/**
 * Ticket database helpers – counters, rename, limits, auto-close,
 * reminders, auto-unclaim, channel creation.
 */
const { ChannelType, PermissionFlagsBits } = require('discord.js');
const { mongoose, withRetry } = require('../db-connection');
const { CONFIG } = require('../config');
const { getPriorityEmoji } = require('../utils');
const { logAutomation } = require('../services/debugLog');
const { enqueueSend, enqueueDelete } = require('./channelQueue');

const Ticket = mongoose.model('Ticket');
const TicketCounter = mongoose.model('TicketCounter');

// --- TICKET NUMBER ---

async function getNextTicketNumber(senderEmail) {
  const senderLocal = senderEmail.split('@')[0].toLowerCase();
  const counter = await TicketCounter.findOneAndUpdate(
    { senderLocal },
    { $inc: { counter: 1 } },
    { upsert: true, new: true, setDefaultsOnInsert: true }
  );
  return { local: senderLocal, number: counter.counter };
}

// --- RENAME + NAMING ---
// Renames flow through utils/renamer.js (RENAMER_BOT secondary token),
// which has its own Discord rate-limit bucket. We no longer gate on the
// primary bot's 2/10min per-channel budget here; 429s from the secondary
// bot surface via utils/renamer.js instead.

const RENAME_WINDOW_MS = 10 * 60 * 1000; // 10 minutes (unused; kept for back-compat)
const RENAME_LIMIT = 2;

function getSenderLocal(senderEmail) {
  return (senderEmail || 'unknown').split('@')[0].toLowerCase();
}

function toDiscordSafeName(str) {
  return str
    .toLowerCase()
    .replace(/\s+/g, '-')
    .replace(/[^\p{L}\p{N}\p{Emoji_Presentation}-]/gu, '')
    .replace(/-{2,}/g, '-')
    .replace(/^-+|-+$/g, '')
    .slice(0, 100);
}

/**
 * Resolve a human-friendly creator nickname for channel naming.
 * Discord tickets: guild member displayName. Email tickets: senderLocal.
 * @param {import('discord.js').Guild} guild
 * @param {object} ticket
 * @returns {Promise<string>}
 */
async function resolveCreatorNickname(guild, ticket) {
  if (ticket.gmailThreadId.startsWith('discord-')) {
    const creatorUserId = ticket.gmailThreadId.split('-').pop();
    try {
      const member = await guild.members.fetch(creatorUserId);
      return member.displayName;
    } catch {
      return getSenderLocal(ticket.senderEmail);
    }
  }
  return getSenderLocal(ticket.senderEmail);
}

/**
 * Build a channel name from ticket state.
 * @param {'unclaimed'|'claimed'|'escalated'|'escalated-claimed'} state
 * @param {object} ticket
 * @param {string} creatorNickname - pre-resolved via resolveCreatorNickname
 * @param {string} [claimerEmoji] - required for claimed / escalated-claimed
 * @returns {string}
 */
function makeTicketName(state, ticket, creatorNickname, claimerEmoji) {
  const num = ticket.ticketNumber || 1;
  switch (state) {
    case 'claimed':
      return toDiscordSafeName(`${claimerEmoji}-${creatorNickname}-${num}`);
    case 'escalated':
      return toDiscordSafeName(`escalated-${creatorNickname}-${num}`);
    case 'escalated-claimed':
      return toDiscordSafeName(`e-${claimerEmoji}-${creatorNickname}-${num}`);
    case 'unclaimed':
    default:
      return toDiscordSafeName(`unclaimed-${creatorNickname}-${num}`);
  }
}

// Retained for external callers (bOSScord, scripts). The gate now lives in
// the secondary bot's rate bucket; this helper no longer touches Mongo.
async function canRename(_ticket) {
  return { ok: true, remaining: RENAME_LIMIT, waitMs: 0 };
}

function minutesFromMs(ms) {
  return Math.max(1, Math.ceil(ms / 60000));
}

// --- RATE LIMIT (per-user ticket creation) ---

const ticketCreationByUser = new Map(); // userId -> { count, resetAt }

const TICKET_CREATION_SWEEP_TTL_MS = 48 * 60 * 60 * 1000;
const TICKET_CREATION_SWEEP_INTERVAL_MS = 6 * 60 * 60 * 1000;

