'use client'

import React, { useState, useEffect, useMemo, useCallback } from 'react'
import { useSDK } from '@/lib/sdk'
import { StepHeader, STEP_EXPLANATIONS } from '@/components/sdk/StepHeader'
import {
  WhistleblowerReport,
  WhistleblowerStatistics,
  ReportCategory,
  ReportStatus,
  ReportPriority,
  isAcknowledgmentOverdue,
  isFeedbackOverdue,
} from '@/lib/sdk/whistleblower/types'
import { fetchSDKWhistleblowerList } from '@/lib/sdk/whistleblower/api'
import { TabNavigation, type Tab, type TabId } from './_components/TabNavigation'
import { StatCard } from './_components/StatCard'
import { FilterBar } from './_components/FilterBar'
import { ReportCard } from './_components/ReportCard'
import { WhistleblowerCreateModal } from './_components/WhistleblowerCreateModal'
import { CaseDetailPanel } from './_components/CaseDetailPanel'

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

export default function WhistleblowerPage() {
  const { state } = useSDK()
  const [activeTab, setActiveTab] = useState<TabId>('overview')
  const [reports, setReports] = useState<WhistleblowerReport[]>([])
  const [statistics, setStatistics] = useState<WhistleblowerStatistics | null>(null)
  const [isLoading, setIsLoading] = useState(true)
  const [showCreateModal, setShowCreateModal] = useState(false)
  const [selectedReport, setSelectedReport] = useState<WhistleblowerReport | null>(null)

  // Filters
  const [selectedCategory, setSelectedCategory] = useState<ReportCategory | 'all'>('all')
  const [selectedStatus, setSelectedStatus] = useState<ReportStatus | 'all'>('all')
  const [selectedPriority, setSelectedPriority] = useState<ReportPriority | 'all'>('all')

  // Load data from SDK backend
  const loadData = useCallback(async () => {
    setIsLoading(true)
    try {
      const { reports: wbReports, statistics: wbStats } = await fetchSDKWhistleblowerList()
      setReports(wbReports)
      setStatistics(wbStats)
    } catch (error) {
      console.error('Failed to load Whistleblower data:', error)
    } finally {
      setIsLoading(false)
    }
  }, [])

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

  // Locally computed overdue counts (always fresh)
  const overdueCounts = useMemo(() => {
    const overdueAck = reports.filter(r => isAcknowledgmentOverdue(r)).length
    const overdueFb = reports.filter(r => isFeedbackOverdue(r)).length
    return { overdueAck, overdueFb }
  }, [reports])

  // Calculate tab counts
  const tabCounts = useMemo(() => {
    const investigationStatuses: ReportStatus[] = ['acknowledged', 'under_review', 'investigation', 'measures_taken']
    const closedStatuses: ReportStatus[] = ['closed', 'rejected']
    return {
      new_reports: reports.filter(r => r.status === 'new').length,
      investigation: reports.filter(r => investigationStatuses.includes(r.status)).length,
      closed: reports.filter(r => closedStatuses.includes(r.status)).length
    }
  }, [reports])

  // Filter reports based on active tab and filters
  const filteredReports = useMemo(() => {
    let filtered = [...reports]

    // Tab-based filtering
    const investigationStatuses: ReportStatus[] = ['acknowledged', 'under_review', 'investigation', 'measures_taken']
    const closedStatuses: ReportStatus[] = ['closed', 'rejected']

    if (activeTab === 'new_reports') {
      filtered = filtered.filter(r => r.status === 'new')
    } else if (activeTab === 'investigation') {
      filtered = filtered.filter(r => investigationStatuses.includes(r.status))
    } else if (activeTab === 'closed') {
      filtered = filtered.filter(r => closedStatuses.includes(r.status))
    }

    // Category filter
    if (selectedCategory !== 'all') {
      filtered = filtered.filter(r => r.category === selectedCategory)
    }

