/**
 * Per-channel rename rate limiting with queue.
 * Discord allows 2 channel renames per 10 minutes per channel.
 * We use a 9-minute window for safety margin.
 */

const RENAME_WINDOW_MS = 9 * 60 * 1000;
const RENAME_LIMIT = 2;
const { logWarn } = require('../services/debugLog');

// Per-channel state: { count, windowStart, queue: [{newName, started}], processing }
const renameState = new Map();

function getOrInitState(channelId) {
  let state = renameState.get(channelId);
  if (!state) {
    state = { count: 0, windowStart: 0, queue: [], processing: false };
    renameState.set(channelId, state);
  }
  return state;
}

async function executeRename(channel, newName) {
  await channel.setName(newName);
}

function processQueue(channel, state) {
  if (state.queue.length === 0 || state.processing) return;

  const now = Date.now();
  const timeUntilExpiry = (state.windowStart + RENAME_WINDOW_MS) - now;

  if (timeUntilExpiry > 0) {
    state.processing = true;
    setTimeout(async () => {
      state.processing = false;
      // New window
      if (state.queue.length > 3) {
        logWarn('renameQueue', `Channel ${channel.name} has ${state.queue.length} renames queued`).catch(() => {});
      }
      const item = state.queue.shift();
      if (!item) return;
      item.started = true;
      state.count = 1;
      state.windowStart = Date.now();
      try {
        await executeRename(channel, item.newName);
      } catch (err) {
        logWarn('renameQueue', `Queued rename failed for ${channel.name}: ${err.message || err}`).catch(() => {});
      }
      // Continue processing remaining queue items
      processQueue(channel, state);
    }, timeUntilExpiry);
  }
}

function enqueueRename(channel, newName) {
  const state = getOrInitState(channel.id);
  const now = Date.now();

  // Window expired — reset
  if (now - state.windowStart >= RENAME_WINDOW_MS) {
    state.count = 1;
    state.windowStart = now;
    executeRename(channel, newName).catch((err) => {
      logWarn('renameQueue', `Immediate rename failed for ${channel.name}: ${err.message || err}`).catch(() => {});
    });
    return Promise.resolve();
  }

  // Within window and under limit
  if (state.count < RENAME_LIMIT) {
    state.count++;
    executeRename(channel, newName).catch((err) => {
      logWarn('renameQueue', `Immediate rename failed for ${channel.name}: ${err.message || err}`).catch(() => {});
    });
    return Promise.resolve();
  }

  // At limit — queue it
  const queueSize = state.queue.length + 1;
  const queuedItem = { newName, started: false };
  state.queue.push(queuedItem);

  // Only notify if this rename is still waiting after ~2s.
  setTimeout(() => {
    if (queuedItem.started) return;
    const estMinutes = Math.max(1, Math.ceil((queueSize * RENAME_WINDOW_MS) / 60000));
    channel.send(`⏳ Channel will be renamed in ~${estMinutes} minute${estMinutes === 1 ? '' : 's'}.`).catch(() => {});
  }, 2000);

  processQueue(channel, state);
  return Promise.resolve();
}

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

module.exports = { enqueueRename, enqueueMove };