#!/usr/bin/env bash

# --
# Description: Script that watches when new videos are added to a folder and optimizes them.
# --
# Requirements: Install inotify-tools and ffmpeg
# Example Debian: $sudo apt install ffmpeg
# --
# Cron: @reboot bash-folders-video-optimizer.sh >/dev/null 2>&1 &
# --

# START
set -e

# VARIABLES
PROGNAME=$(basename "$0")
FOLDER_ORIGIN="$2"
EXTENSIONS_TO_WATCH=("mkv" "mp4" "avi" "mov")
MESSAGE_WAITING="optimizing_please_wait"

# FUNCTIONS

usage() {
    if [ "$*" != "" ] ; then
        echo "Error: $*"
    fi

    cat << EOF
Usage: $PROGNAME [OPTION]
Watches when new videos are added to a folder and optimizes them.
Options:
--folder [path]  Folder path where new video will be monitored and optimized
--help           Display this usage message and exit
EOF

    exit 1
}

start() {
    # Monitors the selected folder
    inotifywait -m -e create,moved_to --format '%f' "$FOLDER_ORIGIN" |
	while read -r filename; do
	    # Gets the file extension
	    extension="${filename##*.}"
	    # Checks if the extension is in the extension list
	    for ext in "${EXTENSIONS_TO_WATCH[@]}"; do
		if [[ "$ext" = "$extension" ]]; then
		    # Check if the file name starts with "optimized"
		    if [[ "$filename" != optimized* ]]; then
		    	filename_output="optimized_${filename%.*}.mp4"
			# Displays a flat file of information
			touch "$FOLDER_ORIGIN/$MESSAGE_WAITING"
			# Convert the file to MP4 format using ffmpeg in /tmp/
			ffmpeg -i "$FOLDER_ORIGIN/$filename" -c:v libx264 -tune stillimage -c:a aac -b:a 192k -pix_fmt yuv420p -nostdin -shortest "/tmp/$filename_output"
			# When finished move the optimized file
			mv "/tmp/$filename_output" "$FOLDER_ORIGIN/$filename_output"
			# Remove a flat file of information
			rm "$FOLDER_ORIGIN/$MESSAGE_WAITING"
		    fi
		fi
	    done
	done
}

# CONTROLE ARGUMENTS
isArg=""

while [ $# -gt 0 ] ; do
    case "$1" in
    --help)
        usage
        ;;
    --folder)
        isArg="1"
	if [ $# -eq 2 ]; then
	    start
	else
	    usage "You need to specify the path of the folder to watch."
	fi
        ;;
    *)
    esac
    shift
done

if [ -z $isArg ] ; then
    usage "Not enough arguments"
fi