/**
 * GET /api/chat/sse — Server-Sent Events stream for real-time chat messages
 */
import { subscribe, authorConnected, authorDisconnected, isAuthorOnline, userConnected, userDisconnected } from "#server/service/chat"
import { getCurrentUser } from "#server/utils/context"

export default defineEventHandler(async (event) => {
  const res = event.node.res

  const user = await getCurrentUser(event)
  const isAuthor = user?.role === 'admin'
  const userId = user?.id

  // Register connection BEFORE sending connected event (so isAuthorOnline is accurate)
  if (isAuthor) authorConnected()
  if (userId) userConnected(String(userId))

  res.writeHead(200, {
    'Content-Type': 'text/event-stream',
    'Cache-Control': 'no-cache, no-transform',
    'Connection': 'keep-alive',
    'X-Accel-Buffering': 'no',
  })

  // Send actual global author online status (not just the connecting user's role)
  res.write(`data: ${JSON.stringify({ type: 'connected', authorOnline: isAuthorOnline() })}\n\n`)

  const unsub = subscribe((msg) => {
    // msg is either a ChatMessage object or a status-string from broadcastStatus
    if (typeof msg === 'string') {
      // Status broadcast: send directly (already JSON: {"type":"authorOnline","data":true})
      res.write(`data: ${msg}\n\n`)
    } else {
      res.write(`data: ${JSON.stringify({ type: 'message', data: msg })}\n\n`)
    }
  })

  const heartbeat = setInterval(() => {
    res.write(': heartbeat\n\n')
  }, 30_000)

  event.node.req.on('close', () => {
    unsub()
    clearInterval(heartbeat)
    if (isAuthor) authorDisconnected()
    if (userId) userDisconnected(String(userId))
  })

  await new Promise<void>((resolve) => {
    event.node.req.on('close', () => resolve())
  })
})