function sweepTicketCreationByUser(now = Date.now()) {
  // An entry is stale when its window has been expired long enough that no
  // legitimate rate-limit decision would still consult it. resetAt is a future
  // ms timestamp when the window ends; cutoff is 48h past that.
  const cutoff = now - TICKET_CREATION_SWEEP_TTL_MS;
  for (const [key, entry] of ticketCreationByUser.entries()) {
    if ((entry?.resetAt ?? 0) < cutoff) ticketCreationByUser.delete(key);
  }
}

function startTicketsSweeps(trackInterval) {
  const handle = setInterval(() => sweepTicketCreationByUser(), TICKET_CREATION_SWEEP_INTERVAL_MS);
  if (typeof handle.unref === 'function') handle.unref();
  if (typeof trackInterval === 'function') trackInterval(handle);
  return handle;
}

/**
 * Check if the user can create a ticket (rate limit). If allowed, consumes one slot.
 * @param {string} userId - Discord user ID
 * @returns {{ allowed: boolean, retryAfterMs?: number }}
 */
function checkTicketCreationRateLimit(userId) {
  const limit = CONFIG.RATE_LIMIT_TICKETS_PER_USER;
  const windowMs = (CONFIG.RATE_LIMIT_WINDOW_MINUTES || 60) * 60 * 1000;
  if (!limit || limit <= 0) return { allowed: true };

  const now = Date.now();
  let entry = ticketCreationByUser.get(userId);
  if (!entry || now >= entry.resetAt) {
    entry = { count: 1, resetAt: now + windowMs };
    ticketCreationByUser.set(userId, entry);
    return { allowed: true };
  }
  if (entry.count >= limit) {
    return { allowed: false, retryAfterMs: entry.resetAt - now };
  }
  entry.count++;
  return { allowed: true };
}

// --- CHANNEL CREATION (overflow: Discord limit 50 channels per category) ---

const CHANNELS_PER_CATEGORY_LIMIT = 50;

function escapeCategoryNameForRegex(name) {
  return String(name).replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
}

/**
 * @deprecated Use getOrCreateTicketCategory instead.
 * @returns {null}
 */
function pickTicketCategoryId(guild, categoryIds) {
  console.warn('[tickets] pickTicketCategoryId is deprecated; use getOrCreateTicketCategory() instead');
  return null;
}

function countChannelsInCategory(guild, categoryId) {
  return guild.channels.cache.filter(c => c.parentId === categoryId).size;
}

/**
 * Resolve or create a ticket category with dynamic overflow (Discord max 50 channels per category).
 * @param {import('discord.js').Guild} guild
 * @param {string} primaryCategoryId
 * @param {string} categoryName Display base name (primary category should match; overflows are "(Overflow N)")
 * @returns {Promise<string>}
 */
async function getOrCreateTicketCategory(guild, primaryCategoryId, categoryName) {
  if (!guild) {
    throw new Error('getOrCreateTicketCategory: guild is required');
  }
  if (!primaryCategoryId || !String(primaryCategoryId).trim()) {
    throw new Error('getOrCreateTicketCategory: primaryCategoryId is required');
  }
  try {
    let primary = guild.channels.cache.get(primaryCategoryId);
    if (!primary) {
      primary = await guild.channels.fetch(primaryCategoryId).catch(() => null);
    }
    if (!primary || primary.type !== ChannelType.GuildCategory) {
      throw new Error(`getOrCreateTicketCategory: primary category ${primaryCategoryId} not found or not a category`);
    }

    const escaped = escapeCategoryNameForRegex(categoryName);
    const overflowRe = new RegExp(`^${escaped} \\(Overflow (\\d+)\\)$`);

    const overflowMatches = [];
    for (const ch of guild.channels.cache.values()) {
      if (!ch || ch.type !== ChannelType.GuildCategory) continue;
      if (ch.id === primaryCategoryId) continue;
      const m = ch.name.match(overflowRe);
      if (m) overflowMatches.push({ ch, n: parseInt(m[1], 10) });
    }
    overflowMatches.sort((a, b) => a.n - b.n);

    const existingCategories = [primary, ...overflowMatches.map(x => x.ch)];

    for (const cat of existingCategories) {
      if (countChannelsInCategory(guild, cat.id) < CHANNELS_PER_CATEGORY_LIMIT) {
        return cat.id;
      }
    }

    const highestN = overflowMatches.length > 0 ? Math.max(...overflowMatches.map(x => x.n)) : 0;
    const nextN = highestN + 1;
    const newName = `${categoryName} (Overflow ${nextN})`;
    const lastCat = existingCategories[existingCategories.length - 1];
    const position = (lastCat?.rawPosition ?? lastCat?.position ?? 0) + 1;

