refactor: standardize help generation

plugins/plugin/help-functions

@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+set -eo pipefail
+[[ $DOKKU_TRACE ]] && set -x
+
+cmd-plugin-help() {
+  declare desc="help command"
+  declare CMD="$1"
+  local plugin_name="plugin"
+  local plugin_description="Manage installed plugins"
+
+  if [[ "$CMD" == "$plugin_name:help" ]]; then
+    echo -e "Usage: dokku $plugin_name[:COMMAND]"
+    echo ''
+    echo "$plugin_description"
+    echo ''
+    echo 'Additional commands:'
+    fn-help-content | sort | column -c2 -t -s,
+  elif [[ $(ps -o command= $PPID) == *"--all"* ]]; then
+    fn-help-content
+  else
+    cat <<help_desc
+    $plugin_name, $plugin_description
+help_desc
+  fi
+}
+
+fn-help-content() {
+  declare desc="return help content"
+  cat <<help_content
+    plugin:disable <name>, Disable an installed plugin (third-party only)
+    plugin:enable <name>, Enable a previously disabled plugin
+    plugin:install [--core|git-url [--committish tag|branch|commit|--name custom-plugin-name]], Optionally download git-url (with custom tag/committish) & run install trigger for active plugins (or only core ones)
+    plugin:install-dependencies [--core], Run install-dependencies trigger for active plugins (or only core ones)
+    plugin:list, Print active plugins
+    plugin:trigger <args...>, Trigger an arbitrary plugin hook
+    plugin:uninstall <name>, Uninstall a plugin (third-party only)
+    plugin:update [name [committish]], Optionally update named plugin from git (with custom tag/committish) & run update trigger for active plugins
+help_content
+}