import * as fs from "node:fs";
import * as net from "node:net";
import * as path from "node:path";
import * as tls from "node:tls";
import { fileURLToPath } from "node:url";

import { afterEach, describe, expect, test } from "vitest";

import {
  addListenerTyped,
  addRequestListenerTyped,
  parserFromSchema,
  sendRequestTyped,
} from "../src/communicator.js";

import { create, TestDataSchema, type TestData, toBinary, PacketBaseSchema } from "../src/packets/message_common_pb.js";
import { connectNodeWs, connectNodeWss, NodeWebSocket, NodeWsClient } from "../src/node_ws_client.js";
import { NodeWsServer } from "../src/node_ws_server.js";

const certsDir = path.join(path.dirname(fileURLToPath(import.meta.url)), "certs");
const cert = fs.readFileSync(path.join(certsDir, "server.crt"));
const key = fs.readFileSync(path.join(certsDir, "server.key"));

function parserMap() {
  return new Map([[TestDataSchema.typeName, parserFromSchema(TestDataSchema)]]);
}

async function waitForClientMessage(client: NodeWsClient): Promise<TestData> {
  return new Promise<TestData>((resolve) => {
    addListenerTyped(client.communicator, TestDataSchema, (msg) => resolve(msg));
  });
}

describe("WS", () => {
  const cleanup: Array<() => Promise<void>> = [];

  afterEach(async () => {
    while (cleanup.length > 0) {
      const fn = cleanup.pop();
      if (fn) {
        await fn();
      }
    }
  });

  test("connectWs sends and receives TestData", async () => {
    const server = new NodeWsServer("127.0.0.1", 0, "/", (ws) => new NodeWsClient(ws, 0, 0, parserMap()));
    cleanup.push(async () => server.stop());
    await server.start();

    server.onClientConnected = (client) => {
      addListenerTyped(client.communicator, TestDataSchema, async (msg) => {
        if (msg.index === 11 && msg.message === "hello over ws") {
          await client.communicator.send(
            create(TestDataSchema, { index: 200, message: "push from ws server" }),
          );
        }
      });
    };

    const client = await connectNodeWs("127.0.0.1", server.port, "/", 0, 0, parserMap());
    cleanup.push(async () => client.close());

    const pushed = waitForClientMessage(client);
    await client.communicator.send(create(TestDataSchema, { index: 11, message: "hello over ws" }));

    await expect(pushed).resolves.toMatchObject({
      index: 200,
      message: "push from ws server",
    });
  });

  test("sendRequest/response roundtrip over WS", async () => {
    const server = new NodeWsServer("127.0.0.1", 0, "/", (ws) => new NodeWsClient(ws, 0, 0, parserMap()));
    cleanup.push(async () => server.stop());
    await server.start();

    server.onClientConnected = (client) => {
      addRequestListenerTyped(client.communicator, TestDataSchema, (req) =>
        create(TestDataSchema, {
          index: req.index * 2,
          message: `echo: ${req.message}`,
        }),
      );
    };

    const client = await connectNodeWs("127.0.0.1", server.port, "/", 0, 0, parserMap());
    cleanup.push(async () => client.close());

    await expect(
      sendRequestTyped(
        client.communicator,
        create(TestDataSchema, { index: 21, message: "request over ws" }),
        TestDataSchema,
        500,
      ),
    ).resolves.toMatchObject({
      index: 42,
      message: "echo: request over ws",
    });
  });

  test("connectWss sends and receives TestData", async () => {
    const server = new NodeWsServer("127.0.0.1", 0, "/", (ws) => new NodeWsClient(ws, 0, 0, parserMap()), {
      cert,
      key,
    });
    cleanup.push(async () => server.stop());
    await server.start();

    server.onClientConnected = (client) => {
      addListenerTyped(client.communicator, TestDataSchema, async (msg) => {
        if (msg.index === 12 && msg.message === "hello over wss") {
          await client.communicator.send(
            create(TestDataSchema, { index: 201, message: "push from wss server" }),
          );
        }
      });
    };

    const client = await connectNodeWss(
      "127.0.0.1",
      server.port,
      "/",
      { ca: cert },
      0,
      0,
      parserMap(),
    );
    cleanup.push(async () => client.close());

    const pushed = waitForClientMessage(client);
    await client.communicator.send(create(TestDataSchema, { index: 12, message: "hello over wss" }));

    await expect(pushed).resolves.toMatchObject({
      index: 201,
      message: "push from wss server",
    });
  });

