'use client'

import React, { useState, useEffect } from 'react'
import { useSDK } from '@/lib/sdk'
import { StepHeader, STEP_EXPLANATIONS } from '@/components/sdk/StepHeader'

// =============================================================================
// TYPES
// =============================================================================

interface AISystem {
  id: string
  name: string
  description: string
  classification: 'prohibited' | 'high-risk' | 'limited-risk' | 'minimal-risk' | 'unclassified'
  purpose: string
  sector: string
  status: 'draft' | 'classified' | 'compliant' | 'non-compliant'
  obligations: string[]
  assessmentDate: Date | null
  assessmentResult: Record<string, unknown> | null
}

// =============================================================================
// LOADING SKELETON
// =============================================================================

function LoadingSkeleton() {
  return (
    <div className="grid grid-cols-1 md:grid-cols-2 gap-6">
      {[1, 2, 3, 4].map(i => (
        <div key={i} className="bg-white rounded-xl border border-gray-200 p-6 animate-pulse">
          <div className="flex items-center gap-2 mb-3">
            <div className="h-5 w-24 bg-gray-200 rounded-full" />
            <div className="h-5 w-20 bg-gray-200 rounded-full" />
          </div>
          <div className="h-6 w-3/4 bg-gray-200 rounded mb-2" />
          <div className="h-4 w-full bg-gray-100 rounded mb-4" />
          <div className="h-4 w-1/2 bg-gray-100 rounded" />
          <div className="mt-4 pt-4 border-t border-gray-100">
            <div className="flex gap-2">
              <div className="h-8 flex-1 bg-gray-200 rounded-lg" />
              <div className="h-8 w-24 bg-gray-200 rounded-lg" />
            </div>
          </div>
        </div>
      ))}
    </div>
  )
}

// =============================================================================
// COMPONENTS
// =============================================================================

function RiskPyramid({ systems }: { systems: AISystem[] }) {
  const counts = {
    prohibited: systems.filter(s => s.classification === 'prohibited').length,
    'high-risk': systems.filter(s => s.classification === 'high-risk').length,
    'limited-risk': systems.filter(s => s.classification === 'limited-risk').length,
    'minimal-risk': systems.filter(s => s.classification === 'minimal-risk').length,
  }

  return (
    <div className="bg-white rounded-xl border border-gray-200 p-6">
      <h3 className="text-lg font-semibold text-gray-900 mb-4">AI Act Risikopyramide</h3>
      <div className="flex flex-col items-center space-y-1">
        <div className="w-24 h-12 bg-red-500 text-white flex items-center justify-center rounded-t-lg text-sm font-medium">
          Verboten ({counts.prohibited})
        </div>
        <div className="w-40 h-12 bg-orange-500 text-white flex items-center justify-center text-sm font-medium">
          Hochrisiko ({counts['high-risk']})
        </div>
        <div className="w-56 h-12 bg-yellow-500 text-white flex items-center justify-center text-sm font-medium">
          Begrenztes Risiko ({counts['limited-risk']})
        </div>
        <div className="w-72 h-12 bg-green-500 text-white flex items-center justify-center rounded-b-lg text-sm font-medium">
          Minimales Risiko ({counts['minimal-risk']})
        </div>
      </div>
      <div className="mt-4 text-center text-sm text-gray-500">
        {systems.filter(s => s.classification === 'unclassified').length} System(e) noch nicht klassifiziert
      </div>
    </div>
  )
}

function AddSystemForm({
  onSubmit,
  onCancel,
  initialData,
}: {
  onSubmit: (system: Omit<AISystem, 'id' | 'assessmentDate' | 'assessmentResult'>) => void
  onCancel: () => void
  initialData?: AISystem | null
}) {
  const [formData, setFormData] = useState({
    name: initialData?.name || '',
    description: initialData?.description || '',
    purpose: initialData?.purpose || '',
    sector: initialData?.sector || '',
    classification: (initialData?.classification || 'unclassified') as AISystem['classification'],
    status: (initialData?.status || 'draft') as AISystem['status'],
    obligations: initialData?.obligations || [] as string[],
  })

