import { NextResponse } from 'next/server'
import { auth } from '@/auth'
import prisma from '@/lib/prisma'
import { agentSuggestionService } from '@/lib/ai/services/agent-suggestion.service'
import { bridgeNotesService } from '@/lib/ai/services/bridge-notes.service'
import { buildDashboardPaths, buildOpenLoops } from '@/lib/dashboard/paths.service'
import { hasUserAiConsent } from '@/lib/consent/server-consent'
import { getSystemConfig } from '@/lib/config'
import { getChatProvider } from '@/lib/ai/factory'

function excerptNoteContent(content: string | null | undefined, max = 200): string {
  if (!content) return ''
  const plain = content.replace(/<[^>]+>/g, ' ').replace(/&nbsp;/g, ' ').replace(/\s+/g, ' ').trim()
  if (plain.length <= max) return plain
  return `${plain.slice(0, max)}…`
}

interface PathsBriefingSnapshot {
  recentNote?: {
    id: string
    title: string | null
    content: string
    notebookId: string | null
  } | null
  inboxCount?: number
  dueFlashcards?: number
  insights?: Array<{
    id: string
    insight: string
    score: number
    viewed: boolean
    note1: { id: string; title: string | null }
    note2: { id: string; title: string | null }
    note1Excerpt?: string
    note2Excerpt?: string
  }>
  bridgeSuggestions?: Array<{
    clusterAId: number
    clusterBId: number
    clusterAName: string
    clusterBName: string
    suggestedTitle: string
    suggestedContent: string
    justification: string
  }>
  agentSuggestions?: Array<{
    id: string
    topic: string
    reason: string
    clusterId: number | null
  }>
  includeOpenLoops?: boolean
}

async function resolvePathsPayload(userId: string, snapshot?: PathsBriefingSnapshot | null) {
  const now = new Date()
  const hasSnapshot = !!snapshot?.recentNote

  const needsAgents = !snapshot?.agentSuggestions
  const needsBridges = !snapshot?.bridgeSuggestions
  const needsInsights = !snapshot?.insights
  const needsCounts = snapshot?.inboxCount === undefined || snapshot?.dueFlashcards === undefined
  const needsFocusNote = !snapshot?.recentNote

  const [
    aiConsent,
    aiSettings,
    systemConfig,
    recentNotes,
    inboxCount,
    dueFlashcards,
    unviewedInsights,
    agentSuggestions,
    bridgeSuggestions,
  ] = await Promise.all([
    hasUserAiConsent(),
    prisma.userAISettings.findUnique({
      where: { userId },
      select: { memoryEcho: true },
    }),
    getSystemConfig(),
    needsFocusNote
      ? prisma.note.findMany({
          where: { userId, trashedAt: null, isArchived: false },
          select: { id: true, title: true, content: true, notebookId: true, updatedAt: true },
          orderBy: { updatedAt: 'desc' },
          take: 1,
        })
      : Promise.resolve([]),
    needsCounts
      ? prisma.note.count({
          where: { userId, notebookId: null, isArchived: false, trashedAt: null },
        })
      : Promise.resolve(snapshot!.inboxCount!),
    needsCounts
      ? prisma.flashcard.count({
          where: { deck: { userId }, nextReviewAt: { lte: now } },
        })
      : Promise.resolve(snapshot!.dueFlashcards!),
    needsInsights
      ? prisma.memoryEchoInsight.findMany({
          where: { userId, dismissed: false },
          select: {
            id: true, insight: true, similarityScore: true, viewed: true,
            note1: { select: { id: true, title: true, content: true } },
            note2: { select: { id: true, title: true, content: true } },
          },
          orderBy: { insightDate: 'desc' },
          take: 5,
        }).catch(() => [])
      : Promise.resolve([]),
    needsAgents
      ? agentSuggestionService.getPending(userId, 3).catch(() => [])
      : Promise.resolve([]),
    needsBridges
      ? bridgeNotesService.getBridgeSuggestions(userId).catch(() => [])
      : Promise.resolve([]),
  ])

  const aiProviderReady = !!getChatProvider(systemConfig)
  const memoryEchoEnabled = aiSettings?.memoryEcho ?? true
  const aiActive = aiConsent && aiProviderReady && memoryEchoEnabled

  const focusNotes = hasSnapshot && snapshot?.recentNote
    ? [{
        ...snapshot.recentNote,
        updatedAt: now,
      }]
    : recentNotes

  const insights = snapshot?.insights ?? unviewedInsights.map(i => ({
    id: i.id,
    insight: i.insight,
    score: i.similarityScore,
    viewed: i.viewed,
    note1: { id: i.note1.id, title: i.note1.title },
    note2: { id: i.note2.id, title: i.note2.title },
    note1Excerpt: excerptNoteContent(i.note1.content),
    note2Excerpt: excerptNoteContent(i.note2.content),
  }))

  const resolvedBridges = snapshot?.bridgeSuggestions
    ?? bridgeSuggestions.slice(0, 3).map(s => ({
      clusterAId: s.clusterAId,
      clusterBId: s.clusterBId,
      clusterAName: s.clusterAName,
      clusterBName: s.clusterBName,
      suggestedTitle: s.suggestedTitle,
      suggestedContent: s.suggestedContent,
      justification: s.justification,
    }))

  const resolvedAgents = snapshot?.agentSuggestions
    ?? agentSuggestions.map(s => ({
      id: s.id,
      topic: s.topic,
      reason: s.reason,
      clusterId: s.clusterId,
    }))

  const paths = await buildDashboardPaths({
    userId,
    aiActive,
    recentNotes: focusNotes,
    inboxCount: needsCounts ? inboxCount : snapshot!.inboxCount!,
    dueFlashcards: needsCounts ? dueFlashcards : snapshot!.dueFlashcards!,
    insights,
    bridgeSuggestions: resolvedBridges,
    agentSuggestions: resolvedAgents,
  }).catch(() => [])

  const openLoops = snapshot?.includeOpenLoops === false
    ? []
    : await buildOpenLoops(userId).catch(() => [])

  return { paths, openLoops }
}

/**
 * GET /api/briefing/paths — pistes enrichies (fallback sans snapshot client).
 */
export async function GET() {
  const session = await auth()
  if (!session?.user?.id) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
  }

  const payload = await resolvePathsPayload(session.user.id)
  return NextResponse.json(payload)
}

/**
 * POST /api/briefing/paths — enrichissement avec snapshot briefing (évite re-fetch agents/ponts).
 */
export async function POST(request: Request) {
  const session = await auth()
  if (!session?.user?.id) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
  }

  const snapshot = await request.json().catch(() => null) as PathsBriefingSnapshot | null
  const payload = await resolvePathsPayload(session.user.id, snapshot)
  return NextResponse.json(payload)
}