  test("WSS sendRequest/response roundtrip", async () => {
    const server = new NodeWsServer("127.0.0.1", 0, "/", (ws) => new NodeWsClient(ws, 0, 0, parserMap()), {
      cert,
      key,
    });
    cleanup.push(async () => server.stop());
    await server.start();

    server.onClientConnected = (client) => {
      addRequestListenerTyped(client.communicator, TestDataSchema, (req) =>
        create(TestDataSchema, {
          index: req.index * 2,
          message: `wss echo: ${req.message}`,
        }),
      );
    };

    const client = await connectNodeWss(
      "127.0.0.1",
      server.port,
      "/",
      { ca: cert },
      0,
      0,
      parserMap(),
    );
    cleanup.push(async () => client.close());

    await expect(
      sendRequestTyped(
        client.communicator,
        create(TestDataSchema, { index: 22, message: "request over wss" }),
        TestDataSchema,
        500,
      ),
    ).resolves.toMatchObject({
      index: 44,
      message: "wss echo: request over wss",
    });
  });

  test("concurrent sendRequest/response roundtrip over WS", async () => {
    const server = new NodeWsServer("127.0.0.1", 0, "/", (ws) => new NodeWsClient(ws, 0, 0, parserMap()));
    cleanup.push(async () => server.stop());
    await server.start();

    server.onClientConnected = (client) => {
      addRequestListenerTyped(client.communicator, TestDataSchema, (req) =>
        create(TestDataSchema, {
          index: req.index * 2,
          message: `echo: ${req.message}`,
        }),
      );
    };

    const client = await connectNodeWs("127.0.0.1", server.port, "/", 0, 0, parserMap());
    cleanup.push(async () => client.close());

    const results = await Promise.all(
      Array.from({ length: 5 }, (_, i) =>
        sendRequestTyped(
          client.communicator,
          create(TestDataSchema, { index: 30 + i, message: `request ${i}` }),
          TestDataSchema,
          2000,
        ),
      ),
    );

    results.forEach((res, i) => {
      expect(res.index).toBe((30 + i) * 2);
      expect(res.message).toBe(`echo: request ${i}`);
    });
  });

  test(
    "WS read loop drives server inbound gateway: concurrent request-response keeps FIFO/nonce",
    async () => {
      const server = new NodeWsServer("127.0.0.1", 0, "/", (ws) => new NodeWsClient(ws, 0, 0, parserMap()));
      cleanup.push(async () => server.stop());
      await server.start();

      let lastNonce = 0;
      let fifoViolation = false;
      server.onClientConnected = (client) => {
        const comm = client.communicator;
        // 실제 WS read loop가 onReceivedFrame으로 흘린 raw binary message를 기본 receive gateway가
        // decode하고, reorder 후 coordinator가 FIFO로 dispatch하는지 검증한다.
        comm.enableInboundGateway({ workers: 2 });
        // raw addRequestListener로 nonce를 받아 gateway reorder 이후에도 connection별 nonce가
        // 단조 증가(FIFO)하는지 확인한다.
        comm.addRequestListener(TestDataSchema.typeName, (msg, nonce) => {
          if (nonce < lastNonce) {
            fifoViolation = true;
          }
          lastNonce = nonce;
          const req = msg as TestData;
          return create(TestDataSchema, { index: req.index * 2, message: `gw echo: ${req.message}` });
        });
      };

      const client = await connectNodeWs("127.0.0.1", server.port, "/", 0, 0, parserMap());
      cleanup.push(async () => client.close());

      // 동시 요청이 기본 receive gateway(inline decode + reorder)를 거쳐도 nonce 상관관계가 유지되어야 한다.
      // 많은 동시 요청이 몰리는 혼합 경로 테스트이므로 요청 timeout에 충분한 여유를 둔다.
      const results = await Promise.all(
        Array.from({ length: 16 }, (_, i) =>
          sendRequestTyped(
            client.communicator,
            create(TestDataSchema, { index: i, message: `req ${i}` }),
            TestDataSchema,
            8000,
          ),
        ),
      );

      results.forEach((res, i) => {
        expect(res.index).toBe(i * 2);
        expect(res.message).toBe(`gw echo: req ${i}`);
      });
      expect(fifoViolation).toBe(false);
    },
    15000,
  );

  test("connectNodeWss rejects when peer never completes WebSocket handshake", async () => {
    const server = tls.createServer({ cert, key }, (socket) => {
      socket.on("data", () => {});
    });
    cleanup.push(
      () =>
        new Promise<void>((resolve) => {
          server.close(() => resolve());
        }),
    );
    await new Promise<void>((resolve) => server.listen(0, "127.0.0.1", resolve));
    const port = (server.address() as net.AddressInfo).port;

