#!/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 set $TERMINAL), 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}"

preview_file () {
    clear
    lines=$(($(tput lines)-1))
    cols=$(tput cols)
    encoding="$(file -b --mime-encoding "$1")"

    if [ -d "$1" ]; then
        # Print directory tree
        cd "$1" && tree | head -n $lines | cut -c 1-"$cols"
    elif [ "$encoding" = "binary" ] ; then
        # Binary file: just print filetype info
        echo "-------- Binary file --------"
        file -b "$1"
    else
        # Text file: print file head
        head -n $lines "$1" | cut -c 1-"$cols"
    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
    tmux split-window -e "NNN_FIFO=$NNN_FIFO" -e "PREVIEW_MODE=1" -dh "$0" "$1"
else
    PREVIEW_MODE=1 $TERMINAL -e "$0" "$1" &
fi