Moved everything into functions for scoping; added option to specify quality at runtime

bash-folders-image-to-webp.sh

@@ -3,66 +3,79 @@
 set -e
 
 usage() {
-    [[ -n "${*}" ]] && printf '%s\n' "Error: ${*}" >&2
-
     cat << EOF
-USAGE: ${0##*/} [OPTION] --folder PATH
+USAGE: ${0##*/} [OPTIONS] PATH
 
 Watches when new image (PNG or JPEG) are added and transform to WebP format
 
 OPTIONS:
-    --help              Display this usage message and exit
-    --folder PATH       PATH to be monitored
+    -h, --help          Display this usage message and exit
+    -q, --quaity INT    Specify the compression factor between 0-100 (default: 90)
+
+SEE ALSO:
+    cwebp(1), inotifywait(1)
 EOF
 
     exit 1
 }
 
-start() {
-    inotifywait -m -e create,moved_to --format '%f' "$FOLDER_ORIGIN" | while read -r filename; do
-        extension="${filename##*.}"
-        for ext in "${EXTENSIONS_TO_WATCH[@]}"; do
-            if [[ "$ext" == "$extension" ]]; then
-                filename_output="${filename%.*}.webp"
-                touch "$FOLDER_ORIGIN/$MESSAGE_WAITING"
-                cwebp -q "$QUALITY" "$FOLDER_ORIGIN/$filename" -o "$FOLDER_ORIGIN/$filename_output"
-                rm "$FOLDER_ORIGIN/$MESSAGE_WAITING"
-            fi
-        done
-    done
+require() {
+    command -v "${1}" &>/dev/null && return
+    printf '%s\n' "Missing required application: '${1}'" >&2
+    return 1
 }
 
-while [[ $# -gt 0 ]]
-do
-    key="$1"
-    case $key in
-    --folder)
-        FOLDER_ORIGIN="$2"
-        shift 2
-        ;;
-    --quality)
-        QUALITY="$2"
-        shift 2
-        ;;
+run() {
+    local file extension
+
+    mkdir --parents "${1}"
+
+    while read -r file; do
+        extension="${file##*.}"
+        [[ "${extension,,}" =~ ^(png|jpe?g)$ ]] || continue
+
+        printf '%s\n' "Converting file '${file}'..."
+        if ! cwebp -q "${quality}" -o "${1}/${file%.*}.webp" "${1}/${file}"; then
+            printf '%s\n' "Failed to convert file: '${file}'" >&2
+        fi
+    done < <(inotifywait --monitor --event "create" --event "moved_to" --format '%f' "${1}")
+}
+
+main() {
+    local opts quality
+
+    quality="90"
+    opts="$(getopt \
+        --options hq: \
+        --longoptions help,quality: \
+        --name "${0##*/}" \
+        -- "${@}" \
+    )"
+
+    eval set -- "${opts}"
+    while true; do
+        case "${1}" in
+            -h | --help )       usage; return 0;;
+            -q | --quality )    quality="${2}"; shift;;
+            -- )                shift; break;;
             * )
-        usage "Unknown option: $1"
+                printf '%s\n' "Unknown option: '${1}'" >&2
+                usage
+                return 1
                 ;;
         esac
+        shift
     done
 
-QUALITY="90"
-MESSAGE_WAITING="converting_please_wait"
-EXTENSIONS_TO_WATCH=("jpg" "jpeg" "png")
-
-if ! command -v cwebp > /dev/null; then
-	printf '%s\n' "Error: You must install WebP tooling" >&2
-    exit 1
+    if [[ -z "${1}" ]]; then
+        printf '%s\n' "No folder specified" >&2
+        return 1
     fi
 
-# Check if the required --folder flag is provided
-if [[ -z "$FOLDER_ORIGIN" ]]; then
-	printf '%s\n' "Error: The --folder flag is required" >&2
-    exit 1
-fi
+    require "inotifywait" || return
+    require "cwebp" || return
 
-start
+    run "${1}"
+}
+
+main "${@}"