/**
 * Multi-node integration test: gossipsub + challenge-response + failover.
 *
 * Proves that gossipsub pub/sub and custom protocol streams (challenge-response)
 * coexist on the same libp2p instance pair with real networking, and that the
 * failover transport correctly resolves HTTP endpoints to multiaddrs via SyncStorage.
 */

import { describe, it, expect, beforeEach, afterEach } from "vitest";
import { mkdtempSync, rmSync } from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";
import Database from "better-sqlite3";
import type { Helia } from "@helia/interface";
import type { Libp2p } from "@libp2p/interface";
import { readCarWithRoot } from "@atproto/repo";

import { IpfsService, commitTopic, type CommitNotification } from "../ipfs.js";
import type { BlockStore } from "../ipfs.js";
import { SqliteBlockstore } from "../sqlite-blockstore.js";
import { SqliteDatastore } from "../sqlite-datastore.js";
import { RepoManager } from "../repo-manager.js";
import type { Config } from "../config.js";
import { encode as cborEncode, decode as cborDecode } from "../cbor-compat.js";
import { generateChallenge } from "./challenge-response/challenge-generator.js";
import { respondToChallenge } from "./challenge-response/challenge-responder.js";
import { verifyResponse } from "./challenge-response/challenge-verifier.js";
import { Libp2pChallengeTransport } from "./challenge-response/libp2p-transport.js";
import { FailoverChallengeTransport } from "./challenge-response/failover-transport.js";
import type { ChallengeTransport } from "./challenge-response/transport.js";
import type { StorageChallenge, StorageChallengeResponse } from "./challenge-response/types.js";
import { SyncStorage } from "./sync-storage.js";

function testConfig(dataDir: string): Config {
	return {
		DID: "did:plc:test123",
		HANDLE: "test.example.com",
		PDS_HOSTNAME: "test.example.com",
		AUTH_TOKEN: "test-auth-token",
		SIGNING_KEY:
			"0000000000000000000000000000000000000000000000000000000000000001",
		SIGNING_KEY_PUBLIC:
			"zQ3shP2mWsZYWgvZM9GJ3EvMfRXQJwuTh6BdXLvJB9gFhT3Lr",
		JWT_SECRET: "test-jwt-secret",
		PASSWORD_HASH: "$2a$10$test",
		DATA_DIR: dataDir,
		PORT: 3000,
		IPFS_ENABLED: true,
		IPFS_NETWORKING: false,
		REPLICATE_DIDS: [],
		FIREHOSE_URL: "wss://localhost/xrpc/com.atproto.sync.subscribeRepos",
		FIREHOSE_ENABLED: false,
		RATE_LIMIT_ENABLED: false,
		RATE_LIMIT_READ_PER_MIN: 300,
		RATE_LIMIT_SYNC_PER_MIN: 30,
		RATE_LIMIT_SESSION_PER_MIN: 10,
		RATE_LIMIT_WRITE_PER_MIN: 200,
		RATE_LIMIT_CHALLENGE_PER_MIN: 20,
		RATE_LIMIT_MAX_CONNECTIONS: 100,
		RATE_LIMIT_FIREHOSE_PER_IP: 3,
		OAUTH_ENABLED: false, PUBLIC_URL: "http://localhost:3000",
	};
}

/**
 * Create a minimal Helia node with TCP + gossipsub + identify.
 * Supports both gossipsub pub/sub and custom protocol streams.
 */
async function createGossipsubChallengeNode(
	db: Database.Database,
): Promise<Helia> {
	const { createHelia } = await import("helia");
	const { noise } = await import("@chainsafe/libp2p-noise");
	const { yamux } = await import("@chainsafe/libp2p-yamux");
	const { tcp } = await import("@libp2p/tcp");
	const { identify } = await import("@libp2p/identify");
	const { gossipsub } = await import("@libp2p/gossipsub");
	const { createLibp2p } = await import("libp2p");

	const blockstore = new SqliteBlockstore(db);
	const datastore = new SqliteDatastore(db);

	const libp2p = await createLibp2p({
		addresses: {
			listen: ["/ip4/127.0.0.1/tcp/0"],
		},
		transports: [tcp()],
		connectionEncrypters: [noise()],
		streamMuxers: [yamux()],
		services: {
			identify: identify(),
			pubsub: gossipsub({
				emitSelf: false,
				allowPublishToZeroTopicPeers: true,
			}),
		},
	});

	return createHelia({
		libp2p,
		blockstore: blockstore as any,
		datastore: datastore as any,
	});
}

async function waitFor(
	fn: () => Promise<boolean> | boolean,
	timeoutMs: number = 10_000,
	intervalMs: number = 200,
): Promise<void> {
	const deadline = Date.now() + timeoutMs;
	while (Date.now() < deadline) {
		if (await fn()) return;
		await new Promise((r) => setTimeout(r, intervalMs));
	}
	throw new Error(`waitFor timed out after ${timeoutMs}ms`);
}

