/**
 * rest-poll.js — REST-only Discord client for HuggingFace Spaces
 * ================================================================
 * When WebSocket connection to Discord gateway fails (common on HF),
 * this module provides a polling-based fallback that:
 *
 * 1. Polls for new messages in monitored channels every 2-3 seconds
 * 2. Processes them through zelinRespond()
 * 3. Sends responses via REST API
 * 4. Maintains a minimal cache of guild/channels/members
 *
 * REST API via discordapp.com works from HF (28ms latency).
 * WebSocket via gateway.discord.gg does NOT work from HF.
 */

import { REST, Routes, GuildMember, User, Message } from 'discord.js';

// ── Configuration ─────────────────────────────────────────────────────────────

const API_BASE = 'https://discordapp.com/api/v10';
const POLL_INTERVAL_MS = 2500;     // Poll every 2.5s
const CHANNEL_BATCH_SIZE = 3;      // Poll 3 channels per cycle
const MAX_MESSAGES_PER_POLL = 10;  // Check last 10 messages per channel
const ZELIN_BOT_ID = '1477476406819557507';

// Channels to monitor (by name or ID) — prioritize test-bot and chat
const PRIORITY_CHANNELS = [
  '1491133019140919337', // 🧪︱test-bot
  '1243623374568292474', // 💬︱chat
  '1459976980404633673', // 💬︱chat-staff
  '1241168930354237463', // 🤖︱comandos
];

// ── State ─────────────────────────────────────────────────────────────────────

let restClient = null;
let botToken = '';
let guildId = '';
let isRunning = false;
let lastSeenMessageIds = new Map(); // channelId → lastMessageId
let channelCache = new Map();       // channelId → channel object
let memberCache = new Map();        // userId → member data
let guildData = null;

// ── REST API helpers ──────────────────────────────────────────────────────────

async function apiCall(method, path, body = null) {
  const opts = {
    method,
    headers: {
      'Authorization': `Bot ${botToken}`,
      'Content-Type': 'application/json',
    },
  };
  if (body) opts.body = JSON.stringify(body);

  const res = await fetch(`${API_BASE}${path}`, opts);

  // Rate limit handling
  if (res.status === 429) {
    const retryAfter = parseFloat(res.headers.get('Retry-After') || '2');
    console.warn(`[RestPoll] Rate limited, waiting ${retryAfter}s`);
    await new Promise(r => setTimeout(r, retryAfter * 1000));
    return apiCall(method, path, body); // Retry
  }

  if (!res.ok && res.status !== 204) {
    const text = await res.text().catch(() => '');
    throw new Error(`API ${res.status}: ${text.slice(0, 200)}`);
  }

  if (res.status === 204) return null;
  return res.json();
}

// ── Initialize caches ─────────────────────────────────────────────────────────

async function initCaches() {
  try {
    // Get guild data
    guildData = await apiCall('GET', `/guilds/${guildId}`);
    console.log(`[RestPoll] Guild: ${guildData?.name}`);

    // Get all channels
    const channels = await apiCall('GET', `/guilds/${guildId}/channels`);
    if (Array.isArray(channels)) {
      for (const ch of channels) {
        channelCache.set(ch.id, ch);
        // Add to priority channels if not already there
        if (ch.name?.includes('test-bot') || ch.name?.includes('chat') || ch.name?.includes('comando')) {
          if (!PRIORITY_CHANNELS.includes(ch.id)) {
            PRIORITY_CHANNELS.push(ch.id);
          }
        }
      }
      console.log(`[RestPoll] Cached ${channelCache.size} channels`);
    }

    // Initialize last seen message IDs
    for (const chId of PRIORITY_CHANNELS) {
      try {
        const msgs = await apiCall('GET', `/channels/${chId}/messages?limit=1`);
        if (Array.isArray(msgs) && msgs.length > 0) {
          lastSeenMessageIds.set(chId, msgs[0].id);
        }
      } catch {}
    }
    console.log(`[RestPoll] Initialized ${lastSeenMessageIds.size} channel cursors`);
  } catch (err) {
    console.error('[RestPoll] Cache init error:', err.message);
  }
}

