'use client'

import { useState } from 'react'
import { BookOpen, ExternalLink, Scale, ChevronDown, ChevronUp, Info } from 'lucide-react'
import {
  DSFALicenseCode,
  DSFA_LICENSE_LABELS,
  SourceAttributionProps
} from '@/lib/sdk/types'

/**
 * Get license badge color based on license type
 */
function getLicenseBadgeColor(licenseCode: DSFALicenseCode): string {
  switch (licenseCode) {
    case 'DL-DE-BY-2.0':
    case 'DL-DE-ZERO-2.0':
      return 'bg-blue-100 text-blue-700 border-blue-200'
    case 'CC-BY-4.0':
      return 'bg-green-100 text-green-700 border-green-200'
    case 'EDPB-LICENSE':
      return 'bg-purple-100 text-purple-700 border-purple-200'
    case 'PUBLIC_DOMAIN':
      return 'bg-gray-100 text-gray-700 border-gray-200'
    case 'PROPRIETARY':
      return 'bg-amber-100 text-amber-700 border-amber-200'
    default:
      return 'bg-slate-100 text-slate-700 border-slate-200'
  }
}

/**
 * Get license URL based on license code
 */
function getLicenseUrl(licenseCode: DSFALicenseCode): string | null {
  switch (licenseCode) {
    case 'DL-DE-BY-2.0':
      return 'https://www.govdata.de/dl-de/by-2-0'
    case 'DL-DE-ZERO-2.0':
      return 'https://www.govdata.de/dl-de/zero-2-0'
    case 'CC-BY-4.0':
      return 'https://creativecommons.org/licenses/by/4.0/'
    case 'EDPB-LICENSE':
      return 'https://edpb.europa.eu/about-edpb/legal-notice_en'
    default:
      return null
  }
}

/**
 * License badge component
 */
function LicenseBadge({ licenseCode }: { licenseCode: DSFALicenseCode }) {
  const licenseUrl = getLicenseUrl(licenseCode)
  const colorClass = getLicenseBadgeColor(licenseCode)
  const label = DSFA_LICENSE_LABELS[licenseCode] || licenseCode

  if (licenseUrl) {
    return (
      <a
        href={licenseUrl}
        target="_blank"
        rel="noopener noreferrer"
        className={`inline-flex items-center gap-1 px-2 py-0.5 rounded text-xs border ${colorClass} hover:opacity-80 transition-opacity`}
      >
        <Scale className="w-3 h-3" />
        {label}
        <ExternalLink className="w-2.5 h-2.5" />
      </a>
    )
  }

  return (
    <span className={`inline-flex items-center gap-1 px-2 py-0.5 rounded text-xs border ${colorClass}`}>
      <Scale className="w-3 h-3" />
      {label}
    </span>
  )
}

/**
 * Single source item in the attribution list
 */
function SourceItem({
  source,
  index,
  showScore
}: {
  source: SourceAttributionProps['sources'][0]
  index: number
  showScore: boolean
}) {
  return (
    <li className="text-sm">
      <div className="flex items-start gap-2">
        <span className="text-slate-400 font-mono text-xs mt-0.5 min-w-[1.5rem]">
          {index + 1}.
        </span>
        <div className="flex-1 min-w-0">
          <div className="flex items-center gap-2 flex-wrap">
            {source.sourceUrl ? (
              <a
                href={source.sourceUrl}
                target="_blank"
                rel="noopener noreferrer"
                className="text-blue-600 hover:text-blue-800 hover:underline font-medium truncate"
              >
                {source.sourceName}
              </a>
            ) : (
              <span className="text-slate-700 font-medium truncate">
                {source.sourceName}
              </span>
            )}
            {showScore && source.score !== undefined && (
              <span className="text-xs text-slate-400 font-mono">
                ({(source.score * 100).toFixed(0)}%)
              </span>
            )}
          </div>
          <p className="text-xs text-slate-500 mt-0.5 leading-relaxed">
            {source.attributionText}
          </p>
          <div className="mt-1.5">
            <LicenseBadge licenseCode={source.licenseCode} />
          </div>
        </div>
      </div>
    </li>
  )
}

/**
 * Compact source badge for inline display
 */
function CompactSourceBadge({
  source
}: {
  source: SourceAttributionProps['sources'][0]
}) {
  return (
    <span className="inline-flex items-center gap-1 px-2 py-0.5 rounded-full text-xs bg-slate-100 text-slate-600 border border-slate-200">
      <BookOpen className="w-3 h-3" />
      {source.sourceCode}
    </span>
  )
}

