import { Component, ReactNode, useEffect, useRef, useState } from 'react'

// ---- spinners ----
export function Spinner({ size = 14 }: { size?: number }) {
  return <span className="spin" style={{ width: size, height: size }} aria-hidden="true" />
}
// The × in the corner of a detail pane. A drawn cross rather than the × glyph, which sits
// differently in every font and theme.
export function CloseBtn({ onClick, title = 'Close' }: { onClick: () => void; title?: string }) {
  return (
    <button type="button" className="detail-close" title={title} aria-label={title} onClick={onClick}>
      <svg width="14" height="14" viewBox="0 0 14 14" aria-hidden="true"><path d="M2 2l10 10M12 2L2 12" stroke="currentColor" strokeWidth="1.8" strokeLinecap="round" fill="none" /></svg>
    </button>
  )
}

// A filled bar. Red past 95%, amber past 85%, unless the caller says otherwise.
export function Meter({ frac, cls }: { frac: number; cls?: string }) {
  const c = cls ?? (frac >= 0.95 ? 'bad' : frac >= 0.85 ? 'warn' : '')
  return <div className="meter"><div className={'fill ' + c} style={{ width: `${Math.min(100, Math.max(0, frac * 100))}%` }} /></div>
}

export function Loading({ label = 'Loading…' }: { label?: string }) {
  return <div className="center muted loading"><Spinner size={22} /><div>{label}</div></div>
}

// Button that shows a spinner while its async handler runs; `confirm` asks first.
export function Btn({ onClick, busy, confirm, className = 'btn', disabled, title, children }: {
  onClick: () => unknown | Promise<unknown>; busy?: boolean; confirm?: string; className?: string; disabled?: boolean; title?: string; children: ReactNode
}) {
  const [inner, setInner] = useState(false)
  const b = !!busy || inner
  return (
    <button className={className + (b ? ' busy' : '')} disabled={disabled || b} title={title}
      onClick={async () => {
        if (confirm && !(await askYes(confirm))) return
        const r = onClick()
        if (r && typeof (r as Promise<unknown>).then === 'function') {
          setInner(true)
          try { await r } finally { setInner(false) }
        }
      }}>
      {b && <Spinner />}{children}
    </button>
  )
}

// ---- toasts: short feedback for actions ----
interface Toast { id: number; kind: 'ok' | 'err' | 'info'; msg: string }
const listeners = new Set<(t: Toast[]) => void>()
let toasts: Toast[] = []
let seq = 0
function emit() { listeners.forEach((l) => l(toasts)) }
export function dismissToast(id: number) { toasts = toasts.filter((t) => t.id !== id); emit() }
export function toast(msg: string, kind: Toast['kind'] = 'ok') {
  const t = { id: ++seq, kind, msg }
  toasts = [...toasts.slice(-4), t]
  emit()
  window.setTimeout(() => dismissToast(t.id), kind === 'err' ? 8000 : 3500)
}
export function Toasts() {
  const [list, setList] = useState(toasts)
  useEffect(() => { listeners.add(setList); return () => { listeners.delete(setList) } }, [])
  return (
    <div className="toasts">
      {list.map((t) => <div key={t.id} className={'toast ' + t.kind} onClick={() => dismissToast(t.id)}>{t.msg}</div>)}
    </div>
  )
}

// act runs an action and toasts its outcome. Returns whether it succeeded.
export async function act(label: string, fn: () => Promise<unknown>): Promise<boolean> {
  try { await fn(); toast(label); return true }
  catch (e) { toast(`${label} — ${e instanceof Error ? e.message : 'failed'}`, 'err'); return false }
}

// ---- thin activity bar at the top while any request is in flight ----
export function NetBar() {
  const [n, setN] = useState(0)
  useEffect(() => {
    const h = (e: Event) => setN((e as CustomEvent<number>).detail)
    window.addEventListener('hamlab:inflight', h)
    return () => window.removeEventListener('hamlab:inflight', h)
  }, [])
  return <div className={'netbar' + (n > 0 ? ' on' : '')} />
}

// useEscape runs fn when Escape is pressed while active — every menu and dialog closes that way.
// A question (askYes/askText) sits on top of whatever asked it: Escape answers the question and
// goes no further, or one key would cancel the question and close the dialog underneath as well.
let escapeTaken: Event | null = null
export function useEscape(fn: () => void, active = true, isAsk = false) {
  const ref = useRef(fn); ref.current = fn
  useEffect(() => {
    if (!active) return
    const h = (e: KeyboardEvent) => {
      if (e.key !== 'Escape') return
      if (isAsk) { escapeTaken = e; ref.current() } else if (asks.length === 0 && escapeTaken !== e) ref.current()
    }
    window.addEventListener('keydown', h)
    return () => window.removeEventListener('keydown', h)
  }, [active])
}

