#!/bin/sh

# Heavily modified after https://stackoverflow.com/questions/44951515/bash-find-duplicate-file-in-directory-and-rename

TARGET="renamed"
ext="pdf"

for i in *.$ext
do
	declare -i cnt=1				## counter for filename_$cnt
	test -z "$i" && {			## validate one argument given
		printf "error: insufficient input\nusage: %s filename\n" "${0##*/}"
		exit 1
	}

	test -w "$i" || {			## validate valid filename is writeable
		printf "error: file not found or lack permission to move '%s'.\n" "$i"
		exit 1
	}

	DATUM=`pdfgrep 'Datum' "$i" | sed -e "s/\ .*Datum.\ *//;s/2019.*$/2019/g;s/^.P//;s/,/\./;s/\ //g"`
	OPERATION=`pdfgrep 'Operation.en' "$i" | sed -e "s/^.*Operation.en..//;s/^.\ *//;s/\ /_/g;s/,/_/g;s/__*/_/g;s/ä/ae/g;s/ü/ue/g;s/Ü/Ue/g;s/ö/oe/g"`
	if [ ! -z "$OPERATION" -a "$OPERATION" != " " ]
	then
		OPERATION="-$OPERATION"
	fi
echo
echo $DATUM
echo
echo $OPERATION
echo

	if [[ $DATUM =~ ^(0[1-9]|[1-2][0-9]|3[0-1]).(0[1-9]|1[0-2]).[0-9]{4}$ ]]
	then
		echo "DATUM of $i is correct"
	else
		echo "DATUM has to fall back to $i"
		DATUM="${i%.*}"
	fi

	vfn="$DATUM$OPERATION.$ext"			## set valid filename = filename

	## form valid filename e.g. "$fn_1.$ext" if duplicate found
	while test -e "$TARGET/$vfn"; do
		printf -v vfn "%s-%01d.%s" "$DATUM$OPERATION" "$((cnt++))" "$ext"
	done

	echo "$i" "$TARGET/$vfn"		## move file under non-conflicting name
	cp "$i" "$TARGET/$vfn"			## move file under non-conflicting name


#	cd $TARGET
#	k=1
#	while [[ `ls -1 | grep "$DATUM"` ]]
#	do
#		DATUM=$DATUM-$(expr $k + 1)
#	done
#	cd -
#	cp -n "$i" "$TARGET"/"$DATUM".pdf
done