#!/bin/sh

# The MIT License (MIT)
#
# Copyright (c) 2026 pacman64
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.


# bytedump [options...] [files...]
#
# Show bytes in hexadecimal notation, with an ASCII panel on the side which
# shows 2 lines worth of visible-ASCII symbols, which allows reliable matching
# for strings up to 16 symbols long.
#
# The only option available is to show this help message, using any of
# `-h`, `--h`, `-help`, or `--help`, without the quotes.


case "$1" in
    -h|--h|-help|--help)
        awk '/^# +bytedump /, /^$/ { gsub(/^# ?/, ""); print }' "$0"
        exit 0
    ;;
esac

[ "$1" = '--' ] && shift

command='awk'
if { [ -p /dev/stdout ] || [ -t 1 ]; } && [ -e /usr/bin/stdbuf ]; then
    command='stdbuf -oL awk'
fi

# show all non-existing files given
failed=0
for arg in "$@"; do
    if [ "${arg}" = "-" ]; then
        continue
    fi
    if [ ! -e "${arg}" ]; then
        printf "no file named \"%s\"\n" "${arg}" > /dev/stderr
        failed=1
    fi
done

if [ "${failed}" -gt 0 ]; then
    exit 2
fi

od -v -t x1 "${@:-/dev/stdin}" | ${command} '
    BEGIN {
        s = s "                                "
        s = s " !\"#$%&'"'"'()*+,-./0123456789:;<=>?"
        s = s "@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_"
        s = s "`abcdefghijklmnopqrstuvwxyz{|}~ "
        s = s "                                "
        s = s "                                "
        s = s "                                "
        s = s "                                "
        split(s, v, "")
        for (i = 0; i < 256; i++) vascii[sprintf("%02x", i)] = v[i + 1]
    }

    NR > 1 {
        printf "%s ", offset

        for (i = 1; i <= n; i++) printf " %s", cur[i]
        # printf "%*s", 3 * (maxw - n), "" # not working with busybox
        for (i = n + 1; i <= maxw; i++) printf "   "

        printf "  "
        for (i = 1; i <= n; i++) printf "%s", vascii[cur[i]]
        for (i = 2; i <= NF; i++) printf "%s", vascii[$i]
        print ""
    }

    {
        n = 0
        offset = $1
        for (i = 2; i <= NF; i++) cur[++n] = $i
        if (maxw < n) maxw = n
    }
'