From 34831bbc59b0cb62ec837e1791457cf3bd4574ce Mon Sep 17 00:00:00 2001
From: Sam Anthony <sam@samanthony.xyz>
Date: Mon, 4 Nov 2024 10:34:37 -0500
Subject: server: humidity record for each room

---
 server/Makefile  | 10 +++++++
 server/record.go | 60 ++++++++++++++++++++++++++++++++++++++++++
 server/server.go | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 150 insertions(+)
 create mode 100644 server/Makefile
 create mode 100644 server/record.go
 create mode 100644 server/server.go

(limited to 'server')

diff --git a/server/Makefile b/server/Makefile
new file mode 100644
index 0000000..8954492
--- /dev/null
+++ b/server/Makefile
@@ -0,0 +1,10 @@
+SRC = server.go record.go
+
+server: ${SRC}
+	go build $^
+
+fmt:
+	gofmt -l -s -w ${SRC}
+
+clean:
+	rm -f server
diff --git a/server/record.go b/server/record.go
new file mode 100644
index 0000000..9051146
--- /dev/null
+++ b/server/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/server.go b/server/server.go
new file mode 100644
index 0000000..2795890
--- /dev/null
+++ b/server/server.go
@@ -0,0 +1,80 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+	"strconv"
+)
+
+const addr = ":9090"
+var rooms = []RoomID {
+	",4AL[+V*:*k*n{7vL{}/d=K#Mo*y*^.@",
+	"Jq!+<p3g-iu%-vU]FZp2H,AKZWp@!4![",
+}
+
+type Humidity float32
+type RoomID string
+
+type HumidityHandler struct {
+	rooms map[RoomID]Record[Humidity]
+}
+
+func newHumidityHandler(rooms []RoomID) HumidityHandler {
+	h := HumidityHandler{make(map[RoomID]Record[Humidity])}
+	for _, id := range rooms {
+		h.rooms[id] = newRecord[Humidity]()
+	}
+	return h
+}
+
+func (h HumidityHandler) Close() {
+	for _, record := range h.rooms {
+		record.Close()
+	}
+}
+
+func (h HumidityHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	log.Println(r.Method, r.URL)
+	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, "%.2f", humidity)
+}
+
+func (h HumidityHandler) post(w http.ResponseWriter, r *http.Request) {
+	query := r.URL.RawQuery
+	humidity, err := strconv.ParseFloat(query, 32)
+	if err != nil {
+		w.WriteHeader(http.StatusBadRequest)
+		fmt.Fprintf(w, "invalid query string: '%s'", query)
+		return
+	}
+	h.humidity.put <- float32(humidity)
+}
+
+func main() {
+	humidityHandler := newHumidityHandler()
+	defer humidityHandler.Close()
+
+	http.Handle("/humidity", humidityHandler)
+	fmt.Printf("Listening on %s...\n", addr)
+	log.Fatal(http.ListenAndServe(addr, nil))
+}
-- 
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