1 files changed, 155 insertions, 0 deletions
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..d6b59b9
--- /dev/null
+++ b/main.go
@@ -0,0 +1,155 @@
+// vim: shiftwidth=4 tabstop=4 noexpandtab
+
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"net/netip"
+	"text/template"
+)
+
+type RuntimeConfig struct {
+	Devices DevicesConfig
+	Web     WebConfig
+}
+
+type DevicesConfig struct {
+	Hs100 []Hs100Conf
+}
+
+type WebConfig struct {
+	Listen netip.AddrPort
+}
+
+// main() contains the control flow of this program.
+func main() {
+	configPath := parseFlags()
+	config := parseConfig(configPath)
+	http.HandleFunc("/", index(config.Devices))
+	http.HandleFunc("/api", api())
+	http.HandleFunc("/webiot.css", css())
+	fmt.Printf("Serving at http://%s\n", config.Web.Listen)
+	log.Fatal(http.ListenAndServe(config.Web.Listen.String(), nil))
+}
+
+// parseFlags() handles command line interface (CLI) flags.
+func parseFlags() string {
+
+	var r string // return value
+
+	flag.StringVar(&r, "c", "config.json",
+		"path to configuration file")
+	flag.Parse()
+
+	return r
+}
+
+// parseConfig() parses and validates the runtime configuration file and
+// returns it as Go datastructure.
+func parseConfig(path string) RuntimeConfig {
+
+	// read config file and ensure proper JSON formatting
+	data := mustRead(path)
+	if !json.Valid(data) {
+		log.Fatalf("%s contains invalid JSON!", path)
+	}
+
+	// read to RuntimeConfig struct and handle errors
+	config := RuntimeConfig{}
+	err := json.Unmarshal(data, &config)
+	if err != nil {
+		log.Fatalf("Could not parse configuration file:\n%s\n", err)
+	}
+
+	return config
+}
+
+// index() returns a HTTP handler for the index page.
+func index(config DevicesConfig) func(http.ResponseWriter, *http.Request) {
+
+	// prepare HTML
+	html := mustRender("index.html.tmpl", config)
+
+	return func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprint(w, html)
+	}
+}
+
+func css() func(http.ResponseWriter, *http.Request) {
+
+	// read CSS file
+	css := string(mustRead("./libweb/libweb.css"))
+
+	return func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "text/css; charset=utf-8")
+		fmt.Fprint(w, css)
+	}
+}
+
+// mustRead() reads a file and panics if this is not possible.
+func mustRead(path string) []byte {
+	data, err := ioutil.ReadFile(path)
+	if err != nil {
+		log.Fatalf("Could not read '%s'!", path)
+	}
+	return data
+}
+
+// mustRender() renders a template file with the given data and panics if this
+// is not possible.
+func mustRender(filepath string, data interface{}) string {
+
+	file := mustRead(filepath)
+	tmpl, err := template.New(filepath).Parse(string(file))
+	var buffer bytes.Buffer
+	err = tmpl.Execute(&buffer, data)
+	if err != nil {
+		fmt.Println(err)
+		log.Fatalf("Could not execute template for %s!", filepath)
+	}
+
+	return buffer.String()
+}
+
+// api() returns the HTTP handler for the API endpoint.
+func api() func(http.ResponseWriter, *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+
+		// TODO assert correct HTTP method
+
+		// read parameters and handle errors
+		errHost, host := assertSingleParam(r, "host")
+		errState, state := assertSingleParam(r, "state")
+		if (errHost != nil) || (errState != nil) {
+			http.Error(w,
+				"Provide exactly one host and one state parameter!", 400)
+			return
+		}
+
+		// set WiFi plug
+		err := set(host, state)
+		if err != nil {
+			http.Error(w, "Could not set WiFi plug.", 500)
+		} else {
+			fmt.Fprint(w, "ok")
+		}
+	}
+}
+
+// assertSingleParam() returns the value of given URL key and panics if there
+// is not exactly one match for this key.
+func assertSingleParam(r *http.Request, key string) (error, string) {
+
+	values := r.URL.Query()[key]
+	if len(values) != 1 {
+		return fmt.Errorf("Provide exactly one '%s' parameter!", key), ""
+	}
+	return nil, values[0]
+
+}