    let newCat;
    try {
      newCat = await guild.channels.create({
        name: newName,
        type: ChannelType.GuildCategory,
        position
      });
    } catch (createErr) {
      console.error('getOrCreateTicketCategory: failed to create overflow category:', createErr);
      throw createErr;
    }
    return newCat.id;
  } catch (err) {
    console.error('getOrCreateTicketCategory:', err);
    const fallback = guild.channels.cache.get(primaryCategoryId);
    if (fallback?.type === ChannelType.GuildCategory) {
      return primaryCategoryId;
    }
    throw err;
  }
}

/**
 * Delete an overflow category if it is empty and its name matches "${categoryName} (Overflow N)".
 * Never deletes the primary category (exact name match).
 * @param {import('discord.js').Guild} guild
 * @param {string} categoryId
 * @param {string} categoryName
 */
async function cleanupEmptyOverflowCategory(guild, categoryId, categoryName) {
  try {
    if (!guild || !categoryId) return;
    const cached = guild.channels.cache.filter(c => c.parentId === categoryId);
    if (cached.size !== 0) return;

    let cat = guild.channels.cache.get(categoryId);
    if (!cat) {
      cat = await guild.channels.fetch(categoryId).catch(() => null);
    }
    if (!cat || cat.type !== ChannelType.GuildCategory) return;
    if (cat.name === categoryName) return;

    const escaped = escapeCategoryNameForRegex(categoryName);
    const overflowRe = new RegExp(`^${escaped} \\(Overflow \\d+\\)$`);
    if (!overflowRe.test(cat.name)) return;

    await cat.delete().catch(deleteErr => {
      console.error('cleanupEmptyOverflowCategory: delete failed:', deleteErr);
    });
  } catch (err) {
    console.error('cleanupEmptyOverflowCategory:', err);
  }
}

async function createTicketChannel(guild, ticketNumber, userId, subject, creatorNickname) {
  let parentId;
  try {
    parentId = await getOrCreateTicketCategory(guild, CONFIG.TICKET_CATEGORY_ID, CONFIG.TICKET_CATEGORY_NAME);
  } catch (e) {
    console.error('getOrCreateTicketCategory (createTicketChannel):', e);
    throw new Error('Ticket category not found or could not be allocated');
  }

  let channel;
  try {
    channel = await guild.channels.create({
      name: creatorNickname ? toDiscordSafeName(`unclaimed-${creatorNickname}-${ticketNumber}`) : `ticket-${ticketNumber}`,
      type: ChannelType.GuildText,
      parent: parentId,
      permissionOverwrites: [
        {
          id: guild.id,
          deny: [PermissionFlagsBits.ViewChannel]
        },
        {
          id: userId,
          allow: [
            PermissionFlagsBits.ViewChannel,
            PermissionFlagsBits.SendMessages,
            PermissionFlagsBits.ReadMessageHistory
          ]
        },
        {
          id: CONFIG.ROLE_ID_TO_PING,
          allow: [
            PermissionFlagsBits.ViewChannel,
            PermissionFlagsBits.SendMessages,
            PermissionFlagsBits.ReadMessageHistory
          ]
        }
      ]
    });
  } catch (e) {
    console.error('guild.channels.create (createTicketChannel):', e);
    throw e;
  }

  return channel;
}

// --- LIMITS & PERMISSIONS ---

async function checkTicketLimits(senderEmail) {
  if (!CONFIG.GLOBAL_TICKET_LIMIT) return { ok: true };

  const currentCount = await Ticket.countDocuments({ senderEmail, status: 'open' });
  if (currentCount >= CONFIG.GLOBAL_TICKET_LIMIT) {
    return {
      ok: false,
      reason: `You have reached the maximum limit of ${CONFIG.GLOBAL_TICKET_LIMIT} open tickets.`
    };
  }

  return { ok: true };
}

function hasBlacklistedRole(member) {
  if (!CONFIG.BLACKLISTED_ROLES || CONFIG.BLACKLISTED_ROLES.length === 0) {
    return false;
  }
  return member.roles.cache.some(role =>
    CONFIG.BLACKLISTED_ROLES.includes(role.id)
  );
}