/**
 * Wrap a Helia blockstore as the BlockStore interface used by challenge-response.
 */
function makeBlockStoreAdapter(helia: Helia): BlockStore {
	return {
		async putBlock(cidStr: string, bytes: Uint8Array) {
			const { CID } = await import("multiformats");
			await helia.blockstore.put(CID.parse(cidStr), bytes);
		},
		async getBlock(cidStr: string) {
			try {
				const { CID } = await import("multiformats");
				const bytes = await helia.blockstore.get(CID.parse(cidStr), { offline: true } as any);
				const chunks: Uint8Array[] = [];
				for await (const chunk of bytes) {
					chunks.push(chunk);
				}
				if (chunks.length === 0) return null;
				if (chunks.length === 1) return chunks[0]!;
				const total = chunks.reduce((acc, c) => acc + c.length, 0);
				const result = new Uint8Array(total);
				let offset = 0;
				for (const c of chunks) {
					result.set(c, offset);
					offset += c.length;
				}
				return result;
			} catch {
				return null;
			}
		},
		async hasBlock(cidStr: string) {
			try {
				const { CID } = await import("multiformats");
				return await helia.blockstore.has(CID.parse(cidStr));
			} catch {
				return false;
			}
		},
		async putBlocks() {},
		async deleteBlock() {},
	};
}

function getPubsub(node: Helia) {
	return (node.libp2p.services as Record<string, unknown>).pubsub as {
		subscribe(topic: string): void;
		publish(topic: string, data: Uint8Array): Promise<unknown>;
		addEventListener(event: string, handler: (evt: unknown) => void): void;
	};
}

describe("E2E multi-node: gossipsub + challenge + failover", () => {
	let tmpDir: string;
	let db: InstanceType<typeof Database>;
	let ipfsService: IpfsService;
	let repoManager: RepoManager;
	let nodeA: Helia | null = null;
	let nodeB: Helia | null = null;
	let nodeDbA: Database.Database | null = null;
	let nodeDbB: Database.Database | null = null;
	let transportA: Libp2pChallengeTransport | null = null;
	let transportB: Libp2pChallengeTransport | null = null;

	beforeEach(async () => {
		tmpDir = mkdtempSync(join(tmpdir(), "e2e-multi-node-test-"));
		const config = testConfig(tmpDir);

		db = new Database(join(tmpDir, "test.db"));
		ipfsService = new IpfsService({
			db,
			networking: false,
		});
		await ipfsService.start();
		repoManager = new RepoManager(db, config);
		repoManager.init(undefined, ipfsService, ipfsService);

		// Create 5 test records
		for (let i = 0; i < 5; i++) {
			await repoManager.createRecord(
				"app.bsky.feed.post",
				undefined,
				{
					$type: "app.bsky.feed.post",
					text: `E2E multi-node test post ${i}`,
					createdAt: new Date().toISOString(),
				},
			);
		}
	});

	afterEach(async () => {
		const stops: Promise<void>[] = [];
		if (transportA) stops.push(transportA.stop().catch(() => {}));
		if (transportB) stops.push(transportB.stop().catch(() => {}));
		if (nodeA) stops.push(nodeA.stop().catch(() => {}));
		if (nodeB) stops.push(nodeB.stop().catch(() => {}));
		await Promise.all(stops);
		transportA = null;
		transportB = null;
		nodeA = null;
		nodeB = null;

		if (nodeDbA) { nodeDbA.close(); nodeDbA = null; }
		if (nodeDbB) { nodeDbB.close(); nodeDbB = null; }

		if (ipfsService.isRunning()) {
			await ipfsService.stop();
		}
		db.close();
		rmSync(tmpDir, { recursive: true, force: true });
	});

	async function getRepoRootCid(): Promise<string> {
		const carBytes = await repoManager.getRepoCar();
		const { root, blocks } = await readCarWithRoot(carBytes);
		await ipfsService.putBlocks(blocks);
		return root.toString();
	}

	async function getRecordPaths(): Promise<string[]> {
		const records = await repoManager.listRecords("app.bsky.feed.post", {
			limit: 100,
		});
		return records.records.map((r) => {
			const rkey = r.uri.split("/").pop()!;
			return `app.bsky.feed.post/${rkey}`;
		});
	}

