import { useEffect, useState } from 'react'
import { api } from '../utils/api'

function summarizeCheck(kind, res) {
  if (!res) return ''
  if (kind === 'components') return `${res.attributes ?? 0} Stoffe erkannt`
  return `${res.foods ?? 0} Lebensmittel, ${res.attribute_columns ?? 0} Stoffspalten`
}

function ImportSwitch({ on, disabled, busy, onEnable }) {
  return (
    <label style={{ display: 'flex', alignItems: 'center', gap: 10, opacity: disabled ? 0.5 : 1 }}>
      <button
        type="button"
        role="switch"
        aria-checked={on}
        aria-label="Import"
        disabled={disabled || busy || on}
        onClick={() => { if (!on && !disabled && !busy) onEnable() }}
        style={{
          width: 44,
          height: 24,
          borderRadius: 12,
          border: 'none',
          padding: 0,
          background: on ? 'var(--accent)' : 'var(--border)',
          position: 'relative',
          cursor: disabled || busy || on ? 'not-allowed' : 'pointer',
        }}
      >
        <span
          style={{
            position: 'absolute',
            top: 2,
            left: on ? 22 : 2,
            width: 20,
            height: 20,
            borderRadius: '50%',
            background: '#fff',
            display: 'block',
          }}
        />
      </button>
      <span style={{ fontSize: 14, color: 'var(--text1)' }}>
        {on ? 'Importiert' : 'Import'}
      </span>
    </label>
  )
}

function FileImportBlock({ label, kind, onImported }) {
  const [file, setFile] = useState(null)
  const [check, setCheck] = useState(null)
  const [error, setError] = useState(null)
  const [busy, setBusy] = useState(null)
  const [imported, setImported] = useState(false)
  const [applyResult, setApplyResult] = useState(null)

  const apiFn = kind === 'components' ? api.adminBlsImportComponents : api.adminBlsImportFoods

  const checkFile = async (nextFile) => {
    setError(null)
    setCheck(null)
    setApplyResult(null)
    setImported(false)
    if (!nextFile) return
    setBusy('check')
    try {
      setCheck(await apiFn(nextFile, true))
    } catch (e) {
      setError(e.message)
    } finally {
      setBusy(null)
    }
  }

  const applyImport = async () => {
    if (!file || !check) return
    setBusy('apply')
    setError(null)
    try {
      const res = await apiFn(file, false)
      setApplyResult(res)
      setImported(true)
      onImported?.()
    } catch (e) {
      setError(e.message)
      setImported(false)
    } finally {
      setBusy(null)
    }
  }

  return (
    <div className="form-row" style={{ flexDirection: 'column', alignItems: 'stretch', gap: 8, marginTop: 16 }}>
      <label className="form-label">{label}</label>
      <input
        type="file"
        accept=".xlsx"
        className="form-input"
        disabled={busy}
        onChange={(e) => {
          const next = e.target.files?.[0] || null
          setFile(next)
          checkFile(next)
        }}
      />
      {busy && <p style={{ fontSize: 13, color: 'var(--text2)', margin: 0 }}>{busy === 'apply' ? 'Importiere…' : 'Prüfe…'}</p>}
      {error && <p style={{ color: 'var(--danger)', margin: 0 }}>{error}</p>}
      {check && !error && (
        <p style={{ fontSize: 13, color: 'var(--text2)', margin: 0 }}>
          Prüfung: {summarizeCheck(kind, check)}
        </p>
      )}
      {applyResult && (
        <p style={{ fontSize: 13, color: 'var(--text2)', margin: 0 }}>
          {applyResult.inserted ?? 0} neu · {applyResult.updated ?? 0} aktualisiert
        </p>
      )}
      <ImportSwitch
        on={imported}
        disabled={!check || !!error}
        busy={busy}
        onEnable={applyImport}
      />
    </div>
  )
}

export default function AdminBlsImportPage() {
  const [status, setStatus] = useState(null)
  const [error, setError] = useState(null)

  const load = () => {
    api.adminBlsStatus().then(setStatus).catch((e) => setError(e.message))
  }
  useEffect(() => { load() }, [])

  return (
    <div className="card">
      <h1 className="page-title">BLS 4.0 importieren</h1>
      <p style={{ fontSize: 13, color: 'var(--text2)', lineHeight: 1.6 }}>
        Offizielle Dateien von blsdb.de (frei verfügbar, MRI). Codes bleiben erhalten.
        Datei wählen prüft automatisch. Der Schalter startet den Import. Zuerst Components, dann Daten.
      </p>
      {status && (
        <p style={{ fontSize: 13 }}>
          {status.official_foods} offizielle Lebensmittel · {status.official_attributes} Stoffe ·
          {status.manual_foods} manuell · {status.source}
        </p>
      )}
      {error && <p style={{ color: 'var(--danger)' }}>{error}</p>}
      <FileImportBlock label="Components XLSX" kind="components" onImported={load} />
      <FileImportBlock label="Daten XLSX" kind="foods" onImported={load} />
    </div>
  )
}