const test = require("node:test");
const assert = require("node:assert/strict");
const { MediaPlayer } = require("../build/MediaPlayer");

const makePlayer = (url = "https://example.test/watch?v=abc", playlist = [{ id: 42, filename: url }]) => {
  const player = Object.create(MediaPlayer.prototype);
  const starts = [];
  const commands = [];
  let stops = 0;
  const state = {
    eventSubscribers: [],
    playbackErrors: new Map(),
    currentFile: null,
    lastLoadCandidate: null,
    activeEntryId: null,
    activeUrl: null,
    currentMediaTitle: null,
    currentPlaybackMetadata: {},
    dataBuffer: "",
    activeAttemptGeneration: 0,
    fallbackSuppressedUntilStart: false,
    fallbackCandidates: new Set(),
    entryCandidates: new Map(),
    pendingCandidateUrls: [],
    browserUrl: null,
    metadata: new Map(),
  };
  Object.assign(player, state);
  player.browserFallback = {
    isRunning: false,
    start: async (requestedUrl, isCurrent) => {
      starts.push(requestedUrl);
      if (!isCurrent()) return false;
      player.browserFallback.isRunning = true;
      return true;
    },
    stop: async () => {
      stops += 1;
      player.browserFallback.isRunning = false;
    },
  };
  player.writeCommand = async (command, args) => {
    commands.push([command, args]);
    if (command === "loadfile") return { error: "success" };
    if (command === "get_property") return { data: playlist };
    return { error: "success" };
  };
  player.fetchMetadataAndNotify = async () => undefined;
  return { player, starts, commands, get stops() { return stops; }, set playlist(value) { playlist = value; } };
};

const begin = (player, entryId = 42) => player.receiveData(`${JSON.stringify({ event: "start-file", playlist_entry_id: entryId })}\n`);
const send = (player, event, entryId = player.activeEntryId) => player.receiveData(`${JSON.stringify({
  event: "end-file", playlist_entry_id: entryId, ...event,
})}\n`);
const settle = async () => { await new Promise((resolve) => setImmediate(resolve)); await new Promise((resolve) => setImmediate(resolve)); };

test("successful MPV completion does not start fallback", async () => {
  const { player, starts } = makePlayer();
  player.fallbackCandidates.add("https://example.test/watch?v=abc");
  player.entryCandidates.set(42, "https://example.test/watch?v=abc");
  begin(player);
  send(player, { reason: "eof" });
  await settle();
  assert.deepEqual(starts, []);
});

test("actual MPV error opens the exact original URL and mirrors indeterminate state", async () => {
  const url = "https://example.test/watch?v=x&next=1;touch%20/tmp/nope";
  const { player, starts } = makePlayer(url);
  player.fallbackCandidates.add(url);
  player.entryCandidates.set(42, url);
  begin(player);
  send(player, { reason: "error", file_error: "demux failed" });
  await settle();
  assert.deepEqual(starts, [url]);
  assert.equal(player.browserUrl, url);
  assert.equal((await player.getNowPlaying()).filename, url);
  assert.equal(await player.getPauseState(), false);
  assert.equal(await player.getIdle(), false);
  assert.equal(await player.getTimePosition(), null);
  assert.equal(await player.getDuration(), null);
  assert.equal(await player.getSeekable(), false);
});

test("queue append leaves active A eligible when queued B is added", async () => {
  const a = "https://example.test/a";
  const b = "https://example.test/b";
  const { player, starts, commands } = makePlayer(a, [{ id: 42, filename: a }]);
  player.fallbackCandidates.add(a);
  player.entryCandidates.set(42, a);
  begin(player, 42);
  await player.append(b);
  await settle();
  assert.equal(commands.filter(([name]) => name === "loadfile").at(-1)[1][1], "append-play");
  send(player, { reason: "error", file_error: "failed A" }, 42);
  await settle();
  assert.deepEqual(starts, [a]);
  assert.equal(player.browserUrl, a);
  assert.equal(player.fallbackCandidates.has(b), true);
});

test("queue append during fallback startup keeps browser A open without starting B", async () => {
  const a = "https://example.test/a";
  const b = "https://example.test/b";
  const { player, starts, commands } = makePlayer(a, [{ id: 42, filename: a }]);
  player.fallbackCandidates.add(a);
  player.entryCandidates.set(42, a);
  begin(player, 42);
  send(player, { reason: "error", file_error: "failed A" }, 42);
  await player.append(b);
  await settle();
  const load = commands.filter(([name]) => name === "loadfile").at(-1);
  assert.equal(load[1][1], "append");
  assert.deepEqual(starts, [a]);
  assert.equal(player.browserUrl, a);
});

test("append then skipTo keeps the selected entry eligible for its actual MPV error", async () => {
  const url = "https://example.test/shared-original?x=1&y=2";
  const { player, starts } = makePlayer(url, [{ id: 42, filename: url }]);
  await player.append(url);
  await settle();
  await player.skipTo(0);
  begin(player, 42);
  send(player, { reason: "error", file_error: "load failed" }, 42);
  await settle();
  assert.deepEqual(starts, [url]);
});

test("failure is correlated from MPV end-file entry id without querying a cleared playlist", async () => {
  const url = "https://example.test/fails";
  const { player, starts } = makePlayer(url);
  player.fallbackCandidates.add(url);
  player.entryCandidates.set(42, url);
  begin(player, 42);
  player.writeCommand = async (command) => {
    assert.notEqual(command, "get_property", "failure correlation must use the emitted entry id");
    return { data: [] };
  };
  player.activeEntryId = null;
  player.activeUrl = null;
  player.currentFile = null;
  send(player, { reason: "error", file_error: "network unavailable" }, 42);
  await settle();
  assert.deepEqual(starts, [url]);
  assert.equal(player.playbackErrors.get(url), "network unavailable");
});

test("EOF, user stop, cancel, replacement, or stale queue events do not fallback", async () => {
  const eof = makePlayer();
  eof.player.fallbackCandidates.add("https://example.test/watch?v=abc");
  eof.player.entryCandidates.set(42, "https://example.test/watch?v=abc");
  begin(eof.player);
  send(eof.player, { reason: "eof" });

  for (const action of ["stop", "cancel", "replacement", "shutdown"]) {
    const replacementUrl = "https://example.test/replacement";
    const { player, starts } = makePlayer(replacementUrl);
    if (action === "shutdown") await player.shutdown();
    else if (action === "stop") await player.stop();
    else if (action === "replacement") await player.replace(replacementUrl);
    else await player.cancelBrowserFallback();
    send(player, { reason: "error" }, 42);
    await settle();
    assert.deepEqual(starts, [], `${action} must invalidate the callback`);
  }

  const stale = makePlayer();
  stale.player.fallbackCandidates.add("https://example.test/watch?v=abc");
  stale.player.entryCandidates.set(42, "https://example.test/watch?v=abc");
  begin(stale.player, 42);
  begin(stale.player, 43);
  send(stale.player, { reason: "error" }, 42);
  await settle();
  assert.deepEqual(stale.starts, []);
});

test("fallback startup failure leaves MPV state usable", async () => {
  const { player, starts } = makePlayer();
  const url = "https://example.test/watch?v=abc";
  player.fallbackCandidates.add(url);
  player.entryCandidates.set(42, url);
  player.browserFallback.start = async () => { throw new Error("chromium missing"); };
  begin(player);
  send(player, { reason: "error" });
  await settle();
  assert.equal(player.browserUrl, null);
  assert.deepEqual(starts, []);
  assert.equal(player.playbackErrors.get(url), "Unknown playback error");
});