  return (
    <div className="bg-white rounded-xl border border-gray-200 p-6">
      <h3 className="text-lg font-semibold text-gray-900 mb-4">{initialData ? 'KI-System bearbeiten' : 'Neues KI-System registrieren'}</h3>
      <div className="space-y-4">
        <div>
          <label className="block text-sm font-medium text-gray-700 mb-1">Name *</label>
          <input
            type="text"
            value={formData.name}
            onChange={e => setFormData({ ...formData, name: e.target.value })}
            placeholder="z.B. Dokumenten-Scanner"
            className="w-full px-4 py-2 border border-gray-300 rounded-lg focus:ring-2 focus:ring-purple-500 focus:border-transparent"
          />
        </div>
        <div>
          <label className="block text-sm font-medium text-gray-700 mb-1">Beschreibung</label>
          <textarea
            value={formData.description}
            onChange={e => setFormData({ ...formData, description: e.target.value })}
            placeholder="Beschreiben Sie das KI-System..."
            rows={2}
            className="w-full px-4 py-2 border border-gray-300 rounded-lg focus:ring-2 focus:ring-purple-500 focus:border-transparent"
          />
        </div>
        <div className="grid grid-cols-2 gap-4">
          <div>
            <label className="block text-sm font-medium text-gray-700 mb-1">Einsatzzweck</label>
            <input
              type="text"
              value={formData.purpose}
              onChange={e => setFormData({ ...formData, purpose: e.target.value })}
              placeholder="z.B. Texterkennung"
              className="w-full px-4 py-2 border border-gray-300 rounded-lg focus:ring-2 focus:ring-purple-500 focus:border-transparent"
            />
          </div>
          <div>
            <label className="block text-sm font-medium text-gray-700 mb-1">Sektor</label>
            <input
              type="text"
              value={formData.sector}
              onChange={e => setFormData({ ...formData, sector: e.target.value })}
              placeholder="z.B. Verwaltung"
              className="w-full px-4 py-2 border border-gray-300 rounded-lg focus:ring-2 focus:ring-purple-500 focus:border-transparent"
            />
          </div>
        </div>
        <div>
          <label className="block text-sm font-medium text-gray-700 mb-1">Vorklassifizierung</label>
          <select
            value={formData.classification}
            onChange={e => setFormData({ ...formData, classification: e.target.value as AISystem['classification'] })}
            className="w-full px-4 py-2 border border-gray-300 rounded-lg focus:ring-2 focus:ring-purple-500 focus:border-transparent"
          >
            <option value="unclassified">Noch nicht klassifiziert</option>
            <option value="minimal-risk">Minimales Risiko</option>
            <option value="limited-risk">Begrenztes Risiko</option>
            <option value="high-risk">Hochrisiko</option>
            <option value="prohibited">Verboten</option>
          </select>
        </div>
      </div>
      <div className="mt-6 flex items-center justify-end gap-3">
        <button onClick={onCancel} className="px-4 py-2 text-gray-600 hover:bg-gray-100 rounded-lg transition-colors">
          Abbrechen
        </button>
        <button
          onClick={() => onSubmit(formData)}
          disabled={!formData.name}
          className={`px-6 py-2 rounded-lg font-medium transition-colors ${
            formData.name ? 'bg-purple-600 text-white hover:bg-purple-700' : 'bg-gray-200 text-gray-400 cursor-not-allowed'
          }`}
        >
          {initialData ? 'Speichern' : 'Registrieren'}
        </button>
      </div>
    </div>
  )
}

function AISystemCard({
  system,
  onAssess,
  onEdit,
  onDelete,
  assessing,
}: {
  system: AISystem
  onAssess: () => void
  onEdit: () => void
  onDelete: () => void
  assessing: boolean
}) {
  const classificationColors = {
    prohibited: 'bg-red-100 text-red-700 border-red-200',
    'high-risk': 'bg-orange-100 text-orange-700 border-orange-200',
    'limited-risk': 'bg-yellow-100 text-yellow-700 border-yellow-200',
    'minimal-risk': 'bg-green-100 text-green-700 border-green-200',
    unclassified: 'bg-gray-100 text-gray-500 border-gray-200',
  }

  const classificationLabels = {
    prohibited: 'Verboten',
    'high-risk': 'Hochrisiko',
    'limited-risk': 'Begrenztes Risiko',
    'minimal-risk': 'Minimales Risiko',
    unclassified: 'Nicht klassifiziert',
  }

  const statusColors = {
    draft: 'bg-gray-100 text-gray-500',
    classified: 'bg-blue-100 text-blue-700',
    compliant: 'bg-green-100 text-green-700',
    'non-compliant': 'bg-red-100 text-red-700',
  }

  const statusLabels = {
    draft: 'Entwurf',
    classified: 'Klassifiziert',
    compliant: 'Konform',
    'non-compliant': 'Nicht konform',
  }

