raw2preview: Refactor and add functionality

Add support for multiple arguments.
Make the code more modular and extendable for other raw formats by
keeping the differentiation code in the main loop and removing the
hardcoded file extension from extractRAW().
Write some of the EXIF tags that the original raw image had into the JPG
like Orientation and some technical details.

.local/bin/raw2preview

@@ -1,34 +1,39 @@
-#!/bin/sh
+#!/bin/bash
 
-errorAndExit () {
-    printf "\033[1;31m$1\033[0m" >&2
-    exit $2
-}
+TAGS_TO_TRANSFER=(
+	-Orientation
+	-CreateDate
+	-ExposureTime
+	-FNumber
+	-ISO
+	-FocalLength
+)
 
-extractRAW () {
-	if [ -r "$1" ]; then
-		if [ "$1" != "${1%CR2}" ] && [ ! -f "${1%CR2}JPG" ]; then
-			exiftool "$1" -PreviewImage -b > "${1%CR2}JPG"
-			echo "${1%CR2}JPG"
-		else
-			printf "\033[1;31mPreview for $1 exists already.\n\033[0m" >&2
-		fi
+extractRAW() {
+	[[ -n "$1" ]] || return
+	prev="./JPGs/${1%.*}.JPG"
+	if [[ ! -e "$prev" ]]; then
+		mkdir -p JPGs
+		exiftool -progress \
+		         -b \
+		         -PreviewImage \
+		         "$1" \
+		         > "$prev"
+		exiftool -overwrite_original \
+		         -tagsFromFile="$1" \
+		         "${TAGS_TO_TRANSFER[@]}" \
+		         "$prev"
 	fi
 }
 
-if [ $# -ne 1 ] || [ ! -r "$1" ]; then
-	errorAndExit "Please specify one readable file.\n" 1
-fi
-
-if [ "$(file -b --mime-type "$1")" = "image/x-canon-cr2" ]; then
-	extractRAW "$1"
-elif [ "$(head -n 1 "$1")" = "#Geeqie collection" ]; then
-	while read line; do
-		if echo "$line" | grep -qv "^#"; then
-			line="${line#\"}"
-			extractRAW "${line%\"}"
-		fi
-	done < "$1" # <"$(sed -r '/#/d;s/(^"|"$)//g' "$1")"
-else
-	errorAndExit "Please specify either a CR2 or a geeqie collection\n" 1
-fi
+for file; do
+	if [[ "$(file -b --mime-type "$file")" = "image/x-canon-cr2" ]]; then
+		extractRAW "$file"
+	elif [[ "$(head -1 "$file")" = "#Geeqie collection" ]]; then
+		while read line; do
+			extractRAW "$file"
+		done <"$(sed -E '/^#/d;s/(^"|"$)//g' "$file")"
+	else
+		>&2 printf "Unrecognized format: $file\n"
+	fi
+done