    await expect(
      connectNodeWss("127.0.0.1", port, "/", { ca: cert }, 0, 0, parserMap()),
    ).rejects.toThrow(/websocket handshake timed out/);
  });
  test("1MB message WS roundtrip", async () => {
    const server = new NodeWsServer("127.0.0.1", 0, "/", (ws) => new NodeWsClient(ws, 0, 0, parserMap()));
    cleanup.push(async () => server.stop());
    await server.start();

    server.onClientConnected = (client) => {
      addRequestListenerTyped(client.communicator, TestDataSchema, (req) =>
        create(TestDataSchema, {
          index: req.index * 2,
          message: req.message,
        }),
      );
    };

    const client = await connectNodeWs("127.0.0.1", server.port, "/", 0, 0, parserMap());
    cleanup.push(async () => client.close());

    const largeMessage = "A".repeat(1024 * 1024); // 1MB
    const res = await sendRequestTyped(
      client.communicator,
      create(TestDataSchema, { index: 50, message: largeMessage }),
      TestDataSchema,
      10000,
    );

    expect(res.index).toBe(100);
    expect(res.message.length).toBe(largeMessage.length);
    expect(res.message).toBe(largeMessage);
  }, 15000);

  test("fragmented large binary frame regression test using raw net.Socket", async () => {
    const { randomBytes } = await import("node:crypto");
    const server = new NodeWsServer("127.0.0.1", 0, "/", (ws) => new NodeWsClient(ws, 0, 0, parserMap()));
    cleanup.push(async () => server.stop());
    await server.start();

    const receivedPromise = new Promise<TestData>((resolve) => {
      server.onClientConnected = (client) => {
        addListenerTyped(client.communicator, TestDataSchema, (msg) => {
          resolve(msg);
        });
      };
    });

    const socket = new net.Socket();
    await new Promise<void>((resolve, reject) => {
      socket.connect(server.port, "127.0.0.1", () => resolve());
      socket.on("error", reject);
    });
    cleanup.push(async () => {
      socket.destroy();
    });

    const key = randomBytes(16).toString("base64");
    socket.write(
      [
        `GET / HTTP/1.1`,
        `Host: 127.0.0.1:${server.port}`,
        "Upgrade: websocket",
        "Connection: Upgrade",
        `Sec-WebSocket-Key: ${key}`,
        "Sec-WebSocket-Version: 13",
        "\r\n",
      ].join("\r\n"),
    );

    await new Promise<void>((resolve, reject) => {
      let response = Buffer.alloc(0);
      const onData = (chunk: Buffer) => {
        response = Buffer.concat([response, chunk]);
        if (response.indexOf("\r\n\r\n") >= 0) {
          socket.off("data", onData);
          socket.off("error", onError);
          resolve();
        }
      };
      const onError = (err: Error) => reject(err);
      socket.on("data", onData);
      socket.on("error", onError);
    });

    const largeMessage = "B".repeat(1024 * 1024); // 1MB
    const testData = create(TestDataSchema, { index: 12345, message: largeMessage });

    const encodedTestData = toBinary(TestDataSchema, testData);

    const base = create(PacketBaseSchema, {
      typeName: TestDataSchema.typeName,
      nonce: 42,
      data: encodedTestData,
    });

    const rawPayload = toBinary(PacketBaseSchema, base);

    const payloadLength = rawPayload.byteLength;
    const lengthBytes = payloadLength < 126 ? 0 : payloadLength <= 0xffff ? 2 : 8;
    const header = Buffer.allocUnsafe(2 + lengthBytes + 4);
    let offset = 0;
    header[offset] = 0x80 | 0x2;
    offset += 1;
    if (payloadLength < 126) {
      header[offset] = 0x80 | payloadLength;
      offset += 1;
    } else if (payloadLength <= 0xffff) {
      header[offset] = 0x80 | 126;
      offset += 1;
      header.writeUInt16BE(payloadLength, offset);
      offset += 2;
    } else {
      header[offset] = 0x80 | 127;
      offset += 1;
      header.writeBigUInt64BE(BigInt(payloadLength), offset);
      offset += 8;
    }

    const maskingKey = randomBytes(4);
    maskingKey.copy(header, offset);

    const maskedPayload = Buffer.allocUnsafe(payloadLength);
    for (let i = 0; i < payloadLength; i++) {
      maskedPayload[i] = rawPayload[i] ^ maskingKey[i % 4];
    }