/**
 * SourceAttribution component - displays source/license information for DSFA RAG results
 *
 * @example
 * ```tsx
 * <SourceAttribution
 *   sources={[
 *     {
 *       sourceCode: "WP248",
 *       sourceName: "WP248 rev.01 - Leitlinien zur DSFA",
 *       attributionText: "Quelle: WP248 rev.01, Artikel-29-Datenschutzgruppe (2017)",
 *       licenseCode: "EDPB-LICENSE",
 *       sourceUrl: "https://ec.europa.eu/newsroom/article29/items/611236/en",
 *       score: 0.87
 *     }
 *   ]}
 *   showScores
 * />
 * ```
 */
export function SourceAttribution({
  sources,
  compact = false,
  showScores = false
}: SourceAttributionProps) {
  const [isExpanded, setIsExpanded] = useState(!compact)

  if (!sources || sources.length === 0) {
    return null
  }

  // Compact mode - just show badges
  if (compact && !isExpanded) {
    return (
      <div className="flex items-center gap-2 flex-wrap">
        <button
          onClick={() => setIsExpanded(true)}
          className="inline-flex items-center gap-1 text-xs text-slate-500 hover:text-slate-700"
        >
          <Info className="w-3 h-3" />
          Quellen ({sources.length})
          <ChevronDown className="w-3 h-3" />
        </button>
        {sources.slice(0, 3).map((source, i) => (
          <CompactSourceBadge key={i} source={source} />
        ))}
        {sources.length > 3 && (
          <span className="text-xs text-slate-400">+{sources.length - 3}</span>
        )}
      </div>
    )
  }

  return (
    <div className="bg-slate-50 border border-slate-200 rounded-lg p-4 mt-4">
      <div className="flex items-center justify-between">
        <h4 className="text-sm font-medium text-slate-700 flex items-center gap-2">
          <BookOpen className="w-4 h-4" />
          Quellen & Lizenzen
        </h4>
        {compact && (
          <button
            onClick={() => setIsExpanded(false)}
            className="text-xs text-slate-400 hover:text-slate-600 flex items-center gap-1"
          >
            Einklappen
            <ChevronUp className="w-3 h-3" />
          </button>
        )}
      </div>

      <ul className="mt-3 space-y-3">
        {sources.map((source, i) => (
          <SourceItem
            key={i}
            source={source}
            index={i}
            showScore={showScores}
          />
        ))}
      </ul>

      {/* Aggregated license notice */}
      {sources.length > 1 && (
        <div className="mt-4 pt-3 border-t border-slate-200">
          <p className="text-xs text-slate-500">
            <strong>Hinweis:</strong> Die angezeigten Inhalte stammen aus {sources.length} verschiedenen Quellen
            mit unterschiedlichen Lizenzen. Bitte beachten Sie die jeweiligen Attributionsanforderungen.
          </p>
        </div>
      )}
    </div>
  )
}

/**
 * Inline source reference for use within text
 */
export function InlineSourceRef({
  sourceCode,
  sourceName,
  sourceUrl
}: {
  sourceCode: string
  sourceName: string
  sourceUrl?: string
}) {
  if (sourceUrl) {
    return (
      <a
        href={sourceUrl}
        target="_blank"
        rel="noopener noreferrer"
        className="inline-flex items-center gap-0.5 text-blue-600 hover:text-blue-800 text-sm"
        title={sourceName}
      >
        [{sourceCode}]
        <ExternalLink className="w-3 h-3" />
      </a>
    )
  }

  return (
    <span className="text-slate-600 text-sm" title={sourceName}>
      [{sourceCode}]
    </span>
  )
}

/**
 * Attribution footer for generated documents
 */
export function AttributionFooter({
  sources,
  generatedAt
}: {
  sources: SourceAttributionProps['sources']
  generatedAt?: Date
}) {
  if (!sources || sources.length === 0) {
    return null
  }

  // Group by license
  const byLicense = sources.reduce((acc, source) => {
    const key = source.licenseCode
    if (!acc[key]) acc[key] = []
    acc[key].push(source)
    return acc
  }, {} as Record<string, typeof sources>)

  return (
    <footer className="mt-8 pt-4 border-t border-slate-200 text-xs text-slate-500">
      <h5 className="font-medium text-slate-600 mb-2">Quellennachweis</h5>
      <ul className="space-y-1">
        {Object.entries(byLicense).map(([licenseCode, licenseSources]) => (
          <li key={licenseCode}>
            <span className="font-medium">{DSFA_LICENSE_LABELS[licenseCode as DSFALicenseCode]}:</span>{' '}
            {licenseSources.map(s => s.sourceName).join(', ')}
          </li>
        ))}
      </ul>
      {generatedAt && (
        <p className="mt-2 text-slate-400">
          Generiert am {generatedAt.toLocaleDateString('de-DE')} um {generatedAt.toLocaleTimeString('de-DE')}
        </p>
      )}
    </footer>
  )
}

export default SourceAttribution