/**
 * 金额格式化工具模块
 * 提供千分位分隔、输入清洗、展示格式化、数值解析等功能
 */

/** 字符串分段拼接千分位，禁止使用前瞻正则 */
export function addThousandSeparators(intStr: string): string {
  if (!intStr) return ''
  const isNegative = intStr.startsWith('-')
  const absStr = isNegative ? intStr.slice(1) : intStr
  const parts: string[] = []
  const len = absStr.length
  for (let i = len; i > 0; i -= 3) {
    const start = Math.max(0, i - 3)
    parts.unshift(absStr.slice(start, i))
  }
  const result = parts.join(',')
  return isNegative ? `-${result}` : result
}

/** 输入清洗：去逗号、仅保留数字与一个点、截断小数位 */
export function sanitizeMoneyInput(value: string, precision = 2): string {
  if (!value) return ''
  // 去逗号
  let cleaned = value.replace(/,/g, '')
  // 去非数字非点字符
  cleaned = cleaned.replace(/[^0-9.]/g, '')
  // 只保留第一个小数点
  const dotIndex = cleaned.indexOf('.')
  if (dotIndex !== -1) {
    const intPart = cleaned.slice(0, dotIndex + 1)
    const decPart = cleaned.slice(dotIndex + 1).replace(/\./g, '')
    cleaned = intPart + decPart
  }
  // 截断小数到 precision 位
  if (dotIndex !== -1) {
    const dotIdx = cleaned.indexOf('.')
    const intPart = cleaned.slice(0, dotIdx + 1)
    let decPart = cleaned.slice(dotIdx + 1)
    if (decPart.length > precision) {
      decPart = decPart.slice(0, precision)
    }
    cleaned = intPart + decPart
  }
  return cleaned
}

/** 展示：整数部分千分位，小数部分按实际位数展示，不补尾零 */
export function formatMoneyDisplay(
  value: string | number | null | undefined,
  precision = 2
): string {
  if (value === null || value === undefined || value === '') return ''
  const num = typeof value === 'string' ? parseFloat(value) : value
  if (isNaN(num)) return ''
  const isNegative = num < 0
  const absNum = Math.abs(num)
  const factor = Math.pow(10, precision)
  const rounded = Math.round(absNum * factor) / factor
  const raw = String(rounded)
  const dotIdx = raw.indexOf('.')
  if (dotIdx === -1) {
    const formatted = addThousandSeparators(raw)
    return isNegative ? `-${formatted}` : formatted
  }
  const intStr = raw.slice(0, dotIdx)
  const decStr = raw.slice(dotIdx)
  const formatted = addThousandSeparators(intStr)
  const result = `${formatted}${decStr}`
  return isNegative ? `-${result}` : result
}

/** 将已清洗的金额字符串加上千分位，保留用户输入的小数形态 */
export function formatMoneyInputDisplay(sanitized: string): string {
  if (!sanitized || sanitized === '.' || sanitized === '-' || sanitized === '-.') return ''
  const isNegative = sanitized.startsWith('-')
  const body = isNegative ? sanitized.slice(1) : sanitized
  const dotIdx = body.indexOf('.')
  if (dotIdx === -1) {
    const formatted = addThousandSeparators(body)
    return isNegative ? `-${formatted}` : formatted
  }
  const intStr = body.slice(0, dotIdx)
  const decStr = body.slice(dotIdx)
  const formatted = addThousandSeparators(intStr)
  const result = `${formatted}${decStr}`
  return isNegative ? `-${result}` : result
}

/** 提交：number | null；空串 / 仅 '.' → null */
export function parseMoneyToNumber(value: string, precision = 2): number | null {
  const sanitized = sanitizeMoneyInput(value, precision)
  if (!sanitized || sanitized === '.') return null
  const num = Number(sanitized)
  if (isNaN(num)) return null
  const factor = Math.pow(10, precision)
  return Math.round(num * factor) / factor
}