function normalizeText(value) {
  if (typeof value === 'string') {
    return value.trim()
  }
  if (value === null || value === undefined) {
    return ''
  }
  return String(value).trim()
}

function resolveOperationLabelFromSource(source) {
  switch (normalizeText(source).toLowerCase()) {
    case 'onlyoffice':
      return '在线编辑保存'
    case 'content-import':
      return '导入表格'
    case 'upload':
      return '上传表格'
    case 'restore':
      return '恢复历史版本'
    case 'review-submit':
      return '提交审核固化'
    case 'preview':
      return '预览版本'
    default:
      return ''
  }
}

export function resolveSpreadsheetOperationLabel(record) {
  const explicitLabel = normalizeText(record?.operationLabel)
  if (explicitLabel) {
    return explicitLabel
  }

  const sourceLabel = resolveOperationLabelFromSource(record?.spreadsheetMeta?.source)
  if (sourceLabel) {
    return sourceLabel
  }

  const note = normalizeText(record?.note).toLowerCase()
  if (note.includes('onlyoffice')) {
    return '在线编辑保存'
  }
  if (note.includes('导入')) {
    return '导入表格'
  }
  if (note.includes('恢复')) {
    return '恢复历史版本'
  }
  if (note.includes('上传')) {
    return '上传表格'
  }

  return '表格修改'
}

function normalizeChangeRecord(record) {
  const version = normalizeText(record?.version)
  if (!version) {
    return null
  }

  return {
    version,
    operationLabel: resolveSpreadsheetOperationLabel(record),
    operationActor:
      normalizeText(record?.operationActor || record?.createdBy || record?.spreadsheetMeta?.updated_by) ||
      '系统',
    note: normalizeText(record?.note) || '用户修改了表格内容。',
    time: normalizeText(record?.time || record?.createdAt || record?.spreadsheetMeta?.updated_at),
    isWorking: record?.isWorking !== false,
    isPendingLocalEdit: Boolean(record?.isPendingLocalEdit),
    disabledReason: normalizeText(record?.disabledReason)
  }
}

function toTimestamp(value) {
  const normalized = normalizeText(value)
  if (!normalized) {
    return 0
  }
  const parsed = Date.parse(normalized)
  return Number.isNaN(parsed) ? 0 : parsed
}

function dedupeChangeRecords(records) {
  const seen = new Set()
  return records.filter((item) => {
    const key = [item.version, item.operationLabel, item.note].join('::')
    if (seen.has(key)) {
      return false
    }
    seen.add(key)
    return true
  })
}

export function buildSpreadsheetChangeRecords({
  history = [],
  localRecords = [],
  publishedVersion = '',
  limit = 5
} = {}) {
  const normalizedPublishedVersion = normalizeText(publishedVersion)
  const normalizedHistoryRecords = Array.isArray(history)
    ? history.map(normalizeChangeRecord).filter(Boolean)
    : []
  const normalizedLocalRecords = Array.isArray(localRecords)
    ? localRecords.map(normalizeChangeRecord).filter(Boolean)
    : []

  const unpublishedHistoryRecords = normalizedHistoryRecords.filter(
    (item) => item.version !== normalizedPublishedVersion
  )
  const preferredHistoryRecords =
    unpublishedHistoryRecords.length || !normalizedPublishedVersion
      ? unpublishedHistoryRecords
      : normalizedHistoryRecords

  return dedupeChangeRecords([...normalizedLocalRecords, ...preferredHistoryRecords])
    .sort((left, right) => toTimestamp(right.time) - toTimestamp(left.time))
    .slice(0, limit)
}