/**
 * Fleet tab — multi-host roster cards (PearDock-style).
 */

/**
 * @typedef {{
 *   id: string,
 *   publicKeyHex: string,
 *   alias: string,
 *   connected: boolean,
 *   active: boolean,
 *   reconnecting: boolean,
 *   failed: boolean,
 *   attempts: number,
 *   maxAttempts: number,
 *   invite: string|null,
 *   capability: string|null,
 *   adminSeed: string|null,
 *   lastConnectedAt: number|null,
 *   cpu?: number|null,
 *   ram?: number|null,
 *   health?: string|null,
 * }} FleetPeer
 */

/**
 * Merge saved peers + live connections into a sorted roster.
 * @param {{
 *   saved: Array<object>,
 *   live: Array<{ publicKeyHex: string, connected?: boolean }>,
 *   activeId: string|null,
 *   getReconnectInfo: (id: string) => { attempts: number, maxAttempts: number, reconnecting: boolean, failed: boolean },
 * }} opts
 * @returns {FleetPeer[]}
 */
export function buildFleetRoster(opts) {
  const byId = new Map()
  for (const b of opts.saved || []) {
    const id = String(b.publicKeyHex || b.id || '').toLowerCase()
    if (!/^[0-9a-f]{64}$/.test(id)) continue
    byId.set(id, {
      id,
      publicKeyHex: id,
      alias: b.alias || '',
      connected: false,
      active: false,
      reconnecting: false,
      failed: false,
      attempts: 0,
      maxAttempts: 0,
      invite: b.invite || null,
      capability: b.capability || null,
      adminSeed: b.adminSeed || null,
      lastConnectedAt: b.lastConnectedAt || null,
    })
  }
  for (const c of opts.live || []) {
    const id = String(c.publicKeyHex || '').toLowerCase()
    if (!/^[0-9a-f]{64}$/.test(id)) continue
    const prev = byId.get(id) || {
      id,
      publicKeyHex: id,
      alias: '',
      invite: null,
      capability: null,
      adminSeed: null,
      lastConnectedAt: null,
    }
    const info = opts.getReconnectInfo?.(id) || {
      attempts: 0,
      maxAttempts: 0,
      reconnecting: false,
      failed: false,
    }
    byId.set(id, {
      ...prev,
      connected: Boolean(c.connected),
      active: opts.activeId === id,
      reconnecting: Boolean(info.reconnecting) && !c.connected,
      failed: Boolean(info.failed) && !c.connected,
      attempts: info.attempts || 0,
      maxAttempts: info.maxAttempts || 0,
    })
  }
  // Also surface reconnecting peers that dropped from connections map
  for (const [id, peer] of byId) {
    if (peer.connected) continue
    const info = opts.getReconnectInfo?.(id)
    if (!info) continue
    peer.reconnecting = Boolean(info.reconnecting)
    peer.failed = Boolean(info.failed)
    peer.attempts = info.attempts || 0
    peer.maxAttempts = info.maxAttempts || 0
  }

  const rank = (p) => {
    if (p.active && p.connected) return 0
    if (p.connected) return 1
    if (p.reconnecting) return 2
    if (p.failed) return 3
    return 4
  }
  return [...byId.values()].sort((a, b) => {
    const d = rank(a) - rank(b)
    if (d) return d
    return (a.alias || a.id).localeCompare(b.alias || b.id)
  })
}

/**
 * @param {FleetPeer[]} roster
 */
export function summarizeFleet(roster) {
  let live = 0
  let reconnecting = 0
  let failed = 0
  let offline = 0
  for (const p of roster) {
    if (p.connected) live++
    else if (p.reconnecting) reconnecting++
    else if (p.failed) failed++
    else offline++
  }
  return { total: roster.length, live, reconnecting, failed, offline }
}

/**
 * Render Fleet cards into a container.
 * @param {HTMLElement} root
 * @param {FleetPeer[]} roster
 * @param {{
 *   onActivate: (peer: FleetPeer) => void|Promise<void>,
 *   onReconnect: (peer: FleetPeer) => void|Promise<void>,
 *   onForget: (peer: FleetPeer) => void|Promise<void>,
 *   onOpenCharts: (peer: FleetPeer) => void|Promise<void>,
 *   onAlias: (peer: FleetPeer) => void|Promise<void>,
 *   onConnect?: () => void,
 * }} handlers
 */
export function renderFleetCards(root, roster, handlers) {
  if (!root) return
  root.innerHTML = ''

  if (!roster.length) {
    const empty = document.createElement('div')
    empty.className = 'fleet-empty'
    empty.innerHTML = `
      <p class="fleet-empty-title">No agents yet</p>
      <p class="muted">Connect a public key or <code>pd1.</code> invite — saved agents appear here and restore on launch.</p>
      <p class="fleet-empty-actions"></p>
    `
    const actions = empty.querySelector('.fleet-empty-actions')
    if (actions && handlers.onConnect) {
      const go = document.createElement('button')
      go.type = 'button'
      go.className = 'btn btn-primary'
      go.textContent = 'Connect an agent'
      go.addEventListener('click', () => handlers.onConnect?.())
      actions.appendChild(go)
    }
    root.appendChild(empty)
    return
  }

  const grid = document.createElement('div')
  grid.className = 'fleet-grid'
  for (const peer of roster) {
    grid.appendChild(buildCard(peer, handlers))
  }
  root.appendChild(grid)
}

