import { NextResponse } from 'next/server';
import pool from '@/lib/db';

if (!process.env.DISCORD_BOT_TOKEN || !process.env.DISCORD_CHANNEL_ID) {
  throw new Error('Please define DISCORD_BOT_TOKEN and DISCORD_CHANNEL_ID in .env.local');
}

const DISCORD_API_URL = `https://discord.com/api/v10/channels/${process.env.DISCORD_CHANNEL_ID}/messages`;

export async function POST(request: Request) {
  try {
    const formData = await request.formData();
    const fileId = formData.get('file_id') as string;
    const partIndex = formData.get('part_index') as string;
    const chunk = formData.get('encrypted_chunk') as Blob;

    if (!fileId || !partIndex || !chunk) {
      return NextResponse.json({ error: 'Missing required form fields' }, { status: 400 });
    }

    // Forward the chunk to Discord via the Bot API
    const discordFormData = new FormData();
    discordFormData.append('file', chunk, `chunk-${partIndex}.bin`);

    const discordRes = await fetch(DISCORD_API_URL, {
      method: 'POST',
      headers: {
        'Authorization': `Bot ${process.env.DISCORD_BOT_TOKEN}`,
      },
      body: discordFormData,
    });

    if (!discordRes.ok) {
      const errorBody = await discordRes.json();
      console.error('Discord API Error:', errorBody);
      return NextResponse.json({ error: 'Failed to upload to Discord' }, { status: 500 });
    }

    const discordData = await discordRes.json();
    const attachment = discordData.attachments[0];

    if (!attachment) {
        return NextResponse.json({ error: 'No attachment found in Discord response' }, { status: 500 });
    }

    const discordMessageId = discordData.id;
    const discordAttachmentUrl = attachment.url; // This URL is temporary
    const partSize = attachment.size;

    // Save part metadata to the database
    const connection = await pool.getConnection();
    try {
      await connection.query(
        'INSERT INTO file_parts (file_id, part_index, discord_message_id, discord_attachment_url, size) VALUES (?, ?, ?, ?, ?)',
        [fileId, parseInt(partIndex), discordMessageId, discordAttachmentUrl, partSize]
      );
    } finally {
      connection.release();
    }

    return NextResponse.json({ success: true, part_index: partIndex });

  } catch (error) {
    console.error('Error uploading part:', error);
    return NextResponse.json({ error: 'Internal Server Error' }, { status: 500 });
  }
}