import { NextRequest, NextResponse } from 'next/server'
import prisma from '@/lib/prisma'
import { auth } from '@/auth'
import { z } from 'zod'
import { runLaneWithBillingUser, willUseByokForLane } from '@/lib/ai/provider-for-user'
import { getSystemConfig } from '@/lib/config'
import { embeddingService } from '@/lib/ai/services/embedding.service'
import {
  checkSessionEntitlementOrThrow,
  QuotaExceededError,
} from '@/lib/entitlements'
import {
  billingOwnerFromSession,
  verifyParticipant,
  resolveAiContextUserId,
  sanitizeNotesForGuest,
  captureSnapshot,
  logActivity,
} from '@/lib/brainstorm-collab'
import { emitToSession } from '@/lib/socket-emit'

const expandSchema = z.object({
  ideaId: z.string().min(1),
  locale: z.string().optional(),
})

interface ParentNoteRef {
  noteId: string | null
  relation: string
  explanation: string
  noteTitle?: string | null
  noteSnippet?: string
}

// [UPDATE - SÉCURITÉ] allowedNoteIds : null = hôte (accès total), string[] = invité (IDs publics uniquement)
async function getParentContext(
  ideaId: string,
  hostUserId: string,
  allowedNoteIds: string[] | null
): Promise<{ notes: ParentNoteRef[]; noteIds: string[] }> {
  const refs = await prisma.brainstormNoteRef.findMany({
    where: { ideaId },
    include: { note: { select: { id: true, title: true, content: true } } },
  })

  const noteIds = refs.map(r => r.noteId).filter(Boolean) as string[]

  const notes: ParentNoteRef[] = refs.map(r => ({
    noteId: r.noteId,
    relation: r.relation,
    explanation: r.explanation,
    noteTitle: r.note?.title || null,
    noteSnippet: (r.note?.content || '').slice(0, 200),
  }))

  // [UPDATE - SÉCURITÉ] Enrichissement vectoriel uniquement pour l'hôte
  const isGuest = allowedNoteIds !== null
  if (!isGuest && noteIds.length < 3) {
    try {
      const idea = await prisma.brainstormIdea.findUnique({ where: { id: ideaId } })
      if (idea) {
        const embedding = await embeddingService.generateEmbedding(`${idea.title} ${idea.description}`)
        const vectorStr = embeddingService.toVectorString(embedding.embedding)
        const excludeList = noteIds.length > 0
          ? noteIds.map(id => `'${id}'`).join(',')
          : "''"
        const extra = await prisma.$queryRawUnsafe(
          `SELECT n.id, n.title
           FROM "NoteEmbedding" e
           JOIN "Note" n ON n.id = e."noteId"
           WHERE n."userId" = $1 AND n."trashedAt" IS NULL AND n.id NOT IN (${excludeList})
           ORDER BY e.embedding::vector <=> $2::vector
           LIMIT 5`,
          hostUserId, vectorStr
        ) as any[]
        for (const n of extra) {
          if (!noteIds.includes(n.id)) {
            noteIds.push(n.id)
            notes.push({ noteId: n.id, relation: 'extends', explanation: `Related to your note "${n.title}"`, noteTitle: n.title })
          }
        }
      }
    } catch {}
  }

  // [UPDATE - SÉCURITÉ] Filtrer selon les permissions invité
  if (isGuest) {
    const allowedSet = new Set(allowedNoteIds)
    return {
      notes: notes.filter(n => n.noteId === null || allowedSet.has(n.noteId!)),
      noteIds: noteIds.filter(id => allowedSet.has(id)),
    }
  }

  return { notes, noteIds }
}

function buildExpandPromptV2(
  parentTitle: string,
  parentDesc: string,
  seedIdea: string,
  parentRefs: ParentNoteRef[],
  extraNotes: { id: string; title: string; snippet: string }[],
  locale?: string
): string {
  let notesSection = ''
  const allNotes = [
    ...parentRefs.filter(r => r.noteId).map(r => ({
      id: r.noteId!,
      title: r.noteTitle || 'Untitled',
      snippet: r.noteSnippet || '',
      relation: r.relation,
    })),
    ...extraNotes,
  ]

  if (allNotes.length > 0) {
    notesSection = `\nUSER'S NOTES (context from parent idea and knowledge base):\n`
    notesSection += allNotes.map(n => `- [ID: ${n.id}] "${n.title}": ${n.snippet || 'See note for details'}`).join('\n')
  }

  return `You are a creative brainstorming assistant. The user wants to DEEPEN a specific idea from a brainstorming session. Generate 3 waves of sub-ideas that CROSS with the user's existing notes.