/**
 * @param {FleetPeer} peer
 * @param {object} handlers
 */
function buildCard(peer, handlers) {
  const card = document.createElement('article')
  const state = peer.connected
    ? peer.active
      ? 'active'
      : 'online'
    : peer.reconnecting
      ? 'reconnecting'
      : peer.failed
        ? 'failed'
        : 'offline'
  card.className = `fleet-card fleet-card--${state}`
  card.dataset.fleetId = peer.id

  const title = peer.alias || `${peer.id.slice(0, 12)}…`
  const badge = badgeFor(state, peer)
  const health = healthLine(peer, state)

  const chips = metricChips(peer)

  card.innerHTML = `
    <header class="fleet-card-head">
      <div class="fleet-card-titles">
        <h3 class="fleet-card-title" title="Double-click to rename">${escapeHtml(title)}</h3>
        <p class="fleet-card-key muted">${escapeHtml(peer.id.slice(0, 24))}…</p>
      </div>
      <span class="fleet-badge fleet-badge--${state}">${escapeHtml(badge)}</span>
    </header>
    ${chips}
    <ul class="fleet-card-meta">
      <li><span class="muted">Status</span><strong>${escapeHtml(health)}</strong></li>
      <li><span class="muted">Role</span><strong>${peer.active ? 'Active' : peer.connected ? 'Standby' : '—'}</strong></li>
      <li><span class="muted">Last seen</span><strong>${escapeHtml(formatLastSeen(peer))}</strong></li>
    </ul>
    <footer class="fleet-card-actions"></footer>
  `

  const footer = card.querySelector('.fleet-card-actions')
  appendActions(footer, peer, state, handlers)

  card.querySelector('.fleet-card-title')?.addEventListener('dblclick', (ev) => {
    ev.stopPropagation()
    handlers.onAlias?.(peer)
  })

  return card
}

function badgeFor(state, peer) {
  if (state === 'active') return 'Active'
  if (state === 'online') return 'Online'
  if (state === 'reconnecting') {
    return peer.maxAttempts
      ? `Retry ${peer.attempts}/${peer.maxAttempts}`
      : 'Retrying'
  }
  if (state === 'failed') return 'Failed'
  return 'Offline'
}

function healthLine(peer, state) {
  if (peer.health === 'critical') return 'Critical'
  if (peer.health === 'degraded') return 'Degraded'
  if (state === 'active' || state === 'online') return 'Connected'
  if (state === 'reconnecting') return 'Reconnecting…'
  if (state === 'failed') return 'Max reconnects reached'
  return 'Saved · not connected'
}

/** @param {FleetPeer} peer */
function metricChips(peer) {
  if (!peer.connected && peer.cpu == null && peer.ram == null) return ''
  const cpu =
    peer.cpu != null && Number.isFinite(Number(peer.cpu))
      ? `${Number(peer.cpu).toFixed(0)}%`
      : '—'
  const ram =
    peer.ram != null && Number.isFinite(Number(peer.ram))
      ? `${Number(peer.ram).toFixed(0)} MiB`
      : '—'
  return `<div class="fleet-card-chips" aria-label="Live metrics">
    <span class="fleet-chip"><span class="muted">CPU</span><strong>${escapeHtml(cpu)}</strong></span>
    <span class="fleet-chip"><span class="muted">RAM</span><strong>${escapeHtml(ram)}</strong></span>
  </div>`
}

function formatLastSeen(peer) {
  if (peer.connected) return 'now'
  if (!peer.lastConnectedAt) return '—'
  const age = Math.max(0, Date.now() - Number(peer.lastConnectedAt))
  if (age < 60_000) return 'just now'
  if (age < 3600_000) return `${Math.floor(age / 60_000)}m ago`
  if (age < 86400_000) return `${Math.floor(age / 3600_000)}h ago`
  return `${Math.floor(age / 86400_000)}d ago`
}

function appendActions(footer, peer, state, handlers) {
  if (!footer) return

  if (state === 'active') {
    const active = btn('Active', 'ghost', true)
    footer.appendChild(active)
    footer.appendChild(
      btn('Open Charts', 'ghost', false, () => handlers.onOpenCharts?.(peer))
    )
  } else if (state === 'online') {
    footer.appendChild(
      btn('Set active', 'primary', false, () => handlers.onActivate?.(peer))
    )
    footer.appendChild(
      btn('Charts', 'ghost', false, () => handlers.onOpenCharts?.(peer))
    )
  } else if (state === 'reconnecting') {
    footer.appendChild(btn('Retrying…', 'ghost', true))
  } else {
    footer.appendChild(
      btn('Reconnect', state === 'failed' ? 'warn' : 'ghost', false, () =>
        handlers.onReconnect?.(peer)
      )
    )
  }

  footer.appendChild(
    btn('Forget', 'danger-ghost', false, () => handlers.onForget?.(peer))
  )
}

function btn(label, kind, disabled, onClick) {
  const b = document.createElement('button')
  b.type = 'button'
  b.className =
    kind === 'primary'
      ? 'btn btn-primary'
      : kind === 'warn'
        ? 'btn btn-warn'
        : kind === 'danger-ghost'
          ? 'btn btn-ghost danger'
          : 'btn btn-ghost'
  b.textContent = label
  b.disabled = Boolean(disabled)
  if (onClick) {
    b.addEventListener('click', (ev) => {
      ev.stopPropagation()
      onClick()
    })
  }
  return b
}

function escapeHtml(s) {
  return String(s)
    .replace(/&/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
}