// --- ACTIVITY ---

async function updateTicketActivity(gmailThreadId) {
  const now = new Date();
  await Ticket.updateOne(
    { gmailThreadId },
    { $set: { lastActivity: now, reminderSent: false } }
  );
}

// --- SCHEDULED CHECKS ---
// These accept `client` and optionally `sendTicketClosedEmail` to avoid circular deps.

async function checkAutoClose(client, sendTicketClosedEmail) {
  if (!CONFIG.AUTO_CLOSE_ENABLED) return;

  const cutoffTime = new Date(Date.now() - (CONFIG.AUTO_CLOSE_AFTER_HOURS * 60 * 60 * 1000));
  // Bounded per-tick so a huge backlog drains across successive hourly runs.
  const staleTickets = await withRetry(() => Ticket.find({
    status: 'open',
    lastActivity: { $lt: cutoffTime, $ne: null }
  }).sort({ createdAt: 1 }).limit(500).lean());

  let checked = 0, closed = 0;
  for (const ticket of staleTickets) {
    checked++;
    try {
      const guild = client.guilds.cache.first();
      if (!guild) continue;

      const channel = await guild.channels.fetch(ticket.discordThreadId).catch(() => null);
      if (channel) {
        await enqueueSend(channel, CONFIG.DISCORD_AUTO_CLOSE_MESSAGE);

        // Persist pendingDelete BEFORE the delay so a shutdown mid-delay can be
        // resumed on boot via resumePendingDeletes(). Cleared after enqueueDelete
        // resolves; if the doc is gone the unset is a no-op.
        await withRetry(() => Ticket.updateOne(
          { gmailThreadId: ticket.gmailThreadId },
          { $set: { status: 'closed', pendingDelete: true } }
        ));

        await sendTicketClosedEmail(ticket, 'Auto-Close System');

        setTimeout(() => {
          enqueueDelete(channel).then(() => {
            withRetry(() => Ticket.updateOne(
              { gmailThreadId: ticket.gmailThreadId },
              { $unset: { pendingDelete: '' } }
            )).catch(() => {});
          }).catch(() => {});
        }, 5000);
        closed++;
      }
    } catch (error) {
      console.error(`Auto-close error for ticket ${ticket.gmailThreadId}:`, error);
    }
  }
  logAutomation('Auto-close run', null, `checked: ${checked}, closed: ${closed}`).catch(() => {});
}

async function checkReminders(client) {
  if (!CONFIG.REMINDER_ENABLED) return;

  const reminderTime = new Date(Date.now() - (CONFIG.REMINDER_AFTER_HOURS * 60 * 60 * 1000));
  const ticketsNeedingReminder = await withRetry(() => Ticket.find({
    status: 'open',
    lastActivity: { $lt: reminderTime, $ne: null },
    reminderSent: false
  }).lean());

  let checked = 0, reminded = 0;
  for (const ticket of ticketsNeedingReminder) {
    checked++;
    try {
      const guild = client.guilds.cache.first();
      if (!guild) continue;

      const channel = await guild.channels.fetch(ticket.discordThreadId).catch(() => null);
      if (channel) {
        const ping = ticket.claimedBy
          ? `<@${ticket.claimedBy}>`
          : (CONFIG.ROLE_ID_TO_PING ? `<@&${CONFIG.ROLE_ID_TO_PING}>` : 'everyone');
        const message = CONFIG.REMINDER_MESSAGE
          .replace(/\{hours\}/g, String(CONFIG.REMINDER_AFTER_HOURS))
          .replace(/\{ping\}/g, ping);
        await enqueueSend(channel, message);

        await withRetry(() => Ticket.updateOne(
          { gmailThreadId: ticket.gmailThreadId },
          { $set: { reminderSent: true } }
        ));
        reminded++;
      }
    } catch (error) {
      console.error(`Reminder error for ticket ${ticket.gmailThreadId}:`, error);
    }
  }
  logAutomation('Reminder run', null, `checked: ${checked}, reminded: ${reminded}`).catch(() => {});
}

async function checkAutoUnclaim(client) {
  if (!CONFIG.AUTO_UNCLAIM_ENABLED) return;

  const unclaimTime = new Date(Date.now() - (CONFIG.AUTO_UNCLAIM_AFTER_HOURS * 60 * 60 * 1000));
  const staleClaimedTickets = await withRetry(() => Ticket.find({
    status: 'open',
    claimedBy: { $ne: null },
    lastActivity: { $lt: unclaimTime, $ne: null }
  }).lean());