// ── Build a minimal Message-like object from REST API data ────────────────────

function buildMessageProxy(msgData) {
  // Create a proxy object that mimics Discord.js Message enough for zelinRespond()
  const author = {
    id: msgData.author.id,
    username: msgData.author.username,
    globalName: msgData.author.global_name,
    bot: msgData.author.bot || false,
    avatar: msgData.author.avatar,
  };

  const channelId = msgData.channel_id;
  const channelObj = channelCache.get(channelId);

  // Minimal message object
  return {
    id: msgData.id,
    content: msgData.content || '',
    author,
    channelId,
    guildId: msgData.guild_id || guildId,
    guild: guildData ? { id: guildId, name: guildData.name } : null,
    member: msgData.member ? {
      displayName: msgData.member.nick || msgData.author.global_name || msgData.author.username,
      roles: msgData.member.roles || [],
      user: author,
    } : null,
    channel: {
      id: channelId,
      name: channelObj?.name || 'unknown',
      send: async (content) => {
        const result = await apiCall('POST', `/channels/${channelId}/messages`,
          typeof content === 'string' ? { content } : content
        );
        return result;
      },
      sendTyping: async () => {
        await apiCall('POST', `/channels/${channelId}/typing`).catch(() => {});
      },
      messages: {
        fetch: async (options) => {
          if (typeof options === 'string') {
            // Fetch single message by ID
            const msg = await apiCall('GET', `/channels/${channelId}/messages/${options}`);
            return msg ? buildMessageProxy(msg) : null;
          }
          const limit = options?.limit || 10;
          const msgs = await apiCall('GET', `/channels/${channelId}/messages?limit=${limit}`);
          if (!Array.isArray(msgs)) return new Map();
          const map = new Map();
          for (const m of msgs) map.set(m.id, buildMessageProxy(m));
          return map;
        },
      },
    },
    reference: msgData.message_reference || null,
    reply: async ({ content, allowedMentions }) => {
      const body = {
        content: typeof content === 'string' ? content : content?.content || '',
        message_reference: { message_id: msgData.id, channel_id: channelId, guild_id: guildId },
        allowed_mentions: allowedMentions || { repliedUser: true },
      };
      const result = await apiCall('POST', `/channels/${channelId}/messages`, body);
      return result;
    },
    react: async (emoji) => {
      await apiCall('PUT', `/channels/${channelId}/messages/${msgData.id}/reactions/${encodeURIComponent(emoji)}/@me`).catch(() => {});
    },
    webhookId: msgData.webhook_id || null,
    attachments: { size: (msgData.attachments || []).length },
    embeds: msgData.embeds || [],
    createdAt: new Date(msgData.timestamp || Date.now()),
    _raw: msgData, // Keep raw data for debugging
  };
}

// ── Poll for new messages ─────────────────────────────────────────────────────

async function pollChannel(channelId) {
  try {
    const lastId = lastSeenMessageIds.get(channelId);
    let url = `/channels/${channelId}/messages?limit=${MAX_MESSAGES_PER_POLL}`;
    if (lastId) url += `&after=${lastId}`;

    const msgs = await apiCall('GET', url);
    if (!Array.isArray(msgs) || msgs.length === 0) return [];

    // Messages come newest-first, reverse to chronological
    const newMsgs = msgs.reverse();

    // Update cursor to newest message
    lastSeenMessageIds.set(channelId, msgs[msgs.length - 1].id);

    return newMsgs;
  } catch (err) {
    // Channel might not exist or no access
    return [];
  }
}

// ── Main polling loop ─────────────────────────────────────────────────────────

let onMessageCallback = null;
let pollTimer = null;

async function pollCycle() {
  if (!isRunning) return;

  try {
    // Poll each priority channel
    for (const chId of PRIORITY_CHANNELS) {
      if (!isRunning) break;

      const newMsgs = await pollChannel(chId);

      for (const msgData of newMsgs) {
        // Skip bot messages (including our own)
        if (msgData.author?.bot) continue;
        // Skip empty messages
        if (!msgData.content?.trim()) continue;