// ---- dialogs: askYes / askText replace the browser's confirm() and prompt() ----
// Same promise shape as the natives (false / null on cancel), drawn like the rest of the
// console, usable on a phone, closed by Escape or a tap outside.
interface Ask { id: number; msg: string; input?: string; ok: string; danger: boolean; done: (v: string | boolean | null) => void }
let asks: Ask[] = []
let nextId = 0
const askListeners = new Set<(a: Ask[]) => void>()
const emitAsks = () => askListeners.forEach((l) => l(asks))
function ask(msg: string, input: string | undefined, ok?: string): Promise<string | boolean | null> {
  return new Promise((resolve) => {
    const id = ++nextId
    const danger = /^(delete|remove|revoke|close|send sig|stop|disable|reset|discard|force)/i.test(msg) || /\bforce\b/i.test(msg)
    asks = [...asks, { id, msg, input, ok: ok ?? (input !== undefined ? 'OK' : danger ? msg.split(/[ ?]/)[0] : 'OK'), danger, done: (v) => { asks = asks.filter((a) => a.id !== id); emitAsks(); resolve(v) } }]
    emitAsks()
  })
}
export const askYes = (msg: string, ok?: string) => ask(msg, undefined, ok) as Promise<boolean>
export const askText = (msg: string, initial = '', ok?: string) => ask(msg, initial, ok) as Promise<string | null>

function AskBox({ a }: { a: Ask }) {
  const [val, setVal] = useState(a.input ?? '')
  const cancel = () => a.done(a.input !== undefined ? null : false)
  const accept = () => a.done(a.input !== undefined ? val : true)
  useEscape(cancel, true, true)
  return (
    <div className="modal-back ask-back" onClick={cancel}>
      <form className="modal ask" onClick={(e) => e.stopPropagation()} onSubmit={(e) => { e.preventDefault(); accept() }}>
        <div className="ask-msg">{a.msg}</div>
        {a.input !== undefined && <input autoFocus value={val} onChange={(e) => setVal(e.target.value)} onFocus={(e) => e.target.select()} spellCheck={false} autoCapitalize="off" autoCorrect="off" />}
        <div className="svc-actions">
          <button type="submit" autoFocus={a.input === undefined} className={'btn ' + (a.danger ? 'danger' : 'on')}>{a.ok}</button>
          <span className="spacer" />
          <button type="button" className="btn" onClick={cancel}>Cancel</button>
        </div>
      </form>
    </div>
  )
}
export function Dialogs() {
  const [list, setList] = useState<Ask[]>(asks)
  useEffect(() => { askListeners.add(setList); return () => { askListeners.delete(setList) } }, [])
  const top = list[list.length - 1]
  return top ? <AskBox key={top.id} a={top} /> : null
}

// Unsaved work: whoever holds some says so, and whoever is about to navigate away asks.
let unsaved = ''
export function setUnsaved(what: string) { unsaved = what }
export const hasUnsaved = () => unsaved !== ''
export async function okToLeave(): Promise<boolean> {
  if (!unsaved || (await askYes(`Discard unsaved changes to ${unsaved}?`, 'Discard'))) { unsaved = ''; return true }
  return false
}

// A page that throws takes the whole console down with it: React unmounts the tree, and what
// is left is a blank window with no clue in it. The VPN tab did exactly that on a machine
// whose tunnel list came back null. So each page is rendered inside one of these, and a fault
// costs that page rather than the session — the rail, the switcher and every other tab still
// work, and the error says which page and what it said.
export class PageBoundary extends Component<{ page: string; children: ReactNode }, { err: Error | null }> {
  constructor(props: { page: string; children: ReactNode }) {
    super(props)
    this.state = { err: null }
  }
  static getDerivedStateFromError(err: Error) { return { err } }
  componentDidCatch(err: Error) { console.error('page failed:', err) }
  // A different page is a different mount; clear the fault when the page changes.
  componentDidUpdate(prev: { page: string }) { if (prev.page !== this.props.page && this.state.err) this.setState({ err: null }) }
  render() {
    if (!this.state.err) return this.props.children
    return (
      <div className="dash">
        <div className="dash-bar"><h2 className="section">{this.props.page}</h2></div>
        <section className="card">
          <div className="error">This page hit a fault and stopped drawing. The rest of the console is unaffected.</div>
          <div className="muted small mono" style={{ marginTop: 8 }}>{String(this.state.err)}</div>
          <div className="svc-actions" style={{ marginTop: 10 }}>
            <button className="btn" onClick={() => this.setState({ err: null })}>Try again</button>
          </div>
        </section>
      </div>
    )
  }
}