implement server GET /humidity

2 files changed, 111 insertions, 0 deletions

diff --git a/record.go b/record.go
new file mode 100644
index 0000000..9051146
--- /dev/null
+++ b/record.go
@@ -0,0 +1,60 @@
+package main
+
+import (
+	"time"
+)
+
+type Record[T any] struct {
+	put       chan<- T
+	get       chan<- chan T
+	getRecent chan<- chan T
+}
+
+type entry[T any] struct {
+	t time.Time
+	v T
+}
+
+func newRecord[T any]() Record[T] {
+	put := make(chan T)
+	get := make(chan chan T)
+	getRecent := make(chan chan T)
+
+	go func() {
+		var entries []entry[T]
+
+		for {
+			select {
+			case v, ok := <-put:
+				if !ok {
+					return
+				}
+				entries = append(entries, entry[T]{time.Now(), v})
+			case c, ok := <-get:
+				if !ok {
+					return
+				}
+				for _, e := range entries {
+					c <- e.v
+				}
+				close(c)
+			case c, ok := <-getRecent:
+				if !ok {
+					return
+				}
+				if len(entries) > 0 {
+					c <- entries[len(entries)-1].v
+				}
+				close(c)
+			}
+		}
+	}()
+
+	return Record[T]{put, get, getRecent}
+}
+
+func (l Record[T]) Close() {
+	close(l.put)
+	close(l.get)
+	close(l.getRecent)
+}
diff --git a/server.go b/server.go
new file mode 100644
index 0000000..67d153d
--- /dev/null
+++ b/server.go
@@ -0,0 +1,51 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+)
+
+const addr = ":9090"
+
+type humidityHandler struct {
+	humidity Record[float32]
+}
+
+func newHumidityHandler() humidityHandler {
+	return humidityHandler{newRecord[float32]()}
+}
+
+func (h *humidityHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	switch r.Method {
+	case http.MethodGet:
+		h.get(w, r)
+	case http.MethodPost:
+		h.post(w, r)
+	default:
+		w.WriteHeader(http.StatusMethodNotAllowed)
+		fmt.Fprintf(w, "invalid method: '%s'", r.Method)
+	}
+}
+
+func (h *humidityHandler) get(w http.ResponseWriter, r *http.Request) {
+	c := make(chan float32)
+	h.humidity.getRecent <- c
+	humidity, ok := <-c
+	if !ok {
+		w.WriteHeader(http.StatusGone)
+		fmt.Fprintf(w, "no humidity data stored on server")
+		return
+	}
+	fmt.Fprintf(w, "%f", humidity)
+}
+
+func (h *humidityHandler) post(w http.ResponseWriter, r *http.Request) {
+	w.WriteHeader(http.StatusNotImplemented)
+}
+
+func main() {
+	http.Handle("/humidity", new(humidityHandler))
+	fmt.Printf("Listening on %s...\n", addr)
+	log.Fatal(http.ListenAndServe(addr, nil))
+}