/**
 * FeatureUsageOverview - Full feature usage table for Settings page
 *
 * Shows all features with usage, limits, reset period, and next reset date
 * Phase 3: Frontend Display
 */
import { useState, useEffect } from 'react'
import { api } from '../utils/api'
import './FeatureUsageOverview.css'

const RESET_PERIOD_LABELS = {
  'never': 'Niemals',
  'daily': 'Täglich',
  'monthly': 'Monatlich'
}

const CATEGORY_LABELS = {
  'data': 'Daten',
  'ai': 'KI',
  'export': 'Export',
  'import': 'Import',
  'integration': 'Integration'
}

export default function FeatureUsageOverview() {
  const [features, setFeatures] = useState([])
  const [loading, setLoading] = useState(true)
  const [error, setError] = useState(null)

  useEffect(() => {
    loadFeatures()
  }, [])

  const loadFeatures = async () => {
    try {
      setLoading(true)
      const data = await api.getFeatureUsage()
      setFeatures(data)
      setError(null)
    } catch (err) {
      console.error('Failed to load feature usage:', err)
      setError('Fehler beim Laden der Kontingente')
    } finally {
      setLoading(false)
    }
  }

  const formatResetDate = (resetAt) => {
    if (!resetAt) return '—'
    try {
      const date = new Date(resetAt)
      return date.toLocaleDateString('de-DE', { day: '2-digit', month: '2-digit', year: 'numeric' })
    } catch {
      return '—'
    }
  }

  const getStatusClass = (feature) => {
    if (!feature.allowed || feature.remaining < 0) return 'exceeded'
    if (feature.limit && feature.remaining <= Math.ceil(feature.limit * 0.2)) return 'warning'
    return 'ok'
  }

  // Group by category
  const byCategory = features.reduce((acc, f) => {
    const cat = f.category || 'other'
    if (!acc[cat]) acc[cat] = []
    acc[cat].push(f)
    return acc
  }, {})

  if (loading) {
    return (
      <div className="feature-usage-loading">
        <div className="spinner" />
        Lade Kontingente...
      </div>
    )
  }

  if (error) {
    return (
      <div className="feature-usage-error">
        ⚠️ {error}
      </div>
    )
  }

  if (features.length === 0) {
    return (
      <div className="feature-usage-empty">
        Keine Features gefunden
      </div>
    )
  }

  return (
    <div className="feature-usage-overview">
      {Object.entries(byCategory).map(([category, items]) => (
        <div key={category} className="feature-category">
          <div className="feature-category-label">
            {CATEGORY_LABELS[category] || category}
          </div>
          <div className="feature-list">
            {items.map(feature => (
              <div key={feature.feature_id} className={`feature-item feature-item--${getStatusClass(feature)}`}>
                <div className="feature-main">
                  <div className="feature-name">{feature.name}</div>
                  <div className="feature-usage">
                    {feature.limit === null ? (
                      <span className="usage-unlimited">Unbegrenzt</span>
                    ) : feature.limit_type === 'boolean' ? (
                      <span className={`usage-boolean ${feature.allowed ? 'enabled' : 'disabled'}`}>
                        {feature.allowed ? '✓ Aktiviert' : '✗ Deaktiviert'}
                      </span>
                    ) : (
                      <span className="usage-count">
                        <strong>{feature.used}</strong> / {feature.limit}
                      </span>
                    )}
                  </div>
                </div>
                {feature.limit_type === 'count' && feature.limit !== null && (
                  <div className="feature-meta">
                    <span className="meta-reset">
                      Reset: {RESET_PERIOD_LABELS[feature.reset_period] || feature.reset_period}
                    </span>
                    {feature.reset_at && (
                      <span className="meta-next-reset">
                        Nächster Reset: {formatResetDate(feature.reset_at)}
                      </span>
                    )}
                  </div>
                )}
              </div>
            ))}
          </div>
        </div>
      ))}
    </div>
  )
}