/**
 * Settings → Performance
 * Server-side Docker stats (view-interest streams + push cadence).
 */
import { Methods } from '../shared/protocol.js'
import { manager } from '../client/manager.js'
import { presentError } from '../client/errors.js'

/** @type {object|null} */
let statsState = null
let suppressLiveApply = false
/** @type {ReturnType<typeof setTimeout>|null} */
let applyTimer = null
let applyInFlight = false

function showAlert(type, msg) {
  if (typeof window.showAlert === 'function') window.showAlert(type, msg)
  else if (typeof window.peardockOps?.showAlert === 'function') {
    window.peardockOps.showAlert(type, msg)
  }
}

async function rpc(method, args = {}) {
  if (!manager.active?.connected) {
    throw new Error('Connect to a PearDock server to manage stats settings')
  }
  return manager.request(method, args)
}

function setStatus(msg, tone = 'muted') {
  const el = document.getElementById('stats-status')
  if (!el) return
  el.className = `small mt-2 text-${tone === 'danger' ? 'danger' : tone === 'success' ? 'success' : 'muted'}`
  el.textContent = msg || ''
}

function setEngineStatus(text) {
  const el = document.getElementById('stats-engine-status')
  if (el) el.textContent = text || '—'
}

/**
 * Load config from the active server into the form.
 */
export async function loadStatsPanel() {
  const offline = document.getElementById('stats-offline-hint')
  if (!manager.active?.connected) {
    if (offline) offline.classList.remove('hidden')
    setEngineStatus('Not connected')
    const meta = document.getElementById('stats-runtime-meta')
    if (meta) meta.textContent = ''
    return
  }
  if (offline) offline.classList.add('hidden')
  try {
    const res = await rpc(Methods.getStatsConfig || 'getStatsConfig')
    statsState = res?.config || null
    renderStatsForm(statsState)
    setStatus('')
  } catch (err) {
    setStatus(err.message || 'Failed to load stats config', 'danger')
    setEngineStatus('Error loading')
    presentError?.(err, 'getStatsConfig', { showAlert })
  }
}

/**
 * @param {object|null} config
 */
function renderStatsForm(config) {
  if (!config) return
  suppressLiveApply = true
  try {
    const broadcast = document.getElementById('stats-broadcast-sec')
    if (broadcast) {
      broadcast.value = String(
        config.broadcastIntervalSec ?? Math.round((config.broadcastIntervalMs || 1000) / 1000)
      )
    }
    const listSec = document.getElementById('stats-list-sec')
    if (listSec) {
      listSec.value = String(
        config.listIntervalSec ?? Math.round((config.listIntervalMs || 10000) / 1000)
      )
    }
    const warn = document.getElementById('stats-warn-containers')
    if (warn) warn.value = String(config.warnContainers ?? 80)

    // Keep hidden legacy inputs in sync if present
    const collect = document.getElementById('stats-collect-sec')
    if (collect) {
      collect.value = String(
        config.broadcastIntervalSec ?? Math.round((config.broadcastIntervalMs || 1000) / 1000)
      )
    }

    const active = config.active
      ? `streaming · ${config.streams ?? '?'} streams · ${config.watchers ?? 0} watcher(s)`
      : 'idle (no client on Containers/Dashboard)'
    setEngineStatus(active)
    const meta = document.getElementById('stats-runtime-meta')
    if (meta) {
      const parts = [
        `mode=${config.mode || 'interest-stream'}`,
        `peers=${config.peers ?? 0}`,
        `watchers=${config.watchers ?? 0}`,
        `streams=${config.streams ?? 0}`,
        `broadcast=${config.broadcastIntervalMs}ms`,
        `list=${config.listIntervalMs}ms`,
      ]
      if (config.path) parts.push(`file=${config.path}`)
      meta.textContent = parts.join(' · ')
    }
  } finally {
    setTimeout(() => {
      suppressLiveApply = false
    }, 0)
  }
}

function readFormPartial() {
  const broadcastSec = Number(document.getElementById('stats-broadcast-sec')?.value)
  const listSec = Number(document.getElementById('stats-list-sec')?.value)
  const warnContainers = Number(document.getElementById('stats-warn-containers')?.value)
  return {
    broadcastIntervalSec: Number.isFinite(broadcastSec) ? broadcastSec : undefined,
    listIntervalSec: Number.isFinite(listSec) ? listSec : undefined,
    warnContainers: Number.isFinite(warnContainers) ? warnContainers : undefined,
  }
}

function scheduleApply() {
  if (suppressLiveApply) return
  if (!manager.active?.connected) {
    setStatus('Connect to a server to apply changes', 'danger')
    return
  }
  if (applyTimer) clearTimeout(applyTimer)
  setStatus('Applying…', 'muted')
  applyTimer = setTimeout(() => {
    applyTimer = null
    applyLive().catch((err) => {
      setStatus(err.message || 'Apply failed', 'danger')
      presentError?.(err, 'updateStatsConfig', { showAlert })
    })
  }, 400)
}

async function applyLive() {
  if (applyInFlight) {
    scheduleApply()
    return
  }
  applyInFlight = true
  try {
    const partial = readFormPartial()
    const res = await rpc(Methods.updateStatsConfig || 'updateStatsConfig', {
      config: partial,
    })
    statsState = res?.config || statsState
    renderStatsForm(statsState)
    setStatus('Applied on server', 'success')
  } finally {
    applyInFlight = false
  }
}

async function resetDefaults() {
  if (!manager.active?.connected) {
    setStatus('Connect to a server to reset', 'danger')
    return
  }
  try {
    setStatus('Resetting…', 'muted')
    const res = await rpc(Methods.updateStatsConfig || 'updateStatsConfig', {
      replace: true,
      config: {},
    })
    statsState = res?.config || null
    renderStatsForm(statsState)
    setStatus('Reset to server defaults', 'success')
    showAlert?.('success', 'Stats settings reset to defaults')
  } catch (err) {
    setStatus(err.message || 'Reset failed', 'danger')
    presentError?.(err, 'updateStatsConfig', { showAlert })
  }
}

/**
 * Wire change listeners once.
 */
export function initStatsSettings() {
  const panel = document.getElementById('settings-panel-performance')
  if (!panel || panel.dataset.statsWired === '1') return
  panel.dataset.statsWired = '1'

  panel.querySelectorAll('.stats-live-field').forEach((el) => {
    // Skip hidden legacy fields from auto-apply noise
    if (el.type === 'hidden') return
    el.addEventListener('change', () => scheduleApply())
    el.addEventListener('input', () => {
      if (el.tagName === 'INPUT') scheduleApply()
    })
  })

  document.getElementById('stats-refresh')?.addEventListener('click', () => {
    loadStatsPanel().catch(() => {})
  })
  document.getElementById('stats-reset-defaults')?.addEventListener('click', () => {
    resetDefaults().catch(() => {})
  })
}

export default {
  initStatsSettings,
  loadStatsPanel,
}