import { useState, useEffect } from 'react'
import { Gift, AlertCircle, TrendingUp, Award } from 'lucide-react'
import { api } from '../utils/api'

export default function SubscriptionPage() {
  const [loading, setLoading] = useState(true)
  const [error, setError] = useState('')
  const [subscription, setSubscription] = useState(null)
  const [usage, setUsage] = useState([])
  const [limits, setLimits] = useState([])
  const [couponCode, setCouponCode] = useState('')
  const [redeeming, setRedeeming] = useState(false)
  const [couponSuccess, setCouponSuccess] = useState('')

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

  async function loadData() {
    try {
      setLoading(true)
      const [subData, usageData, limitsData] = await Promise.all([
        api.getMySubscription(),
        api.getMyUsage(),
        api.getMyLimits()
      ])
      setSubscription(subData)
      setUsage(usageData)
      setLimits(limitsData)
      setError('')
    } catch (e) {
      setError(e.message)
    } finally {
      setLoading(false)
    }
  }

  async function handleRedeemCoupon() {
    if (!couponCode.trim()) return

    try {
      setRedeeming(true)
      setError('')
      setCouponSuccess('')
      await api.redeemCoupon(couponCode.trim().toUpperCase())
      setCouponSuccess('Coupon erfolgreich eingelöst!')
      setCouponCode('')
      await loadData()
    } catch (e) {
      setError(e.message)
    } finally {
      setRedeeming(false)
    }
  }

  if (loading) return (
    <div style={{ display: 'flex', justifyContent: 'center', padding: 40 }}>
      <div className="spinner" />
    </div>
  )

  const tierColors = {
    free: { bg: 'var(--surface2)', color: 'var(--text2)', icon: '🆓' },
    basic: { bg: '#E3F2FD', color: '#1565C0', icon: '⭐' },
    premium: { bg: '#F3E5F5', color: '#6A1B9A', icon: '👑' },
    selfhosted: { bg: 'var(--accent-light)', color: 'var(--accent-dark)', icon: '🏠' }
  }

  const currentTier = subscription?.current_tier || 'free'
  const tierStyle = tierColors[currentTier] || tierColors.free

  return (
    <div style={{ paddingBottom: 40 }}>
      {/* Header */}
      <div style={{ marginBottom: 20 }}>
        <div style={{ fontSize: 20, fontWeight: 700, color: 'var(--text1)' }}>
          Mein Abo
        </div>
        <div style={{ fontSize: 13, color: 'var(--text3)', marginTop: 4 }}>
          Tier, Limits und Nutzung
        </div>
      </div>

      {/* Messages */}
      {error && (
        <div style={{
          padding: 12, background: 'var(--danger)', color: 'white',
          borderRadius: 8, marginBottom: 16, fontSize: 14
        }}>
          {error}
        </div>
      )}
      {couponSuccess && (
        <div style={{
          padding: 12, background: 'var(--accent)', color: 'white',
          borderRadius: 8, marginBottom: 16, fontSize: 14
        }}>
          {couponSuccess}
        </div>
      )}

      {/* Current Tier Card */}
      <div className="card" style={{ padding: 20, marginBottom: 16 }}>
        <div style={{ display: 'flex', alignItems: 'center', gap: 12, marginBottom: 16 }}>
          <div style={{
            width: 48, height: 48, borderRadius: 12,
            background: tierStyle.bg,
            display: 'flex', alignItems: 'center', justifyContent: 'center',
            fontSize: 24
          }}>
            {tierStyle.icon}
          </div>
          <div style={{ flex: 1 }}>
            <div style={{ fontSize: 12, color: 'var(--text3)', textTransform: 'uppercase', fontWeight: 600 }}>
              Aktueller Tier
            </div>
            <div style={{ fontSize: 20, fontWeight: 700, color: tierStyle.color }}>
              {currentTier.charAt(0).toUpperCase() + currentTier.slice(1)}
            </div>
          </div>
        </div>

        {subscription?.trial_ends_at && new Date(subscription.trial_ends_at) > new Date() && (
          <div style={{
            padding: 10, background: '#FFF3CD', borderRadius: 8,
            fontSize: 13, color: '#856404', display: 'flex', gap: 8, alignItems: 'center'
          }}>
            <AlertCircle size={16} />
            <div>
              <strong>Trial aktiv:</strong> Endet am {new Date(subscription.trial_ends_at).toLocaleDateString('de-DE')}
            </div>
          </div>
        )}

