#!/usr/bin/env bash

# pdfScale.sh
#
# Scale PDF to specified percentage of original size.
#
# Gustavo Arnosti Neves - 2016 / 07 / 10
#
# This script: https://github.com/tavinus/pdfScale
#    Based on: http://ma.juii.net/blog/scale-page-content-of-pdf-files
#         And: https://gist.github.com/MichaelJCole/86e4968dbfc13256228a


###################################################
# PAGESIZE LOGIC
# 1- Try to get Mediabox with CAT/GREP
#    Remove /BBox search as it is unreliable
# 2- MacOS => try to use mdls
#    Linux => try to use pdfinfo
# 3- Try to use identify (imagemagick)
# 4- Fail
#    Remove postscript method, 
#    may have licensing problems
###################################################


VERSION="1.4.1"
SCALE="0.95"               # scaling factor (0.95 = 95%, e.g.)
VERBOSE=0                  # verbosity Level
BASENAME="$(basename $0)"  # simplified name of this script

# Set with which after we check dependencies
GSBIN=""                   # GhostScript Binaries
BCBIN=""                   # BC Math binary
IDBIN=""                   # Identify Binary
PDFINFOBIN=""              # PDF Info Binary
MDLSBIN=""                 # MacOS mdls binary

OSNAME="$(uname 2>/dev/null)" # Check were we are running

LC_MEASUREMENT="C"         # To make sure our numbers have .decimals
LC_ALL="C"                 # Some languages use , as decimal token
LC_CTYPE="C"
LC_NUMERIC="C"

TRUE=0                     # Silly stuff
FALSE=1

ADAPTIVEMODE=$TRUE         # Automatically try to guess best mode
MODE=""

USEIMGMGK=$FALSE           # ImageMagick Flag, will use identify if true
USECATGREP=$FALSE          # Use old cat + grep method




# Prints version
printVersion() {
        if [[ $1 -eq 2 ]]; then
                echo >&2 "$BASENAME v$VERSION"
        else
                echo "$BASENAME v$VERSION"
        fi
}


# Prints help info
printHelp() {
        printVersion
        echo "
Usage: $BASENAME [-v] [-s <factor>] [-i|-c] <inFile.pdf> [outfile.pdf]
       $BASENAME -h
       $BASENAME -V

Parameters:
 -v          Verbose mode, prints extra information
             Use twice for even more information
 -h          Print this help to screen and exits
 -V          Prints version to screen and exits
 -i          Use imagemagick to get page size, 
             instead of postscript method
 -c          Use cat + grep to get page size, 
             instead of postscript method
 -s <factor> Changes the scaling factor, defaults to 0.95
             MUST be a number bigger than zero. 
             Eg. -s 0.8 for 80% of the original size 

Notes:
 - Options must be passed before the file names to be parsed
 - The output filename is optional. If no file name is passed
   the output file will have the same name/destination of the
   input file, with .SCALED.pdf at the end (instead of just .pdf)
 - Having the extension .pdf on the output file name is optional,
   it will be added if not present
 - Should handle file names with spaces without problems
 - The scaling is centered and using a scale bigger than 1 may
   result on cropping parts of the pdf.

Examples:
 $BASENAME myPdfFile.pdf
 $BASENAME myPdfFile.pdf myScaledPdf
 $BASENAME -v -v myPdfFile.pdf
 $BASENAME -s 0.85 myPdfFile.pdf myScaledPdf.pdf
 $BASENAME -i -s 0.80 -v myPdfFile.pdf
 $BASENAME -v -v -s 0.7 myPdfFile.pdf
 $BASENAME -h
"
}


# Prints usage info
usage() { 
        printVersion 2
        echo >&2 "Usage: $BASENAME [-v] [-s <factor>] [-i|-c] <inFile.pdf> [outfile.pdf]"
        echo >&2 "Try:   $BASENAME -h # for help"
        exit 1
}


# Prints Verbose information
vprint() {
        [[ $VERBOSE -eq 0 ]] && return 0
        timestamp=""
        [[ $VERBOSE -gt 1 ]] && timestamp="$(date +%Y-%m-%d:%H:%M:%S) | "
        echo "$timestamp$1"
}