	/**
	 * Create two gossipsub+challenge nodes, connect them, copy repo blocks to Node A,
	 * and create Libp2pChallengeTransport on both.
	 */
	async function setupConnectedNodes(): Promise<void> {
		nodeDbA = new Database(join(tmpDir, "node-a.db"));
		nodeDbB = new Database(join(tmpDir, "node-b.db"));
		nodeA = await createGossipsubChallengeNode(nodeDbA);
		nodeB = await createGossipsubChallengeNode(nodeDbB);

		// Connect B -> A
		await nodeB.libp2p.dial(nodeA.libp2p.getMultiaddrs()[0]!);
		await waitFor(
			() =>
				nodeA!.libp2p.getConnections().length > 0 &&
				nodeB!.libp2p.getConnections().length > 0,
			5_000,
		);

		// Copy all repo blocks to node A's blockstore
		const carBytes = await repoManager.getRepoCar();
		const { blocks } = await readCarWithRoot(carBytes);
		const internalMap = (
			blocks as unknown as { map: Map<string, Uint8Array> }
		).map;
		if (internalMap) {
			const { CID } = await import("multiformats");
			for (const [cidStr, bytes] of internalMap) {
				const cid = CID.parse(cidStr);
				await nodeA!.blockstore.put(cid, bytes);
			}
		}

		transportA = new Libp2pChallengeTransport(nodeA.libp2p as unknown as Libp2p);
		transportB = new Libp2pChallengeTransport(nodeB.libp2p as unknown as Libp2p);
	}

	it(
		"gossipsub notification + challenge roundtrip on same node pair",
		{ timeout: 60_000 },
		async () => {
			await setupConnectedNodes();

			const rootCid = await getRepoRootCid();
			const recordPaths = await getRecordPaths();
			const testDid = "did:plc:test123";
			const topic = commitTopic(testDid);

			// Register challenge handler on Node A
			const nodeABlockStore = makeBlockStoreAdapter(nodeA!);
			transportA!.onChallenge(async (challenge) => {
				return respondToChallenge(challenge, nodeABlockStore, "did:plc:prover");
			});

			// Both nodes subscribe (needed for gossipsub mesh formation)
			const pubsubA = getPubsub(nodeA!);
			const pubsubB = getPubsub(nodeB!);
			pubsubA.subscribe(topic);
			pubsubB.subscribe(topic);

			// Node B collects received gossipsub notifications
			const received: CommitNotification[] = [];
			pubsubB.addEventListener("message", (evt: unknown) => {
				try {
					const detail = (evt as { detail: { topic: string; data: Uint8Array } }).detail;
					if (detail.topic === topic) {
						const notification = cborDecode(detail.data) as CommitNotification;
						received.push(notification);
					}
				} catch {
					// ignore decode errors
				}
			});

			// Node A publishes CBOR notification (with retry loop for mesh formation)
			const notification: CommitNotification = {
				did: testDid,
				commit: rootCid,
				rev: "3jui7kd2xxxx2",
				time: new Date().toISOString(),
				peer: nodeA!.libp2p.peerId.toString(),
			};
			const data = cborEncode(notification);

			await waitFor(
				async () => {
					if (received.length > 0) return true;
					await pubsubA.publish(topic, data).catch(() => {});
					await new Promise((r) => setTimeout(r, 1000));
					return received.length > 0;
				},
				30_000,
				500,
			);

			// Assert notification received with correct fields
			expect(received.length).toBe(1);
			expect(received[0]!.did).toBe(testDid);
			expect(received[0]!.commit).toBe(rootCid);
			expect(received[0]!.rev).toBe("3jui7kd2xxxx2");
			expect(received[0]!.peer).toBe(nodeA!.libp2p.peerId.toString());

