const assert = require("node:assert/strict");
const test = require("node:test");

const { createPreloadApi } = require("./preload/api.cjs");
const {
  clearTerminalDataSession,
  createTerminalDataBacklog,
  createTerminalDataDispatcher,
} = require("./preload/terminalDataBacklog.cjs");

test("stores early terminal data until the listener is registered", () => {
  const backlog = createTerminalDataBacklog();

  backlog.append("session-1", "Linux banner\r\n");
  backlog.append("session-1", "root@host:~# ");

  assert.equal(backlog.take("session-1"), "Linux banner\r\nroot@host:~# ");
  assert.equal(backlog.take("session-1"), "");
});

test("keeps each session backlog isolated", () => {
  const backlog = createTerminalDataBacklog();

  backlog.append("session-1", "one");
  backlog.append("session-2", "two");

  assert.equal(backlog.take("session-2"), "two");
  assert.equal(backlog.take("session-1"), "one");
});

test("trims old data when the per-session limit is exceeded", () => {
  const backlog = createTerminalDataBacklog({ maxBytesPerSession: 5 });

  backlog.append("session-1", "hello");
  backlog.append("session-1", " world");

  assert.equal(backlog.take("session-1"), "world");
});

test("clear drops pending data for a closed session", () => {
  const backlog = createTerminalDataBacklog();

  backlog.append("session-1", "pending");
  backlog.clear("session-1");

  assert.equal(backlog.size("session-1"), 0);
  assert.equal(backlog.take("session-1"), "");
});

test("onSessionData flushes pending terminal data on subscribe", () => {
  const dataListeners = new Map();
  const displayDataListeners = new Map();
  const terminalDataBacklog = createTerminalDataBacklog();
  terminalDataBacklog.append("session-1", "early MOTD\r\n");

  const api = createPreloadApi({
    ipcRenderer: {
      invoke() {},
      send() {},
      on() {},
      removeListener() {},
    },
    os: {
      release: () => "10.0.19045",
    },
    dataListeners,
    displayDataListeners,
    terminalDataBacklog,
  });

  const received = [];
  const unsubscribe = api.onSessionData("session-1", (chunk) => {
    received.push(chunk);
  }, { replayBacklog: true });

  assert.deepEqual(received, ["early MOTD\r\n"]);
  assert.equal(terminalDataBacklog.size("session-1"), 0);
  assert.equal(displayDataListeners.get("session-1").size, 1);

  unsubscribe();
  assert.equal(dataListeners.has("session-1"), false);
  assert.equal(displayDataListeners.has("session-1"), false);
});

test("non-display listeners do not drain pending terminal data", () => {
  const dataListeners = new Map();
  const displayDataListeners = new Map();
  const terminalDataBacklog = createTerminalDataBacklog();
  terminalDataBacklog.append("session-1", "early prompt");

  const api = createPreloadApi({
    ipcRenderer: {
      invoke() {},
      send() {},
      on() {},
      removeListener() {},
    },
    os: {
      release: () => "10.0.19045",
    },
    dataListeners,
    displayDataListeners,
    terminalDataBacklog,
  });

  const observerReceived = [];
  const displayReceived = [];

  api.onSessionData("session-1", (chunk) => {
    observerReceived.push(chunk);
  });
  assert.deepEqual(observerReceived, []);
  assert.equal(terminalDataBacklog.size("session-1"), "early prompt".length);

  api.onSessionData("session-1", (chunk) => {
    displayReceived.push(chunk);
  }, { replayBacklog: true });

  assert.deepEqual(observerReceived, []);
  assert.deepEqual(displayReceived, ["early prompt"]);
  assert.equal(terminalDataBacklog.size("session-1"), 0);
});

test("keeps early data for display replay while only observer listeners exist", () => {
  const observed = [];
  const dataListeners = new Map([
    ["session-1", new Set([(chunk) => observed.push(chunk)])],
  ]);
  const displayDataListeners = new Map();
  const terminalDataBacklog = createTerminalDataBacklog();
  const deliverToListeners = createTerminalDataDispatcher({
    dataListeners,
    displayDataListeners,
    terminalDataBacklog,
  });

  deliverToListeners("session-1", "Linux banner\r\n");

  assert.deepEqual(observed, ["Linux banner\r\n"]);
  assert.equal(terminalDataBacklog.take("session-1"), "Linux banner\r\n");
});

test("does not backlog data once the display listener is registered", () => {
  const observed = [];
  const displayed = [];
  const displayListener = (chunk) => displayed.push(chunk);
  const dataListeners = new Map([
    ["session-1", new Set([(chunk) => observed.push(chunk), displayListener])],
  ]);
  const displayDataListeners = new Map([
    ["session-1", new Set([displayListener])],
  ]);
  const terminalDataBacklog = createTerminalDataBacklog();
  const deliverToListeners = createTerminalDataDispatcher({
    dataListeners,
    displayDataListeners,
    terminalDataBacklog,
  });

  deliverToListeners("session-1", "live output");

  assert.deepEqual(observed, ["live output"]);
  assert.deepEqual(displayed, ["live output"]);
  assert.equal(terminalDataBacklog.take("session-1"), "");
});

test("clearTerminalDataSession drops listener and backlog state together", () => {
  const listener = () => {};
  const dataListeners = new Map([
    ["session-1", new Set([listener])],
  ]);
  const displayDataListeners = new Map([
    ["session-1", new Set([listener])],
  ]);
  const terminalDataBacklog = createTerminalDataBacklog();
  terminalDataBacklog.append("session-1", "pending");

  clearTerminalDataSession({
    dataListeners,
    displayDataListeners,
    terminalDataBacklog,
  }, "session-1");

  assert.equal(dataListeners.has("session-1"), false);
  assert.equal(displayDataListeners.has("session-1"), false);
  assert.equal(terminalDataBacklog.take("session-1"), "");
});