ORIGINAL SESSION SEED: ${seedIdea}
PARENT IDEA TO EXPAND: ${parentTitle}: ${parentDesc}
${notesSection}

GENERATION RULES:

WAVE 1 — VARIATIONS (3 sub-ideas):
- Direct expansions, details, or implementations of the parent idea
- At least 1 should build on a note referenced above

WAVE 2 — ANALOGIES (3 sub-ideas):
- Cross-domain parallels from other fields
- At least 1 should transpose a pattern from the user's notes

WAVE 3 — DISRUPTIONS (3 sub-ideas):
- Radical inversions or challenges to the parent idea
- At least 1 should synthesize or oppose a note concept

RESPOND ONLY with a valid JSON array of 9 objects:
{
  "wave": number (1, 2, or 3),
  "title": string (short, 2-6 words),
  "description": string (1-2 sentences, specific and actionable),
  "connectionToSeed": string (how it relates to the parent idea),
  "noveltyScore": number (1-10),
  "noteRefs": [
    {
      "noteId": string (must match an ID provided above, or null),
      "relation": "derived_from" | "opposes" | "extends" | "synthesizes" | "transposes",
      "explanation": string
    }
  ]
}

  CRITICAL: Each idea MUST have at least 1 noteRef when notes are provided.

LANGUAGE: You MUST write ALL titles, descriptions, connectionToSeed, and explanation fields in ${locale === 'fr' ? 'French' : locale === 'es' ? 'Spanish' : locale === 'de' ? 'German' : locale === 'it' ? 'Italian' : locale === 'pt' ? 'Portuguese' : locale === 'nl' ? 'Dutch' : locale === 'ru' ? 'Russian' : locale === 'zh' ? 'Chinese' : locale === 'ja' ? 'Japanese' : locale === 'ko' ? 'Korean' : locale === 'ar' ? 'Arabic' : locale === 'fa' ? 'Farsi' : locale === 'hi' ? 'Hindi' : locale === 'pl' ? 'Polish' : 'the same language as the seed idea'}.`
}

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()
    const { ideaId, locale } = expandSchema.parse(body)

    // [UPDATE - SÉCURITÉ] Vérification du rôle participant (couvre hôte + invités éditeurs)
    const { isParticipant } = await verifyParticipant(sessionId, session.user.id, 'editor')
    if (!isParticipant) {
      return NextResponse.json({ error: 'No edit permission' }, { status: 403 })
    }

    const brainstormSession = await prisma.brainstormSession.findFirst({
      where: { id: sessionId },
      include: { ideas: true },
    })

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

    const { billingOwnerId, isGuestActor } = billingOwnerFromSession(
      brainstormSession.userId,
      session.user.id,
    )
    // Story 3.5: per-provider BYOK bypass
    const earlyConfig = await getSystemConfig()
    const { usedByok: willUseByok } = await willUseByokForLane('tags', earlyConfig, billingOwnerId)
    if (!willUseByok) {
      await checkSessionEntitlementOrThrow(
        billingOwnerId,
        session.user.id,
        isGuestActor,
        'brainstorm_expand',
      )
    }

    const parentIdea = (brainstormSession.ideas || []).find(i => i.id === ideaId)
    if (!parentIdea) {
      return NextResponse.json({ error: 'Idea not found' }, { status: 404 })
    }

    // [UPDATE - SÉCURITÉ] Résoudre le périmètre de notes autorisé selon le rôle
    const { isGuest, publicNoteIds, aiUserId } = await resolveAiContextUserId(sessionId, session.user.id)

    const { notes: parentRefs, noteIds } = await getParentContext(ideaId, aiUserId, isGuest ? (publicNoteIds ?? []) : null)

    let extraNotes: { id: string; title: string; snippet: string }[] = []
    if (noteIds.length > 0) {
      const dbNotes = await prisma.note.findMany({
        where: { id: { in: noteIds }, trashedAt: null },
        select: { id: true, title: true, content: true },
      })
      const rawNotes = dbNotes.map(n => ({ id: n.id, title: n.title || 'Untitled', summary: (n.content || '').slice(0, 200) }))
      // [UPDATE - SÉCURITÉ] Sanitize le contenu si invité
      const sanitized = isGuest ? sanitizeNotesForGuest(rawNotes) : rawNotes
      extraNotes = sanitized.map(n => ({ id: n.id, title: n.title, snippet: n.summary }))
    }

    const config = await getSystemConfig()

    const prompt = buildExpandPromptV2(
      parentIdea.title,
      parentIdea.description,
      brainstormSession.seedIdea,
      parentRefs,
      extraNotes,
      locale
    )

    const { result: llmResponse } = await runLaneWithBillingUser(
      'tags',
      config,
      billingOwnerId,
      (provider) => provider.generateText(prompt),
    )

