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

const inviteSchema = z.object({
  role: z.enum(['editor', 'viewer']).default('editor'),
  expiresInHours: z.number().min(1).max(168).default(24),
  email: z.string().email().optional(),
})

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

  try {
    const { sessionId } = await params
    const { isParticipant } = await verifyParticipant(sessionId, session.user.id, 'host')

    if (!isParticipant) {
      return NextResponse.json({ error: 'Only the host can invite' }, { status: 403 })
    }

    const body = await request.json()
    const { role: inviteRole, expiresInHours, email } = inviteSchema.parse(body)

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

    if (!brainstormSession) {
      return NextResponse.json({ error: 'Session not found' }, { status: 404 })
    }

    let token = brainstormSession.inviteToken
    let expiry = brainstormSession.inviteExpiry

    if (!token || (expiry && expiry < new Date())) {
      token = crypto.randomBytes(24).toString('hex')
      expiry = new Date(Date.now() + expiresInHours * 60 * 60 * 1000)
      await prisma.brainstormSession.update({
        where: { id: sessionId },
        data: { inviteToken: token, inviteExpiry: expiry },
      })
    }

    const inviteUrl = `/brainstorm?invite=${token}`

    if (email) {
      const recipient = await prisma.user.findUnique({
        where: { email },
        select: { id: true, name: true, email: true },
      })

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

      if (recipient.id === session.user.id) {
        return NextResponse.json({ error: 'Cannot invite yourself' }, { status: 400 })
      }

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

      if (existing) {
        return NextResponse.json({ error: 'Already a participant' }, { status: 409 })
      }

      await prisma.notification.create({
        data: {
          userId: recipient.id,
          type: 'brainstorm_invite',
          title: brainstormSession.seedIdea.length > 50
            ? brainstormSession.seedIdea.substring(0, 50) + '…'
            : brainstormSession.seedIdea,
          message: `${session.user.name || 'Someone'} invited you to a brainstorm session`,
          actionUrl: inviteUrl,
          relatedId: sessionId,
        },
      })

      await logActivity(sessionId, 'invite_created', session.user.id, {
        role: inviteRole,
        targetEmail: email,
        targetUserId: recipient.id,
      })

      return NextResponse.json({
        success: true,
        mode: 'email',
        invitedUser: { name: recipient.name, email: recipient.email },
        inviteUrl,
        expiresAt: expiry,
      })
    }

    await logActivity(sessionId, 'invite_created', session.user.id, { role: inviteRole })

    return NextResponse.json({
      success: true,
      mode: 'link',
      inviteUrl,
      token,
      expiresAt: expiry,
    })
  } catch (error: any) {
    if (error instanceof z.ZodError) {
      return NextResponse.json({ error: error.issues }, { status: 400 })
    }
    console.error('Error creating invite:', error)
    return NextResponse.json({ error: 'Failed to create invite' }, { status: 500 })
  }
}