#!/bin/bash

if [ -z "$1" ]; then
	echo "usage: ./vithumbs.sh INPUT [COLS=5] [ROWS=5] [SIZE=1600]"
	exit
fi

# Define variables
INPUT=$1
COLS=$2
if [ -z "$COLS" ]; then
	COLS=5
fi
ROWS=$3
if [ -z "$ROWS" ]; then
	ROWS=5
fi
SIZE=$4
if [ -z "$SIZE" ]; then
	SIZE=1600
fi
FONTFILE=""
if [ -z "$FONTFILE" ]; then
	FONT="font=Mono"
else
	FONT="fontfile=$FONTFILE"
fi

NFRAMES=$(echo "scale=0;$COLS*$ROWS" | bc)
DURX=$(ffmpeg -i "$INPUT" 2>&1 | grep Duration | awk '{print $2}' | tr -d ,)
DURATION=$(ffmpeg -i "$INPUT" 2>&1 | grep "Duration"| cut -d ' ' -f 4 | sed s/,// | sed 's@\..*@@g' | awk '{ split($1, A, ":"); split(A[3], B, "."); print 3600*A[1] + 60*A[2] + B[1] }')
RES=$(ffprobe -v error -select_streams v:0 -show_entries stream=width,height -of csv=s=x:p=0 "$INPUT")
FILESIZE=$(du -sm "$INPUT" | awk '{print $1}')
METADATA_PX=90
TMPDIR="/tmp/thumbnails-${RANDOM}/"
mkdir $TMPDIR

for (( VARIABLE=0; VARIABLE<NFRAMES; VARIABLE++ ))
	do
	OFFSET=$(echo "scale=2;$VARIABLE*$DURATION/$NFRAMES+$DURATION/$NFRAMES/2" | bc)

	if [ $VARIABLE -gt 9 ];then
		ZEROS="00"
			if [ $VARIABLE -gt 99 ];then
			ZEROS="0"
				if  [ $VARIABLE -gt 999 ];then
				ZEROS=""
			fi
		fi
	else
		ZEROS="000"
	fi

	# Create thumbnails
	ffmpeg -start_at_zero -copyts -ss $OFFSET -i "$INPUT" \
	-vf "drawtext=$FONT:fontsize=60:fontcolor=0xEEEEEE::shadowcolor=0x111111:shadowx=2:shadowy=2:x=(W-tw)/40:y=H-th-20:text='%{pts\:gmtime\:0\:%H\\\\\\:%M\\\\\:%S}'" \
	-vframes 1 ${TMPDIR}$ZEROS$VARIABLE.png
done

# Merge thumbnails into tile image
ffmpeg -pattern_type glob -i "${TMPDIR}*.png" -filter_complex tile=${COLS}x${ROWS}:margin=5:padding=5:color=white ${TMPDIR}tiled.png

# Output metadata to file
echo "Filename:   $INPUT" >>${TMPDIR}metadata.txt
echo "Resolution: $RES" >>${TMPDIR}metadata.txt
echo "Filesize:   $FILESIZE Mb" >>${TMPDIR}metadata.txt
echo "Duration:   $DURX" >>${TMPDIR}metadata.txt

# Get dimensions of tile image
thewidth=$(ffmpeg -i ${TMPDIR}tiled.png 2>&1 |grep Video|awk '{ split( $6, pieces,  /[x,]/ ) ; print pieces[1] }')
theheight=$(ffmpeg -i ${TMPDIR}tiled.png 2>&1 |grep Video|awk '{ split( $6, pieces,  /[x,]/ ) ; print pieces[2] }')

# Redefine height & scale (according to $SIZE)
scaledheight=$(echo "scale=0;$theheight*$SIZE/$thewidth" | bc)
ffmpeg -i ${TMPDIR}tiled.png -vf scale=${SIZE}x${scaledheight} -vframes 1 ${TMPDIR}tiled_resized.png

# Add space to the top of the image
finalheight=$(echo "$scaledheight+$METADATA_PX" | bc)

# Add Metadata
ffmpeg -f lavfi -i color=0x282828:${SIZE}x${finalheight} -i ${TMPDIR}tiled_resized.png \
-filter_complex "[0:v][1:v] overlay=0:$METADATA_PX,drawtext=$FONT:fontsize=20:fontcolor=0xEEEEEE:line_spacing=5:x=12:y=12:textfile=${TMPDIR}metadata.txt" \
-vframes 1 th${RANDOM}.png