/**
 * 申论题批复解析（与管理端 UserProgressList 约定一致）
 * review_comment 格式：【第1题】\n评语\n\n【第2题】\n评语\n\n__IMG_COUNTS__:n1,n2,...
 * review_images 为一维数组，按 __IMG_COUNTS__ 数量依次对应各题
 */

const IMG_COUNTS_MARKER = '__IMG_COUNTS__:'

/**
 * 从 progress.review_comment + review_images 解析出各题评语与各题图片数量
 * @param {Object} progress - 进度对象，含 review_comment（或 review_comment）
 * @returns {{ comments: string[], imageCounts: number[] }}
 */
function parseEssayReview(progress) {
  var comments = []
  var imageCounts = []
  var rawComment = (progress && (progress.review_comment || progress.reviewComment)) || ''
  var text = String(rawComment).trim()
  if (!text) return { comments: comments, imageCounts: imageCounts }

  var idx = text.indexOf(IMG_COUNTS_MARKER)
  if (idx >= 0) {
    var rest = text.slice(idx + IMG_COUNTS_MARKER.length).trim()
    var parts = rest.split(',').map(function (s) { return parseInt(s, 10) })
    parts.forEach(function (n) {
      if (!Number.isNaN(n)) imageCounts.push(n)
    })
    text = text.slice(0, idx).trim()
  }

  var regex = /【第(\d+)题】\s*\n?/g
  var starts = []
  var match
  while ((match = regex.exec(text)) !== null) {
    starts.push({ num: parseInt(match[1], 10), index: match.index })
  }
  for (var i = 0; i < starts.length; i++) {
    var startIdx = starts[i].index
    var endIdx = starts[i + 1] ? starts[i + 1].index : text.length
    var block = text.slice(startIdx, endIdx).replace(/^【第\d+题】\s*\n?/, '').trim()
    comments[i] = block
  }
  return { comments: comments, imageCounts: imageCounts }
}

/**
 * 将一维批复图片按各题数量拆成二维数组
 * @param {string[]} flat - 一维图片 URL 数组
 * @param {number[]} counts - 各题图片数量 [n1, n2, ...]
 * @returns {string[][]}
 */
function splitReviewImagesByCounts(flat, counts) {
  var result = []
  var offset = 0
  for (var i = 0; i < counts.length; i++) {
    var n = counts[i]
    var chunk = (flat || []).slice(offset, offset + n).filter(function (u) {
      return u && String(u).trim() !== ''
    })
    result.push(chunk)
    offset += n
  }
  return result
}

module.exports = {
  IMG_COUNTS_MARKER: IMG_COUNTS_MARKER,
  parseEssayReview: parseEssayReview,
  splitReviewImagesByCounts: splitReviewImagesByCounts
}