import * as fs from "node:fs";
import * as path from "node:path";
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 } from "../src/packets/message_common_pb.js";
import { connectTcp, connectTcpTls, TcpClient } from "../src/tcp_client.js";
import { TcpServer } from "../src/tcp_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: TcpClient): Promise<TestData> {
  return new Promise<TestData>((resolve) => {
    addListenerTyped(client.communicator, TestDataSchema, (msg) => resolve(msg));
  });
}

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

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

  test("connectTcp sends and receives TestData", async () => {
    const server = new TcpServer("127.0.0.1", 0, (socket) => new TcpClient(socket, 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 tcp") {
          await client.communicator.send(
            create(TestDataSchema, { index: 200, message: "push from tcp server" }),
          );
        }
      });
    };

    const client = await connectTcp("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 tcp" }));

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

  test("sendRequest/response roundtrip", async () => {
    const server = new TcpServer("127.0.0.1", 0, (socket) => new TcpClient(socket, 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 connectTcp("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 tcp" }),
        TestDataSchema,
        500,
      ),
    ).resolves.toMatchObject({
      index: 42,
      message: "echo: request over tcp",
    });
  });

  test("connectTcpTls sends and receives TestData", async () => {
    const server = new TcpServer(
      "127.0.0.1",
      0,
      (socket) => new TcpClient(socket, 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 tls") {
          await client.communicator.send(
            create(TestDataSchema, { index: 201, message: "push from tls server" }),
          );
        }
      });
    };

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

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

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

  test("TLS sendRequest/response roundtrip", async () => {
    const server = new TcpServer(
      "127.0.0.1",
      0,
      (socket) => new TcpClient(socket, 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: `tls echo: ${req.message}`,
        }),
      );
    };

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

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

  test("concurrent sendRequest/response roundtrip over TCP", async () => {
    const server = new TcpServer("127.0.0.1", 0, (socket) => new TcpClient(socket, 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 connectTcp("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(
    "TCP read loop drives server inbound gateway: concurrent request-response keeps FIFO/nonce",
    async () => {
      const server = new TcpServer("127.0.0.1", 0, (socket) => new TcpClient(socket, 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 TCP read loop가 onReceivedFrame으로 흘린 raw frame을 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 connectTcp("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 몰려도 순차 처리가 안전하게 보장되는지 검증하기 위해 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("TCP inbound backpressure pauses socket read on server", async () => {
    let serverClient: TcpClient | null = null;
    const server = new TcpServer("127.0.0.1", 0, (socket) => {
      serverClient = new TcpClient(socket, 0, 0, parserMap());
      return serverClient;
    });
    cleanup.push(async () => server.stop());
    await server.start();

    let resolveHandler: (() => void) | null = null;
    const handlerPromise = new Promise<void>((r) => {
      resolveHandler = r;
    });

    server.onClientConnected = (client) => {
      addRequestListenerTyped(client.communicator, TestDataSchema, async () => {
        await handlerPromise;
        return create(TestDataSchema, { index: 100, message: "done" });
      });
    };

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

    const firstReq = sendRequestTyped(
      client.communicator,
      create(TestDataSchema, { index: 1, message: "first" }),
      TestDataSchema,
      5000,
    );

    await new Promise<void>((r) => setTimeout(r, 20));

    for (let i = 2; i <= 65; i++) {
      await client.communicator.send(create(TestDataSchema, { index: i, message: "heavy" }));
    }

    await client.communicator.send(create(TestDataSchema, { index: 66, message: "overflow" }));
    await new Promise<void>((r) => setTimeout(r, 100));

    expect(serverClient).not.toBeNull();
    expect(((serverClient as any).socket as any).isPaused()).toBe(true);

    resolveHandler!();
    await firstReq;

    await new Promise<void>((r) => setTimeout(r, 50));
    expect(((serverClient as any).socket as any).isPaused()).toBe(false);
  });
});