import type { Exam } from '../types'

export const validateExam = (data: unknown): string | null => {
  if (!data || typeof data !== 'object') return 'Not a JSON object'
  const d = data as Record<string, unknown>
  if (!d['title']) return 'Missing "title"'
  if (!Array.isArray(d['questions']) || d['questions'].length === 0) return 'Missing "questions" array'
  for (const q of d['questions'] as Record<string, unknown>[]) {
    if (!q['id']) return 'Question missing id'
    if (!q['type']) return `Question "${String(q['id'])}" missing type`
    if (!q['prompt']) return `Question "${String(q['id'])}" missing prompt`
  }
  return null
}

function generateId(): string {
  return Math.random().toString(36).slice(2, 10)
}

export const parseExam = (data: unknown): Exam => {
  const exam = data as Exam
  if (!exam.id) {
    exam.id = generateId()
  }
  return exam
}