# Prints dependency information and aborts execution
printDependency() {
        printVersion 2
        echo >&2 $'\n'"ERROR! You need to install the package '$1'"$'\n'
        echo >&2 "Linux apt-get.: sudo apt-get install $1"
        echo >&2 "Linux yum.....: sudo yum install $1"
        echo >&2 "MacOS homebrew: brew install $1"
        echo >&2 $'\n'"Aborting..."
        exit 3
}


# Parses and validates the scaling factor
parseScale() {
        if ! [[ -n "$1" && "$1" =~ ^-?[0-9]*([.][0-9]+)?$ && (($1 > 0 )) ]] ; then
                echo >&2 "Invalid factor: $1"
                echo >&2 "The factor must be a floating point number greater than 0"
                echo >&2 "Example: for 80% use 0.8"
                exit 2
        fi
        SCALE=$1
}


# Gets page size using imagemagick's identify
getPageSizeImagemagick() {
        # get data from image magick
        local identify="$("$IDBIN" -format '%[fx:w] %[fx:h]BREAKME' "$INFILEPDF" 2>/dev/null)"

        identify="${identify%%BREAKME*}"   # get page size only for 1st page
        identify=($identify)               # make it an array
        PGWIDTH=$(printf '%.0f' "${identify[0]}")             # assign
        PGHEIGHT=$(printf '%.0f' "${identify[1]}")            # assign
}


# Gets page size using Mac Quarts mdls
getPageSizeMdls() {
	[[ ! $OSNAME = "Darwin" ]] && return
        # get data from image magick
        local identify="$("$MDLSBIN" -mdls -name kMDItemPageHeight -name kMDItemPageWidth "$INFILEPDF" 2>/dev/null)"

        identify=($identify)               # make it an array
	echo " - ${identify[0]} - ${identify[1] - ${identify[3]} - ${identify[4]}}"
	
        PGWIDTH=$(printf '%.0f' "${identify[1]}")             # assign
        PGHEIGHT=$(printf '%.0f' "${identify[3]}")            # assign
}


# Gets page size using Mac Quarts mdls
getPageSizePdfInfo() {
        # get data from image magick
        local identify="$("$MDLSBIN" -mdls -name kMDItemPageHeight -name kMDItemPageWidth "$INFILEPDF" 2>/dev/null)"

        identify=($identify)               # make it an array
	echo " - ${identify[0]} - ${identify[1] - ${identify[3]} - ${identify[4]}}"
	
        PGWIDTH=$(printf '%.0f' "${identify[1]}")             # assign
        PGHEIGHT=$(printf '%.0f' "${identify[3]}")            # assign
}




# Gets page size using cat and grep
getPageSizeCatGrep() {
        # get MediaBox info from PDF file using cat and grep, these are all possible
        # /MediaBox [0 0 595 841]
        # /MediaBox [ 0 0 595.28 841.89]
        # /MediaBox[ 0 0 595.28 841.89 ]

        # Get MediaBox data if possible
        local mediaBox="$(cat "$INFILEPDF" | grep -a '/MediaBox' | head -n1)"
        mediaBox="${mediaBox##*/MediaBox}"

        # No page size data available
        if [[ -z $mediaBox && $ADAPTIVEMODE = $FALSE ]]; then
                echo "Error when reading input file!"
                echo "Could not determine the page size!"
                echo "There is no MediaBox in the pdf document!"
                echo "Aborting! You may want to try the adaptive mode."
                exit 15
	elif [[ -z $mediaBox && $ADAPTIVEMODE = $TRUE ]]; then
		return $FALSE
        fi

        # remove chars [ and ]
        mediaBox="${mediaBox//[}"
        mediaBox="${mediaBox//]}"

        mediaBox=($mediaBox)        # make it an array
        mbCount=${#mediaBox[@]}     # array size

        # sanity
        if [[ $mbCount -lt 4 ]]; then 
            echo "Error when reading the page size!"
            echo "The page size information is invalid!"
            exit 16
        fi

