/**
 * Per-channel rename serialization with coalescing.
 * Renames route through utils/renamer.js (secondary bot token, RENAMER_BOT),
 * which has its own Discord-side rate bucket — no in-process throttle needed.
 * We serialize per channel so concurrent PATCHes don't land out of order, and
 * coalesce rapid successive calls so only the latest name is written.
 */

const { logWarn } = require('../services/debugLog');
const { renameChannel } = require('../utils/renamer');

// Per-channel: { chain: Promise, pendingName: string | null }.
// enqueueRename updates pendingName synchronously (latest wins) and chains an
// executeRename link. executeRename reads the latest pendingName at start.
const renameChains = new Map();

async function executeRename(channel, entry) {
  const currentName = entry.pendingName;
  if (currentName == null) return;
  try {
    await renameChannel(channel.id, currentName);
  } finally {
    // Clear only if no newer call arrived during the PATCH. If pendingName
    // has changed, leave it — the link queued by that newer call picks it up.
    if (entry.pendingName === currentName) {
      entry.pendingName = null;
    }
  }
}

function enqueueRename(channel, newName) {
  let entry = renameChains.get(channel.id);
  if (!entry) {
    entry = { chain: Promise.resolve(), pendingName: newName };
    renameChains.set(channel.id, entry);
  } else {
    entry.pendingName = newName;
  }

  const next = entry.chain.catch(() => {}).then(() => executeRename(channel, entry));
  entry.chain = next;

  next.catch((err) => {
    logWarn('renameQueue', `Rename failed for ${channel.name}: ${err && err.message || err}`).catch(() => {});
  }).finally(() => {
    if (renameChains.get(channel.id) === entry && entry.chain === next && entry.pendingName == null) {
      renameChains.delete(channel.id);
    }
  });
  return next;
}

function enqueueMove(channel, categoryId) {
  return channel.setParent(categoryId, { lockPermissions: true });
}

// Per-channel promise chain for send ordering and to prevent interleaving.
const sendChains = new Map();

function enqueueSend(channel, ...args) {
  if (!channel || typeof channel.send !== 'function') {
    return Promise.reject(new Error('enqueueSend: invalid channel'));
  }
  const prev = sendChains.get(channel.id) || Promise.resolve();
  const next = prev.catch(() => {}).then(() => channel.send(...args));
  sendChains.set(channel.id, next);
  next.catch(() => {}).finally(() => {
    if (sendChains.get(channel.id) === next) sendChains.delete(channel.id);
  });
  return next;
}

module.exports = { enqueueRename, enqueueMove, enqueueSend };