// ST-1104: User-scoped Server-Sent Events stream voor de notificatie-bel (M11).
//
// Wordt door <NotificationsBridge /> in app/(app)/layout.tsx gemount zodra de
// gebruiker is ingelogd. In tegenstelling tot /api/realtime/solo (product-
// scoped, voor één Solo-bord) is deze stream **user-scoped**: hij filtert
// op alle producten waar de ingelogde user toegang toe heeft, zodat de bell
// flikkert ongeacht op welke pagina je staat.
//
// Auth: iron-session cookie. Demo-tokens mogen lezen.
// Output: text/event-stream — `event:state` met initial open-questions list,
// daarna `data:` events bij elke status-overgang in scrum4me_changes.
// Sluit zelf na 240s als safety-net; client herconnect.

import { NextRequest } from 'next/server'
import { Client } from 'pg'
import { getSession } from '@/lib/auth'
import { prisma } from '@/lib/prisma'
import { productAccessFilter } from '@/lib/product-access'
import { closePgClientSafely } from '@/lib/realtime/pg-client-cleanup'

export const runtime = 'nodejs'
export const dynamic = 'force-dynamic'
export const maxDuration = 300

const CHANNEL = 'scrum4me_changes'
const HEARTBEAT_MS = 25_000
const HARD_CLOSE_MS = 240_000

// Question-payloads: emitted by the notify_question_change trigger on
// claude_questions. story_id and idea_id are mutually exclusive (DB-level
// check-constraint added in M12).
interface QuestionPayload {
  op: 'I' | 'U'
  entity: 'question'
  id: string
  product_id: string
  story_id?: string | null
  task_id?: string | null
  idea_id?: string | null
  assignee_id?: string | null
  status?: string
}

// Idea-job-payloads: emitted by actions/ideas.ts (startGrillJobAction etc.)
// via prisma.$executeRaw pg_notify. Always carries user_id + idea_id + kind.
interface IdeaJobPayload {
  type: 'claude_job_enqueued' | 'claude_job_status'
  job_id: string
  idea_id: string
  user_id: string
  product_id?: string | null
  kind: 'IDEA_GRILL' | 'IDEA_MAKE_PLAN' | 'PLAN_CHAT'
  status: string
}

// UserQuestion-payloads: emitted by app/api/user-questions/[id]/answer and
// actions/user-questions.ts via prisma.$executeRaw pg_notify.
interface UserQuestionPayload {
  op: 'I' | 'U'
  entity: 'user_question'
  id: string
  idea_id: string
  status: 'pending' | 'answered'
}

type NotifyPayload = QuestionPayload | IdeaJobPayload | UserQuestionPayload

function isQuestionPayload(p: NotifyPayload): p is QuestionPayload {
  return 'entity' in p && p.entity === 'question'
}

function isUserQuestionPayload(p: NotifyPayload): p is UserQuestionPayload {
  return 'entity' in p && p.entity === 'user_question'
}

function isIdeaJobPayload(p: NotifyPayload): p is IdeaJobPayload {
  return (
    'type' in p &&
    (p.type === 'claude_job_enqueued' || p.type === 'claude_job_status') &&
    'idea_id' in p &&
    'kind' in p &&
    (p.kind === 'IDEA_GRILL' || p.kind === 'IDEA_MAKE_PLAN' || p.kind === 'PLAN_CHAT')
  )
}

export async function GET(request: NextRequest) {
  const session = await getSession()
  if (!session.userId) {
    return Response.json({ error: 'Niet ingelogd' }, { status: 401 })
  }
  const userId = session.userId

  // Haal alle accessible product-IDs één keer op — gebruikt voor SSE-filter en
  // voor de initial-state query. Geen real-time refresh als de user halverwege
  // toegang krijgt of verliest; reconnect lost dat op (frontend doet dat al).
  const products = await prisma.product.findMany({
    where: { archived: false, ...productAccessFilter(userId) },
    select: { id: true },
  })
  const accessibleProductIds = new Set(products.map((p) => p.id))

  // M12: idea-questions zijn strikt user_id-only (geen productAccessFilter).
  // We pre-fetchen de user's idea-ids zodat we snel kunnen filteren op het
  // SSE-pad — geen DB-call per event.
  const userIdeas = await prisma.idea.findMany({
    where: { user_id: userId },
    select: { id: true },
  })
  const accessibleIdeaIds = new Set(userIdeas.map((i) => i.id))

  const directUrl = process.env.DIRECT_URL ?? process.env.DATABASE_URL
  if (!directUrl) {
    return Response.json(
      { error: 'DIRECT_URL/DATABASE_URL niet geconfigureerd' },
      { status: 500 },
    )
  }

  const encoder = new TextEncoder()
  const pgClient = new Client({ connectionString: directUrl })

  let heartbeatTimer: ReturnType<typeof setInterval> | null = null
  let hardCloseTimer: ReturnType<typeof setTimeout> | null = null
  let closed = false

  const stream = new ReadableStream({
    async start(controller) {
      const enqueue = (chunk: string) => {
        if (closed) return
        try {
          controller.enqueue(encoder.encode(chunk))
        } catch {
          // controller al gesloten — negeren
        }
      }

      const cleanup = async (reason: string) => {
        if (closed) return
        closed = true
        if (heartbeatTimer) clearInterval(heartbeatTimer)
        if (hardCloseTimer) clearTimeout(hardCloseTimer)
        await closePgClientSafely(pgClient, 'realtime/notifications')
        try {
          controller.close()
        } catch {
          // already closed
        }
        if (process.env.NODE_ENV !== 'production') {
          console.log(`[realtime/notifications] closed: ${reason}`)
        }
      }

