#!/bin/bash

IMG=$1
COUNT_HORIZONTAL=$2
COUNT_VERTICAL=$3
LANDSCAPE=${4}

panic(){ echo $@; exit 2; }

[[ ! -f $IMG ]] && panic "$IMG does not exist"

SMALL_SIDE=3000
LARGE_SIDE=4350

# /tmp/out.pdf PDF 567x822 567x822+0+0 16-bit sRGB 980KB 0.010u 0:00.009
read name type GEOMETRY canvas depth format size other <<< $( identify $IMG )
IMG_WIDTH=$( cut -d "x" -f 1 <<< $GEOMETRY )
IMG_HEIGHT=$( cut -d "x" -f 2 <<< $GEOMETRY )

TOTAL_WIDTH=$( [[ "$LANDSCAPE" == "1" ]] && echo $LARGE_SIDE || echo $SMALL_SIDE )
TOTAL_HEIGHT=$( [[ "$LANDSCAPE" == "1" ]] && echo $SMALL_SIDE || echo $LARGE_SIDE )

REQ_WIDTH=$(( $TOTAL_WIDTH / $COUNT_HORIZONTAL  ))
REQ_HEIGHT=$(( $TOTAL_HEIGHT / $COUNT_VERTICAL  ))

DUP=$(( ( $COUNT_HORIZONTAL * $COUNT_VERTICAL ) - 1 ))

DATE=$( date +%s )
OUTPUT_DIR=$( dirname ~+ )/a4
FILENAME=$( basename $IMG ) 
PDF_NAME=${OUTPUT_DIR}/${DATE}_${FILENAME}.pdf
OUT=$( montage -tile ${COUNT_HORIZONTAL}x${COUNT_VERTICAL} -density 150x150 -units pixelspercentimeter -border 0 -page ${TOTAL_WIDTH}x${TOTAL_HEIGHT} -compress zip -quality 100 "$IMG" -geometry ${REQ_WIDTH}x${REQ_HEIGHT} -duplicate ${DUP},0 ${PDF_NAME} )

[ 0 -eq $? ] && echo $PDF_NAME || panic "An error occured... $OUT"