Got it working!

Database.go

@@ -0,0 +1,27 @@
+package main
+
+import (
+	"database/sql"
+	"fmt"
+)
+
+var ClimateDb *sql.DB
+
+func InitDb() error {
+	db, err := sql.Open("mysql", "admin:sekna123jk@tcp(127.0.0.1:3306)/climate")
+	if err != nil {
+		fmt.Println("error connecting to database")
+		return err
+	}
+	ClimateDb = db
+	return nil
+}
+
+func CloseDb() {
+	if ClimateDb != nil {
+		err := ClimateDb.Close()
+		if err != nil {
+			fmt.Println("error closing database: " + err.Error())
+		}
+	}
+}

HandlerHelpers.go

@@ -0,0 +1,91 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+)
+
+type HandlerFuncWithError = func (http.ResponseWriter, *http.Request) error
+
+type HttpMethod string
+
+const(
+	HttpGet HttpMethod = "GET"
+	HttpPost HttpMethod = "POST"
+)
+
+type RequestContext struct {
+	ResponseWriter http.ResponseWriter
+	Request *http.Request
+	MethodType HttpMethod
+	Pattern string
+}
+
+type Router struct {
+	patterns map[string] *PatternRouter
+}
+
+type PatternRouter struct {
+	Get HandlerFuncWithError
+	Post HandlerFuncWithError
+}
+
+func (p *Router) MethodFuncForPattern(methodType HttpMethod, pattern string) (HandlerFuncWithError, error) {
+	var methodFunc HandlerFuncWithError
+	switch methodType {
+	case HttpGet:
+		methodFunc = p.patterns[pattern].Get
+	case HttpPost:
+		methodFunc = p.patterns[pattern].Post
+	}
+	if methodFunc == nil {
+		return nil, fmt.Errorf("method %s not defined on pattern %s", methodType, pattern)
+	}
+	return methodFunc, nil
+}
+
+func (p *Router) setGet(pattern string, cb HandlerFuncWithError) {
+	if _, ok := p.patterns[pattern]; ok  {
+		p.patterns[pattern].Get = cb
+	} else {
+		p.patterns[pattern] = &PatternRouter{cb, nil}
+		http.HandleFunc(pattern, getPatternHandler(pattern))
+	}
+}
+
+func (p *Router) setPost(pattern string, cb HandlerFuncWithError) {
+	if _, ok := p.patterns[pattern]; ok  {
+		p.patterns[pattern].Post = cb
+	} else {
+		p.patterns[pattern] = &PatternRouter{nil, cb}
+		http.HandleFunc(pattern, getPatternHandler(pattern))
+	}
+}
+
+var MainRouter = Router{make(map[string] *PatternRouter)}
+
+func getPatternHandler(pattern string) http.HandlerFunc {
+	return func (w http.ResponseWriter, r *http.Request) {
+		cb, err := MainRouter.MethodFuncForPattern(HttpMethod(r.Method), pattern)
+		if err == nil {
+			err = cb(w, r)
+		}
+		if err != nil {
+			context := RequestContext{w, r, HttpMethod(r.Method), pattern}
+			sendInternalError(err, context)
+		}
+	}
+}
+
+func sendInternalError(err error, context RequestContext) {
+	errorMessage := "Internal Server Error!"
+	if DEBUG {
+		errorMessage += fmt.Sprintf( " Happened during %s request for pattern '%s': %s",
+			context.MethodType,
+			context.Pattern,
+			err.Error())
+	}
+	fmt.Println(errorMessage)
+	http.Error(context.ResponseWriter, errorMessage, 500)
+}
+

