/**
 * /response (saved tags) and its autocomplete.
 *
 * /response is itself a router over its subcommands:
 *   send / create / edit / delete / list
 * The autocomplete handler also lives here since the only autocompleting
 * slash command is /response.
 */
const {
  ActionRowBuilder,
  ButtonBuilder,
  ButtonStyle,
  EmbedBuilder,
  MessageFlags
} = require('discord.js');
const { mongoose } = require('../../db-connection');
const { CONFIG } = require('../../config');
const { replaceVariables } = require('../../utils');
const { logError } = require('../../services/debugLog');

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

async function handleResponse(interaction) {
  const subcommand = interaction.options.getSubcommand();
  const handler = RESPONSE_SUBCOMMANDS[subcommand];
  if (!handler) return;
  try {
    await handler(interaction);
  } catch (err) {
    logError('response-command', err, interaction).catch(() => {});
    const errorMsg = '❌ An error occurred while processing the response command.';
    if (interaction.deferred) {
      await interaction.editReply(errorMsg);
    } else {
      await interaction.reply({ content: errorMsg, flags: MessageFlags.Ephemeral });
    }
  }
}

async function handleResponseSend(interaction) {
  const name = interaction.options.getString('name');
  const tag = await Tag.findOne({ name }).lean();
  if (!tag) {
    return interaction.reply({ content: `❌ Tag "${name}" not found.`, flags: MessageFlags.Ephemeral });
  }

  const ticket = await Ticket.findOne({ discordThreadId: interaction.channel.id }).lean();
  const context = {
    ticket: ticket || {},
    staff: {
      username: interaction.user.username,
      displayName: interaction.member?.displayName,
      mention: interaction.user.toString()
    },
    guild: interaction.guild
  };

  const content = replaceVariables(tag.content, context);
  await Tag.updateOne({ name }, { $inc: { useCount: 1 } });
  // Tag bodies are staff-authored but may include variable substitutions from user/ticket data.
  // Disable mention parsing so a `@everyone` in a tag body never pings.
  await interaction.reply({ content, allowedMentions: { parse: [] } });
}

async function handleResponseCreate(interaction) {
  const name = interaction.options.getString('name');
  const content = interaction.options.getString('content');

  try {
    await Tag.create({ name, content, createdBy: interaction.user.id });
    await interaction.reply({ content: `✅ Tag "${name}" created successfully.`, flags: MessageFlags.Ephemeral });
  } catch (err) {
    if (err.code === 11000 || err.message?.includes('duplicate')) {
      await interaction.reply({ content: `❌ Tag "${name}" already exists.`, flags: MessageFlags.Ephemeral });
    } else {
      logError('tag-create', err, interaction).catch(() => {});
      await interaction.reply({ content: '❌ Failed to create tag.', flags: MessageFlags.Ephemeral });
    }
  }
}

async function handleResponseEdit(interaction) {
  const name = interaction.options.getString('name');
  const content = interaction.options.getString('content');

  try {
    const result = await Tag.updateOne({ name }, { $set: { content } });
    if (result.matchedCount === 0) {
      await interaction.reply({ content: `❌ Tag "${name}" not found.`, flags: MessageFlags.Ephemeral });
    } else {
      await interaction.reply({ content: `✅ Tag "${name}" updated successfully.`, flags: MessageFlags.Ephemeral });
    }
  } catch (err) {
    logError('tag-edit', err, interaction).catch(() => {});
    await interaction.reply({ content: '❌ Failed to edit tag.', flags: MessageFlags.Ephemeral });
  }
}

async function handleResponseDelete(interaction) {
  const name = interaction.options.getString('name');
  // Use :: delimiter so tag names with underscores parse correctly (Discord customId max 100 chars).
  const customId = `confirm_delete_tag::${name}`.slice(0, 100);
  const confirmRow = new ActionRowBuilder().addComponents(
    new ButtonBuilder()
      .setCustomId(customId)
      .setLabel('Yes, Delete Tag')
      .setStyle(ButtonStyle.Danger),
    new ButtonBuilder()
      .setCustomId('cancel_delete_tag')
      .setLabel('Cancel')
      .setStyle(ButtonStyle.Secondary)
  );

  return interaction.reply({
    content: `⚠️  Are you sure you want to delete the tag "${name}"? This action cannot be undone.`,
    components: [confirmRow],
    flags: MessageFlags.Ephemeral
  });
}

async function handleResponseList(interaction) {
  await interaction.deferReply({ flags: MessageFlags.Ephemeral });

  const tags = await Tag.find().sort({ useCount: -1 }).select('name useCount').lean();
  if (!tags || tags.length === 0) {
    return interaction.editReply({ content: '📋 No tags available.' });
  }

  const embed = new EmbedBuilder()
    .setTitle('📋 Available Saved Responses')
    .setDescription(
      tags.map((t, i) => `${i + 1}. **${t.name}** (used ${t.useCount || 0}x)`).join('\n')
    )
    .setColor(CONFIG.EMBED_COLOR_INFO)
    .setFooter({ text: `Total: ${tags.length} tags` });

  await interaction.editReply({ embeds: [embed] });
}

const RESPONSE_SUBCOMMANDS = {
  send: handleResponseSend,
  create: handleResponseCreate,
  edit: handleResponseEdit,
  delete: handleResponseDelete,
  list: handleResponseList
};

/** Autocomplete handler. Currently only /response uses it. */
async function handleAutocomplete(interaction) {
  if (interaction.commandName !== 'response') return;
  const subcommand = interaction.options.getSubcommand();
  if (!['send', 'edit', 'delete'].includes(subcommand)) return;

  const focusedValue = interaction.options.getFocused();
  const tags = await Tag.find().sort({ name: 1 }).select('name').lean();
  const filtered = tags
    .filter(t => t.name.toLowerCase().includes(focusedValue.toLowerCase()))
    .slice(0, 25)
    .map(t => ({ name: t.name, value: t.name }));

  await interaction.respond(filtered);
}

module.exports = { handleResponse, handleAutocomplete };