From 1470afb71572f7e95597285eb4d1dac40b69979f Mon Sep 17 00:00:00 2001
From: binwiederhier <phil@heckel.io>
Date: Sun, 27 Jul 2025 10:15:48 +0200
Subject: [PATCH] Make templateMode more understandable

---
 server/server.go | 14 ++++++--------
 server/types.go  | 37 ++++++++++++++++++++++++++++++++-----
 2 files changed, 38 insertions(+), 13 deletions(-)

diff --git a/server/server.go b/server/server.go
index 0b7880cd..ac7b10dc 100644
--- a/server/server.go
+++ b/server/server.go
@@ -992,12 +992,10 @@ func (s *Server) parsePublishParams(r *http.Request, m *message) (cache bool, fi
 		return false, false, "", "", "", false, errHTTPBadRequestPhoneNumberInvalid
 	}
 	template = templateMode(readParam(r, "x-template", "template", "tpl"))
-	var messageStr string
-	if template.Enabled() && template.Name() == "" {
-		// don't convert "\n" to literal newline for inline templates
-		messageStr = readParam(r, "x-message", "message", "m")
-	} else {
-		messageStr = strings.ReplaceAll(readParam(r, "x-message", "message", "m"), "\\n", "\n")
+	messageStr := readParam(r, "x-message", "message", "m")
+	if !template.InlineMode() {
+		// Convert "\n" to literal newline everything but inline mode
+		messageStr = strings.ReplaceAll(messageStr, "\\n", "\n")
 	}
 	if messageStr != "" {
 		m.Message = messageStr
@@ -1125,8 +1123,8 @@ func (s *Server) handleBodyAsTemplatedTextMessage(m *message, template templateM
 		return errHTTPEntityTooLargeJSONBody
 	}
 	peekedBody := strings.TrimSpace(string(body.PeekedBytes))
-	if templateName := template.Name(); templateName != "" {
-		if err := s.renderTemplateFromFile(m, templateName, peekedBody); err != nil {
+	if template.FileMode() {
+		if err := s.renderTemplateFromFile(m, template.FileName(), peekedBody); err != nil {
 			return err
 		}
 	} else {
diff --git a/server/types.go b/server/types.go
index ea6b8615..65492e46 100644
--- a/server/types.go
+++ b/server/types.go
@@ -245,19 +245,46 @@ func (q *queryFilter) Pass(msg *message) bool {
 	return true
 }
 
+// templateMode represents the mode in which templates are used
+//
+// It can be
+// - empty: templating is disabled
+// - a boolean string (yes/1/true/no/0/false): inline-templating mode
+// - a filename (e.g. grafana): template mode with a file
 type templateMode string
 
+// Enabled returns true if templating is enabled
 func (t templateMode) Enabled() bool {
 	return t != ""
 }
 
-func (t templateMode) Name() string {
-	if isBoolValue(string(t)) {
-		return ""
-	}
-	return string(t)
+// InlineMode returns true if inline-templating mode is enabled
+func (t templateMode) InlineMode() bool {
+	return t.Enabled() && isBoolValue(string(t))
 }
 
+// FileMode returns true if file-templating mode is enabled
+func (t templateMode) FileMode() bool {
+	return t.Enabled() && !isBoolValue(string(t))
+}
+
+// FileName returns the filename if file-templating mode is enabled, or an empty string otherwise
+func (t templateMode) FileName() string {
+	if t.FileMode() {
+		return string(t)
+	}
+	return ""
+}
+
+// templateFile represents a template file with title and message
+// It is used for file-based templates, e.g. grafana, influxdb, etc.
+//
+// Example YAML:
+//
+//	  title: "Alert: {{ .Title }}"
+//	  message: |
+//		   This is a {{ .Type }} alert.
+//		   It can be multiline.
 type templateFile struct {
 	Title   *string `yaml:"title"`
 	Message *string `yaml:"message"`