#!/usr/bin/env sh

# Description: Create and verify checksums
#
# If selection is used: it will generate one file containing the checksums with file names
#                       [and with paths if they are in another directory]
#                       The output checksum filename will be checksum_timestamp.checksum_type
# If file is used: if the file is a checksum, the plugin does the verification
#                  if the file is not a checksum, checksum will be generated for it
#                  The output checksum filename will be filename.checksum_type
#
# Shell: POSIX compliant
# Author: ath3

selection=${XDG_CONFIG_HOME:-$HOME/.config}/nnn/.selection
resp=f
chsum=md5

checksum_type()
{
    echo "possible checksums: md5, sha1, sha224, sha256, sha384, sha512"
    echo -n "create md5 (m), sha256 (s), sha512 (S) (or type one of the above checksums) [default=m]: "
    read chsum_resp
    for chks in md5 sha1 sha224 sha256 sha384 sha512
    do
        if [ "$chsum_resp" = "$chks" ]; then
            chsum=$chsum_resp
            return
        fi
    done
    if [ "$chsum_resp" = "s" ]; then
        chsum=sha256
    elif [ "$chsum_resp" = "S" ]; then
        chsum=sha512
    fi
}

if [ -s "$selection" ]; then
    echo -n "work with selection (s) or current file (f) [default=f]: "
    read resp
fi

if [ "$resp" = "s" ]; then
    checksum_type
    sed 's|'"$PWD/"'||g' < "$selection" | xargs -0 -I{} ${chsum}sum {} > "checksum_$(date '+%Y%m%d%H%M').$chsum"
else
    if [ -n "$1" ] && [ -f "$1" ]; then
        for chks in md5 sha1 sha224 sha256 sha384 sha512
        do
            if [ "$(echo "$1" | grep \.${chks}$)" ]; then
                ${chks}sum -c < "$1"
                read dummy
                exit
            fi
        done
        checksum_type
        file=$(basename "$1").$chsum
        ${chsum}sum "$1" > "$file"
    fi
fi