/**
 * Staff discussion threads — creates a private thread on each ticket channel
 * for staff-only communication.
 *
 * Notes:
 * - The bot requires CREATE_PRIVATE_THREADS and SEND_MESSAGES_IN_THREADS
 *   permissions on every ticket category.
 * - Private threads (ChannelType.PrivateThread) require the server to have Community features
 *   OR the channel to be in a server with Boost level that unlocks private
 *   threads. If thread creation fails with code 50024 or 160004, a warning
 *   is logged via logWarn.
 * - invitable: false means only staff with MANAGE_THREADS can add additional
 *   members — this is intentional for privacy.
 * - guild.members.fetch() in addRoleMembersToThread can be slow on large
 *   servers. The 300ms delay between adds avoids the thread member add rate
 *   limit (approximately 5/second).
 */
const { ChannelType } = require('discord.js');
const { CONFIG } = require('../config');
const { logError, logWarn } = require('./debugLog');

/**
 * Create a private staff thread on a ticket channel.
 * @param {import('discord.js').TextChannel} channel
 * @param {import('discord.js').Client} client
 * @returns {Promise<import('discord.js').ThreadChannel|null>}
 */
async function createStaffThread(channel, client) {
  if (!CONFIG.STAFF_THREAD_ENABLED) return null;

  try {
    const threadName = CONFIG.STAFF_THREAD_NAME.slice(0, 100);

    const thread = await channel.threads.create({
      name: threadName,
      type: ChannelType.PrivateThread,
      invitable: false,
      reason: 'Staff discussion thread for ticket'
    });

    if (CONFIG.STAFF_THREAD_AUTO_ADD_ROLE && CONFIG.STAFF_THREAD_ROLE_ID) {
      await addRoleMembersToThread(thread, channel.guild, client);
    }

    return thread;
  } catch (err) {
    // Detect permission / channel type errors
    if (err.code === 50024 || err.code === 160004) {
      logWarn('staffThread', `Cannot create private thread in ${channel.name}: server may lack Community features or required boost level (code ${err.code}).`).catch(() => {});
    }
    await logError('staffThread:create', err, null, client).catch(() => {});
    return null;
  }
}

/**
 * Add all members of the staff role to the thread.
 */
async function addRoleMembersToThread(thread, guild, client) {
  try {
    const role = await guild.roles.fetch(CONFIG.STAFF_THREAD_ROLE_ID).catch(() => null);
    if (!role) return;

    await guild.members.fetch();
    const members = guild.members.cache.filter(m =>
      m.roles.cache.has(CONFIG.STAFF_THREAD_ROLE_ID) && !m.user.bot
    );

    for (const [, member] of members) {
      await thread.members.add(member.id).catch(() => {});
      await new Promise(r => setTimeout(r, 300));
    }
  } catch (err) {
    await logError('staffThread:addMembers', err, null, client).catch(() => {});
  }
}

/**
 * Add a single member to the staff thread for a ticket channel.
 * Call this when a ticket is claimed.
 */
async function addMemberToStaffThread(channel, memberId) {
  if (!CONFIG.STAFF_THREAD_ENABLED) return;

  try {
    const threads = await channel.threads.fetchActive();
    const staffThread = threads.threads.find(t =>
      t.name === CONFIG.STAFF_THREAD_NAME && t.type === ChannelType.PrivateThread
    );
    if (!staffThread) return;
    await staffThread.members.add(memberId);
  } catch {
    // non-critical, ignore
  }
}

module.exports = { createStaffThread, addMemberToStaffThread };