import { NextRequest, NextResponse } from 'next/server';
import { getServerSession } from 'next-auth';
import { authOptions } from '@/lib/auth';
import { db } from '@/lib/db';
import { classes, periods, eq } from '@/lib/db/schema';

export async function GET() {
  try {
    const session = await getServerSession(authOptions);
    
    if (!session?.user || session.user.role !== 'admin') {
      return NextResponse.json(
        { error: 'No autorizado' },
        { status: 401 }
      );
    }

    const allClasses = await db
      .select({
        id: classes.id,
        name: classes.name,
        code: classes.code,
        credits: classes.credits,
        description: classes.description,
        periodId: classes.periodId,
        isActive: classes.isActive,
        createdAt: classes.createdAt,
        period: {
          id: periods.id,
          name: periods.name,
          startDate: periods.startDate,
          endDate: periods.endDate,
          isActive: periods.isActive,
        },
      })
      .from(classes)
      .leftJoin(periods, eq(classes.periodId, periods.id))
      .orderBy(classes.name);

    return NextResponse.json(allClasses);
  } catch (error) {
    console.error('Error fetching classes:', error);
    return NextResponse.json(
      { error: 'Error interno del servidor' },
      { status: 500 }
    );
  }
}

export async function POST(request: NextRequest) {
  try {
    const session = await getServerSession(authOptions);
    
    if (!session?.user || session.user.role !== 'admin') {
      return NextResponse.json(
        { error: 'No autorizado' },
        { status: 401 }
      );
    }

    const { name, code, credits, description, periodId } = await request.json();

    // Validaciones
    if (!name || !code || !credits || !periodId) {
      return NextResponse.json(
        { error: 'Nombre, código, créditos y período académico son requeridos' },
        { status: 400 }
      );
    }

    if (typeof credits !== 'number' || credits < 1) {
      return NextResponse.json(
        { error: 'Los créditos deben ser un número mayor a 0' },
        { status: 400 }
      );
    }

    // Verificar si ya existe una clase con el mismo código
    const existingClass = await db
      .select()
      .from(classes)
      .where(eq(classes.code, code))
      .limit(1);

    if (existingClass.length > 0) {
      return NextResponse.json(
        { error: 'Ya existe una clase con este código' },
        { status: 400 }
      );
    }

    // Crear clase
    const [newClass] = await db
      .insert(classes)
      .values({
        name,
        code,
        credits,
        description: description || null,
        periodId,
        isActive: true,
      })
      .returning({
        id: classes.id,
        name: classes.name,
        code: classes.code,
        credits: classes.credits,
        description: classes.description,
        periodId: classes.periodId,
        isActive: classes.isActive,
        createdAt: classes.createdAt,
      });

    return NextResponse.json(newClass, { status: 201 });
  } catch (error) {
    console.error('Error creating class:', error);
    return NextResponse.json(
      { error: 'Error interno del servidor' },
      { status: 500 }
    );
  }
}