import { createSignal, For, Show } from 'solid-js'
import QrScanner from '../components/QrScanner'
import { searchBook, downloadBook, type GmeEntry } from '../api'

type State =
  | { type: 'idle' }
  | { type: 'searching' }
  | { type: 'found'; title: string; gmeUrls: GmeEntry[] }
  | { type: 'not_found' }
  | { type: 'downloading' }
  | { type: 'done'; filename: string }
  | { type: 'error'; message: string }

export default function ScanPage() {
  const [state, setState] = createSignal<State>({ type: 'idle' })
  const [query, setQuery] = createSignal('')

  const search = async (q: string) => {
    if (!q.trim()) return
    setState({ type: 'searching' })
    try {
      const data = await searchBook(q.trim())
      if (data.error || !data.gmeUrls?.length) {
        setState({ type: 'not_found' })
      } else {
        setState({ type: 'found', title: data.title!, gmeUrls: data.gmeUrls! })
      }
    } catch (e) {
      setState({ type: 'error', message: e instanceof Error ? e.message : String(e) })
    }
  }

  const download = async (gmeUrl: string, imageUrl?: string) => {
    setState({ type: 'downloading' })
    try {
      const data = await downloadBook(gmeUrl, imageUrl)
      if (data.filename) {
        setState({ type: 'done', filename: data.filename })
      } else {
        setState({ type: 'error', message: data.message })
      }
    } catch (e) {
      setState({ type: 'error', message: e instanceof Error ? e.message : String(e) })
    }
  }

  const reset = () => {
    setState({ type: 'idle' })
    setQuery('')
  }

  const isIdle = () => ['idle', 'not_found', 'done'].includes(state().type)

  return (
    <div class="page">

      {/* Suchfeld */}
      <Show when={state().type === 'idle' || state().type === 'not_found'}>
        <div>
          <Show when={state().type === 'not_found'}>
            <p class="hint" style="margin-bottom:0.6rem">
              Kein Buch gefunden – Titel oder Artikelnummer eingeben:
            </p>
          </Show>
          <div class="search-row">
            <input
              class="input"
              type="search"
              placeholder="z. B. Tierkinder oder 55476"
              value={query()}
              onInput={e => setQuery(e.currentTarget.value)}
              onKeyDown={e => e.key === 'Enter' && search(query())}
            />
            <button class="btn" onClick={() => search(query())}>
              <IconSearch />
            </button>
          </div>
        </div>
      </Show>

      {/* Scanner */}
      <Show when={isIdle() && 'BarcodeDetector' in window}>
        <QrScanner onScan={search} />
      </Show>

      {/* Suche läuft */}
      <Show when={state().type === 'searching'}>
        <div class="status">
          <span class="spinner" />
          Suche läuft…
        </div>
      </Show>

      {/* Ergebnis */}
      <Show when={state().type === 'found'}>
        {(() => {
          const s = state() as { type: 'found'; title: string; gmeUrls: GmeEntry[] }
          return (
            <div class="result-list">
              <p class="result-card__title">{s.title}</p>
              <For each={s.gmeUrls}>
                {(entry) => (
                  <div class="card result-card">
                    <Show when={entry.imageUrl}>
                      <img src={entry.imageUrl!} class="result-card__image" alt={entry.label} />
                    </Show>
                    <button class="btn" onClick={() => download(entry.url, entry.imageUrl ?? undefined)}>
                      <IconDownload />
                      Herunterladen
                    </button>
                  </div>
                )}
              </For>
            </div>
          )
        })()}
      </Show>

      {/* Download läuft */}
      <Show when={state().type === 'downloading'}>
        <div class="status">
          <span class="spinner" />
          Download läuft…
        </div>
      </Show>

      {/* Erfolg */}
      <Show when={state().type === 'done'}>
        {(() => {
          const s = state() as { type: 'done'; filename: string }
          return (
            <div class="card">
              <p class="status status--ok">
                <IconCheck /> {s.filename} wurde gespeichert
              </p>
            </div>
          )
        })()}
      </Show>

      {/* Fehler */}
      <Show when={state().type === 'error'}>
        {(() => {
          const s = state() as { type: 'error'; message: string }
          return (
            <div class="card">
              <p class="status status--error">Fehler: {s.message}</p>
            </div>
          )
        })()}
      </Show>

      {/* Zurück */}
      <Show when={state().type !== 'idle'}>
        <button class="btn btn--ghost" onClick={reset}>Neu scannen</button>
      </Show>
    </div>
  )
}

function IconSearch() {
  return (
    <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" width="18" height="18">
      <circle cx="11" cy="11" r="8"/><line x1="21" y1="21" x2="16.65" y2="16.65"/>
    </svg>
  )
}

function IconDownload() {
  return (
    <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" width="18" height="18">
      <path d="M21 15v4a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2v-4"/><polyline points="7 10 12 15 17 10"/><line x1="12" y1="15" x2="12" y2="3"/>
    </svg>
  )
}

function IconCheck() {
  return (
    <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round" width="18" height="18">
      <polyline points="20 6 9 17 4 12"/>
    </svg>
  )
}