        {subscription?.access_until && (
          <div style={{
            padding: 10, background: 'var(--accent-light)', borderRadius: 8,
            fontSize: 13, color: 'var(--accent-dark)', display: 'flex', gap: 8, alignItems: 'center',
            marginTop: 12
          }}>
            <Award size={16} />
            <div>
              <strong>Zugriff bis:</strong> {new Date(subscription.access_until).toLocaleDateString('de-DE')}
            </div>
          </div>
        )}
      </div>

      {/* Feature Limits */}
      <div className="card" style={{ padding: 20, marginBottom: 16 }}>
        <div style={{
          fontSize: 14, fontWeight: 600, marginBottom: 12,
          display: 'flex', alignItems: 'center', gap: 6
        }}>
          <TrendingUp size={16} color="var(--accent)" />
          Feature-Limits & Nutzung
        </div>

        {limits.length === 0 ? (
          <div style={{ textAlign: 'center', padding: 20, color: 'var(--text3)', fontSize: 13 }}>
            Keine Limits konfiguriert
          </div>
        ) : (
          <div style={{ display: 'grid', gap: 12 }}>
            {limits.map(limit => {
              const usageEntry = usage.find(u => u.feature_id === limit.feature_id)
              const used = usageEntry?.usage_count || 0
              const limitValue = limit.limit_value
              const percentage = limitValue ? Math.min((used / limitValue) * 100, 100) : 0

              return (
                <div key={limit.feature_id} style={{
                  padding: 12, background: 'var(--surface)', borderRadius: 8
                }}>
                  <div style={{ display: 'flex', justifyContent: 'space-between', marginBottom: 8 }}>
                    <div style={{ fontWeight: 500, fontSize: 13 }}>{limit.feature_name}</div>
                    <div style={{ fontSize: 13, color: 'var(--text3)' }}>
                      {used} / {limitValue === null ? '∞' : limitValue}
                    </div>
                  </div>

                  {limitValue !== null && (
                    <div style={{
                      height: 6, background: 'var(--border)', borderRadius: 3, overflow: 'hidden'
                    }}>
                      <div style={{
                        width: `${percentage}%`,
                        height: '100%',
                        background: percentage > 90 ? 'var(--danger)' : percentage > 70 ? '#FFA726' : 'var(--accent)',
                        transition: 'width 0.3s'
                      }} />
                    </div>
                  )}

                  {limit.reset_period !== 'never' && (
                    <div style={{ fontSize: 11, color: 'var(--text3)', marginTop: 4 }}>
                      Reset: {limit.reset_period === 'daily' ? 'Täglich' : 'Monatlich'}
                    </div>
                  )}
                </div>
              )
            })}
          </div>
        )}
      </div>

      {/* Coupon Redemption */}
      <div className="card" style={{ padding: 20 }}>
        <div style={{
          fontSize: 14, fontWeight: 600, marginBottom: 12,
          display: 'flex', alignItems: 'center', gap: 6
        }}>
          <Gift size={16} color="var(--accent)" />
          Coupon einlösen
        </div>

        <div style={{ fontSize: 12, color: 'var(--text3)', marginBottom: 12 }}>
          Hast du einen Coupon-Code? Löse ihn hier ein um Zugriff auf Premium-Features zu erhalten.
        </div>

        <div style={{ display: 'flex', gap: 8 }}>
          <input
            className="form-input"
            style={{ flex: 1, textTransform: 'uppercase', fontFamily: 'monospace' }}
            value={couponCode}
            onChange={(e) => setCouponCode(e.target.value)}
            placeholder="Z.B. PROMO-2026"
            onKeyPress={(e) => e.key === 'Enter' && handleRedeemCoupon()}
          />
          <button
            className="btn btn-primary"
            onClick={handleRedeemCoupon}
            disabled={!couponCode.trim() || redeeming}
          >
            {redeeming ? 'Prüfen...' : 'Einlösen'}
          </button>
        </div>
      </div>
    </div>
  )
}