  return (
    <div className={`bg-white rounded-xl border-2 p-6 ${
      system.classification === 'high-risk' ? 'border-orange-200' :
      system.classification === 'prohibited' ? 'border-red-200' : 'border-gray-200'
    }`}>
      <div className="flex items-start justify-between">
        <div className="flex-1">
          <div className="flex items-center gap-2 mb-2">
            <span className={`px-2 py-1 text-xs rounded-full ${classificationColors[system.classification]}`}>
              {classificationLabels[system.classification]}
            </span>
            <span className={`px-2 py-1 text-xs rounded-full ${statusColors[system.status]}`}>
              {statusLabels[system.status]}
            </span>
          </div>
          <h3 className="text-lg font-semibold text-gray-900">{system.name}</h3>
          <p className="text-sm text-gray-500 mt-1">{system.description}</p>
          <div className="mt-2 text-sm text-gray-500">
            <span>Sektor: {system.sector}</span>
            {system.assessmentDate && (
              <span className="ml-4">Klassifiziert: {system.assessmentDate.toLocaleDateString('de-DE')}</span>
            )}
          </div>
        </div>
      </div>

      {system.obligations.length > 0 && (
        <div className="mt-4 pt-4 border-t border-gray-100">
          <p className="text-sm font-medium text-gray-700 mb-2">Pflichten nach AI Act:</p>
          <div className="flex flex-wrap gap-2">
            {system.obligations.map(obl => (
              <span key={obl} className="px-2 py-1 text-xs bg-purple-50 text-purple-700 rounded">
                {obl}
              </span>
            ))}
          </div>
        </div>
      )}

      {system.assessmentResult && (
        <div className="mt-3 p-3 bg-blue-50 rounded-lg">
          <p className="text-xs font-medium text-blue-700">KI-Risikobewertung abgeschlossen</p>
        </div>
      )}

      <div className="mt-4 flex items-center gap-2">
        <button
          onClick={onAssess}
          disabled={assessing}
          className="flex-1 px-4 py-2 text-sm bg-purple-50 text-purple-700 rounded-lg hover:bg-purple-100 transition-colors disabled:opacity-50"
        >
          {assessing ? (
            <span className="flex items-center justify-center gap-2">
              <svg className="w-4 h-4 animate-spin" fill="none" viewBox="0 0 24 24">
                <circle className="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" strokeWidth="4" />
                <path className="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4z" />
              </svg>
              Bewertung laeuft...
            </span>
          ) : (
            system.classification === 'unclassified' ? 'Klassifizierung starten' : 'Risikobewertung starten'
          )}
        </button>
        <button
          onClick={onEdit}
          className="px-4 py-2 text-sm text-gray-600 hover:bg-gray-100 rounded-lg transition-colors"
        >
          Bearbeiten
        </button>
        <button
          onClick={onDelete}
          className="px-4 py-2 text-sm text-red-600 hover:bg-red-50 rounded-lg transition-colors"
        >
          Loeschen
        </button>
      </div>
    </div>
  )
}

// =============================================================================
// MAIN PAGE
// =============================================================================

export default function AIActPage() {
  const { state } = useSDK()
  const [systems, setSystems] = useState<AISystem[]>([])
  const [filter, setFilter] = useState<string>('all')
  const [showAddForm, setShowAddForm] = useState(false)
  const [editingSystem, setEditingSystem] = useState<AISystem | null>(null)
  const [assessingId, setAssessingId] = useState<string | null>(null)
  const [error, setError] = useState<string | null>(null)
  const [loading, setLoading] = useState(true)

  // Fetch systems from backend on mount
  useEffect(() => {
    const fetchSystems = async () => {
      setLoading(true)
      try {
        const res = await fetch('/api/sdk/v1/compliance/ai/systems')
        if (res.ok) {
          const data = await res.json()
          const backendSystems = data.systems || []
          setSystems(backendSystems.map((s: Record<string, unknown>) => ({
            id: s.id as string,
            name: s.name as string,
            description: (s.description || '') as string,
            purpose: (s.purpose || '') as string,
            sector: (s.sector || '') as string,
            classification: (s.classification || 'unclassified') as AISystem['classification'],
            status: (s.status || 'draft') as AISystem['status'],
            obligations: (s.obligations || []) as string[],
            assessmentDate: s.assessment_date ? new Date(s.assessment_date as string) : null,
            assessmentResult: (s.assessment_result || null) as Record<string, unknown> | null,
          })))
        }
      } catch {
        // Backend unavailable — start with empty list
      } finally {
        setLoading(false)
      }
    }
    fetchSystems()
  }, [])

