import { NextRequest, NextResponse } from 'next/server'
import prisma from '@/lib/prisma'
import { auth } from '@/auth'
import { runLaneWithBillingUser } from '@/lib/ai/provider-for-user'
import { getSystemConfig } from '@/lib/config'
import { verifyParticipant } from '@/lib/brainstorm-collab'

function localeToLanguageName(locale?: string): string {
  const map: Record<string, string> = {
    en: 'English', fr: 'French', es: 'Spanish', de: 'German',
    it: 'Italian', pt: 'Portuguese', nl: 'Dutch', ru: 'Russian',
    zh: 'Chinese', ja: 'Japanese', ko: 'Korean', ar: 'Arabic',
    fa: 'Farsi', hi: 'Hindi', pl: 'Polish',
  }
  return map[locale ?? ''] ?? 'English'
}

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 body = await request.json().catch(() => ({}))
    const locale: string = body.locale || 'en'

    const brainstormSession = await prisma.brainstormSession.findFirst({
      where: { id: sessionId },
      include: {
        ideas: {
          where: { status: { not: 'dismissed' } },
          orderBy: [{ waveNumber: 'asc' }, { createdAt: 'asc' }],
        },
      },
    })

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

    const { isParticipant } = await verifyParticipant(sessionId, session.user.id, 'viewer')
    if (!isParticipant) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 403 })
    }

    const ideas = brainstormSession.ideas
    if (ideas.length === 0) {
      return NextResponse.json({ error: 'No ideas to summarize' }, { status: 400 })
    }

    const ideasText = ideas
      .map((idea, i) => `${i + 1}. [Wave ${idea.waveNumber}] ${idea.title}: ${idea.description}`)
      .join('\n')

    const starredIdeas = ideas.filter(i => i.isStarred)
    const starredText = starredIdeas.length > 0
      ? `\nStarred/favorite ideas: ${starredIdeas.map(i => i.title).join(', ')}`
      : ''

    const language = localeToLanguageName(locale)

    const prompt = `You are summarizing a brainstorming session. Respond in ${language}.

Seed idea: "${brainstormSession.seedIdea}"

Ideas generated (${ideas.length} total):
${ideasText}${starredText}

Write a concise synthesis (4-6 sentences) that:
1. Captures the main themes and directions explored
2. Highlights the most promising ideas or clusters
3. Suggests a concrete next step

Be direct and action-oriented. No bullet points, just flowing prose.`

    const config = await getSystemConfig()
    const { result: summary } = await runLaneWithBillingUser(
      'tags',
      config,
      session.user.id,
      (provider) => provider.generateText(prompt),
    )

    return NextResponse.json({ success: true, data: { summary: summary.trim() } })
  } catch (error) {
    console.error('Error summarizing brainstorm:', error)
    return NextResponse.json({ error: 'Failed to summarize' }, { status: 500 })
  }
}