    // Status filter
    if (selectedStatus !== 'all') {
      filtered = filtered.filter(r => r.status === selectedStatus)
    }

    // Priority filter
    if (selectedPriority !== 'all') {
      filtered = filtered.filter(r => r.priority === selectedPriority)
    }

    // Sort: overdue first, then by priority, then by date
    return filtered.sort((a, b) => {
      const closedStatuses: ReportStatus[] = ['closed', 'rejected']

      const getUrgency = (r: WhistleblowerReport) => {
        if (closedStatuses.includes(r.status)) return 1000
        const ackOd = isAcknowledgmentOverdue(r)
        const fbOd = isFeedbackOverdue(r)
        if (ackOd || fbOd) return -100
        const priorityScore = { critical: 0, high: 1, normal: 2, low: 3 }
        return priorityScore[r.priority] ?? 2
      }

      const urgencyDiff = getUrgency(a) - getUrgency(b)
      if (urgencyDiff !== 0) return urgencyDiff

      return new Date(b.receivedAt).getTime() - new Date(a.receivedAt).getTime()
    })
  }, [reports, activeTab, selectedCategory, selectedStatus, selectedPriority])

  const tabs: Tab[] = [
    { id: 'overview', label: 'Uebersicht' },
    { id: 'new_reports', label: 'Neue Meldungen', count: tabCounts.new_reports, countColor: 'bg-blue-100 text-blue-600' },
    { id: 'investigation', label: 'In Untersuchung', count: tabCounts.investigation, countColor: 'bg-yellow-100 text-yellow-600' },
    { id: 'closed', label: 'Abgeschlossen', count: tabCounts.closed, countColor: 'bg-green-100 text-green-600' },
    { id: 'settings', label: 'Einstellungen' }
  ]

  const stepInfo = STEP_EXPLANATIONS['whistleblower']

  const clearFilters = () => {
    setSelectedCategory('all')
    setSelectedStatus('all')
    setSelectedPriority('all')
  }

  return (
    <div className="space-y-6">
      {/* Step Header */}
      <StepHeader
        stepId="whistleblower"
        title={stepInfo.title}
        description={stepInfo.description}
        explanation={stepInfo.explanation}
        tips={stepInfo.tips}
      >
        <button
          onClick={() => setShowCreateModal(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>
          Meldung erfassen
        </button>
      </StepHeader>

      {/* Tab Navigation */}
      <TabNavigation
        tabs={tabs}
        activeTab={activeTab}
        onTabChange={setActiveTab}
      />

      {/* Loading State */}
      {isLoading ? (
        <div className="flex items-center justify-center py-12">
          <svg className="animate-spin w-8 h-8 text-purple-600" 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 12h4zm2 5.291A7.962 7.962 0 014 12H0c0 3.042 1.135 5.824 3 7.938l3-2.647z" />
          </svg>
        </div>
      ) : activeTab === 'settings' ? (
        /* Settings Tab */
        <div className="bg-white rounded-xl border border-gray-200 p-8 text-center">
          <div className="w-16 h-16 mx-auto bg-gray-100 rounded-full flex items-center justify-center mb-4">
            <svg className="w-8 h-8 text-gray-400" fill="none" stroke="currentColor" viewBox="0 0 24 24">
              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M10.325 4.317c.426-1.756 2.924-1.756 3.35 0a1.724 1.724 0 002.573 1.066c1.543-.94 3.31.826 2.37 2.37a1.724 1.724 0 001.065 2.572c1.756.426 1.756 2.924 0 3.35a1.724 1.724 0 00-1.066 2.573c.94 1.543-.826 3.31-2.37 2.37a1.724 1.724 0 00-2.572 1.065c-.426 1.756-2.924 1.756-3.35 0a1.724 1.724 0 00-2.573-1.066c-1.543.94-3.31-.826-2.37-2.37a1.724 1.724 0 00-1.065-2.572c-1.756-.426-1.756-2.924 0-3.35a1.724 1.724 0 001.066-2.573c-.94-1.543.826-3.31 2.37-2.37.996.608 2.296.07 2.572-1.065z" />
              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M15 12a3 3 0 11-6 0 3 3 0 016 0z" />
            </svg>
          </div>
          <h3 className="text-lg font-semibold text-gray-900">Einstellungen</h3>
          <p className="mt-2 text-gray-500">
            Hinweisgebersystem-Einstellungen, Meldekanal-Konfiguration, Ombudsperson-Verwaltung
            und E-Mail-Vorlagen werden in einer spaeteren Version verfuegbar sein.
          </p>
        </div>
      ) : (
        <>
          {/* Statistics (Overview Tab) */}
          {activeTab === 'overview' && statistics && (
            <div className="grid grid-cols-1 md:grid-cols-4 gap-4">
              <StatCard
                label="Gesamt Meldungen"
                value={statistics.totalReports}
                color="gray"
              />
              <StatCard
                label="Neue Meldungen"
                value={statistics.newReports}
                color="blue"
              />
              <StatCard
                label="In Untersuchung"
                value={statistics.underReview}
                color="yellow"
              />
              <StatCard
                label="Ueberfaellige Bestaetigung"
                value={overdueCounts.overdueAck}
                color={overdueCounts.overdueAck > 0 ? 'red' : 'green'}
              />
            </div>
          )}