      try {
        await pgClient.connect()
        await pgClient.query(`LISTEN ${CHANNEL}`)
      } catch (err) {
        console.error('[realtime/notifications] pg connect/listen failed:', err)
        enqueue(
          `event: error\ndata: ${JSON.stringify({ message: 'pg connect failed' })}\n\n`,
        )
        await cleanup('pg connect failed')
        return
      }

      pgClient.on('notification', (msg) => {
        if (!msg.payload) return
        let payload: NotifyPayload
        try {
          payload = JSON.parse(msg.payload) as NotifyPayload
        } catch {
          return
        }

        if (isIdeaJobPayload(payload)) {
          // M12: idea-jobs zijn user-scoped, niet product-scoped.
          if (payload.user_id !== userId) return
          enqueue(`data: ${msg.payload}\n\n`)
          return
        }

        // UserQuestion (PLAN_CHAT answer-event): user-scoped via idea ownership.
        if (isUserQuestionPayload(payload)) {
          if (!accessibleIdeaIds.has(payload.idea_id)) return
          enqueue(`data: ${msg.payload}\n\n`)
          return
        }

        if (!isQuestionPayload(payload)) return

        // Idea-question: alleen voor de eigenaar van het idee.
        if (payload.idea_id) {
          if (!accessibleIdeaIds.has(payload.idea_id)) return
          enqueue(`data: ${msg.payload}\n\n`)
          return
        }

        // Story-question: bestaande product-access-check.
        if (!accessibleProductIds.has(payload.product_id)) return
        enqueue(`data: ${msg.payload}\n\n`)
      })

      pgClient.on('error', (err) => {
        console.error('[realtime/notifications] pg client error:', err)
        cleanup('pg error')
      })

      // Initial state ná LISTEN actief — race-fix conform M10 ST-1004 / ST-1006.
      // Voorkomt dat een vraag die net vóór SSE-open landt verloren gaat.
      // M12 hotfix: óók idea-questions (user-private), zodat de bel
      // gehydrateerd blijft na elke close+reconnect-cycle.
      const [storyOpen, ideaOpen] = await Promise.all([
        prisma.claudeQuestion.findMany({
          where: {
            status: 'open',
            expires_at: { gt: new Date() },
            product_id: { in: products.map((p) => p.id) },
          },
          orderBy: { created_at: 'desc' },
          take: 100,
          select: {
            id: true,
            product_id: true,
            story_id: true,
            task_id: true,
            question: true,
            options: true,
            created_at: true,
            expires_at: true,
            story: { select: { code: true, title: true, assignee_id: true } },
          },
        }),
        prisma.claudeQuestion.findMany({
          where: {
            status: 'open',
            expires_at: { gt: new Date() },
            idea: { user_id: userId },
          },
          orderBy: { created_at: 'desc' },
          take: 100,
          select: {
            id: true,
            product_id: true,
            idea_id: true,
            question: true,
            options: true,
            created_at: true,
            expires_at: true,
            idea: { select: { id: true, code: true, title: true } },
          },
        }),
      ])

      const stateQuestions = [
        ...storyOpen.flatMap((q) => {
          if (!q.story || q.story_id === null) return []
          return [{
            kind: 'story' as const,
            id: q.id,
            product_id: q.product_id,
            story_id: q.story_id,
            task_id: q.task_id,
            story_code: q.story.code,
            story_title: q.story.title,
            assignee_id: q.story.assignee_id,
            question: q.question,
            options: q.options,
            created_at: q.created_at.toISOString(),
            expires_at: q.expires_at.toISOString(),
          }]
        }),
        ...ideaOpen.flatMap((q) => {
          if (!q.idea || q.idea_id === null) return []
          return [{
            kind: 'idea' as const,
            id: q.id,
            product_id: q.product_id,
            idea_id: q.idea_id,
            idea_code: q.idea.code,
            idea_title: q.idea.title,
            question: q.question,
            options: q.options,
            created_at: q.created_at.toISOString(),
            expires_at: q.expires_at.toISOString(),
          }]
        }),
      ].sort((a, b) => (a.created_at < b.created_at ? 1 : -1))

      const userQuestionsInit = await prisma.userQuestion.findMany({
        where: { idea: { user_id: userId } },
        orderBy: { created_at: 'desc' },
        take: 100,
        select: { id: true, idea_id: true, question: true, answer: true, status: true, created_at: true },
      })

      enqueue(`event: state\ndata: ${JSON.stringify({ questions: stateQuestions, userQuestions: userQuestionsInit.map(uq => ({ ...uq, created_at: uq.created_at.toISOString() })) })}\n\n`)

      heartbeatTimer = setInterval(() => {
        enqueue(`: heartbeat\n\n`)
      }, HEARTBEAT_MS)

      hardCloseTimer = setTimeout(() => {
        cleanup('hard close 240s')
      }, HARD_CLOSE_MS)

      request.signal.addEventListener('abort', () => {
        cleanup('client aborted')
      })
    },
  })

  return new Response(stream, {
    headers: {
      'Content-Type': 'text/event-stream; charset=utf-8',
      'Cache-Control': 'no-cache, no-transform',
      Connection: 'keep-alive',
      'X-Accel-Buffering': 'no',
    },
  })
}