import { NextRequest, NextResponse } from 'next/server';
import { z } from 'zod';
import { prisma, getTenantPrisma } from '@/lib/prisma';
import {
  generateJitsiToken,
  generateJitsiMeetingUrl,
  JITSI_DOMAIN,
} from '@/lib/jitsi';

const JoinRequestSchema = z.object({
  userId: z.string().min(1, 'userId is required'),
  role: z.enum(['INSTRUCTOR', 'CLIENT', 'SUPER_ADMIN']).optional(),
});

export async function POST(
  req: NextRequest,
  context: { params: Promise<{ id: string }> }
) {
  try {
    const { id: classSessionId } = await context.params;
    const body = await req.json();
    const validated = JoinRequestSchema.parse(body);

    // 1. Fetch ClassSession with its parent Tenant and existing bookings
    const session = await prisma.classSession.findUnique({
      where: { id: classSessionId },
      include: {
        tenant: true,
        bookings: {
          include: {
            user: true,
          },
        },
      },
    });

    if (!session) {
      return NextResponse.json(
        { error: 'Class session not found' },
        { status: 404 }
      );
    }

    // 2. Fetch User and verify tenant membership
    const user = await prisma.user.findUnique({
      where: { id: validated.userId },
    });

    if (!user) {
      return NextResponse.json(
        { error: 'User not found' },
        { status: 404 }
      );
    }

    if (user.tenantId !== session.tenantId) {
      return NextResponse.json(
        { error: 'Cross-tenant access forbidden. User does not belong to this tenant.' },
        { status: 403 }
      );
    }

    const effectiveRole = validated.role || user.role;
    const isInstructor = effectiveRole === 'INSTRUCTOR' || effectiveRole === 'SUPER_ADMIN';

    // 3. For CLIENT, validate booking or enroll if space is available
    let booking = session.bookings.find((b) => b.userId === user.id);

    if (!isInstructor) {
      if (!booking) {
        // Check capacity
        if (session.bookings.length >= session.capacity) {
          return NextResponse.json(
            { error: 'Class is full. Maximum capacity reached.' },
            { status: 409 }
          );
        }

        // Auto-enroll client into booking
        const tenantPrisma = getTenantPrisma(session.tenantId);
        booking = await tenantPrisma.booking.create({
          data: {
            tenantId: session.tenantId,
            userId: user.id,
            classSessionId: session.id,
            status: 'CONFIRMED',
            signedWaiverAt: new Date(),
          },
          include: {
            user: true,
          },
        });
      } else if (booking.status === 'CANCELLED') {
        return NextResponse.json(
          { error: 'Booking for this class has been cancelled.' },
          { status: 403 }
        );
      }
    }

    // 4. Generate JWT room authentication token
    const token = generateJitsiToken({
      roomName: session.jitsiRoomId,
      tenantSlug: session.tenant.slug,
      user: {
        id: user.id,
        name: user.name || (isInstructor ? 'Instructor' : 'Athlete'),
        email: user.email,
        role: effectiveRole,
      },
      expiresInSeconds: 7200, // 2 hours
    });

    // 5. Construct full meeting URL
    const meetingUrl = generateJitsiMeetingUrl(session.jitsiRoomId, token);

    return NextResponse.json({
      success: true,
      roomName: session.jitsiRoomId,
      token,
      meetingUrl,
      domain: JITSI_DOMAIN,
      user: {
        id: user.id,
        name: user.name || 'Participant',
        email: user.email,
        role: effectiveRole,
        isHost: isInstructor,
      },
      session: {
        id: session.id,
        title: session.title,
        description: session.description,
        startTime: session.startTime,
        endTime: session.endTime,
        capacity: session.capacity,
        currentParticipants: session.bookings.length,
      },
      tenant: {
        id: session.tenant.id,
        name: session.tenant.name,
        slug: session.tenant.slug,
      },
    });
  } catch (error: any) {
    if (error instanceof z.ZodError) {
      return NextResponse.json(
        { error: 'Validation failed', details: error.issues },
        { status: 400 }
      );
    }

    console.error('Error joining classroom:', error);
    return NextResponse.json(
      { error: error.message || 'Internal server error' },
      { status: 500 }
    );
  }
}