nnn/plugins/preview-tui

#!/usr/bin/env sh

# Description: Text based file previewer
#
# Note: This plugin needs a "NNN_FIFO" to work.
#
# Dependencies: tmux (>=3.0) or xterm or $TERMINAL, less or $PAGER, file, tree
#
# Usage:
#   You need to set a NNN_FIFO path and set a key for the plugin,
#   then start `nnn`:
#
#     $ NNN_FIFO=/tmp/nnn.fifo nnn
#
#   Then in `nnn`, launch the `preview-tui` plugin.
#
#   If you provide the same NNN_FIFO to all nnn instances, there will be a
#   single common preview window. I you provide different FIFO path, they
#   will be independent.
#
# Shell: POSIX compliant
# Authors: Todd Yamakawa, Léo Villeveygoux

TERMINAL="${TERMINAL:-xterm}"
PAGER="${PAGER:-less}"

preview_file () {
    kill %- %+ 2>/dev/null
    clear

    # prevent shell pipe reuse
    tmpfifopath="${TMPDIR:-/tmp}/nnn-preview-tui-fifo.$$"
    mkfifo "$tmpfifopath" || return

    encoding="$(file -b --mime-encoding "$1")"

    $PAGER < "$tmpfifopath" &

    (
        exec > "$tmpfifopath"

        if [ -d "$1" ]; then
            # Print directory tree
            cd "$1" && tree
        elif [ "$encoding" = "binary" ] ; then
            # Binary file: just print filetype info
            echo "-------- Binary file --------"
            file -b "$1"
        else
            # Text file:
            cat "$1"
        fi &

    )

    rm "$tmpfifopath"
}

if [ "$PREVIEW_MODE" ] ; then
    if [ ! -r "$NNN_FIFO" ] ; then
        echo "No FIFO available! (\$NNN_FIFO='$NNN_FIFO')" >&2
        read -r
        exit 1
    fi

    preview_file "$1"

    exec < "$NNN_FIFO"
    while read -r selection ; do
        preview_file "$selection"
    done
    exit 0
fi

if [ -e "${TMUX%%,*}" ] && [ "$(tmux -V | cut -c6)" -eq 3 ] ; then
    tmux split-window -e "NNN_FIFO=$NNN_FIFO" -e "PREVIEW_MODE=1" -dh "$0" "$1"
else
    PREVIEW_MODE=1 $TERMINAL -e "$0" "$1" &
fi