added visualisation

climate-server.go

@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 	_ "github.com/go-sql-driver/mysql"
+	"github.com/gorilla/mux"
 	"log"
 	"net/http"
 )
@@ -31,40 +32,57 @@ func teardown() {
 
 func startServer() {
 	port := "8001"
-	MainRouter.setGet("/", showCharts)
-	MainRouter.setGet("/data/", sendData)
-	MainRouter.setPost("/", saveSnapshot)
+	r := mux.NewRouter()
+	r.HandleFunc("/", showCharts).Methods("GET")
+	r.HandleFunc("/data", sendData).Methods("GET")
+	r.HandleFunc("/", saveSnapshot).Methods("POST")
+	http.Handle("/", r)
 	fmt.Printf("Listening on port %s...\n", port)
-	log.Fatal(http.ListenAndServe(":" + port, nil))
+	log.Fatal(http.ListenAndServe(":"+port, nil))
 }
 
-func showCharts(w http.ResponseWriter, r *http.Request) error {
-	_, err := fmt.Fprint(w, "<h1>Climate Stuff</h1><div>The data will show up here at some stage...</div>")
-	return err
+func showCharts(w http.ResponseWriter, r *http.Request) {
+	http.ServeFile(w, r, "charts.html")
 }
 
-func sendData(w http.ResponseWriter, r *http.Request) error {
+func sendData(w http.ResponseWriter, r *http.Request) {
 	records, err := getSnapshotRecordsFromDb(50)
 	if err != nil {
-		return fmt.Errorf("couldn't read rows from the database: %w", err)
+		sendInternalError(fmt.Errorf("couldn't read rows from the database: %w", err), w, r)
+		return
 	}
 	json, err := createJsonFromSnapshotRecords(records)
 	if err != nil {
-		return fmt.Errorf("couldn't create a json from the records: %w", err)
+		sendInternalError(fmt.Errorf("couldn't create a json from the records: %w", err), w, r)
+		return
 	}
 	w.Header().Set("Content-Type", "application/json")
 	_, err = fmt.Fprintf(w, string(json))
-	return err
+	if err != nil {
+		sendInternalError(err, w, r)
+		return
+	}
 }
 
-func saveSnapshot(w http.ResponseWriter, r *http.Request) error {
+func saveSnapshot(w http.ResponseWriter, r *http.Request) {
 	snapshotSub, err := createSnapshotSubFromJsonBodyStream(r.Body)
 	if err != nil {
-		return fmt.Errorf("couldn't create snapshot from JSON: %w", err)
+		sendInternalError(fmt.Errorf("couldn't create snapshot from JSON: %w", err), w, r)
 	}
 	err = writeSnapshotToDb(snapshotSub)
 	if err != nil {
-		return fmt.Errorf("couldn't submit snapshot into the database: %w", err)
+		sendInternalError(fmt.Errorf("couldn't submit snapshot into the database: %w", err), w, r)
 	}
-	return nil
-}
+}
+
+func sendInternalError(err error, w http.ResponseWriter, r *http.Request) {
+	errorMessage := "Internal Server Error!"
+	if DEBUG {
+		errorMessage += fmt.Sprintf(" Happened during %s request for pattern '%s': %s",
+			r.Method,
+			r.URL,
+			err.Error())
+	}
+	fmt.Println(errorMessage)
+	http.Error(w, errorMessage, 500)
+}