import {
  ActionRowBuilder,
  ButtonBuilder,
  ButtonStyle,
  Colors,
  EmbedBuilder,
  type Message,
  ThreadChannel,
} from 'discord.js';

function findFirstImage(message: Message): string | undefined {
  const result = message.attachments.find((attach) => {
    return attach.contentType?.startsWith('image/');
  });
  if (result == undefined) {
    return undefined;
  } else {
    return result.url;
  }
}

export async function expandDiscordLink(message: Message): Promise<void> {
  if (message.author.bot && !message.author.webhookId) return;
  
  const re =
    /(https?:\/\/)?(?:canary\.|ptb\.)?discord(?:app)?\.com\/channels\/(?<server_id>\d+)\/(?<channel_id>\d+)\/(?<message_id>\d+)/g;

  const results = message.content.matchAll(re);

  let n = 0;

  for (const r of results) {
    if (n >= 3) break; // only process three previews

    if (r.groups == undefined || r.groups.server_id != message.guildId)
      continue; // do not let the bot leak messages from one server to another

    const channel = await message.guild?.channels.fetch(r.groups.channel_id);

    if (!channel || !channel.isTextBased()) continue;

    if (channel instanceof ThreadChannel) {
      if (
        !channel.parent?.members?.some((user) => user.id == message.author.id)
      )
        continue; // do not reveal a message to a user who can't see it
    } else {
      if (!channel.members?.some((user) => user.id == message.author.id))
        continue; // do not reveal a message to a user who can't see it
    }

    try {
      const messageToShow = await channel.messages.fetch(r.groups.message_id);

      const builder = new EmbedBuilder()
        .setAuthor({
          name: `${messageToShow.author.username}#${messageToShow.author.discriminator}`,
          iconURL: messageToShow.author.displayAvatarURL(),
        })
        .setColor(Colors.Aqua)
        .setTimestamp(messageToShow.createdTimestamp)
        .setFooter({ text: `#${messageToShow.channel.name}` });
      if (messageToShow.content) {
        builder.setDescription(messageToShow.content);
      }
      if (messageToShow.attachments.size > 0) {
        let attachmentsString = '';
        messageToShow.attachments.forEach((value) => {
          attachmentsString += `[${value.name}](${value.url}) `;
        });

        builder.addFields({ name: 'Attachments', value: attachmentsString });

        const firstImage = findFirstImage(messageToShow);
        if (firstImage != undefined) {
          builder.setImage(firstImage);
        }
      }

      const row = new ActionRowBuilder<ButtonBuilder>().addComponents(
        new ButtonBuilder()
          .setLabel('Jump to original message')
          .setStyle(ButtonStyle.Link)
          .setURL(messageToShow.url),
        new ButtonBuilder()
          .setCustomId('delete-message')
          .setLabel('Delete')
          .setStyle(ButtonStyle.Danger)
      );

      await message.reply({
        embeds: [builder],
        components: [row],
        allowedMentions: { repliedUser: false },
      });
      n++;
    } catch (e) {
      console.error(e);
    }
  }
}