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http.go
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package sdm630
import (
"encoding/json"
"fmt"
"html/template"
"log"
"net/http"
"runtime"
"strconv"
"time"
"github.com/gorilla/handlers"
"github.com/gorilla/mux"
"github.com/jcuga/golongpoll"
)
const (
SECONDS_BETWEEN_STATUSUPDATE = 1
)
// Generate the embedded assets using https://github.com/aprice/embed
//go:generate go run github.com/aprice/embed/cmd/embed -c "embed.json"
func MkIndexHandler(mc *MeasurementCache) func(http.ResponseWriter, *http.Request) {
loader := GetEmbeddedContent()
mainTemplate, err := loader.GetContents("/index.html")
if err != nil {
log.Fatal("Failed to load embedded template: " + err.Error())
}
t, err := template.New("gosdm630").Parse(string(mainTemplate))
if err != nil {
log.Fatal("Failed to create main page template: ", err.Error())
}
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/html; charset=UTF-8")
w.WriteHeader(http.StatusOK)
data := struct {
SoftwareVersion string
GolangVersion string
}{
SoftwareVersion: RELEASEVERSION,
GolangVersion: runtime.Version(),
}
err := t.Execute(w, data)
if err != nil {
log.Fatal("Failed to render main page: ", err.Error())
}
})
}
func MkLastAllValuesHandler(mc *MeasurementCache) func(http.ResponseWriter, *http.Request) {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusOK)
ids := mc.GetSortedIDs()
lasts := ReadingSlice{}
for _, id := range ids {
reading, err := mc.GetCurrent(id)
if err != nil {
// Skip this meter, it will simply not be displayed
continue
//w.WriteHeader(http.StatusBadRequest)
//fmt.Fprintf(w, err.Error())
//return
}
lasts = append(lasts, *reading)
}
if len(lasts) == 0 {
w.WriteHeader(http.StatusBadRequest)
fmt.Fprintf(w, "All meters are inactive.")
return
}
if err := json.NewEncoder(w).Encode(lasts); err != nil {
log.Printf("Failed to create JSON representation of measurements: %s", err.Error())
}
})
}
func MkLastSingleValuesHandler(mc *MeasurementCache) func(http.ResponseWriter, *http.Request) {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
vars := mux.Vars(r)
id, err := strconv.Atoi(vars["id"])
if err != nil {
w.WriteHeader(http.StatusBadRequest)
return
}
last, err := mc.GetCurrent(byte(id))
if err != nil {
w.WriteHeader(http.StatusBadRequest)
fmt.Fprintf(w, err.Error())
return
}
w.WriteHeader(http.StatusOK)
if err := json.NewEncoder(w).Encode(last); err != nil {
log.Printf("Failed to create JSON representation of measurement %s", last.String())
}
})
}
func MkLastMinuteAvgSingleHandler(mc *MeasurementCache) func(http.ResponseWriter, *http.Request) {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
vars := mux.Vars(r)
id, err := strconv.Atoi(vars["id"])
if err != nil {
w.WriteHeader(http.StatusBadRequest)
return
}
avg, err := mc.GetMinuteAvg(byte(id))
if err != nil {
w.WriteHeader(http.StatusBadRequest)
fmt.Fprintf(w, err.Error())
return
}
w.WriteHeader(http.StatusOK)
if err := json.NewEncoder(w).Encode(avg); err != nil {
log.Printf("Failed to create JSON representation of measurement %s", avg.String())
}
})
}
func MkLastMinuteAvgAllHandler(mc *MeasurementCache) func(http.ResponseWriter, *http.Request) {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusOK)
ids := mc.GetSortedIDs()
avgs := ReadingSlice{}
for _, id := range ids {
reading, err := mc.GetMinuteAvg(id)
if err != nil {
// Skip this meter, it will simply not be displayed
continue
}
avgs = append(avgs, *reading)
}
if len(avgs) == 0 {
w.WriteHeader(http.StatusBadRequest)
fmt.Fprintf(w, "All meters are inactive.")