			// Node B generates MST-proof challenge using the received commitCid
			const challenge = generateChallenge({
				challengerDid: "did:plc:verifier",
				targetDid: "did:plc:prover",
				subjectDid: testDid,
				commitCid: received[0]!.commit,
				availableRecordPaths: recordPaths,
				challengeType: "mst-proof",
				epoch: 1,
				nonce: "e2e-multi-node-nonce",
				config: { recordCount: 2 },
			});

			// Node B sends challenge to Node A via libp2p
			const addrA = nodeA!.libp2p.getMultiaddrs()[0]!.toString();
			const response = await transportB!.sendChallenge(addrA, challenge);

			// Assert challenge response is valid
			expect(response.challengeId).toBe(challenge.id);
			expect(response.mstProofs).toBeDefined();
			expect(response.mstProofs!.length).toBe(challenge.recordPaths.length);

			// Verify proof cryptographically
			const result = await verifyResponse(challenge, response, ipfsService);
			expect(result.passed).toBe(true);
			expect(result.mstResults).toBeDefined();
			expect(result.mstResults!.every((r) => r.valid)).toBe(true);
		},
	);

	it(
		"failover transport resolves HTTP endpoint to multiaddr via SyncStorage",
		{ timeout: 60_000 },
		async () => {
			await setupConnectedNodes();

			const rootCid = await getRepoRootCid();
			const recordPaths = await getRecordPaths();

			// Register challenge handler on Node A
			const nodeABlockStore = makeBlockStoreAdapter(nodeA!);
			transportA!.onChallenge(async (challenge) => {
				return respondToChallenge(challenge, nodeABlockStore, "did:plc:prover");
			});

			// Create SyncStorage with Node A's multiaddr mapped to a fake HTTP endpoint
			const syncStorage = new SyncStorage(db);
			syncStorage.initSchema();

			const fakeEndpoint = "https://pds-a.example.com";
			const nodeAMultiaddr = nodeA!.libp2p.getMultiaddrs()[0]!.toString();
			// Ensure multiaddr includes /p2p/ suffix with peer ID
			const nodeAPeerId = nodeA!.libp2p.peerId.toString();
			const fullMultiaddr = nodeAMultiaddr.includes("/p2p/")
				? nodeAMultiaddr
				: `${nodeAMultiaddr}/p2p/${nodeAPeerId}`;

			// Store the mapping: fake endpoint -> Node A's multiaddr
			syncStorage.upsertState({
				did: "did:plc:nodeA",
				pdsEndpoint: fakeEndpoint,
				status: "synced",
			});
			syncStorage.updatePeerInfo("did:plc:nodeA", nodeAPeerId, [fullMultiaddr]);

			// Sanity check: resolver returns a multiaddr with /p2p/
			const resolved = syncStorage.getMultiaddrForPdsEndpoint(fakeEndpoint);
			expect(resolved).not.toBeNull();
			expect(resolved!).toContain("/p2p/");

			// Create mock HTTP transport that tracks calls and throws if invoked
			let httpCalls = 0;
			let fallbackCalled = false;
			const mockHttp: ChallengeTransport = {
				async sendChallenge() {
					httpCalls++;
					throw new Error("HTTP transport should not be called");
				},
				onChallenge() {},
			};

			// Create failover transport: libp2p primary, mock HTTP fallback
			const failover = new FailoverChallengeTransport(
				transportB!,
				mockHttp,
				{
					resolveEndpoint: (endpoint) =>
						syncStorage.getMultiaddrForPdsEndpoint(endpoint),
					onFallback: () => {
						fallbackCalled = true;
					},
				},
			);

			// Generate MST-proof challenge
			const challenge = generateChallenge({
				challengerDid: "did:plc:verifier",
				targetDid: "did:plc:prover",
				subjectDid: "did:plc:test123",
				commitCid: rootCid,
				availableRecordPaths: recordPaths,
				challengeType: "mst-proof",
				epoch: 1,
				nonce: "e2e-failover-nonce",
				config: { recordCount: 2 },
			});

			// Send via failover transport using the HTTP endpoint
			const response = await failover.sendChallenge(fakeEndpoint, challenge);

			// Assert: response valid, HTTP not called, no fallback
			expect(response.challengeId).toBe(challenge.id);
			expect(response.mstProofs).toBeDefined();
			expect(httpCalls).toBe(0);
			expect(fallbackCalled).toBe(false);

			// Verify proof cryptographically
			const result = await verifyResponse(challenge, response, ipfsService);
			expect(result.passed).toBe(true);
		},
	);
});