        // Build proxy message and call handler
        const proxy = buildMessageProxy(msgData);

        if (onMessageCallback) {
          // Run async, don't await — process all messages in parallel
          onMessageCallback(proxy).catch(err => {
            console.error(`[RestPoll] Message handler error:`, err.message?.slice(0, 100));
          });
        }
      }

      // Small delay between channels to avoid rate limits
      if (PRIORITY_CHANNELS.indexOf(chId) < PRIORITY_CHANNELS.length - 1) {
        await new Promise(r => setTimeout(r, 500));
      }
    }
  } catch (err) {
    console.error('[RestPoll] Poll cycle error:', err.message?.slice(0, 100));
  }

  // Schedule next poll
  if (isRunning) {
    pollTimer = setTimeout(pollCycle, POLL_INTERVAL_MS);
  }
}

// ── Presence update via REST ──────────────────────────────────────────────────

async function updatePresence(status = 'online', activity = 'TomateSMP') {
  try {
    // Note: Bots can't set presence via REST API directly
    // But we can update it through the gateway if connected
    // For REST-only mode, presence will show as offline
    // This is a known limitation
    console.log(`[RestPoll] Presence: ${status} / ${activity} (limited in REST mode)`);
  } catch {}
}

// ── Public API ────────────────────────────────────────────────────────────────

export async function startRestPolling(token, gid, messageHandler) {
  botToken = token;
  guildId = gid;
  onMessageCallback = messageHandler;
  isRunning = true;

  console.log('[RestPoll] Starting REST polling mode...');
  console.log('[RestPoll] API base:', API_BASE);

  // Test REST API access
  try {
    const me = await apiCall('GET', '/users/@me');
    console.log(`[RestPoll] Authenticated as: ${me.username}#${me.discriminator} (${me.id})`);
  } catch (err) {
    console.error('[RestPoll] Authentication failed:', err.message);
    isRunning = false;
    return false;
  }

  // Initialize caches
  await initCaches();

  // Start polling
  pollCycle();

  console.log(`[RestPoll] ✅ Polling ${PRIORITY_CHANNELS.length} channels every ${POLL_INTERVAL_MS}ms`);
  return true;
}

export function stopRestPolling() {
  isRunning = false;
  if (pollTimer) clearTimeout(pollTimer);
  console.log('[RestPoll] Stopped');
}

export function isRestPollingActive() {
  return isRunning;
}

export function addChannel(channelId) {
  if (!PRIORITY_CHANNELS.includes(channelId)) {
    PRIORITY_CHANNELS.push(channelId);
    console.log(`[RestPoll] Added channel: ${channelId}`);
  }
}

export function removeChannel(channelId) {
  const idx = PRIORITY_CHANNELS.indexOf(channelId);
  if (idx >= 0) {
    PRIORITY_CHANNELS.splice(idx, 1);
    console.log(`[RestPoll] Removed channel: ${channelId}`);
  }
}

export function getRestPollStats() {
  return {
    mode: 'rest-poll',
    isRunning,
    channels: PRIORITY_CHANNELS.length,
    cachedChannels: channelCache.size,
    lastMessageCursors: lastSeenMessageIds.size,
    pollIntervalMs: POLL_INTERVAL_MS,
  };
}

// ── Send message to channel (utility for modules) ─────────────────────────────

export async function sendToChannel(channelId, content) {
  return apiCall('POST', `/channels/${channelId}/messages`,
    typeof content === 'string' ? { content } : content
  );
}

export async function readChannelMessages(channelId, limit = 10) {
  return apiCall('GET', `/channels/${channelId}/messages?limit=${limit}`);
}

// ── Get guild members (minimal, for tools) ────────────────────────────────────

export async function fetchMember(userId) {
  if (memberCache.has(userId)) return memberCache.get(userId);
  try {
    const member = await apiCall('GET', `/guilds/${guildId}/members/${userId}`);
    if (member) {
      memberCache.set(userId, member);
      return member;
    }
  } catch {}
  return null;
}

export async function fetchGuildMembers(limit = 100) {
  try {
    const members = await apiCall('GET', `/guilds/${guildId}/members?limit=${limit}`);
    if (Array.isArray(members)) {
      for (const m of members) {
        memberCache.set(m.user.id, m);
      }
      return members;
    }
  } catch {}
  return [];
}