          {/* Overdue Alert for Acknowledgment Deadline (7 days HinSchG) */}
          {(overdueCounts.overdueAck > 0 || overdueCounts.overdueFb > 0) && (activeTab === 'overview' || activeTab === 'new_reports' || activeTab === 'investigation') && (
            <div className="bg-red-50 border border-red-200 rounded-xl p-4 flex items-center gap-4">
              <div className="w-10 h-10 bg-red-100 rounded-full flex items-center justify-center flex-shrink-0">
                <svg className="w-5 h-5 text-red-600" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                  <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 9v2m0 4h.01m-6.938 4h13.856c1.54 0 2.502-1.667 1.732-3L13.732 4c-.77-1.333-2.694-1.333-3.464 0L3.34 16c-.77 1.333.192 3 1.732 3z" />
                </svg>
              </div>
              <div className="flex-1">
                <h4 className="font-medium text-red-800">
                  Achtung: Gesetzliche Fristen ueberschritten
                </h4>
                <p className="text-sm text-red-600 mt-0.5">
                  {overdueCounts.overdueAck > 0 && (
                    <span>{overdueCounts.overdueAck} Meldung(en) ohne Eingangsbestaetigung (mehr als 7 Tage, HinSchG ss 17 Abs. 1). </span>
                  )}
                  {overdueCounts.overdueFb > 0 && (
                    <span>{overdueCounts.overdueFb} Meldung(en) ohne Rueckmeldung (mehr als 3 Monate, HinSchG ss 17 Abs. 2). </span>
                  )}
                  Handeln Sie umgehend, um Bussgelder und Haftungsrisiken zu vermeiden.
                </p>
              </div>
              <button
                onClick={() => {
                  if (overdueCounts.overdueAck > 0) {
                    setActiveTab('new_reports')
                  } else {
                    setActiveTab('investigation')
                  }
                }}
                className="px-4 py-2 bg-red-600 text-white rounded-lg hover:bg-red-700 transition-colors text-sm font-medium"
              >
                Anzeigen
              </button>
            </div>
          )}

