//
// str_helper.go
// Copyright (C) 2022 tiglog <me@tiglog.com>
//
// Distributed under terms of the MIT license.
//

package helper

import (
	"math/rand"
	"strings"
	"time"
	"unicode"
)

// 是否是字符串
func IsString(v interface{}) bool {
	_, ok := v.(string)
	return ok
}

// 随机字符串
func RandString(n int) string {
	letterRunes := []rune("1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
	rd := rand.New(rand.NewSource(time.Now().UnixNano()))
	b := make([]rune, n)
	for i := range b {
		b[i] = letterRunes[rd.Intn(len(letterRunes))]
	}
	return string(b)
}

// 首字母大写
func UcFirst(str string) string {
	for _, v := range str {
		u := string(unicode.ToUpper(v))
		return u + str[len(u):]
	}
	return ""
}

// 首字母小写
func LcFirst(str string) string {
	for _, v := range str {
		u := string(unicode.ToLower(v))
		return u + str[len(u):]
	}
	return ""
}

// 驼峰转蛇形, XxYy => xx_yy
func SnakeString(str string) string {
	data := make([]byte, 0, len(str)*2)
	j := false
	num := len(str)
	for i := 0; i < num; i++ {
		d := str[i]
		if i > 0 && d >= 'A' && d <= 'Z' && j {
			data = append(data, '_')
		}
		if d != '_' {
			j = true
		}
		data = append(data, d)
	}
	return strings.ToLower(string(data[:]))
}

// 蛇形转驼峰, xx_yy => XxYy
func CamelString(str string) string {
	data := make([]byte, 0, len(str))
	j := false
	k := false
	num := len(str) - 1
	for i := 0; i <= num; i++ {
		d := str[i]
		if k == false && d >= 'A' && d <= 'Z' {
			k = true
		}
		if d >= 'a' && d <= 'z' && (j || k == false) {
			d = d - 32
			j = false
			k = true
		}
		if k && d == '_' && num > i && str[i+1] >= 'a' && str[i+1] <= 'z' {
			j = true
			continue
		}
		data = append(data, d)
	}
	return string(data[:])
}

// 乱序字符串
func Shuffle(str string) string {
	if str == "" {
		return str
	}

	runes := []rune(str)
	index := 0

	for i := len(runes) - 1; i > 0; i-- {
		index = rand.Intn(i + 1)

		if i != index {
			runes[i], runes[index] = runes[index], runes[i]
		}
	}
	return string(runes)
}

// 反序字符串
func Reverse(str string) string {
	n := len(str)
	runes := make([]rune, n)
	for _, r := range str {
		n--
		runes[n] = r
	}
	return string(runes[n:])
}

func GetCjkRange(code int) string {
	var result string
	if code >= 0x4E00 && code <= 0x9FFF {
		result = "CJK"
	} else if code >= 0x3400 && code <= 0x4DBF {
		result = "EXT-A"
	} else if code >= 0x20000 && code <= 0x2A6DF {
		result = "EXT-B"
	} else if code >= 0x2A700 && code <= 0x2B739 {
		result = "EXT-C"
	} else if code >= 0x2B740 && code <= 0x2B81D {
		result = "EXT-D"
	} else if code >= 0x2B820 && code <= 0x2CEA1 {
		result = "EXT-E"
	} else if code >= 0x2CEB0 && code <= 0x2EBE0 {
		result = "EXT-F"
	} else if code >= 0x30000 && code <= 0x3134A {
		result = "EXT-G"
	} else if code >= 0x31350 && code <= 0x323AF {
		result = "EXT-H"
	} else if code >= 0x2EBF0 && code <= 0x2EE5D {
		result = "EXT-I"
	} else if code == 0x3007 {
		result = "零"
	} else if code >= 0xE000 && code <= 0xF8FF {
		result = "PUA"
	}

	return result
}

// 获取某个字的 unicode 值
func Ord(in string) int {
	s := []rune(in)
	return int(s[0])
}

// 把 unicode 值转成字符串
func Chr(code int) string {
	return string(rune(code))
}