/**
 * GET /api/chats/unread-count
 * Retorna contagem de usuários únicos com mensagens não vistas
 */
import { type NextRequest, NextResponse } from "next/server";
import { requireAuth } from "@/lib/auth/middleware";
import { connectMongoDB } from "@/lib/mongodb/connection";
import { Chat } from "@/lib/mongodb/models/Chat";
import { secureLogger } from "@/lib/secure-logger";

export async function GET(request: NextRequest) {
  try {
    const authResult = await requireAuth(request);
    if (authResult instanceof NextResponse) return authResult;
    const auth = authResult;

    await connectMongoDB();

    // Buscar todos os chats do usuário
    const chats = await Chat.find({
      $or: [{ buyer_id: auth.userId }, { seller_id: auth.userId }],
      is_active: true,
    });

    // Calcular contagem de usuários únicos com mensagens não vistas
    const uniqueUsersWithUnread = new Set<number>();

    chats.forEach((chat) => {
      let unreadCount = 0;
      let otherUserId: number;

      if (chat.buyer_id === auth.userId) {
        unreadCount = chat.buyer_unread_count;
        otherUserId = chat.seller_id;
      } else {
        unreadCount = chat.seller_unread_count;
        otherUserId = chat.buyer_id;
      }

      // Se há mensagens não vistas, adicionar o outro usuário ao Set
      if (unreadCount > 0) {
        uniqueUsersWithUnread.add(otherUserId);
      }
    });

    return NextResponse.json(
      {
        success: true,
        count: uniqueUsersWithUnread.size,
        totalUnreadMessages: chats.reduce((total, chat) => {
          if (chat.buyer_id === auth.userId) {
            return total + chat.buyer_unread_count;
          }
          return total + chat.seller_unread_count;
        }, 0),
      },
      { status: 200 },
    );
  } catch (error) {
    secureLogger.error("❌ Erro ao buscar contagem de chats não lidos", {
      error: error instanceof Error ? error.message : "Erro desconhecido",
      stack: error instanceof Error ? error.stack : undefined,
    });

    return NextResponse.json(
      { success: false, error: "Erro ao buscar contagem" },
      { status: 500 },
    );
  }
}