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, stat, tree, man, tar, unzip, ...
#                      ... add you own! (see examples in code)
#
# Usage:
#   You need to set a NNN_FIFO path and set a key for the plugin,
#   then start `nnn`:
#
#     $ nnn -a
#
#   or
#
#     $ 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 (e.g.
#   with -a), they will be independent.
#
#   Configure SPLIT to either "h" or "v" to set a 'h'orizontal split or a
#   'v'ertical split
#
# Shell: POSIX compliant
# Authors: Todd Yamakawa, Léo Villeveygoux, @Recidiviste

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

fifo_pager() {
    cmd="$1"
    shift

    # We use a FIFO to access $PAGER PID in jobs control
    tmpfifopath="${TMPDIR:-/tmp}/nnn-preview-tui-fifo.$$"
    mkfifo "$tmpfifopath" || return

    $PAGER < "$tmpfifopath" &

    (
        exec > "$tmpfifopath"
        "$cmd" "$@" &
    )

    rm "$tmpfifopath"
}

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

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

    # Detect mime type
    mimetype="$(file -Lb --mime-type -- "$1")"

    # Detect file extention - use if you need
    ext="${1##*.}"
    if [ -n "$ext" ]; then
        ext="$(printf "%s" "${ext}" | tr '[:upper:]' '[:lower:]')"
    fi

    if [ -d "$1" ]; then
        # Print directory tree
        cd "$1" || return
        fifo_pager tree
    #elif [ "${mimetype%%/*}" = "image" ] ; then
    #    catimg "$1"
    elif [ "$mimetype" = "text/troff" ] ; then
        fifo_pager man -Pcat -l "$1"
    elif [ "$mimetype" = "application/zip" ] ; then
        fifo_pager unzip -l "$1"
    elif [ "$ext" = "gz" ] || [ "$ext" = "bz2" ] ; then
        fifo_pager tar -tvf "$1"
    elif [ "$encoding" = "binary" ] ; then
        # Binary file: just print filetype info
        echo "-------- binary file --------"
        file -b "$1"
        echo
        stat "$1"
    else
        # Text file:
        $PAGER "$1" &
    fi
}

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
    if [ -z "$SPLIT" ] && [ $(($(tput lines) * 2)) -gt "$(tput cols)" ] ; then
        SPLIT='v'
    elif [ "$SPLIT" != 'v' ] ; then
        SPLIT='h'
    fi

    tmux split-window -e "NNN_FIFO=$NNN_FIFO" -e "PREVIEW_MODE=1" -d"$SPLIT" "$0" "$1"
else
    PREVIEW_MODE=1 $TERMINAL -e "$0" "$1" &
fi