#!/bin/bash

# ASSUMPTIONS
#
# Read to make sure you can use this script
#
# Platform:
#   This script is for Linux or Mac
#   If you're on Windows, install cygwin with bc math package and type bash in command prompt
#   to enter bash mode.
#
# Tools:
#   You must have ffmpeg installed with --with-libvpx --with-libvorbis
#   If you're on mac, install homebrew and type reinstall ffmpeg --with-libvpx --with-libvorbis
#   If you're on Windows, I think your ffmpeg already comes with it, but make sure you have ffmpeg wiith
#   those tools.
#
# Files:
#   This script should work with mp4, avi, wmv, and mpeg files


# INSTRUCTIONS
#
# Steps to use this bash script to generate WEBMs
#
# 0. Open notepad or a text editor, and save this script as create.sh (or any other name.sh)
# 1. Put this script in a directory which has videos
# 2. In terminal, navigate to your folder containing the script and videos and type: bash create.sh webm
# 3. ???
# 4. Profit
#
# Steps to use this script to generate GIFs
# 0. Open notepad or a text editor, and save this script as create.sh (or any other name.sh)
# 1. Put this script in a directory which has videos
# 2. In terminal, navigate to your folder with the script and videos and type: bash create.sh gif
# 3. ???
# 4. Profit

# TIPS
#
#   1. This script creates 12 webm or gifs by default. You can change numSegements value for more or less.
#   2. The gifs this script generates are 400px wide by default. Change variable filters' scale value to modify this.
#   3. The webms this script generates are 1000px wide by default. Change webmWidth to modify this.
#   4. The webms this script generates are 1500K bitrate by default. Change bitrate to modify this.
#   4. The duration of a webm or gif is 15 seconds by default. You must change this value to be smaller for GIF
# files
#   5. If you want to shut down the script, hold down control-c in terminal or command prompt. Or simply close
#   the terminal / command prompt



# Initialize Variables

# GIF variables and settings
gifDuration="00:00:02.000"
gifWidth=400
filters="fps=25,scale=${gifWidth}:-1:flags=lanczos"
gifFiles=()

# WEBM variables and settings
webmDuration="00:00:15.000"
webmWidth=1000
bitRate="1500K"
webmFiles=()

# General variables
numSegments=12
videosList=()
numFiles=0
mode=$1

checkNumbers(){

    for webm in *.webm; do
        [ -e "${webm}" ] || continue
        webmFiles+=("${webm}")
    done

    for gif in *.gif; do
        [ -e "${gif}" ] || continue
        gifFiles+=("${gif}")
    done

    num_gif_Files=${#gifFiles[@]}
    num_webm_Files=${#webmFiles[@]}

    numFiles=$(( num_gif_Files + num_webm_Files ))

}

composeVidList(){

    for video in *.mp4; do
        [ -e "${video}" ] || continue
        videosList+=("${video}")
    done

    for video in *.wmv; do
        [ -e "${video}" ] || continue
        videosList+=("${video}")
    done

    for video in *.avi; do
        [ -e "${video}" ] || continue
        videosList+=("{$video}")
    done

    for video in *.mpeg; do
        [ -e "${video}" ] || continue
        videosList+=("{$video}")
    done

}

dirGifGen(){

    fileName=$1
    start=$2

    outputMinMP4=${fileName//.mp4/}
    outputMinAVI=${outputMinMP4//.avi/}
    outputMinWMV=${outputMinAVI//.wmv/}
    outputMinMPEG=${outputMinWMV//.mpeg/}
    outputName=${outputMinMPEG}

    if [ "${mode}" == "gif" ]; then

        echo "Creating ${outputName}_${numFiles}.gif from time: ${start}"

        # Extract video segment
        ffmpeg -ss "${start}" -hide_banner -loglevel panic -i "${fileName}" -t "${gifDuration}" "${outputName}_${numFiles}.mp4"

        # Create palette for video
        ffmpeg -hide_banner -loglevel panic -i "${outputName}_${numFiles}.mp4" -vf "$filters,palettegen" -y palette.png

        # Create the gif from video segment
        ffmpeg -hide_banner -loglevel panic -i "${outputName}_${numFiles}.mp4" -i palette.png -lavfi "$filters [x]; [x][1:v] paletteuse" -y "${outputName}_${numFiles}.gif"

        # Delete palette
        rm "palette.png"

    elif [ "${mode}" == "webm" ]; then

        echo "Creating ${outputName}_${numFiles}.webm from time: ${start}"

        # Extract video segment
        ffmpeg -ss "${start}" -hide_banner -loglevel panic -i "${fileName}" -t "${webmDuration}" "${outputName}_${numFiles}.mp4"

        # Generate webm
        ffmpeg -hide_banner -loglevel panic -i "${outputName}_${numFiles}.mp4" -vf scale=${webmWidth}:-2 -c:v libvpx -b:v ${bitRate} -c:a libvorbis "${outputName}_${numFiles}.webm"

    else

        echo "Invalid mode"

        exit 0

    fi

    # Delete video segment if it exists
    [ -e "${outputName}_${numFiles}.mp4" ] || continue
    rm "${outputName}_${numFiles}.mp4"

    ((numFiles++))

}

main() {

    if [ "${mode}" != "webm" ] && [ "${mode}" != "gif" ]; then

        echo "Invalid mode"
        exit 0

    else

        echo
        echo "The current mode is: ${mode}"
        echo

        checkNumbers
        composeVidList

    fi

    for (( i= 0; i < ${#videosList[@]}; i++ )); do

        video="${videosList[i]}"

        videoDuration=`ffprobe -i "${video}" -show_entries format=duration -v quiet -of csv="p=0" -sexagesimal`
        videoDuration=`echo $videoDuration | cut -d "." -f1`

        if [ ${videoDuration:1:1} == ":" ]; then
            videoDuration="0${videoDuration}"
        fi

        hours=${videoDuration:0:2}
        minutes=${videoDuration:3:2}
        seconds=${videoDuration:6:2}

        totalSeconds=$(( (10#$hours * 3600) + (10#$minutes * 60) + 10#$seconds ))

        maxSeconds=$totalSeconds

        interval=$(( 10#$totalSeconds / numSegments ))

        # Starting time in seconds. Let's start at little later in the video, at interval * 2
        startingTime=$(( 10#$interval * 2 ))

        for (( k = 0; k < $numSegments; k++ )); do

            hours="$(( 10#$startingTime / 3600 ))"

            if [ ${hours} -gt "0" ]; then
                minutes="$(( (10#$startingTime - (10#$hours * 3600)) / 60 ))"
            else
                minutes="$(( 10#$startingTime / 60 ))"
            fi

            seconds="$(( 10#$startingTime % 60 ))"

            if [ ${hours} -lt "10" ]; then
                hours="0${hours}"
            fi

            if [ ${seconds} -lt "10" ]; then
                seconds="0${seconds}"
            fi

            if [ ${minutes} -lt "10" ]; then
                minutes="0${minutes}"
            fi

            gifTime="${hours}:${minutes}:${seconds}.000"

            if [ ${startingTime} -ge ${maxSeconds} ]; then
                echo
                echo "Complete."
                echo
                exit 0
            fi

            dirGifGen "${video}" "${gifTime}"

            startingTime=$(( 10#$startingTime + 10#$interval ))

        done

    done

    echo
    echo "Complete."
    echo

}

main