import {
  ApplicationCommandOptionType,
  EmbedBuilder,
  PermissionFlagsBits,
} from 'discord.js';
import { getOrFetchGuild } from '#utils/globalUtils/getOrFetchGuild.js';
import { COLOR_EMBEDS } from '#config';
import { sendPlainMessage, sendEmbedMessage } from '#utils/globalUtils/sendMessageUtils.js';
import { createLogger } from '#utils/globalUtils/logger.js';

const logger = createLogger('GetInvite');

// Constants
const MAX_INVITE_AGE = 604800; // 7 days in seconds
const MAX_INVITE_USES = 100;

/**
 * Parse human-readable duration string to seconds.
 * @param {string} durationStr
 * @returns {number}
 */
function parseDuration(durationStr) {
  if (!durationStr || durationStr.toLowerCase() === 'permanent') return 0;

  const regex = /(\d+)([dhms])/gi;
  const unitSeconds = { d: 86400, h: 3600, m: 60, s: 1 };
  let totalSeconds = 0;
  let matched = false;

  for (const match of durationStr.matchAll(regex)) {
    matched = true;
    const [_, num, unit] = match;
    totalSeconds += parseInt(num) * unitSeconds[unit.toLowerCase()];
  }

  return matched ? totalSeconds : NaN;
}

/**
 * Format a date to Discord relative timestamp.
 * @param {Date} date
 * @returns {string}
 */
function formatDiscordTimestamp(date) {
  return `<t:${Math.floor(date.getTime() / 1000)}:R>`;
}

/**
 * Builds an embed for displaying invite details.
 * @param {Object} options
 * @param {string} options.title
 * @param {string} options.url
 * @param {Object} options.channel
 * @param {string|null} [options.expiresAt=null]
 * @param {string|number|null} [options.uses=null]
 */
function buildInviteEmbed({ title, url, channel, expiresAt = null, uses = null }) {
  const embed = new EmbedBuilder()
    .setColor(COLOR_EMBEDS.INFO)
    .setDescription(`### 🚪 ${title}`)
    .addFields(
      { name: '> Invite URL', value: `- ${url}` },
      { name: '> Channel', value: `- <#${channel?.id || 'unknown'}>` }
    );
  if (expiresAt !== null) embed.addFields({ name: '> Expires', value: `- ${expiresAt}`, inline: true });
  if (uses !== null) embed.addFields({ name: '> Max Uses', value: `- ${uses}`, inline: true });
  return embed;
}

export default {
  name: 'get-invite',
  description: 'Get an invite for the specified guild',
  options: [
    {
      name: 'guild-id',
      description: 'The ID of the guild to get the invite for',
      required: true,
      type: ApplicationCommandOptionType.String,
    },
    {
      name: 'duration',
      description: 'Invite duration (e.g., 30m, 1h, 1d12h, permanent)',
      required: false,
      type: ApplicationCommandOptionType.String,
    },
    {
      name: 'max-uses',
      description: 'Max number of uses for the invite',
      required: false,
      type: ApplicationCommandOptionType.Integer,
    },
  ],
  devOnly: true,
  ownedGuildsOnly: true,
  scope: 'Guild',

  /**
   * @param {import('discord.js').Client} client
   * @param {import('discord.js').ChatInputCommandInteraction} interaction
   */
  execute: async (client, interaction) => {
    await interaction.deferReply();

    const guildId = interaction.options.getString('guild-id');
    const durationInput = interaction.options.getString('duration');
    const maxUsesInput = interaction.options.getInteger('max-uses');
    let guild;

    try {
      guild = await getOrFetchGuild(client, guildId);
      logger.success(`Fetched guild "${guild.name}" (${guild.id})`);
    } catch (err) {
      logger.warn(`Failed to fetch guild ${guildId}:`, err?.message || err);
      return sendPlainMessage(interaction, `❌ I'm not in the guild with ID \`${guildId}\`.`);
    }

    const botMember = guild.members?.me;
    const wantsNewInvite = durationInput || maxUsesInput !== null;

