#!/usr/bin/env sh

# Description: Show diff of 2 directories or multiple files in vimdiff
#
# Note: 1. vim may show the warning: 'Vim: Warning: Input is not from a terminal'
#          press 'Enter' to ignore and proceed.
#       2. if only one file is in selection, the hovered file is considered as the
#          second file to diff with
#
# Shell: POSIX compliant
# Authors: Arun Prakash Jana, ath3

selection=${XDG_CONFIG_HOME:-$HOME/.config}/nnn/.selection

if which nvim >/dev/null 2>&1; then
    diffcmd="nvim -d"
else
    diffcmd="vimdiff +0"
fi

dirdiff() {
    dir1=$(mktemp "${TMPDIR:-/tmp}"/nnn-"$(basename "$1")".XXXXXXXX)
    dir2=$(mktemp "${TMPDIR:-/tmp}"/nnn-"$(basename "$2")".XXXXXXXX)
    ls -A1 "$1" > "$dir1"
    ls -A1 "$2" > "$dir2"
    $diffcmd "$dir1" "$dir2"
    rm "$dir1" "$dir2"
}

if [ -s "$selection" ]; then
    arr=$(tr '\0' '\n' < "$selection")
    if [ "$(echo "$arr" | wc -l)" -gt 1 ]; then
        f1="$(echo "$arr" | sed -n '1p')"
        f2="$(echo "$arr" | sed -n '2p')"
        if [ -d "$f1" ] && [ -d "$f2" ]; then
            dirdiff "$f1" "$f2"
        else
            # If xargs supports the -o option, use it to get rid of:
            #     Vim: Warning: Input is not from a terminal
            # xargs -0 -o vimdiff < $selection

            eval xargs -0 "$diffcmd" < "$selection"
        fi
    elif ! [ -z "$1" ]; then
        f1="$(echo "$arr" | sed -n '1p')"
        if [ -d "$f1" ] && [ -d "$1" ]; then
            dirdiff "$f1" "$1"
        elif [ -f "$f1" ] && [ -f "$1" ]; then
            $diffcmd "$f1" "$1"
        else
            echo "cannot compare file with directory"
        fi
    else
        echo "needs at least 2 files or directories selected for comparison"
    fi
fi