'use client'

import { useState, useEffect } from 'react'
import {
  ArrowLeft, CheckCircle2, Trash2, Pencil, SkipForward,
  ChevronLeft, Scale, BookOpen, ExternalLink, AlertTriangle,
  FileText, Clock,
} from 'lucide-react'
import {
  CanonicalControl, BACKEND_URL,
  SeverityBadge, StateBadge, LicenseRuleBadge, CategoryBadge, TargetAudienceBadge,
} from './helpers'

// =============================================================================
// Compact Control Panel (used on both sides of the comparison)
// =============================================================================

function ControlPanel({ ctrl, label, highlight }: { ctrl: CanonicalControl; label: string; highlight?: boolean }) {
  return (
    <div className={`flex flex-col h-full overflow-y-auto ${highlight ? 'bg-yellow-50' : 'bg-white'}`}>
      {/* Panel Header */}
      <div className={`sticky top-0 z-10 px-4 py-3 border-b ${highlight ? 'bg-yellow-100 border-yellow-200' : 'bg-gray-50 border-gray-200'}`}>
        <div className="text-xs font-semibold uppercase tracking-wide text-gray-500 mb-1">{label}</div>
        <div className="flex items-center gap-2 flex-wrap">
          <span className="text-sm font-mono text-purple-600 bg-purple-50 px-2 py-0.5 rounded">{ctrl.control_id}</span>
          <SeverityBadge severity={ctrl.severity} />
          <StateBadge state={ctrl.release_state} />
          <LicenseRuleBadge rule={ctrl.license_rule} />
          <CategoryBadge category={ctrl.category} />
          <TargetAudienceBadge audience={ctrl.target_audience} />
        </div>
        <h3 className="text-sm font-semibold text-gray-900 mt-1 leading-snug">{ctrl.title}</h3>
      </div>

      {/* Panel Content */}
      <div className="p-4 space-y-4 text-sm">
        {/* Objective */}
        <section>
          <h4 className="text-xs font-semibold text-gray-500 uppercase tracking-wide mb-1">Ziel</h4>
          <p className="text-gray-700 leading-relaxed">{ctrl.objective}</p>
        </section>

        {/* Rationale */}
        {ctrl.rationale && (
          <section>
            <h4 className="text-xs font-semibold text-gray-500 uppercase tracking-wide mb-1">Begruendung</h4>
            <p className="text-gray-700 leading-relaxed">{ctrl.rationale}</p>
          </section>
        )}

        {/* Source Citation (Rule 1+2) */}
        {ctrl.source_citation && (
          <section className="bg-blue-50 border border-blue-200 rounded-lg p-3">
            <div className="flex items-center gap-1.5 mb-1">
              <Scale className="w-3.5 h-3.5 text-blue-600" />
              <span className="text-xs font-semibold text-blue-900">Gesetzliche Grundlage</span>
            </div>
            {ctrl.source_citation.source && (
              <p className="text-xs text-blue-800">
                {ctrl.source_citation.source}
                {ctrl.source_citation.article && ` — ${ctrl.source_citation.article}`}
                {ctrl.source_citation.paragraph && ` ${ctrl.source_citation.paragraph}`}
              </p>
            )}
          </section>
        )}

        {/* Requirements */}
        {ctrl.requirements.length > 0 && (
          <section>
            <h4 className="text-xs font-semibold text-gray-500 uppercase tracking-wide mb-1">Anforderungen</h4>
            <ol className="list-decimal list-inside space-y-1">
              {ctrl.requirements.map((r, i) => (
                <li key={i} className="text-gray-700 text-xs leading-relaxed">{r}</li>
              ))}
            </ol>
          </section>
        )}

        {/* Test Procedure */}
        {ctrl.test_procedure.length > 0 && (
          <section>
            <h4 className="text-xs font-semibold text-gray-500 uppercase tracking-wide mb-1">Pruefverfahren</h4>
            <ol className="list-decimal list-inside space-y-1">
              {ctrl.test_procedure.map((s, i) => (
                <li key={i} className="text-gray-700 text-xs leading-relaxed">{s}</li>
              ))}
            </ol>
          </section>
        )}

        {/* Open Anchors */}
        {ctrl.open_anchors.length > 0 && (
          <section className="bg-green-50 border border-green-200 rounded-lg p-3">
            <div className="flex items-center gap-1.5 mb-2">
              <BookOpen className="w-3.5 h-3.5 text-green-700" />
              <span className="text-xs font-semibold text-green-900">Referenzen ({ctrl.open_anchors.length})</span>
            </div>
            <div className="space-y-1">
              {ctrl.open_anchors.map((a, i) => (
                <div key={i} className="flex items-center gap-1.5 text-xs">
                  <ExternalLink className="w-3 h-3 text-green-600 flex-shrink-0" />
                  <span className="font-medium text-green-800">{a.framework}</span>
                  <span className="text-green-700">{a.ref}</span>
                </div>
              ))}
            </div>
          </section>
        )}

        {/* Tags */}
        {ctrl.tags.length > 0 && (
          <div className="flex items-center gap-1 flex-wrap">
            {ctrl.tags.map(t => (
              <span key={t} className="px-2 py-0.5 bg-gray-100 text-gray-600 rounded text-xs">{t}</span>
            ))}
          </div>
        )}
      </div>
    </div>
  )
}

