import {
  SlashCommandBuilder,
  PermissionFlagsBits,
  MessageFlags,
} from 'discord.js';
import { parseEmoji, isCustomEmojiAvailable } from '../../utilities/emoji.js';
import { requireManageRoles, canBotManageRole } from '../../utilities/permissions.js';
import { ensureBotReaction } from '../../utilities/ensureBotReaction.js';
import {
  resolveInteractionGuild,
  resolveInteractionTextChannel,
} from '../../utilities/channels.js';
import { reactionRoleService } from '../../services/reactionRoleService.js';
import {
  replyEphemeralError,
  describeCommandError,
  isDatabaseError,
} from '../../utilities/errors.js';
import logger from '../../utilities/logger.js';

export default {
  data: new SlashCommandBuilder()
    .setName('reaction-role')
    .setDescription('Create a reaction role on a message in this channel')
    .setDefaultMemberPermissions(PermissionFlagsBits.ManageRoles)
    .setDMPermission(false)
    .addStringOption((option) =>
      option
        .setName('message_id')
        .setDescription('ID of the message in this channel')
        .setRequired(true),
    )
    .addRoleOption((option) =>
      option
        .setName('role')
        .setDescription('Role to assign when the reaction is added')
        .setRequired(true),
    )
    .addStringOption((option) =>
      option
        .setName('emoji')
        .setDescription('Unicode emoji or custom emoji markup')
        .setRequired(true),
    ),

  /**
   * @param {import('discord.js').ChatInputCommandInteraction} interaction
   */
  async execute(interaction) {
    if (!(await requireManageRoles(interaction))) {
      return;
    }

    const guild = await resolveInteractionGuild(interaction);
    if (!guild) {
      await replyEphemeralError(
        interaction,
        'Could not access this server. Make sure the bot is online and has been invited here.',
      );
      return;
    }

    const channel = await resolveInteractionTextChannel(interaction);
    if (!channel) {
      await replyEphemeralError(
        interaction,
        'This command can only be used in a text channel. Make sure the bot can view this channel.',
      );
      return;
    }

    const messageId = interaction.options.getString('message_id', true).trim();
    const role = interaction.options.getRole('role', true);
    const emojiInput = interaction.options.getString('emoji', true);

    if (!/^\d{17,20}$/.test(messageId)) {
      await replyEphemeralError(
        interaction,
        'Invalid message ID. Right-click the message → Copy Message ID (Developer Mode must be enabled).',
      );
      return;
    }

    const parsedEmoji = parseEmoji(emojiInput);
    if (!parsedEmoji) {
      await replyEphemeralError(interaction, describeCommandError(new Error('INVALID_EMOJI')));
      return;
    }

    if (parsedEmoji.type === 'custom' && !isCustomEmojiAvailable(interaction.client, parsedEmoji.id)) {
      await replyEphemeralError(
        interaction,
        describeCommandError(new Error('CUSTOM_EMOJI_UNAVAILABLE')),
      );
      return;
    }

    // Role option may return APIRole; resolve the full Role when possible
    const guildRole =
      'position' in role && typeof role.position === 'number'
        ? role
        : await guild.roles.fetch(role.id).catch(() => null);

    if (!guildRole) {
      await replyEphemeralError(interaction, describeCommandError(new Error('ROLE_NOT_FOUND')));
      return;
    }

    const permissionCheck = canBotManageRole(guild, guildRole);
    if (!permissionCheck.ok) {
      await replyEphemeralError(interaction, permissionCheck.reason);
      return;
    }

    let message;
    try {
      message = await channel.messages.fetch(messageId);
    } catch (error) {
      logger.warn('Failed to fetch target message for reaction role', {
        messageId,
        channelId: channel.id,
        error: error instanceof Error ? error.message : String(error),
      });
      await replyEphemeralError(interaction, describeCommandError(new Error('MESSAGE_NOT_FOUND')));
      return;
    }

    try {
      // Add the emoji if it is missing (or if the bot has not reacted yet)
      await ensureBotReaction(message, parsedEmoji.identifier, parsedEmoji.reactValue);
    } catch (error) {
      await replyEphemeralError(interaction, describeCommandError(error));
      return;
    }

    try {
      reactionRoleService.create({
        guildId: guild.id,
        channelId: channel.id,
        messageId: message.id,
        roleId: guildRole.id,
        emojiIdentifier: parsedEmoji.identifier,
        emojiDisplay: parsedEmoji.display,
        createdBy: interaction.user.id,
      });
    } catch (error) {
      // Best-effort cleanup of the bot reaction if persistence fails
      try {
        const botReaction = message.reactions.cache.find((reaction) => {
          const id = reaction.emoji.id ?? reaction.emoji.name;
          return id === parsedEmoji.identifier;
        });
        if (botReaction) {
          await botReaction.users.remove(interaction.client.user.id);
        }
      } catch (cleanupError) {
        logger.warn('Failed to clean up reaction after DB error', {
          error: cleanupError instanceof Error ? cleanupError.message : String(cleanupError),
        });
      }

      if (isDatabaseError(error) && error.message !== 'DUPLICATE_MAPPING') {
        await replyEphemeralError(interaction, 'A database error occurred while saving the reaction role.');
        return;
      }

      await replyEphemeralError(interaction, describeCommandError(error));
      return;
    }

    await interaction.reply({
      content:
        `Reaction role created.\n` +
        `• Message: [${message.id}](${message.url})\n` +
        `• Role: ${guildRole}\n` +
        `• Emoji: ${parsedEmoji.display}`,
      flags: MessageFlags.Ephemeral,
    });
  },
};