          {/* Info Box about HinSchG (Overview Tab) */}
          {activeTab === 'overview' && (
            <div className="space-y-4">
              {/* Gesetzliche Grundlage */}
              <div className="bg-blue-50 border border-blue-200 rounded-xl p-5">
                <div className="flex items-start gap-3">
                  <svg className="w-5 h-5 text-blue-600 mt-0.5 flex-shrink-0" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M13 16h-1v-4h-1m1-4h.01M21 12a9 9 0 11-18 0 9 9 0 0118 0z" />
                  </svg>
                  <div>
                    <h4 className="font-medium text-blue-800">Gesetzliche Grundlage: Hinweisgeberschutzgesetz (HinSchG)</h4>
                    <p className="text-sm text-blue-600 mt-1">
                      Das HinSchG setzt die <strong>EU-Whistleblowing-Richtlinie (2019/1937)</strong> in deutsches Recht um
                      und ist seit dem <strong>2. Juli 2023</strong> in Kraft. Seit dem <strong>17. Dezember 2023</strong> gilt
                      die Pflicht zur Einrichtung einer internen Meldestelle auch fuer Unternehmen ab 50 Beschaeftigten (ss 12 HinSchG).
                    </p>
                  </div>
                </div>
              </div>

              {/* Fristen & Pflichten */}
              <div className="grid grid-cols-1 md:grid-cols-3 gap-4">
                <div className="bg-white border border-gray-200 rounded-xl p-4">
                  <div className="flex items-center gap-2 mb-2">
                    <svg className="w-4 h-4 text-orange-500" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                      <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 8v4l3 3m6-3a9 9 0 11-18 0 9 9 0 0118 0z" />
                    </svg>
                    <h5 className="text-sm font-semibold text-gray-900">7-Tage-Frist</h5>
                  </div>
                  <p className="text-xs text-gray-600">
                    Eingangsbestaetigung an den Hinweisgeber innerhalb von 7 Tagen nach Meldungseingang (ss 17 Abs. 1 S. 2 HinSchG).
                  </p>
                </div>
                <div className="bg-white border border-gray-200 rounded-xl p-4">
                  <div className="flex items-center gap-2 mb-2">
                    <svg className="w-4 h-4 text-purple-500" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                      <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M8 7V3m8 4V3m-9 8h10M5 21h14a2 2 0 002-2V7a2 2 0 00-2-2H5a2 2 0 00-2 2v12a2 2 0 002 2z" />
                    </svg>
                    <h5 className="text-sm font-semibold text-gray-900">3-Monate-Frist</h5>
                  </div>
                  <p className="text-xs text-gray-600">
                    Rueckmeldung ueber ergriffene Folgemaßnahmen innerhalb von 3 Monaten nach Eingangsbestaetigung (ss 17 Abs. 2 HinSchG).
                  </p>
                </div>
                <div className="bg-white border border-gray-200 rounded-xl p-4">
                  <div className="flex items-center gap-2 mb-2">
                    <svg className="w-4 h-4 text-red-500" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                      <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 9v2m0 4h.01m-6.938 4h13.856c1.54 0 2.502-1.667 1.732-3L13.732 4c-.77-1.333-2.694-1.333-3.464 0L3.34 16c-.77 1.333.192 3 1.732 3z" />
                    </svg>
                    <h5 className="text-sm font-semibold text-gray-900">3 Jahre Aufbewahrung</h5>
                  </div>
                  <p className="text-xs text-gray-600">
                    Dokumentation der Meldungen und Folgemaßnahmen ist 3 Jahre nach Abschluss aufzubewahren (ss 11 Abs. 5 HinSchG).
                  </p>
                </div>
              </div>

