Refactor notifications and add helper functions (#182)

* Refactor notifications and add helper functions

* Add helper functions to simplify sourcing files and executing functions if they exist

* Create notify_v2.sh wrapper script

* Simplify and consolidate notification logic within notify_v2.sh

* Support notification management via environment variables

* Move secrets to dockcheck.config

* Fix NOTIFY_CHANNELS default value when not set

* Feedback changes

* Remove leading spaces from MessageBody

* Check for valid notify v2 variables

* Warn on missing configuration and bypass notifications

* Update readme

* Additional feedback fixes

* More comments in default.config with different # depth for comments and settings

* Rename NOTIFY_TOPIC_NAME variable to NTFY_TOPIC_NAME for consistency

* Add TELEGRAM_TOPIC_ID

* Fix AppriseURL variable

* Add an ending newline to all MessageBody statements for consistency

* Remove troubleshooting echo statement

* Prevent attempting to trigger notifications for notification templates if versions are the same

---------

Co-authored-by: Matthew Oleksowicz <matt@everyoneneeds.it>

notify_templates/notify_ntfy-sh.sh

@@ -1,57 +1,27 @@
 ### DISCLAIMER: This is a third party addition to dockcheck - best effort testing.
-NOTIFY_NTFYSH_VERSION="v0.2"
+NOTIFY_NTFYSH_VERSION="v0.3"
 #
-# Copy/rename this file to notify.sh to enable the notification snippet.
 # Setup app and subscription at https://ntfy.sh
-# Use your unique Topic Name in the URL below.
+# Do not modify this file directly. Set NTFY_TOPIC_NAME in your dockcheck.config file.
 
-FromHost=$(hostname)
+if [[ -z "${NTFY_TOPIC_NAME:-}" ]]; then
+  printf "Ntfy.sh notification channel enabled, but required configuration variables are missing. Ntfy.sh notifications will not be sent.\n"
 
-trigger_notification() {
-    # Modify to fit your setup:
-    NtfyUrl="ntfy.sh/YourUniqueTopicName"
+  remove_channel ntfy-sh
+fi
 
-    if [[ "$PrintMarkdownURL" == true ]]; then
-        ContentType="Markdown: yes"
-    else
-        ContentType="Markdown: no" #text/plain
-    fi
+trigger_ntfy-sh_notification() {
+  NtfyUrl="ntfy.sh/${NTFY_TOPIC_NAME}" # e.g. NTFY_TOPIC_NAME=YourUniqueTopicName
 
-    curl -sS -o /dev/null --show-error --fail \
-      -H "Title: $MessageTitle" \
-      -H "$ContentType"      \
-      -d "$MessageBody" \
-      "$NtfyUrl"
-}
-
-send_notification() {
-    [ -s "$ScriptWorkDir"/urls.list ] && releasenotes || Updates=("$@")
-    UpdToString=$( printf '%s\\n' "${Updates[@]}" )
-
-    printf "\nSending ntfy.sh notification\n"
-
-    MessageTitle="$FromHost - updates available."
-    # Setting the MessageBody variable here.
-    printf -v MessageBody "🐋 Containers on $FromHost with updates available:\n$UpdToString"
-
-    trigger_notification
-}
-
-### Rename (eg. disabled_dockcheck_notification), remove or comment out the following function
-### to not send notifications when dockcheck itself has updates.
-dockcheck_notification() {
-    printf "\nSending ntfy.sh dockcheck notification\n"
-
-    MessageTitle="$FromHost - New version of dockcheck available."
-    # Setting the MessageBody variable here.
-    printf -v MessageBody "Installed version: $1 \nLatest version: $2 \n\nChangenotes: $3"
-
-    RawNotifyUrl="https://raw.githubusercontent.com/mag37/dockcheck/main/notify_templates/notify_ntfy-sh.sh"
-    LatestNotifyRelease="$(curl -s -r 0-150 $RawNotifyUrl | sed -n "/NOTIFY_NTFYSH_VERSION/s/NOTIFY_NTFYSH_VERSION=//p" | tr -d '"')"
-    if [[ "$NOTIFY_NTFYSH_VERSION" != "$LatestNotifyRelease" ]] ; then
-        printf -v NotifyUpdate "\n\nnotify_ntfy-sh.sh update avialable:\n $NOTIFY_NTFYSH_VERSION -> $LatestNotifyRelease\n"
-        MessageBody="${MessageBody}${NotifyUpdate}"
-    fi
-
-    trigger_notification
+  if [[ "$PrintMarkdownURL" == true ]]; then
+      ContentType="Markdown: yes"
+  else
+      ContentType="Markdown: no" #text/plain
+  fi
+
+  curl -sS -o /dev/null --show-error --fail \
+    -H "Title: $MessageTitle" \
+    -H "$ContentType"      \
+    -d "$MessageBody" \
+    "$NtfyUrl"
 }