package utility

import "strings"

// DesensitizeGeneric 通用脱敏函数：
// startReserveCount: 从字符串开头保留的字符数
// endReserveCount: 从字符串末尾保留的字符数
// asteriskChar: 用于替换的字符 (例如 '*')
// 例如：DesensitizeGeneric("这是一个秘密信息", 2, 2, '*') -> 这**信息
func DesensitizeGeneric(text string, startReserveCount int, endReserveCount int, asteriskChar rune) string {
	if text == "" {
		return ""
	}
	runes := []rune(text)
	length := len(runes)

	// 计算实际需要保留的总字符数
	totalReservedLength := startReserveCount + endReserveCount

	// 如果需要保留的字符数大于等于总长度，则不脱敏
	if totalReservedLength >= length {
		return text
	}

	// 确保保留位数不为负数
	if startReserveCount < 0 {
		startReserveCount = 0
	}
	if endReserveCount < 0 {
		endReserveCount = 0
	}

	// 如果保留总长度为0，且字符串不为空，则全部脱敏
	if totalReservedLength == 0 && length > 0 {
		return strings.Repeat(string(asteriskChar), length)
	}

	// 确保保留的长度不超过总长度
	if startReserveCount > length {
		startReserveCount = length
	}
	if endReserveCount > length-startReserveCount {
		endReserveCount = length - startReserveCount
	}

	// 构造脱敏字符串
	var sb strings.Builder
	// 写入前缀
	if startReserveCount > 0 {
		sb.WriteString(string(runes[0:startReserveCount]))
	}
	// 写入星号
	asteriskCount := length - startReserveCount - endReserveCount
	if asteriskCount > 0 {
		sb.WriteString(strings.Repeat(string(asteriskChar), asteriskCount))
	}
	// 写入后缀
	if endReserveCount > 0 && length-endReserveCount >= startReserveCount { // 确保后缀不与前缀重叠
		sb.WriteString(string(runes[length-endReserveCount:]))
	}

	return sb.String()
}