import { NextResponse } from 'next/server';
import { prisma } from '@/lib/db';
import { getCurrentAdmin, AdminPermission, hasPermission } from '@/lib/admin-auth';

export const runtime = 'nodejs';

export async function GET(request: Request) {
  try {
    const admin = await getCurrentAdmin(request as any);
    if (!admin || !hasPermission(admin, AdminPermission.READ_CHAT)) {
      return NextResponse.json(
        { error: 'Unauthorized' },
        { status: 401 }
      );
    }

    const url = new URL(request.url);
    const page = parseInt(url.searchParams.get('page') || '0');
    const pageSize = parseInt(url.searchParams.get('pageSize') || '10');
    const search = url.searchParams.get('search') || '';
    const status = url.searchParams.get('status') || 'all';
    const language = url.searchParams.get('language') || 'all';
    const sortBy = url.searchParams.get('sortBy') || 'lastMessage';

    // Build where clause for filtering
    const where: any = {};
    if (search) {
      where.OR = [
        { title: { contains: search, mode: 'insensitive' } },
        { user: { email: { contains: search, mode: 'insensitive' } } },
        { user: { name: { contains: search, mode: 'insensitive' } } }
      ];
    }
    if (status !== 'all') {
      where.isActive = status === 'active';
    }
    if (language !== 'all') {
      where.language = language;
    }

    // Build order by clause
    let orderBy: any = { lastMessageAt: 'desc' };
    switch (sortBy) {
      case 'created':
        orderBy = { createdAt: 'desc' };
        break;
      case 'messageCount':
        orderBy = { messages: { _count: 'desc' } };
        break;
      case 'lastMessage':
      default:
        orderBy = { lastMessageAt: 'desc' };
        break;
    }

    // Get total count for pagination
    const total = await prisma.chatConversation.count({ where });

    // Get conversations with pagination
    const conversations = await prisma.chatConversation.findMany({
      where,
      select: {
        id: true,
        title: true,
        language: true,
        isActive: true,
        createdAt: true,
        updatedAt: true,
        lastMessageAt: true,
        user: {
          select: {
            id: true,
            email: true,
            name: true,
            role: true
          }
        },
        _count: {
          select: {
            messages: true
          }
        },
        messages: {
          select: {
            id: true,
            role: true,
            content: true,
            timestamp: true
          },
          orderBy: {
            timestamp: 'desc'
          },
          take: 1
        }
      },
      orderBy,
      skip: page * pageSize,
      take: pageSize
    });

    // Add conversation statistics
    const stats = {
      total: await prisma.chatConversation.count(),
      active: await prisma.chatConversation.count({ where: { isActive: true } }),
      inactive: await prisma.chatConversation.count({ where: { isActive: false } }),
      today: await prisma.chatConversation.count({
        where: {
          createdAt: {
            gte: new Date(new Date().setHours(0, 0, 0, 0))
          }
        }
      }),
      thisWeek: await prisma.chatConversation.count({
        where: {
          createdAt: {
            gte: new Date(Date.now() - 7 * 24 * 60 * 60 * 1000)
          }
        }
      })
    };

    return NextResponse.json({
      conversations,
      stats,
      pagination: {
        page,
        pageSize,
        total,
        totalPages: Math.ceil(total / pageSize)
      }
    });

  } catch (error) {
    console.error('Admin chat conversations list error:', error);
    return NextResponse.json(
      { error: 'Server error' },
      { status: 500 }
    );
  }
}