              {/* Sachlicher Anwendungsbereich & Schutz */}
              <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
                <div className="bg-amber-50 border border-amber-200 rounded-xl p-4">
                  <h5 className="text-sm font-semibold text-amber-800 mb-2">Sachlicher Anwendungsbereich (ss 2 HinSchG)</h5>
                  <ul className="text-xs text-amber-700 space-y-1">
                    <li>Verstoesse gegen Strafvorschriften (StGB, Nebenstrafrecht)</li>
                    <li>Verstoesse gegen Datenschutzrecht (DSGVO, BDSG)</li>
                    <li>Geldwaesche und Terrorismusfinanzierung (GwG)</li>
                    <li>Produktsicherheit und Verbraucherschutz</li>
                    <li>Umweltschutz und Lebensmittelsicherheit</li>
                    <li>Arbeitsschutz und Arbeitnehmerrechte</li>
                    <li>Wettbewerbs- und Kartellrecht</li>
                    <li>Steuer- und Abgabenrecht (bei Unternehmen)</li>
                  </ul>
                </div>
                <div className="bg-green-50 border border-green-200 rounded-xl p-4">
                  <h5 className="text-sm font-semibold text-green-800 mb-2">Schutz des Hinweisgebers (ss 36–37 HinSchG)</h5>
                  <ul className="text-xs text-green-700 space-y-1">
                    <li><strong>Repressalienverbot:</strong> Jede Benachteiligung ist untersagt (ss 36)</li>
                    <li><strong>Beweislastumkehr:</strong> Arbeitgeber muss beweisen, dass Maßnahmen nicht mit Meldung zusammenhaengen</li>
                    <li><strong>Schadensersatz:</strong> Bei Verstoessen gegen Repressalienverbot (ss 37)</li>
                    <li><strong>Vertraulichkeit:</strong> Identitaet darf nur bei Zustimmung oder gesetzlicher Pflicht offengelegt werden (ss 8)</li>
                    <li><strong>Bussgelder:</strong> Bis zu 50.000 EUR bei Verstoessen gegen die Einrichtungspflicht (ss 40)</li>
                  </ul>
                </div>
              </div>
            </div>
          )}

          {/* Filters */}
          <FilterBar
            selectedCategory={selectedCategory}
            selectedStatus={selectedStatus}
            selectedPriority={selectedPriority}
            onCategoryChange={setSelectedCategory}
            onStatusChange={setSelectedStatus}
            onPriorityChange={setSelectedPriority}
            onClear={clearFilters}
          />

          {/* Report List */}
          <div className="space-y-4">
            {filteredReports.map(report => (
              <ReportCard
                key={report.id}
                report={report}
                onClick={() => setSelectedReport(report)}
              />
            ))}
          </div>

          {/* Empty State */}
          {filteredReports.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-gray-100 rounded-full flex items-center justify-center mb-4">
                <svg className="w-8 h-8 text-gray-400" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                  <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M20 13V6a2 2 0 00-2-2H6a2 2 0 00-2 2v7m16 0v5a2 2 0 01-2 2H6a2 2 0 01-2-2v-5m16 0h-2.586a1 1 0 00-.707.293l-2.414 2.414a1 1 0 01-.707.293h-3.172a1 1 0 01-.707-.293l-2.414-2.414A1 1 0 006.586 13H4" />
                </svg>
              </div>
              <h3 className="text-lg font-semibold text-gray-900">Keine Meldungen gefunden</h3>
              <p className="mt-2 text-gray-500">
                {selectedCategory !== 'all' || selectedStatus !== 'all' || selectedPriority !== 'all'
                  ? 'Passen Sie die Filter an oder setzen Sie sie zurueck.'
                  : 'Es sind noch keine Meldungen im Hinweisgebersystem vorhanden. Meldungen werden ueber das oeffentliche Meldeformular eingereicht.'
                }
              </p>
              {(selectedCategory !== 'all' || selectedStatus !== 'all' || selectedPriority !== 'all') && (
                <button
                  onClick={clearFilters}
                  className="mt-4 px-4 py-2 text-purple-600 hover:bg-purple-50 rounded-lg transition-colors"
                >
                  Filter zuruecksetzen
                </button>
              )}
            </div>
          )}
        </>
      )}

      {/* Modals */}
      {showCreateModal && (
        <WhistleblowerCreateModal
          onClose={() => setShowCreateModal(false)}
          onSuccess={() => { setShowCreateModal(false); loadData() }}
        />
      )}
      {selectedReport && (
        <CaseDetailPanel
          report={selectedReport}
          onClose={() => setSelectedReport(null)}
          onUpdated={() => { setSelectedReport(null); loadData() }}
          onDeleted={() => { setSelectedReport(null); loadData() }}
        />
      )}
    </div>
  )
}