From c9095928d270a7b2727bacb25d843d4e82c9aeb3 Mon Sep 17 00:00:00 2001
From: Oliver Gugger <gugger@gmail.com>
Date: Mon, 17 Jun 2024 14:16:33 +0200
Subject: [PATCH] http_notif: implement HTTP notifications

---
 http_notif.go | 108 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 105 insertions(+), 3 deletions(-)

diff --git a/http_notif.go b/http_notif.go
index 0284883..bfb5605 100644
--- a/http_notif.go
+++ b/http_notif.go
@@ -1,17 +1,119 @@
 package main
 
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"net/http"
+	"text/template"
+)
+
+type encoding string
+
+func (e encoding) AddHeader(header http.Header) {
+	header.Add("Content-Type", string(e))
+}
+
+func (e encoding) EscapeValue(value string) string {
+	switch e {
+	case EncodingForm:
+		return template.URLQueryEscaper(value)
+
+	case EncodingJson:
+		return template.JSEscapeString(value)
+
+	default:
+		return value
+	}
+}
+
+const (
+	EncodingForm encoding = "application/x-www-form-urlencoded"
+	EncodingJson encoding = "application/json"
+)
+
 type httpNotificator struct {
-	URL string
+	URL          string
+	Method       string
+	Encoding     encoding
+	BodyTemplate string
 }
 
 var _ notificator = (*httpNotificator)(nil)
 
 func NewHttpNotificator(cfg notificatorConfig) *httpNotificator {
-	return &httpNotificator{URL: cfg.Params["Target"]}
+	return &httpNotificator{
+		URL:          cfg.Params["Target"],
+		Method:       cfg.Params["Method"],
+		Encoding:     encoding(cfg.Params["Encoding"]),
+		BodyTemplate: cfg.Params["BodyTemplate"],
+	}
 }
 
 func (h *httpNotificator) Notify(amount uint64, comment string) error {
-	return nil // currently not implemented
+	bodyData := &struct {
+		Amount  uint64
+		Message string
+	}{
+		Amount:  amount,
+		Message: h.Encoding.EscapeValue(comment),
+	}
+
+	urlTemplate, err := template.New("url").Parse(h.URL)
+	if err != nil {
+		return fmt.Errorf("error building URL template: %w", err)
+	}
+
+	bodyTemplate, err := template.New("body").Parse(h.BodyTemplate)
+	if err != nil {
+		return fmt.Errorf("error building body template: %w", err)
+	}
+
+	var buf bytes.Buffer
+	err = urlTemplate.Execute(&buf, bodyData)
+	if err != nil {
+		return fmt.Errorf("error executing URL template: %w", err)
+	}
+	url := buf.String()
+
+	buf.Reset()
+	err = bodyTemplate.Execute(&buf, bodyData)
+	if err != nil {
+		return fmt.Errorf("error executing body template: %w", err)
+	}
+
+	var bodyReader io.Reader
+	if h.Method == http.MethodPost {
+		bodyReader = &buf
+	}
+
+	req, err := http.NewRequest(h.Method, url, bodyReader)
+	if err != nil {
+		return fmt.Errorf("error creating request: %w", err)
+	}
+
+	h.Encoding.AddHeader(req.Header)
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("error sending request: %w", err)
+	}
+
+	defer func() {
+		_ = resp.Body.Close()
+	}()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return fmt.Errorf("error reading response body: %w", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("unexpected status code: %d (%s)",
+			resp.StatusCode, body)
+	}
+
+	return nil
 }
 
 func (h *httpNotificator) Target() string {