  const handleAddSystem = async (data: Omit<AISystem, 'id' | 'assessmentDate' | 'assessmentResult'>) => {
    setError(null)
    if (editingSystem) {
      // Edit existing system via PUT
      try {
        const res = await fetch(`/api/sdk/v1/compliance/ai/systems/${editingSystem.id}`, {
          method: 'PUT',
          headers: { 'Content-Type': 'application/json' },
          body: JSON.stringify({
            name: data.name,
            description: data.description,
            purpose: data.purpose,
            sector: data.sector,
            classification: data.classification,
            status: data.status,
            obligations: data.obligations,
          }),
        })
        if (res.ok) {
          const updated = await res.json()
          setSystems(prev => prev.map(s =>
            s.id === editingSystem.id
              ? { ...s, ...data, id: updated.id || editingSystem.id }
              : s
          ))
        } else {
          setError('Speichern fehlgeschlagen')
        }
      } catch {
        // Fallback: update locally
        setSystems(prev => prev.map(s =>
          s.id === editingSystem.id ? { ...s, ...data } : s
        ))
      }
      setEditingSystem(null)
    } else {
      // Create new system via POST
      try {
        const res = await fetch('/api/sdk/v1/compliance/ai/systems', {
          method: 'POST',
          headers: { 'Content-Type': 'application/json' },
          body: JSON.stringify({
            name: data.name,
            description: data.description,
            purpose: data.purpose,
            sector: data.sector,
            classification: data.classification,
            status: data.status,
            obligations: data.obligations,
          }),
        })
        if (res.ok) {
          const created = await res.json()
          const newSystem: AISystem = {
            ...data,
            id: created.id,
            assessmentDate: created.assessment_date ? new Date(created.assessment_date) : null,
            assessmentResult: created.assessment_result || null,
          }
          setSystems(prev => [...prev, newSystem])
        } else {
          setError('Registrierung fehlgeschlagen')
        }
      } catch {
        // Fallback: add locally
        const newSystem: AISystem = {
          ...data,
          id: `ai-${Date.now()}`,
          assessmentDate: data.classification !== 'unclassified' ? new Date() : null,
          assessmentResult: null,
        }
        setSystems(prev => [...prev, newSystem])
      }
    }
    setShowAddForm(false)
  }

  const handleDelete = async (id: string) => {
    if (!confirm('Moechten Sie dieses KI-System wirklich loeschen?')) return
    try {
      const res = await fetch(`/api/sdk/v1/compliance/ai/systems/${id}`, { method: 'DELETE' })
      if (res.ok) {
        setSystems(prev => prev.filter(s => s.id !== id))
      } else {
        setError('Loeschen fehlgeschlagen')
      }
    } catch {
      setError('Backend nicht erreichbar')
    }
  }

  const handleEdit = (system: AISystem) => {
    setEditingSystem(system)
    setShowAddForm(true)
  }

  const handleAssess = async (systemId: string) => {
    setAssessingId(systemId)
    setError(null)

    try {
      const res = await fetch(`/api/sdk/v1/compliance/ai/systems/${systemId}/assess`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
      })

      if (res.ok) {
        const result = await res.json()

        setSystems(prev => prev.map(s =>
          s.id === systemId
            ? {
                ...s,
                assessmentDate: result.assessment_date ? new Date(result.assessment_date) : new Date(),
                assessmentResult: result.assessment_result || result,
                classification: (result.classification || s.classification) as AISystem['classification'],
                status: (result.status || 'classified') as AISystem['status'],
                obligations: result.obligations || s.obligations,
              }
            : s
        ))
      } else {
        const errData = await res.json().catch(() => ({ error: 'Bewertung fehlgeschlagen' }))
        setError(errData.error || errData.detail || 'Bewertung fehlgeschlagen')
      }
    } catch {
      setError('Verbindung zum KI-Service fehlgeschlagen. Bitte versuchen Sie es spaeter erneut.')
    } finally {
      setAssessingId(null)
    }
  }

  const filteredSystems = filter === 'all'
    ? systems
    : systems.filter(s => s.classification === filter || s.status === filter)

  const highRiskCount = systems.filter(s => s.classification === 'high-risk').length
  const compliantCount = systems.filter(s => s.status === 'compliant').length
  const unclassifiedCount = systems.filter(s => s.classification === 'unclassified').length

  const stepInfo = STEP_EXPLANATIONS['ai-act']

  return (
    <div className="space-y-6">
      {/* Step Header */}
      <StepHeader
        stepId="ai-act"
        title={stepInfo.title}
        description={stepInfo.description}
        explanation={stepInfo.explanation}
        tips={stepInfo.tips}
      >
        <button
          onClick={() => setShowAddForm(true)}
          className="flex items-center gap-2 px-4 py-2 bg-purple-600 text-white rounded-lg hover:bg-purple-700 transition-colors"
        >
          <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
            <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 6v6m0 0v6m0-6h6m-6 0H6" />
          </svg>
          KI-System registrieren
        </button>
      </StepHeader>

