#!/bin/bash

# Function to display usage information and exit
usage() {
	echo "Usage: $0 input.pdf output.pdf [-r resolution] [-h]"
	echo ""
	echo "Options:"
	echo "-r     Set the image resolution (default is 150ppi)"
	echo "-h     Display this help message"
	exit 1
}

# Default settings
RESOLUTION=150

# Parse command-line options
while getopts ":r:h" opt; do
	case ${opt} in
	r)
		RESOLUTION=$OPTARG
		;;
	h)
		usage
		;;
	\?)
		echo "Invalid option: -$OPTARG" >&2
		exit 1
		;;
	:)
		echo "Option -$OPTARG requires an argument." >&2
		exit 1
		;;
	esac
done

shift $((OPTIND - 1))

# Check if the correct number of arguments are provided after parsing options
if [ "$#" -ne 2 ]; then
	usage
fi

INPUT_FILE="$1"
OUTPUT_FILE="$2"

# Check if input file exists
if [ ! -f "$INPUT_FILE" ]; then
	echo "Input file '$INPUT_FILE' does not exist."
	exit 1
fi

# Extract directory and base name from output file path
OUTPUT_DIR=$(dirname "$OUTPUT_FILE")
OUTPUT_BASENAME=$(basename "$OUTPUT_FILE")

# Create the output directory if it doesn't already exist
mkdir -p "$OUTPUT_DIR"

# Run Ghostscript command with specified resolution
gs \
	-sDEVICE=pdfwrite \
	-dCompatibilityLevel=1.7 \
	-dPDFSETTINGS=/prepress \
	-dDownsampleMonoImages=false \
	-dDownsampleColorImages=true \
	-dColorImageResolution=$RESOLUTION \
	-dGrayImageResolution=$RESOLUTION \
	-dMonoImageResolution=$RESOLUTION \
	-dPreserveOPIRequests=false \
	-dSubsetFonts=true \
	-dEmbedAllFonts=true \
	-sProcessColorModel=DeviceRGB \
	-dQUIET -dBATCH -dNOPAUSE \
	-sOutputFile="$OUTPUT_FILE" "$INPUT_FILE"

# Check if Ghostscript command was successful
if [ $? -ne 0 ]; then
	echo "Error: Ghostscript failed to process the file '$INPUT_FILE'."
	exit 1
fi

echo "Successfully converted '$INPUT_FILE' to '$OUTPUT_BASENAME'"