#!/usr/bin/env sh

# Description: Create and verify checksums
#
# Note:  On macOS, install the relevant checksum packages from Homebrew with:
#            brew install coreutils
#
# Details:
#   - selection: it will generate one file with the checksums and filenames
#                (and with paths if they are in another directory)
#                output checksum filename format: checksum_timestamp.checksum_type
#   - file: 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
#   - directory: recursively calculates checksum for all the files in the dir
#                the output checksum filename will be directory.checksum_type
#
# Shell: POSIX compliant
# Authors: ath3, Arun Prakash Jana

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

checksum_type()
{
    echo "possible checksums: md5, sha1, sha224, sha256, sha384, sha512"
    printf "create md5 (m), sha256 (s), sha512 (S) (or type one of the above checksums) [default=m]: "
    read -r 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
    printf "work with selection (s) or current file (f) [default=f]: "
    read -r 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"

    # Clear selection
    if [ -p "$NNN_PIPE" ]; then
        printf "-" > "$NNN_PIPE"
    fi
elif [ -n "$1" ]; then
    if [ -f "$1" ]; then
        for chks in md5 sha1 sha224 sha256 sha384 sha512
        do
            if echo "$1" | grep -q \.${chks}$; then
                ${chks}sum -c < "$1"
                read -r _
                exit
            fi
        done
        checksum_type
        file=$(basename "$1").$chsum
        ${chsum}sum "$1" > "$file"
    elif [ -d "$1" ]; then
        checksum_type
        file=$(basename "$1").$chsum
        find "$1" -type f -exec ${chsum}sum "{}" + > "$file"
    fi
fi