"use client"

import type { ExamNode } from "./selected-question-list"

type ChoiceOption = {
  id: string
  text: string
}

type QuestionContent = {
  text?: string
  options?: ChoiceOption[]
}

type ExamPaperPreviewProps = {
  title: string
  subject: string
  grade: string
  durationMin: number
  totalScore: number
  nodes: ExamNode[]
}

export function ExamPaperPreview({ title, subject, grade, durationMin, totalScore, nodes }: ExamPaperPreviewProps) {
  // Helper to flatten questions for continuous numbering
  let questionCounter = 0

  const parseContent = (raw: unknown): QuestionContent => {
    if (raw && typeof raw === "object") return raw as QuestionContent
    if (typeof raw === "string") {
      try {
        const parsed = JSON.parse(raw) as unknown
        if (parsed && typeof parsed === "object") return parsed as QuestionContent
        return { text: raw }
      } catch {
        return { text: raw }
      }
    }
    return {}
  }

  const renderNode = (node: ExamNode, depth: number = 0) => {
    if (node.type === 'group') {
      return (
        <div key={node.id} className="space-y-4 mb-6">
          <div className="flex items-center gap-2">
            <h3 className={`font-bold ${depth === 0 ? 'text-lg' : 'text-md'} text-foreground/90`}>
              {node.title || "Section"}
            </h3>
            {/* Optional: Show section score if needed */}
          </div>
          <div className="pl-0">
            {node.children?.map(child => renderNode(child, depth + 1))}
          </div>
        </div>
      )
    }

    if (node.type === 'question' && node.question) {
      questionCounter++
      const q = node.question
      const content = parseContent(q.content)
      
      return (
        <div key={node.id} className="mb-6 break-inside-avoid">
          <div className="flex gap-2">
            <span className="font-semibold text-foreground min-w-[24px]">{questionCounter}.</span>
            <div className="flex-1 space-y-2">
              <div className="text-foreground/90 leading-relaxed whitespace-pre-wrap">
                {content.text ?? ""} 
                <span className="text-muted-foreground text-sm ml-2">({node.score}分)</span>
              </div>
              
              {/* Options for Choice Questions */}
              {(q.type === 'single_choice' || q.type === 'multiple_choice') && content.options && (
                <div className="grid grid-cols-1 md:grid-cols-2 gap-y-2 gap-x-4 mt-2 pl-2">
                  {content.options.map((opt) => (
                    <div key={opt.id} className="flex gap-2 text-sm text-muted-foreground hover:text-foreground transition-colors">
                      <span className="font-medium">{opt.id}.</span>
                      <span>{opt.text}</span>
                    </div>
                  ))}
                </div>
              )}

              {/* Space for written answers */}
              {q.type === 'text' && (
                <div className="mt-4 h-24 border-b border-dashed border-muted-foreground/30 w-full"></div>
              )}
            </div>
          </div>
        </div>
      )
    }
    return null
  }

  return (
    <div className="bg-card shadow-sm border p-12 print:shadow-none print:border-none">
      {/* Header */}
      <div className="text-center space-y-4 mb-12 border-b-2 border-primary/20 pb-8">
        <h1 className="text-3xl font-black tracking-tight text-foreground">{title}</h1>
        <div className="flex justify-center gap-8 text-sm text-muted-foreground font-medium uppercase tracking-wide">
          <span>Subject: {subject}</span>
          <span>Grade: {grade}</span>
          <span>Time: {durationMin} mins</span>
          <span>Total: {totalScore} pts</span>
        </div>
        <div className="flex justify-center gap-12 text-sm pt-4">
          <div className="w-32 border-b border-foreground/20 text-left px-1">Class:</div>
          <div className="w-32 border-b border-foreground/20 text-left px-1">Name:</div>
          <div className="w-32 border-b border-foreground/20 text-left px-1">No.:</div>
        </div>
      </div>

      {/* Content */}
      <div className="space-y-2">
        {nodes.length === 0 ? (
          <div className="text-center py-20 text-muted-foreground">
            Empty Exam Paper
          </div>
        ) : (
          nodes.map(node => renderNode(node))
        )}
      </div>
    </div>
  )
}