#!/usr/bin/env bash
# This is here because scanimage's batch mode is broken for my scanner

function help() {
	cat <<EOF
easyscan

easyscan wraps scanimage and joins the resulting pdf.

Usage:
easyscan <target_file> [ -- args ]:
	Scan a (multi-page) document to <target_file>, passing args to scanimage
EOF
}

if [ $# -lt 1 ]; then
	help
	exit 1
fi
OUTPUT_FILE="$1.pdf"
if [ -e "$OUTPUT_FILE" ]; then
	echo "$OUTPUT_FILE" already exists, you are probably making a mistake!
	exit 1
fi
shift

scanimage_args=(
	"-x" "210"
	"-y" "297"
	"--resolution" "300"
)

while [ $# -gt 0 ]; do
	case $1 in
	--help)
		help
		exit
		;;
	--)
		shift
		scanimage_args+=("$@")
		break
		;;
	*)
		shift
		;;
	esac
done

tempdir="$(mktemp -d)"
filenames=()
counter=1

function clean() {
	# Make sure I don't remove things other than pdf
	rm "$tempdir/"*.pdf
	rm -d "$tempdir"
}
trap clean EXIT

while :; do
	ok="true"
	echo "Scanning page $counter"

	CUR_FNAME="$tempdir/easyscan_$counter.pdf"

	# If no size is set, the output will be wonky-sized
	# 210,297 is the size of A4
	scanimage "${scanimage_args[@]}" -o "$CUR_FNAME" || ok="false"

	if $ok; then
		counter=$((counter += 1))
		filenames+=("$CUR_FNAME")
	fi

	IFS= read -r -p "Continue scanning? [Y/n] " cont
	case "$cont" in
	[nN])
		echo "Exiting..."
		break
		;;
	[yY] | *) ;;
	esac
done

# Multiple files are scanned, join them
#
# Note: do NOT use the * glob, because bash orders lexicographically and not
# numerically, the merged ordering will be wrong.
merged_filename="$tempdir/easyscan_final.pdf"
pdfunite "${filenames[@]}" "$merged_filename"

# Copy scan to current directory
mkdir -p "$(dirname "$OUTPUT_FILE")"
cp "$merged_filename" "$OUTPUT_FILE"

clean