package Util

import (
	"fmt"
	"os"
)

func getbyte(a byte)int{
	x := int(a)
	if x > 255 {
		fmt.Println("INVALID_CHARACTER_ERR: DOM Exception 5")
		os.Exit(3)
	}
	return x
}

func Base64(s []byte)string{
	const ALPHA = "LVoJPiCN2R8G90yg+hmFHuacZ1OWMnrsSTXkYpUq/3dlbfKwv6xztjI7DeBE45QA"
	const PADCHAR = "="
	i:=0
	b10:=0
	var x []byte
	imax:=len(s)-len(s)%3
	if len(s)==0{
		return ""
	}
	for i:=0;i<imax;i+=3{
		b10=(getbyte(s[i])<<16)|(getbyte(s[i+1]) << 8)|(getbyte(s[i+2]))
		x=append(x,ALPHA[(b10>>18)])
		x=append(x,ALPHA[((b10 >> 12) & 63)])
		x=append(x,ALPHA[((b10 >> 6) & 63)])
		x=append(x,ALPHA[(b10 & 63)])
	}
	i=imax
	if len(s)-imax==1{
		b10=getbyte(s[i])<<16
		x=append(x,ALPHA[(b10 >> 18)],ALPHA[((b10 >> 12) & 63)],PADCHAR[0],PADCHAR[0])
	}else if len(s)-imax ==2{
		b10=(getbyte(s[i])<<16)|(getbyte(s[i+1])<<8)
		x=append(x,ALPHA[(b10 >> 18)],ALPHA[((b10 >> 12) & 63)],ALPHA[((b10 >> 6) & 63)],PADCHAR[0])
	}
	return string(x)
}