    const fullFrame = Buffer.concat([header, maskedPayload]);

    const chunkSize = 8192;
    for (let i = 0; i < fullFrame.byteLength; i += chunkSize) {
      const chunk = fullFrame.subarray(i, i + chunkSize);
      socket.write(chunk);
      await new Promise((resolve) => setTimeout(resolve, 1));
    }

    const received = await receivedPromise;
    expect(received.index).toBe(12345);
    expect(received.message.length).toBe(largeMessage.length);
    expect(received.message).toBe(largeMessage);
  }, 15000);

  test("empty WS control frame (ping/pong) regression test", async () => {
    const { randomBytes } = await import("node:crypto");
    const server = new NodeWsServer("127.0.0.1", 0, "/", (ws) => new NodeWsClient(ws, 0, 0, parserMap()));
    cleanup.push(async () => server.stop());
    await server.start();

    const socket = new net.Socket();
    await new Promise<void>((resolve, reject) => {
      socket.connect(server.port, "127.0.0.1", () => resolve());
      socket.on("error", reject);
    });
    cleanup.push(async () => {
      socket.destroy();
    });

    const key = randomBytes(16).toString("base64");
    socket.write(
      [
        `GET / HTTP/1.1`,
        `Host: 127.0.0.1:${server.port}`,
        "Upgrade: websocket",
        "Connection: Upgrade",
        `Sec-WebSocket-Key: ${key}`,
        "Sec-WebSocket-Version: 13",
        "\r\n",
      ].join("\r\n"),
    );

    // Wait for handshake response
    await new Promise<void>((resolve, reject) => {
      let response = Buffer.alloc(0);
      const onData = (chunk: Buffer) => {
        response = Buffer.concat([response, chunk]);
        if (response.indexOf("\r\n\r\n") >= 0) {
          socket.off("data", onData);
          socket.off("error", onError);
          resolve();
        }
      };
      const onError = (err: Error) => reject(err);
      socket.on("data", onData);
      socket.on("error", onError);
    });

    // Send empty masked ping frame
    const pingFrame = Buffer.alloc(6);
    pingFrame[0] = 0x80 | 0x9; // FIN | PING
    pingFrame[1] = 0x80 | 0;   // MASKED | payload length 0
    const maskingKey = randomBytes(4);
    maskingKey.copy(pingFrame, 2);

    const pongReceivedPromise = new Promise<Buffer>((resolve, reject) => {
      socket.once("data", (data) => {
        resolve(data);
      });
      socket.once("error", reject);
    });

    socket.write(pingFrame);

    const pongData = await pongReceivedPromise;
    // Expected pong: FIN | PONG (0x8A), payload length 0 (0x00)
    expect(pongData[0]).toBe(0x80 | 0xA);
    expect(pongData[1]).toBe(0x00);
  }, 10000);

  test("NodeWebSocket enables TCP no-delay on its socket", () => {
    // Nagle's algorithm + delayed-ACK 조합으로 인한 ~40ms 고정 지연을 막기 위해
    // NodeWebSocket이 생성 시 socket no-delay를 켜는지 fake socket으로 검증한다.
    let noDelay: boolean | undefined;
    const fakeSocket = {
      setNoDelay(value: boolean) {
        noDelay = value;
      },
      on() {
        return this;
      },
      once() {
        return this;
      },
      destroyed: false,
    };

    new NodeWebSocket(fakeSocket as unknown as net.Socket, true);
    expect(noDelay).toBe(true);
  });

  test("WS masking tail bytes equivalence unit test for various lengths", async () => {
    const lengths = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16, 17, 1023, 1024, 1025];
    const server = new NodeWsServer("127.0.0.1", 0, "/", (ws) => new NodeWsClient(ws, 0, 0, parserMap()));
    cleanup.push(async () => server.stop());
    await server.start();

    server.onClientConnected = (client) => {
      addRequestListenerTyped(client.communicator, TestDataSchema, (req) =>
        create(TestDataSchema, {
          index: req.index,
          message: req.message,
        }),
      );
    };

    const client = await connectNodeWs("127.0.0.1", server.port, "/", 0, 0, parserMap());
    cleanup.push(async () => client.close());

    for (const len of lengths) {
      const msg = "A".repeat(len);
      const res = await sendRequestTyped(
        client.communicator,
        create(TestDataSchema, { index: len, message: msg }),
        TestDataSchema,
        2000,
      );
      expect(res.index).toBe(len);
      expect(res.message.length).toBe(len);
      expect(res.message).toBe(msg);
    }
  });
});