      {/* Error Banner */}
      {error && (
        <div className="p-4 bg-red-50 border border-red-200 rounded-lg text-red-700 flex items-center justify-between">
          <span>{error}</span>
          <button onClick={() => setError(null)} className="text-red-500 hover:text-red-700">&times;</button>
        </div>
      )}

      {/* Add/Edit System Form */}
      {showAddForm && (
        <AddSystemForm
          onSubmit={handleAddSystem}
          onCancel={() => { setShowAddForm(false); setEditingSystem(null) }}
          initialData={editingSystem}
        />
      )}

      {/* Stats */}
      <div className="grid grid-cols-1 md:grid-cols-4 gap-4">
        <div className="bg-white rounded-xl border border-gray-200 p-6">
          <div className="text-sm text-gray-500">KI-Systeme gesamt</div>
          <div className="text-3xl font-bold text-gray-900">{systems.length}</div>
        </div>
        <div className="bg-white rounded-xl border border-orange-200 p-6">
          <div className="text-sm text-orange-600">Hochrisiko</div>
          <div className="text-3xl font-bold text-orange-600">{highRiskCount}</div>
        </div>
        <div className="bg-white rounded-xl border border-green-200 p-6">
          <div className="text-sm text-green-600">Konform</div>
          <div className="text-3xl font-bold text-green-600">{compliantCount}</div>
        </div>
        <div className="bg-white rounded-xl border border-gray-200 p-6">
          <div className="text-sm text-gray-500">Nicht klassifiziert</div>
          <div className="text-3xl font-bold text-gray-500">{unclassifiedCount}</div>
        </div>
      </div>

      {/* Risk Pyramid */}
      <RiskPyramid systems={systems} />

      {/* Filter */}
      <div className="flex items-center gap-2 flex-wrap">
        <span className="text-sm text-gray-500">Filter:</span>
        {['all', 'high-risk', 'limited-risk', 'minimal-risk', 'unclassified', 'compliant', 'non-compliant'].map(f => (
          <button
            key={f}
            onClick={() => setFilter(f)}
            className={`px-3 py-1 text-sm rounded-full transition-colors ${
              filter === f
                ? 'bg-purple-600 text-white'
                : 'bg-gray-100 text-gray-600 hover:bg-gray-200'
            }`}
          >
            {f === 'all' ? 'Alle' :
             f === 'high-risk' ? 'Hochrisiko' :
             f === 'limited-risk' ? 'Begrenztes Risiko' :
             f === 'minimal-risk' ? 'Minimales Risiko' :
             f === 'unclassified' ? 'Nicht klassifiziert' :
             f === 'compliant' ? 'Konform' : 'Nicht konform'}
          </button>
        ))}
      </div>

      {/* Loading */}
      {loading && <LoadingSkeleton />}

      {/* AI Systems List */}
      {!loading && (
        <div className="grid grid-cols-1 md:grid-cols-2 gap-6">
          {filteredSystems.map(system => (
            <AISystemCard
              key={system.id}
              system={system}
              onAssess={() => handleAssess(system.id)}
              onEdit={() => handleEdit(system)}
              onDelete={() => handleDelete(system.id)}
              assessing={assessingId === system.id}
            />
          ))}
        </div>
      )}

      {!loading && filteredSystems.length === 0 && (
        <div className="bg-white rounded-xl border border-gray-200 p-12 text-center">
          <div className="w-16 h-16 mx-auto bg-purple-100 rounded-full flex items-center justify-center mb-4">
            <svg className="w-8 h-8 text-purple-600" fill="none" stroke="currentColor" viewBox="0 0 24 24">
              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9.75 17L9 20l-1 1h8l-1-1-.75-3M3 13h18M5 17h14a2 2 0 002-2V5a2 2 0 00-2-2H5a2 2 0 00-2 2v10a2 2 0 002 2z" />
            </svg>
          </div>
          <h3 className="text-lg font-semibold text-gray-900">Keine KI-Systeme gefunden</h3>
          <p className="mt-2 text-gray-500">Passen Sie den Filter an oder registrieren Sie ein neues KI-System.</p>
        </div>
      )}
    </div>
  )
}