Snapshot.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"time"
+)
+
+type SnapshotRecord struct {
+	Id int
+	Timestamp time.Time
+	Temp float32
+	Humidity float32
+	Co2 float32
+}
+
+type SnapshotSubmission struct {
+	Timestamp float32 `json:"time"`
+	Temp float32 `json:"temp"`
+	Humidity float32 `json:"humidity"`
+	Co2 float32 `json:"co2"`
+}
+
+func createSnapshotFromJson(jsonBodyStream io.ReadCloser) (*SnapshotSubmission, error) {
+	var snapshotSub SnapshotSubmission
+	body, err := ioutil.ReadAll(jsonBodyStream)
+	if err != nil {
+		return nil, fmt.Errorf("error reading body stream: %w", err)
+	}
+	err = jsonBodyStream.Close()
+	if err != nil {
+		return nil, fmt.Errorf("couldn't close body stream: %w", err)
+	}
+	err = json.Unmarshal(body, &snapshotSub)
+	if err != nil {
+		return nil, fmt.Errorf("couldn't unmarshal json: %w", err)
+	}
+	return &snapshotSub, nil
+}

climate-server.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"fmt"
+	_ "github.com/go-sql-driver/mysql"
+	"log"
+	"net/http"
+)
+
+const DEBUG = true
+
+func main() {
+	err := setup()
+	defer teardown()
+	if err == nil {
+		startServer()
+	}
+}
+
+func setup() error {
+	err := InitDb()
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func teardown() {
+	CloseDb()
+}
+
+func startServer() {
+	port := "8001"
+	MainRouter.setGet("/", showCharts)
+	MainRouter.setPost("/", saveSnapshot)
+	fmt.Printf("Listening on port %s...\n", port)
+	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 saveSnapshot(w http.ResponseWriter, r *http.Request) error {
+	snapshotSub, err := createSnapshotFromJson(r.Body)
+	if err != nil {
+		return fmt.Errorf("couldn't create snapshot from JSON: %w", err)
+	}
+	_, err = ClimateDb.Query(
+		fmt.Sprintf("INSERT INTO `snapshots` (`temp`, `humidity`, `co2`, `time`, `id`) VALUES (%v, %v, %v, %v, NULL);",
+			snapshotSub.Temp,
+			snapshotSub.Humidity,
+			snapshotSub.Co2,
+			snapshotSub.Timestamp))
+	if err != nil {
+		return fmt.Errorf("couldn't submit snapshot into the database: %w", err)
+	}
+	return nil
+}

server.go

@@ -1,73 +0,0 @@
-package main
-
-import (
-	"encoding/json"
-	"database/sql"
-	_ "github.com/go-sql-driver/mysql"
-	"fmt"
-	"io/ioutil"
-	"log"
-	"net/http"
-	//"net/url"
-	"time"
-)
-
-type SnapshotRecord struct {
-	Id int
-	Timestamp time.Time
-	Temp float32
-	Humidity float32
-	Co2 float32
-}
-
-type SnapshotSubmission struct {
-	Timestamp float32 `json:"time"`
-	Temp float32 `json:"temp"`
-	Humidity float32 `json:"humidity"`
-	Co2 float32 `json:"co2"`
-}
-
-
-var climateDb *sql.DB
-
-func setupDb() *sql.DB {
-	db, err := sql.Open("mysql", "admin:sekna123jk@tcp(127.0.0.1:3306)/climate")
-	if err != nil {
-		panic(err.Error())
-	}
-	return db
-}
-
-func main() {
-	climateDb = setupDb()
-	defer climateDb.Close()
-	http.HandleFunc("/", viewHandler)
-	fmt.Println("Listening on port 8001...")
-	log.Fatal(http.ListenAndServe(":8001", nil))
-}
-
-func viewHandler(w http.ResponseWriter, r *http.Request) {
-	switch r.Method {
-	case "GET":
-		_, _ = fmt.Fprint(w, "<h1>Climate Stuff</h1><div>The data will show up here at some stage...</div>")
-	case "POST":
-		var snapshotSub SnapshotSubmission
-		body, err := ioutil.ReadAll(r.Body)
-		if err != nil {
-			http.Error(w, "Internal Server Error!", 500)
-		}
-		err = json.Unmarshal(body, &snapshotSub)
-		if err != nil {
-			http.Error(w, "Internal Server Error!", 500)
-		}
-		_, err = climateDb.Query(
-			fmt.Sprintf("INSERT INTO `snapshots` (`temp`, `humidity`, `co2`, `time`, `id`) VALUES (%v, %v, %v, %v, NULL);",
-			snapshotSub.Temp,
-			snapshotSub.Humidity,
-			snapshotSub.Co2,
-			snapshotSub.Timestamp))
-		if err != nil {
-			http.Error(w, "Internal Server Error!", 500)
-		}
-	}
-}