import { NextRequest, NextResponse } from 'next/server'
import prisma from '@/lib/prisma'
import { auth } from '@/auth'
import { z } from 'zod'
import { logActivity } from '@/lib/brainstorm-collab'

const joinSchema = z.object({
  token: z.string().min(1),
})

export async function POST(request: NextRequest) {
  const session = await auth()
  if (!session?.user?.id) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
  }

  try {
    const body = await request.json()
    const { token } = joinSchema.parse(body)

    const brainstormSession = await prisma.brainstormSession.findFirst({
      where: { inviteToken: token },
      select: { id: true, inviteExpiry: true, userId: true, seedIdea: true },
    })

    if (!brainstormSession) {
      return NextResponse.json({ error: 'Invalid invite token' }, { status: 404 })
    }

    if (brainstormSession.inviteExpiry && brainstormSession.inviteExpiry < new Date()) {
      return NextResponse.json({ error: 'Invite expired' }, { status: 410 })
    }

    const existing = await prisma.brainstormParticipant.findFirst({
      where: { sessionId: brainstormSession.id, userId: session.user.id },
    })

    if (existing) {
      return NextResponse.json({
        success: true,
        sessionId: brainstormSession.id,
        role: existing.role,
      })
    }

    const participant = await prisma.brainstormParticipant.create({
      data: {
        sessionId: brainstormSession.id,
        userId: session.user.id,
        role: 'editor',
      },
    })

    await logActivity(brainstormSession.id, 'joined', session.user.id)

    try {
      const joinerName = session.user.name || 'Someone'
      const seedPreview = brainstormSession.seedIdea.length > 40
        ? brainstormSession.seedIdea.substring(0, 40) + '…'
        : brainstormSession.seedIdea
      await prisma.notification.create({
        data: {
          userId: brainstormSession.userId,
          type: 'brainstorm_joined',
          title: `${joinerName} joined your brainstorm`,
          message: seedPreview,
          actionUrl: `/brainstorm?session=${brainstormSession.id}`,
          relatedId: brainstormSession.id,
        },
      })
    } catch {}

    return NextResponse.json({
      success: true,
      sessionId: brainstormSession.id,
      role: participant.role,
    }, { status: 201 })
  } catch (error: any) {
    if (error instanceof z.ZodError) {
      return NextResponse.json({ error: error.issues }, { status: 400 })
    }
    console.error('Error joining brainstorm:', error)
    return NextResponse.json({ error: 'Failed to join' }, { status: 500 })
  }
}