From d4e1f48ff12db48e9a9bdbd3253c1041328ca66d Mon Sep 17 00:00:00 2001
From: xengineering <mail2xengineering@protonmail.com>
Date: Fri, 11 Jun 2021 10:36:20 +0200
Subject: Implement Configuration with JSON

---
 Makefile            |  1 +
 config/default.json |  6 ++++++
 src/main.go         | 41 ++++++++++++++++++++++++++++++++++++++++-
 src/web.go          | 11 ++++++++---
 4 files changed, 55 insertions(+), 4 deletions(-)
 create mode 100644 config/default.json

diff --git a/Makefile b/Makefile
index 88e4c4f..7531fdb 100644
--- a/Makefile
+++ b/Makefile
@@ -16,6 +16,7 @@ clean:
 install: all
 	make -C python install DESTDIR=$(abspath $(DESTDIR))
 	make -C src install DESTDIR=$(abspath $(DESTDIR))
+	install -Dm 644 config/default.json $(DESTDIR)/etc/birdscan/config.json
 	install -Dm 644 systemd/birdscan.service $(DESTDIR)$(PREFIX)/lib/systemd/system/birdscan.service
 	install -Dm 644 systemd/birdscan.sysusers $(DESTDIR)$(PREFIX)/lib/sysusers.d/birdscan.conf
 	install -Dm 644 data/html/index.html $(DESTDIR)$(PREFIX)/share/birdscan/html/index.html
diff --git a/config/default.json b/config/default.json
new file mode 100644
index 0000000..6288daf
--- /dev/null
+++ b/config/default.json
@@ -0,0 +1,6 @@
+{
+    "webserver":{
+        "bind_address":"127.0.0.1",
+        "bind_port":"8080"
+    }
+}
diff --git a/src/main.go b/src/main.go
index 68f2af3..d64533e 100644
--- a/src/main.go
+++ b/src/main.go
@@ -5,14 +5,53 @@ package main
 import (
 	"log"
 	"time"
+	"os"
+	"io/ioutil"
+	"encoding/json"
 )
 
+const (
+	CONFIG_FILE = "/etc/birdscan/config.json"
+)
+
+type config struct {
+	WebConfig webConfig `json:"webserver"`
+}
+
 func main() {
 	log.SetFlags(0)  // disable timestamp because systemd takes care of that
 	log.Println("Starting birdscan")
-	go runServer()
+	cfg := readConfig()
+	go runServer(&cfg.WebConfig)
 	for {
 		time.Sleep(1 * time.Second)
 	}
 }
 
+func readConfig() config {
+
+	log.Printf("Reading config file %s", CONFIG_FILE)
+	var retval config
+
+	// open the config file
+	configFile, err := os.Open(CONFIG_FILE)
+	defer configFile.Close()
+	if err != nil {
+		log.Fatalf("Could not open configuration file %s", CONFIG_FILE)
+	}
+
+	// read byte content
+	byteData, err := ioutil.ReadAll(configFile)
+	if err != nil {
+		log.Fatalf("Could not read configuration file %s", CONFIG_FILE)
+	}
+
+	// parse content to config structs
+	err = json.Unmarshal(byteData, &retval)
+	if err != nil {
+		log.Fatalf("Could not parse configuration file %s", CONFIG_FILE)
+	}
+
+	return retval
+}
+
diff --git a/src/web.go b/src/web.go
index b57c5f5..4306b2c 100644
--- a/src/web.go
+++ b/src/web.go
@@ -15,15 +15,20 @@ const (
 	APP_DATA = "/usr/share/birdscan"
 )
 
-func runServer() {
+type webConfig struct {
+	BindAddress string `json:"bind_address"`
+	BindPort string `json:"bind_port"`
+}
+
+func runServer(cfg *webConfig) {
 	router := chi.NewRouter()
 	router.Use(middleware.Logger)
 
 	router.Get("/", indexHandler)
 	router.Get("/css/birdscan.css", cssHandler)
 
-	log.Println("Binding to 'http://" + "127.0.0.1" + ":" + "8080" + "'")
-	log.Fatal(http.ListenAndServe("127.0.0.1" + ":" + "8080", router))
+	log.Println("Binding to 'http://" + cfg.BindAddress + ":" + cfg.BindPort + "'")
+	log.Fatal(http.ListenAndServe(cfg.BindAddress + ":" + cfg.BindPort, router))
 }
 
 func indexHandler(w http.ResponseWriter, r *http.Request) {
-- 
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