import { NextRequest, NextResponse } from 'next/server';
import { db } from '@/lib/db';
import { requireRole } from '@/lib/auth';
import { getErrorMessage } from '@/lib/errors';

// Admin: Get all conversations
export async function GET() {
  try {
    await requireRole('admin');

    // Get all conversations with participant info and last message
    const { rows } = await db.query(`
      SELECT 
        c.id,
        c.subject,
        c.created_at,
        c.updated_at,
        (SELECT content FROM direct_messages WHERE conversation_id = c.id ORDER BY created_at DESC LIMIT 1) as last_message,
        (SELECT created_at FROM direct_messages WHERE conversation_id = c.id ORDER BY created_at DESC LIMIT 1) as last_message_at,
        (SELECT COUNT(*) FROM direct_messages WHERE conversation_id = c.id) as message_count
      FROM conversations c
      ORDER BY c.updated_at DESC
    `);

    // Get participants for each conversation
    const conversations = await Promise.all(rows.map(async (conv: any) => {
      const { rows: participants } = await db.query(`
        SELECT u.id, u.username, u.first_name, u.last_name, u.role
        FROM conversation_participants cp
        JOIN users u ON cp.user_id = u.id
        WHERE cp.conversation_id = $1
        ORDER BY u.role DESC, u.first_name
      `, [conv.id]);

      // Count unread for admins (messages from customers)
      const { rows: unreadRows } = await db.query(`
        SELECT COUNT(*) as unread
        FROM direct_messages dm
        JOIN users u ON dm.sender_id = u.id
        WHERE dm.conversation_id = $1
          AND u.role != 'admin'
          AND dm.created_at > COALESCE(
            (SELECT joined_at FROM conversation_participants WHERE conversation_id = $1 AND user_id = (SELECT id FROM users WHERE role = 'admin' LIMIT 1)),
            '1970-01-01'::timestamp
          )
      `, [conv.id]);

      return {
        ...conv,
        participants,
        unread_count: parseInt(unreadRows[0]?.unread || '0')
      };
    }));

    return NextResponse.json({ conversations });
  } catch (error) {
    console.error('Admin get conversations error:', error);
    return NextResponse.json(
      { error: getErrorMessage(error, 'Failed to get conversations') },
      { status: 500 }
    );
  }
}