// ── uo-link WebSocket ingest client ────────────────────────────────────────
//
// Long-lived client that connects to the sidecar's push-only WS feed and pumps
// every frame through the ingest dispatcher. This is the server's first
// outbound WebSocket. Lifecycle:
//   • start()  — connect if the config is enabled and has a token; verify the
//                ws.hello protocol; backfill missed events via /history on every
//                (re)connect (INSERT IGNORE dedupes the overlap); reconnect with
//                capped backoff.
//   • stop()   — close the socket and stop reconnecting (graceful shutdown).
// Connection state is mirrored into uo_link_config (plugin_connected / status /
// last_event_at) so the admin panel and public status endpoint have live data.

const WebSocket = require('ws')

const uoLinkConfig = require('../model/uoLinkConfig/uoLinkConfig.model')
const uoLinkClient = require('./uoLinkClient')
const shardIngest = require('./shardIngest')
const log = require('./logger')('uo-link-socket')

const BACKOFF_MIN_MS = 1000
const BACKOFF_MAX_MS = 30000
const BACKFILL_LIMIT = 500

let ws = null
let reconnectTimer = null
let backoff = BACKOFF_MIN_MS
let running = false // set by start()/stop(); guards auto-reconnect
let helloSeen = false

const state = {
  connected: false,
  lastEventAt: null,
  lastConnectedAt: null,
  reconnects: 0,
  protocol: null,
}

function buildUrl(wsUrl, token) {
  const sep = wsUrl.includes('?') ? '&' : '?'
  return token ? `${wsUrl}${sep}token=${encodeURIComponent(token)}` : wsUrl
}

// Pull recent events from the sidecar's own store and replay them through the
// dispatcher (fromBackfill = no SSE re-broadcast). dedupe_key + INSERT IGNORE
// make this idempotent, so overlap with what we already stored is harmless.
async function backfill() {
  try {
    const hist = await uoLinkClient.getHistory({ limit: BACKFILL_LIMIT })
    if (hist.ok && hist.data && Array.isArray(hist.data.events)) {
      // History is newest-first; replay oldest-first so latest-wins state (e.g.
      // house.decay stage) settles correctly.
      const events = [...hist.data.events].reverse()
      for (const ev of events) await shardIngest.ingest(ev, { fromBackfill: true })
      log.info('backfilled events from /history', { count: events.length })
    }
    const eco = await uoLinkClient.getEconomy(200)
    if (eco.ok && eco.data && Array.isArray(eco.data.series)) {
      const series = [...eco.data.series].reverse()
      for (const ev of series) await shardIngest.ingest(ev, { fromBackfill: true })
    }
  } catch (err) {
    log.warn('backfill failed (continuing on live feed)', { message: err.message })
  }
}

function scheduleReconnect() {
  if (!running) return
  clearTimeout(reconnectTimer)
  reconnectTimer = setTimeout(connect, backoff)
  log.info(`reconnecting in ${backoff}ms`)
  backoff = Math.min(backoff * 2, BACKOFF_MAX_MS)
}

async function connect() {
  if (!running) return
  let config
  try {
    config = await uoLinkConfig.getWithToken()
  } catch (err) {
    log.error('could not read uo-link config', err)
    scheduleReconnect()
    return
  }
  if (!config || !config.enabled || !config.wsUrl || !config.token) {
    log.info('uo-link WS not started (disabled or missing url/token)')
    running = false
    return
  }

  state.protocol = config.protocol || 1
  helloSeen = false
  const url = buildUrl(config.wsUrl, config.token)

  try {
    ws = new WebSocket(url)
  } catch (err) {
    log.error('failed to open WS', err)
    scheduleReconnect()
    return
  }

  ws.on('open', async () => {
    log.info('uo-link WS connected')
    state.connected = true
    state.lastConnectedAt = Date.now()
    backoff = BACKOFF_MIN_MS
    await uoLinkConfig.recordStatus({ status: 'connected', statusDetail: null, pluginConnected: true }).catch(() => {})
    await backfill()
  })

  ws.on('message', async (raw) => {
    let event
    try {
      event = JSON.parse(raw.toString())
    } catch {
      log.warn('dropping non-JSON WS frame')
      return
    }

    if (event.kind === 'ws.hello') {
      helloSeen = true
      if (event.protocol && event.protocol !== state.protocol) {
        log.error('uo-link protocol mismatch on ws.hello — closing', {
          expected: state.protocol,
          got: event.protocol,
        })
        await uoLinkConfig
          .recordStatus({ status: 'error', statusDetail: `protocol mismatch: expected ${state.protocol}, got ${event.protocol}` })
          .catch(() => {})
        running = false
        try {
          ws.close()
        } catch {
          /* ignore */
        }
      }
      return
    }
    if (event.kind === 'pong') return // sidecar heartbeat — ignore

    state.lastEventAt = Number.isFinite(event.t) ? event.t : Date.now()
    await shardIngest.ingest(event)
  })

  ws.on('close', async () => {
    state.connected = false
    if (running) state.reconnects += 1
    log.warn('uo-link WS closed')
    await uoLinkConfig
      .recordStatus({ status: running ? 'reconnecting' : 'disconnected', pluginConnected: false })
      .catch(() => {})
    ws = null
    scheduleReconnect()
  })

  ws.on('error', (err) => {
    log.warn('uo-link WS error', { message: err.message })
    // 'close' fires after 'error'; reconnect is scheduled there.
  })
}

// Begin (or restart) the WS client. Idempotent — a running client is stopped
// first so a config save can re-point it at a new URL/token.
async function start() {
  stop()
  running = true
  backoff = BACKOFF_MIN_MS
  await connect()
}

// Stop the client and cancel any pending reconnect. Called on shutdown and
// before a restart.
function stop() {
  running = false
  clearTimeout(reconnectTimer)
  reconnectTimer = null
  if (ws) {
    try {
      ws.removeAllListeners()
      ws.close()
    } catch {
      /* ignore */
    }
    ws = null
  }
  state.connected = false
}

// Ingestion stats for the admin panel.
function getState() {
  return { ...state, running }
}

module.exports = { start, stop, getState }