        # we are done
        PGWIDTH=$(printf '%.0f' "${mediaBox[2]}")  # Get Round Width
        PGHEIGHT=$(printf '%.0f' "${mediaBox[3]}") # Get Round Height

	return $TRUE
}


getPageSize() {
	vprint "Detecting page size with cat+grep method"
	getPageSizeCatGrep
	if [[ -z $PGWIDTH && -z $PGHEIGHT ]]; then
		vprint " -> method failed!"
		if [[ $OSNAME = "Darwin" ]]; then
			vprint "Detecting page size with Mac Quartz mdls"
			getPageSizeMdls
		else
			vprint "Detecting page size with Linux pdfinfo"
			getPageSizePdfInfo
		fi
	fi
	if [[ -z $PGWIDTH && -z $PGHEIGHT ]]; then
		vprint " -> method failed!"
		vprint " Detecting page size with ImageMagick's identify"
		getPageSizeImagemagick
	fi
	if [[ -z $PGWIDTH && -z $PGHEIGHT ]]; then
		echo "Error when detecting PDF paper size!"
		echo "All methods of detection failed"
		exit 17
	fi
}


# Parse options
while getopts ":vichVs:" o; do
    case "${o}" in
        v)
            ((VERBOSE++))
            ;;
        h)
            printHelp
            exit 0
            ;;
        V)
            printVersion
            exit 0
            ;;
        s)
            parseScale ${OPTARG}
            ;;
        i)
            USEIMGMGK=$TRUE
            USECATGREP=$FALSE
            ;;
        c)
            USECATGREP=$TRUE
            USEIMGMGK=$FALSE
            ;;
        *)
            usage
            ;;
    esac
done
shift $((OPTIND-1))



######### START EXECUTION

#Intro message
vprint "$(basename $0) v$VERSION - Verbose execution"


# Dependencies
vprint "Checking for ghostscript and bcmath"
command -v gs >/dev/null 2>&1 || printDependency 'ghostscript'
command -v bc >/dev/null 2>&1 || printDependency 'bc'
if [[ $USEIMGMGK -eq $TRUE ]]; then
        vprint "Checking for imagemagick's identify"
        command -v identify >/dev/null 2>&1 || printDependency 'imagemagick'
        IDBIN=$(which identify 2>/dev/null)
fi


# Get dependency binaries
GSBIN="$(which gs 2>/dev/null)"
BCBIN="$(which bc 2>/dev/null)"
if [[ $OSNAME = "Darwin" ]]; then
	MDLSBIN="$(which mdls 2>/dev/null)"
else
	PDFINFOBIN="$(which pdfinfo 2>/dev/null)"
fi

# Verbose scale info
vprint "  Scale factor: $SCALE"


# Validate args
[[ $# -lt 1 ]] && { usage; exit 1; }
INFILEPDF="$1"
[[ "$INFILEPDF" =~ ^..*\.pdf$ ]] || { usage; exit 2; }
[[ -f "$INFILEPDF" ]] || { echo "Error! File not found: $INFILEPDF"; exit 3; }
vprint "    Input file: $INFILEPDF"


# Parse output filename
if [[ -z $2 ]]; then
        OUTFILEPDF="${INFILEPDF%.pdf}.SCALED.pdf"
else
        OUTFILEPDF="${2%.pdf}.pdf"
fi
vprint "   Output file: $OUTFILEPDF"

getPageSizeMdls

# Set PGWIDTH and PGHEIGHT
#if [[ $USEIMGMGK -eq $TRUE ]]; then
#        getPageSizeImagemagick
#elif [[ $USECATGREP -eq $TRUE ]]; then
#        getPageSize
#else
#        getPageSizeGS
#fi
vprint "         Width: $PGWIDTH postscript-points"
vprint "        Height: $PGHEIGHT postscript-points"


# Compute translation factors (to center page.
XTRANS=$(echo "scale=6; 0.5*(1.0-$SCALE)/$SCALE*$PGWIDTH" | "$BCBIN")
YTRANS=$(echo "scale=6; 0.5*(1.0-$SCALE)/$SCALE*$PGHEIGHT" | "$BCBIN")
vprint " Translation X: $XTRANS"
vprint " Translation Y: $YTRANS"


# Do it.
"$GSBIN" \
-q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -dSAFER \
-dCompatibilityLevel="1.5" -dPDFSETTINGS="/printer" \
-dColorConversionStrategy=/LeaveColorUnchanged \
-dSubsetFonts=true -dEmbedAllFonts=true \
-dDEVICEWIDTH=$PGWIDTH -dDEVICEHEIGHT=$PGHEIGHT \
-sOutputFile="$OUTFILEPDF" \
-c "<</BeginPage{$SCALE $SCALE scale $XTRANS $YTRANS translate}>> setpagedevice" \
-f "$INFILEPDF"