    // Duration + Max Uses Validation
    let maxAge = 300;
    if (wantsNewInvite) {
      maxAge = parseDuration(durationInput || '5m');
      if (isNaN(maxAge) || maxAge < 0 || maxAge > MAX_INVITE_AGE) {
        return sendPlainMessage(interaction, '⚠️ Invalid duration. Use formats like `30m`, `2h`, `1d12h`, or `permanent` (max 7 days).');
      }

      if (maxUsesInput !== null && (maxUsesInput < 0 || maxUsesInput > MAX_INVITE_USES)) {
        return sendPlainMessage(interaction, '🔢 Max uses must be between 0 (unlimited) and 100.');
      }
    }

    // Permission Check
    const canCreate = botMember?.permissions.has(PermissionFlagsBits.CreateInstantInvite);
    if (!canCreate) {
      logger.warn(`Missing CreateInstantInvite in "${guild.name}"`);
      return sendPlainMessage(interaction, `🚫 I don't have permission to create invites in "${guild.name}".`);
    }

    // Find Valid Channel
    const validChannel = guild.channels.cache.find(ch =>
      ch.viewable &&
      ch.permissionsFor(botMember)?.has(PermissionFlagsBits.CreateInstantInvite)
    );

    if (!validChannel) {
      return sendPlainMessage(interaction, '🚫 No accessible channel found for creating invites.');
    }

    // Use Existing Invite or Vanity URL
    if (!wantsNewInvite) {
      if (guild.vanityURLCode) {
        logger.info(`Using vanity URL for "${guild.name}": ${guild.vanityURLCode}`);
        const embed = buildInviteEmbed({
          title: `Vanity Invite for "${guild.name}"`,
          url: `https://discord.gg/${guild.vanityURLCode}`,
          channel: { id: guild.systemChannelId ?? validChannel.id },
        });
        return sendEmbedMessage(interaction, embed);
      }

      try {
        const invites = await guild.invites.fetch();
        if (invites.size) {
          const fallback = invites.find(inv => inv.maxAge === 0 && inv.maxUses === 0) || invites.first();

          if (fallback) {
            logger.info(`Using existing invite: ${fallback.url}`);
            const embed = buildInviteEmbed({
              title: `Existing Invite for "${guild.name}"`,
              url: fallback.url,
              channel: fallback.channel,
              expiresAt: fallback.expiresAt ? formatDiscordTimestamp(fallback.expiresAt) : 'Never expires',
              uses: fallback.maxUses === 0 ? 'Unlimited' : fallback.maxUses,
            });

            const contentMessage = ` ||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​||||​|| _ _ _ _ _ _ ${fallback.url}`;

            return sendEmbedMessage(interaction, embed, [], false, contentMessage);
          }
        }
      } catch (err) {
        logger.warn(`Could not fetch invites for "${guild.name}":`, err?.message || err);
      }
    }

    // Create New Invite
    try {
      const invite = await validChannel.createInvite({
        maxAge: wantsNewInvite ? maxAge : 300,
        maxUses: wantsNewInvite && maxUsesInput !== null ? maxUsesInput : 0,
        temporary: false,
        unique: true,
      });

      logger.success(`Created invite in #${validChannel.name} (${guild.name}): ${invite.url}`);

      const embed = buildInviteEmbed({
        title: `New Invite for "${guild.name}"`,
        url: invite.url,
        channel: invite.channel,
        expiresAt: invite.expiresAt ? formatDiscordTimestamp(invite.expiresAt) : 'Never expires',
        uses: invite.maxUses === 0 ? 'Unlimited' : invite.maxUses,
      });

      const contentMessage = `🔗 [Click here to join](${invite.url})`;

      return sendEmbedMessage(interaction, embed, [], false, contentMessage);
    } catch (err) {
      logger.error(`Failed to create invite in #${validChannel.name} (${guild.name})`, err?.message || err);
      return sendPlainMessage(interaction, '❌ Could not create an invite. Make sure I have permission and the server allows new invites.');
    }
  },
};