  let checked = 0, unclaimed = 0;
  for (const ticket of staleClaimedTickets) {
    checked++;
    try {
      const guild = client.guilds.cache.first();
      if (!guild) continue;

      const channel = await guild.channels.fetch(ticket.discordThreadId).catch(() => null);
      if (channel) {
        await withRetry(() => Ticket.updateOne(
          { gmailThreadId: ticket.gmailThreadId },
          { $set: { claimedBy: null } }
        ));

        await enqueueSend(channel,
          `This ticket has been auto-unclaimed due to inactivity (${CONFIG.AUTO_UNCLAIM_AFTER_HOURS} hours).`
        );

        console.log(`Auto-unclaimed ticket ${ticket.gmailThreadId}`);
        unclaimed++;
      }
    } catch (error) {
      console.error(`Auto-unclaim error for ticket ${ticket.gmailThreadId}:`, error);
    }
  }
  logAutomation('Auto-unclaim run', null, `checked: ${checked}, unclaimed: ${unclaimed}`).catch(() => {});
}

async function reconcileDeletedTicketChannels(client) {
  const guild = client.guilds.cache.get(CONFIG.DISCORD_GUILD_ID) || client.guilds.cache.first();
  if (!guild) return { checked: 0, reconciled: 0 };

  // Bounded per-tick; a larger backlog drains in subsequent hourly runs.
  const openTickets = await Ticket.find({
    status: 'open',
    discordThreadId: { $ne: null }
  }).sort({ createdAt: 1 }).limit(500).lean();

  let checked = 0, reconciled = 0;
  for (const ticket of openTickets) {
    checked++;
    try {
      let channel = guild.channels.cache.get(ticket.discordThreadId);
      if (!channel) {
        channel = await guild.channels.fetch(ticket.discordThreadId).catch(() => null);
      }
      if (!channel) {
        await Ticket.updateOne(
          { gmailThreadId: ticket.gmailThreadId },
          { $set: { status: 'closed', discordThreadId: null } }
        );
        logAutomation('Reconcile: channel deleted', ticket.discordThreadId, `ticket #${ticket.ticketNumber}`).catch(() => {});
        reconciled++;
      }
    } catch (err) {
      console.error(`reconcileDeletedTicketChannels error for ${ticket.gmailThreadId}:`, err);
    }
  }
  if (reconciled > 0) {
    logAutomation('Reconcile run', null, `checked: ${checked}, reconciled: ${reconciled}`).catch(() => {});
  }
  return { checked, reconciled };
}

/**
 * Resume deletes that were pending when the bot last shut down. Called once
 * from the ready handler. Clears the flag regardless of fetch result so a
 * stale flag (e.g. channel already gone) can't loop.
 */
async function resumePendingDeletes(client) {
  const pending = await Ticket.find({ pendingDelete: true }).lean().catch(() => []);
  if (!pending.length) return 0;
  let resumed = 0;
  for (const ticket of pending) {
    try {
      const guild = client.guilds.cache.first();
      if (guild && ticket.discordThreadId) {
        const channel = await guild.channels.fetch(ticket.discordThreadId).catch(() => null);
        if (channel) {
          enqueueDelete(channel).catch(() => {});
          resumed++;
        }
      }
      Ticket.updateOne(
        { gmailThreadId: ticket.gmailThreadId },
        { $unset: { pendingDelete: '' } }
      ).catch(() => {});
    } catch (e) {
      console.error('resumePendingDeletes error:', e);
    }
  }
  logAutomation('Pending-delete resume', null, `pending: ${pending.length}, resumed: ${resumed}`).catch(() => {});
  return resumed;
}

module.exports = {
  getNextTicketNumber,
  getOrCreateTicketCategory,
  cleanupEmptyOverflowCategory,
  RENAME_WINDOW_MS,
  RENAME_LIMIT,
  getSenderLocal,
  toDiscordSafeName,
  resolveCreatorNickname,
  makeTicketName,
  canRename,
  minutesFromMs,
  checkTicketCreationRateLimit,
  createTicketChannel,
  checkTicketLimits,
  hasBlacklistedRole,
  updateTicketActivity,
  checkAutoClose,
  checkReminders,
  checkAutoUnclaim,
  reconcileDeletedTicketChannels,
  resumePendingDeletes,
  startTicketsSweeps,
  sweepTicketCreationByUser,
  _internals: { ticketCreationByUser, TICKET_CREATION_SWEEP_TTL_MS }
};