#!/bin/bash
# $1 (optional): file mask (eg: "*.gif"), else "*.jpg" assumed
# $2 (optional): file prefix (eg: "file"), else "file" assumed
# $3 (optional): destination dir (eg: "~/images"), else "$HOME" assumed
# $4 (optional): ':'-separated list of directories
#                (eg: "/mnt/img1:/mnt/img2"), else "." assumed
# Files named like ${1} in directories ${4} will be copied to ${3}
# with name ${2}000 ... ${2}999 (maximum) with same extension as ${1}

if [ -z "$1" ]; then
	echo "File mask (first parameter) must be given." >&2
	exit 1
fi

MASK="${1:-\*.jpg}"
EXT="${MASK##*.}"
[ -n "$EXT" ] && EXT=".$EXT"
FPFX="${2:-file}"
DEST="${3:-$HOME}"
DIRS="${4:-.}"
DIRS="$(echo "$DIRS" | sed 's|:|\n|g')"
NUM=0

if [ ! -d "$DEST" ]; then
	mkdir -p "$DEST" || ( \
	echo "Destination directory (second parameter) is not valid." >&2
	exit 1)
fi
DEST="$(cd "$DEST" && pwd)"

function formatNum() {
	local result="$1"
	while [ ${#result} -lt $2 ]; do
		result="0$result"
	done
	echo "$result"
}

echo "$DIRS" | while read DIR; do
	if [ -d "$DIR" ]; then
		DIR="$(cd "$DIR" && pwd)"
	else
		echo "Directory $DIR skipped. It does not exist." >&2
		continue
	fi
	if [ -z "${DEST##${DIR}/*}" ]; then
		echo "Directory $DIR skipped. It contains the destination." >&2
	fi
	find "$DIR" -type f -iname "$MASK" -print
done | while read FILE; do
	NUM2=$(formatNum $NUM 3)
	while [ -e "${DEST}/${FPFX}${NUM2}${EXT}" ]; do
		NUM=$(( $NUM + 1 ))
		NUM2=$(formatNum $NUM 3)
	done
	cp -f "$FILE" "${DEST}/${FPFX}${NUM2}${EXT}"
done