// app/api/admin/allowed-students/route.ts
import { NextResponse } from 'next/server';
import type { NextRequest } from 'next/server';
import { getServerSession } from 'next-auth';
import { authOptions } from '@/lib/auth-options';
import { prisma } from '@/lib/prisma';
import { normalizeEmail } from '@/lib/normalize-email';

// Check if user is admin
async function checkAdmin(req: NextRequest) {
  const session = await getServerSession(authOptions);
  if (!session?.user?.email) {
    return null;
  }

  const role = (session as any)?.user?.role ?? null;
  if (!(role === 'admin' || role === 'superadmin')) {
    return null;
  }

  return session;
}

// GET all allowed students
export async function GET(req: NextRequest) {
  try {
    const session = await checkAdmin(req);
    if (!session) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
    }

    const students = await prisma.allowedStudent.findMany({
      orderBy: { createdAt: 'desc' },
    });

    return NextResponse.json(students);
  } catch (err) {
    console.error('GET /api/admin/allowed-students error', err);
    return NextResponse.json(
      { error: 'Failed to fetch allowed students' },
      { status: 500 }
    );
  }
}

// POST create new allowed student
export async function POST(req: NextRequest) {
  try {
    const session = await checkAdmin(req);
    if (!session) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
    }

    const body = await req.json();
    const { email, levels } = body;
    const normalizedEmail = normalizeEmail(email);

    if (!normalizedEmail || !levels) {
      return NextResponse.json(
        { error: 'Email and levels required' },
        { status: 400 }
      );
    }

    // Validate levels are valid course codes
    const levelArray = levels.split(',').map((l: string) => l.trim());
    for (const level of levelArray) {
      const course = await prisma.course.findUnique({ where: { code: level } });
      if (!course) {
        return NextResponse.json(
          { error: `Course code '${level}' not found` },
          { status: 400 }
        );
      }
    }

    // Check if student already exists
    const existing = await prisma.allowedStudent.findFirst({
      where: {
        email: {
          equals: normalizedEmail,
          mode: 'insensitive',
        },
      },
    });

    if (existing) {
      return NextResponse.json(
        { error: 'Email already registered' },
        { status: 409 }
      );
    }

    const student = await prisma.allowedStudent.create({
      data: {
        email: normalizedEmail,
        levels: levelArray.join(','),
        active: true,
      },
    });

    return NextResponse.json(student, { status: 201 });
  } catch (err) {
    console.error('POST /api/admin/allowed-students error', err);
    return NextResponse.json(
      { error: 'Failed to create allowed student' },
      { status: 500 }
    );
  }
}

// PUT update allowed student
export async function PUT(req: NextRequest) {
  try {
    const session = await checkAdmin(req);
    if (!session) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
    }

    const body = await req.json();
    const { id, email, levels, active } = body;
    const normalizedEmail = email ? normalizeEmail(email) : null;

    if (!id) {
      return NextResponse.json({ error: 'Student ID required' }, { status: 400 });
    }

    if (email && !normalizedEmail) {
      return NextResponse.json({ error: 'Valid email required' }, { status: 400 });
    }

    // Validate levels if provided
    if (levels) {
      const levelArray = levels.split(',').map((l: string) => l.trim());
      for (const level of levelArray) {
        const course = await prisma.course.findUnique({ where: { code: level } });
        if (!course) {
          return NextResponse.json(
            { error: `Course code '${level}' not found` },
            { status: 400 }
          );
        }
      }
    }

    const student = await prisma.allowedStudent.update({
      where: { id },
      data: {
        ...(normalizedEmail && { email: normalizedEmail }),
        ...(levels && { levels }),
        ...(active !== undefined && { active }),
      },
    });

    return NextResponse.json(student);
  } catch (err) {
    console.error('PUT /api/admin/allowed-students error', err);
    return NextResponse.json(
      { error: 'Failed to update allowed student' },
      { status: 500 }
    );
  }
}

// DELETE allowed student
export async function DELETE(req: NextRequest) {
  try {
    const session = await checkAdmin(req);
    if (!session) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
    }

    const { searchParams } = new URL(req.url);
    const id = searchParams.get('id');

    if (!id) {
      return NextResponse.json({ error: 'Student ID required' }, { status: 400 });
    }

    await prisma.allowedStudent.delete({
      where: { id },
    });

    return NextResponse.json({ message: 'Student removed' });
  } catch (err) {
    console.error('DELETE /api/admin/allowed-students error', err);
    return NextResponse.json(
      { error: 'Failed to delete allowed student' },
      { status: 500 }
    );
  }
}