# shellcheck shell=sh disable=SC2016

##########################################################################
# Base64 encoder is released under the BSD Zero Clause License
# https://github.com/ko1nksm/sh-base64
##########################################################################
# base64encode
#   $1: the 62nd and 63rd characters and optional padding (default: +/=)
base64encode() {
  set -- "${1:-"+/="}" && set -- "${1%=}" "${1#??}"
  set -- "$@" "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
  od -v -An -tx1 | LC_ALL=C tr -d ' \t\n' | {
    LC_ALL=C fold -b -w120 # fold width must be a multiple of 6
  } | {
    # workaround for nawk: https://github.com/onetrueawk/awk/issues/38
    [ "$2" = '=' ] && set -- "$1" '\075' "$3"
    LC_ALL=C awk -v x="$3$1" -v p="$2" '
      function dec2bin(n, w,  r) {
        for (r = ""; n > 0; n = int(n / 2)) r = (n % 2) r
        return sprintf("%0" w "d", r)
      }
      BEGIN {
        for (i = 0; i < 256; i++) b[sprintf("%02x", i)] = dec2bin(i, 8)
        for (i in b) b[toupper(i)] = b[i]

        # Process in pairs of two characters for better performance
        for (i = 0; i < 64; i++) {
          ik = dec2bin(i, 6); iv = substr(x, i + 1, 1)
          for (j = 0; j < 64; j++) c[ik dec2bin(j, 6)] = iv substr(x, j + 1, 1)
        }
      }
      {
        len = length($0); pad = (3 - (len % 6 / 2)) % 3; bits = chars = ""
        for (i = 0; i < pad; i++) { $0 = $0 "00"; len+=2 }
        for (i = 1; i <= len; i+=2) bits = bits b[substr($0, i, 2)]
        for (i = 1; i <= len * 4; i+=12) chars = chars c[substr(bits, i, 12)]
        if (pad > 0) chars = substr(chars, 1, length(chars) - pad)
        while (pad--) chars = chars p
        printf "%s", chars
      }
      END { print "" }
    '
  }
}

##########################################################################
# Base64 decoder is released under the BSD Zero Clause License
# https://github.com/ko1nksm/sh-base64
##########################################################################
# base64decode
#   $1: the 62nd and 63rd characters and optional padding (default: +/=)
base64decode() {
  set -- "${1:-"+/="}" && set -- "${1%=}" "${1#??}"
  set -- "$@" "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
  LC_ALL=C fold -b -w100 | { # fold width must be a multiple of 4
    # workaround for nawk: https://github.com/onetrueawk/awk/issues/38
    [ "$2" = '=' ] && set -- "$1" '\075' "$3"
    LC_ALL=C awk -v x="$3$1" -v p="$2" '
      function dec2bin(n, w,  r) {
        for (r = ""; n > 0; n = int(n / 2)) r = (n % 2) r
        return sprintf("%0" w "d", r)
      }
      BEGIN {
        # Process in pairs of two characters for better performance
        for (i = 0; i < 64; i++) {
          ik = substr(x, i + 1, 1); iv = dec2bin(i, 6); b[ik] = b[ik p] = iv
          for (j = 0; j < 64; j++) b[ik substr(x, j + 1, 1)] = iv dec2bin(j, 6)
        }

        for (i = 1; i < 256; i++) c[dec2bin(i, 8)] = sprintf("%c", i)
        c["00000000"] = "\\\\000"; c["00001001"] = "\\\\011" # NUL HT
        c["00001010"] = "\\\\012"; c["00001011"] = "\\\\013" # LF  VT
        c["00001100"] = "\\\\014"; c["00001101"] = "\\\\015" # FF  CR
        c["00100000"] = "\\\\040"; c["00100010"] = "\\\\042" # SPC DQ
        c["00100101"] = "\\\\045"; c["00100111"] = "\\\\047" # %   SQ
        c["01011100"] = "\\\\\\\\"
      }
      {
        len = length($0); bits = chars = ""
        for (i = 1; i <= len; i+=2) bits = bits b[substr($0, i, 2)]
        for (i = 1; i <= len * 6; i+=8) chars = chars c[substr(bits, i, 8)]
        print chars
      }
    '
  } | (
    for_mksh='[ ${KSH_VERSION:+x} ] && alias printf="print -n";'
    code='IFS=; printf -- "$*"' prog="${ZSH_ARGZERO:-"$0"}"
    LC_ALL=C xargs -n 1000 -E '' sh -c "${for_mksh}${code}" "$prog"
  )
}