs, so teardown still works.
	globalThis.WebSocket = RealWebSocket;
	activeRelay = null;
	await host.stop("test done");
});

describe("collab read-only links", () => {
	it("welcomes view-link guests read-only and refuses their mutating frames", async () => {
		const { prompts, aborts } = harness;
		expect(host.viewLink).not.toBe(host.link);

		const guest = await joinAsGuest(host.viewLink, "viewer");
		guestCleanups.push(() => guest.socket.close());
		const welcome = await guest.nextFrame();
		if (welcome.t !== "welcome") throw new Error(`expected welcome, got ${welcome.t}`);
		expect(welcome.readOnly).toBe(true);

		guest.socket.send({ t: "prompt", text: "do something" });
		const promptReply = await guest.nextFrame();
		if (promptReply.t !== "error") throw new Error(`expected error, got ${promptReply.t}`);
		expect(promptReply.message).toContain("read-only");
		expect(prompts).toHaveLength(0);

		guest.socket.send({ t: "abort" });
		const abortReply = await guest.nextFrame();
		expect(abortReply.t).toBe("error");
		expect(aborts.count).toBe(0);

		guest.socket.send({ t: "agent-cmd", cmd: "kill", agentId: "nope" });
		const cmdReply = await guest.nextFrame();
		expect(cmdReply.t).toBe("error");

		expect(host.participants.find(p => p.name === "viewer")?.readOnly).toBe(true);
	});

	it("keeps full write capability for guests holding the write token", async () => {
		const { prompts, nextPrompt } = harness;

		const guest = await joinAsGuest(host.link, "writer");
		guestCleanups.push(() => guest.socket.close());
		const welcome = await guest.nextFrame();
		if (welcome.t !== "welcome") throw new Error(`expected welcome, got ${welcome.t}`);
		expect(welcome.readOnly).toBeUndefined();

		const prompted = nextPrompt();
		guest.socket.send({ t: "prompt", text: "real prompt" });
		expect(await prompted).toEqual({ from: "writer" });
		expect(prompts).toHaveLength(1);
		expect(host.participants.find(p => p.name === "writer")?.readOnly).toBeUndefined();
	});

	it("treats a forged write token as read-only", async () => {
		const { prompts } = harness;

		// A viewer knows the room key but not the token; garbage must not escalate.
		const forged = Buffer.alloc(16, 0xab).toString("base64url");
		const guest = await joinAsGuest(host.viewLink, "forger", forged);
		guestCleanups.push(() => guest.socket.close());

		const welcome = await guest.nextFrame();
		if (welcome.t !== "welcome") throw new Error(`expected welcome, got ${welcome.t}`);
		expect(welcome.readOnly).toBe(true);

		guest.socket.send({ t: "prompt", text: "escalation attempt" });
		const reply = await guest.nextFrame();
		expect(reply.t).toBe("error");
		expect(prompts).toHaveLength(0);
	});
});