// =============================================================================
// ReviewCompare — Side-by-Side Duplicate Comparison
// =============================================================================

interface ReviewCompareProps {
  ctrl: CanonicalControl
  onBack: () => void
  onReview: (controlId: string, action: string) => void
  onEdit: () => void
  reviewIndex: number
  reviewTotal: number
  onReviewPrev: () => void
  onReviewNext: () => void
}

export function ReviewCompare({
  ctrl,
  onBack,
  onReview,
  onEdit,
  reviewIndex,
  reviewTotal,
  onReviewPrev,
  onReviewNext,
}: ReviewCompareProps) {
  const [suspectedDuplicate, setSuspectedDuplicate] = useState<CanonicalControl | null>(null)
  const [loading, setLoading] = useState(false)
  const [similarity, setSimilarity] = useState<number | null>(null)

  // Load the suspected duplicate from generation_metadata.similar_controls
  useEffect(() => {
    const loadDuplicate = async () => {
      const similarControls = ctrl.generation_metadata?.similar_controls as Array<{ control_id: string; title: string; similarity: number }> | undefined
      if (!similarControls || similarControls.length === 0) {
        setSuspectedDuplicate(null)
        setSimilarity(null)
        return
      }

      const suspect = similarControls[0]
      setSimilarity(suspect.similarity)
      setLoading(true)

      try {
        const res = await fetch(`${BACKEND_URL}?endpoint=control&id=${encodeURIComponent(suspect.control_id)}`)
        if (res.ok) {
          const data = await res.json()
          setSuspectedDuplicate(data)
        } else {
          setSuspectedDuplicate(null)
        }
      } catch {
        setSuspectedDuplicate(null)
      } finally {
        setLoading(false)
      }
    }

    loadDuplicate()
  }, [ctrl.control_id, ctrl.generation_metadata])

  return (
    <div className="flex flex-col h-full">
      {/* Header */}
      <div className="border-b border-gray-200 bg-white px-6 py-3 flex items-center justify-between">
        <div className="flex items-center gap-3">
          <button onClick={onBack} className="text-gray-400 hover:text-gray-600">
            <ArrowLeft className="w-5 h-5" />
          </button>
          <div>
            <div className="flex items-center gap-2">
              <AlertTriangle className="w-4 h-4 text-amber-500" />
              <span className="text-sm font-semibold text-gray-900">Duplikat-Vergleich</span>
              {similarity !== null && (
                <span className="text-xs font-medium text-amber-600 bg-amber-50 px-2 py-0.5 rounded-full">
                  {(similarity * 100).toFixed(1)}% Aehnlichkeit
                </span>
              )}
            </div>
          </div>
        </div>

        <div className="flex items-center gap-2">
          {/* Navigation */}
          <div className="flex items-center gap-1 mr-3">
            <button onClick={onReviewPrev} disabled={reviewIndex === 0} className="p-1 text-gray-400 hover:text-gray-600 disabled:opacity-30">
              <ChevronLeft className="w-4 h-4" />
            </button>
            <span className="text-xs text-gray-500 font-medium">{reviewIndex + 1} / {reviewTotal}</span>
            <button onClick={onReviewNext} disabled={reviewIndex >= reviewTotal - 1} className="p-1 text-gray-400 hover:text-gray-600 disabled:opacity-30">
              <SkipForward className="w-4 h-4" />
            </button>
          </div>

          {/* Actions */}
          <button
            onClick={() => onReview(ctrl.control_id, 'approve')}
            className="px-3 py-1.5 text-sm text-white bg-green-600 rounded-lg hover:bg-green-700"
          >
            <CheckCircle2 className="w-3.5 h-3.5 inline mr-1" />Behalten
          </button>
          <button
            onClick={() => onReview(ctrl.control_id, 'reject')}
            className="px-3 py-1.5 text-sm text-white bg-red-600 rounded-lg hover:bg-red-700"
          >
            <Trash2 className="w-3.5 h-3.5 inline mr-1" />Duplikat
          </button>
          <button
            onClick={onEdit}
            className="px-3 py-1.5 text-sm text-gray-600 border border-gray-300 rounded-lg hover:bg-gray-50"
          >
            <Pencil className="w-3.5 h-3.5 inline mr-1" />Bearbeiten
          </button>
        </div>
      </div>

      {/* Side-by-Side Panels */}
      <div className="flex-1 flex overflow-hidden">
        {/* Left: Control to review */}
        <div className="w-1/2 border-r border-gray-200 overflow-y-auto">
          <ControlPanel ctrl={ctrl} label="Zu pruefen" highlight />
        </div>

        {/* Right: Suspected duplicate */}
        <div className="w-1/2 overflow-y-auto">
          {loading ? (
            <div className="flex items-center justify-center h-full">
              <div className="animate-spin rounded-full h-6 w-6 border-2 border-purple-600 border-t-transparent" />
            </div>
          ) : suspectedDuplicate ? (
            <ControlPanel ctrl={suspectedDuplicate} label="Bestehendes Control (Verdacht)" />
          ) : (
            <div className="flex items-center justify-center h-full text-gray-400 text-sm">
              Kein Duplikat-Kandidat gefunden
            </div>
          )}
        </div>
      </div>
    </div>
  )
}