    let newIdeas: any[]
    try {
      const cleaned = llmResponse.replace(/```json\n?/g, '').replace(/```\n?/g, '').trim()
      newIdeas = JSON.parse(cleaned)
      if (!Array.isArray(newIdeas)) throw new Error('Not an array')
    } catch {
      const pickNote = (idx: number) => {
        const n = extraNotes[idx % extraNotes.length]
        return n ? { noteId: n.id, relation: 'extends' as const, explanation: `Related to "${n.title}"` } : { noteId: null, relation: 'extends' as const, explanation: 'Purely generative' }
      }
      newIdeas = [
        { wave: 1, title: 'Sub-variation A', description: 'Direct expansion.', connectionToSeed: 'Expansion', noveltyScore: 4, noteRefs: [pickNote(0)] },
        { wave: 1, title: 'Sub-variation B', description: 'Another angle.', connectionToSeed: 'Detail', noveltyScore: 5, noteRefs: [pickNote(1)] },
        { wave: 1, title: 'Sub-variation C', description: 'Implementation detail.', connectionToSeed: 'Implementation', noveltyScore: 3, noteRefs: [pickNote(2)] },
        { wave: 2, title: 'Sub-analogy A', description: 'Cross-domain parallel.', connectionToSeed: 'Analogy', noveltyScore: 7, noteRefs: [pickNote(0)] },
        { wave: 2, title: 'Sub-analogy B', description: 'From another field.', connectionToSeed: 'Parallel', noveltyScore: 6, noteRefs: [pickNote(1)] },
        { wave: 2, title: 'Sub-analogy C', description: 'Inspired by nature.', connectionToSeed: 'Bio-inspired', noveltyScore: 7, noteRefs: [pickNote(2)] },
        { wave: 3, title: 'Sub-disruption A', description: 'Challenge assumption.', connectionToSeed: 'Inversion', noveltyScore: 9, noteRefs: [{ ...pickNote(0), relation: 'opposes' as const }] },
        { wave: 3, title: 'Sub-disruption B', description: 'Remove constraint.', connectionToSeed: 'Removal', noveltyScore: 8, noteRefs: [{ ...pickNote(1), relation: 'synthesizes' as const }] },
        { wave: 3, title: 'Sub-disruption C', description: 'Radical reframe.', connectionToSeed: 'Reframe', noveltyScore: 10, noteRefs: [pickNote(2)] },
      ]
    }

    const validNoteIds = new Set(extraNotes.map(n => n.id))

    for (let idx = 0; idx < newIdeas.length; idx++) {
      const idea = newIdeas[idx]
      const angle = (idx % 3) * (2 * Math.PI / 3) + (idea.wave - 1) * 0.5
      const baseRadius = 150
      const parentRadius = (parentIdea.positionX && parentIdea.positionY)
        ? Math.sqrt(parentIdea.positionX ** 2 + parentIdea.positionY ** 2)
        : 0
      const radius = parentRadius + idea.wave * baseRadius
      const baseAngle = (parentIdea.positionX && parentIdea.positionY)
        ? Math.atan2(parentIdea.positionY, parentIdea.positionX)
        : 0

      const created = await prisma.brainstormIdea.create({
        data: {
          sessionId,
          waveNumber: idea.wave || Math.floor(idx / 3) + 1,
          title: idea.title || `Idea ${idx + 1}`,
          description: idea.description || '',
          connectionToSeed: idea.connectionToSeed || null,
          noveltyScore: idea.noveltyScore || null,
          parentIdeaId: ideaId,
          positionX: Math.cos(baseAngle + angle) * radius,
          positionY: Math.sin(baseAngle + angle) * radius,
        },
      })

      if (idea.noteRefs && Array.isArray(idea.noteRefs)) {
        for (const ref of idea.noteRefs) {
          const noteId = ref.noteId && validNoteIds.has(ref.noteId) ? ref.noteId : null
          await prisma.brainstormNoteRef.create({
            data: {
              ideaId: created.id,
              noteId,
              relation: ref.relation || 'extends',
              explanation: ref.explanation || '',
            },
          })
        }
      }
    }

    const updatedSession = await prisma.brainstormSession.findUnique({
      where: { id: sessionId },
      include: {
        ideas: {
          orderBy: [{ waveNumber: 'asc' }, { createdAt: 'asc' }],
          include: {
            noteRefs: {
              include: {
                note: { select: { id: true, title: true } },
              },
            },
          },
        },
      },
    })

    const cIds = [...new Set((updatedSession?.ideas || []).map((i: any) => i.createdBy).filter(Boolean))]
    if (cIds.length > 0) {
      const crs = await prisma.user.findMany({ where: { id: { in: cIds } }, select: { id: true, name: true, image: true } })
      const cm = new Map(crs.map((c: any) => [c.id, c]))
      for (const idea of updatedSession?.ideas || []) { (idea as any).creator = (idea as any).createdBy ? cm.get((idea as any).createdBy) || null : null }
    }

    await logActivity(sessionId, 'wave_generated', session.user.id, { count: newIdeas.length, parentIdeaId: ideaId })

    await emitToSession(sessionId, 'activity:new', {
      action: 'wave_generated',
      userId: session.user.id,
      userName: session.user.name || 'Guest',
      details: { count: newIdeas.length, parentIdeaId: ideaId }
    })
    // Trigger refetch for all participants
    await emitToSession(sessionId, 'idea:added', {})

    await captureSnapshot(sessionId, `Wave expanded: ${parentIdea.title}`).catch(() => {})

    return NextResponse.json({ success: true, data: updatedSession })
  } catch (error: any) {
    if (error instanceof QuotaExceededError) {
      return NextResponse.json(error.toJSON(), { status: 402 })
    }
    if (error instanceof z.ZodError) {
      return NextResponse.json({ error: error.issues }, { status: 400 })
    }
    console.error('Error expanding idea:', error)
    return NextResponse.json(
      { error: error.message || 'Failed to expand idea' },
      { status: 500 }
    )
  }
}