return
}
if err := json.NewEncoder(w).Encode(avgs); err != nil {
log.Printf("Failed to create JSON representation of measurements: %s", err.Error())
}
})
}
func MkStatusHandler(s *Status) func(http.ResponseWriter, *http.Request) {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(http.StatusOK)
s.Update()
if err := json.NewEncoder(w).Encode(s); err != nil {
log.Printf("Failed to create JSON representation of measurements: %s", err.Error())
}
})
}
func MkSocketHandler(hub *SocketHub) func(http.ResponseWriter, *http.Request) {
return func(w http.ResponseWriter, r *http.Request) {
ServeWebsocket(hub, w, r)
}
}
type Firehose struct {
lpManager *golongpoll.LongpollManager
in QuerySnipChannel
statstream chan string
}
func NewFirehose(inChannel QuerySnipChannel, status *Status, verbose bool) *Firehose {
options := golongpoll.Options{}
// see https://github.com/jcuga/golongpoll/blob/master/longpoll.go#L81
//options := golongpoll.Options{
// LoggingEnabled: false,
// MaxLongpollTimeoutSeconds: 60,
// MaxEventBufferSize: 250,
// EventTimeToLiveSeconds: 60,
// DeleteEventAfterFirstRetrieval: false,
//}
if verbose {
options.LoggingEnabled = true
}
manager, err := golongpoll.StartLongpoll(options)
if err != nil {
log.Fatalf("Failed to create firehose longpoll manager: %q", err)
}
// Attach a goroutine that will push meter status information
// periodically
var statusstream = make(chan string)
go func() {
for {
time.Sleep(SECONDS_BETWEEN_STATUSUPDATE * time.Second)
status.Update()
if bytes, err := json.Marshal(status); err == nil {
statusstream <- string(bytes)
}
}
}()
return &Firehose{
lpManager: manager,
in: inChannel,
statstream: statusstream,
}
}
func (f *Firehose) Run() {
for {
select {
case snip := <-f.in:
f.lpManager.Publish("meterupdate", snip)
case statupdate := <-f.statstream:
f.lpManager.Publish("statusupdate", statupdate)
}
}
}
func (f *Firehose) GetHandler() func(w http.ResponseWriter, r *http.Request) {
return f.lpManager.SubscriptionHandler
}
// serveJson decorates handler with required headers
func serveJson(f http.HandlerFunc) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "application/json; charset=UTF-8")
w.Header().Set("Access-Control-Allow-Origin", "*")
f(w, r)
}
}
func Run_httpd(
mc *MeasurementCache,
firehose *Firehose,
hub *SocketHub,
s *Status,
url string,
) {
log.Printf("Starting API at %s", url)
router := mux.NewRouter().StrictSlash(true)
// static
router.HandleFunc("/", MkIndexHandler(mc))
router.PathPrefix("/js/").Handler(GetEmbeddedContent())
router.PathPrefix("/css/").Handler(GetEmbeddedContent())
// api
router.HandleFunc("/last", serveJson(MkLastAllValuesHandler(mc)))
router.HandleFunc("/last/{id:[0-9]+}", serveJson(MkLastSingleValuesHandler(mc)))
router.HandleFunc("/minuteavg", serveJson(MkLastMinuteAvgAllHandler(mc)))
router.HandleFunc("/minuteavg/{id:[0-9]+}", serveJson(MkLastMinuteAvgSingleHandler(mc)))
router.HandleFunc("/status", serveJson(MkStatusHandler(s)))
// longpoll
if firehose != nil {
router.HandleFunc("/firehose", firehose.GetHandler())
}
// websocket
router.HandleFunc("/ws", MkSocketHandler(hub))
srv := http.Server{
Addr: url,
Handler: handlers.CompressHandler(router),
ReadTimeout: time.Minute,
WriteTimeout: time.Minute,
}
srv.SetKeepAlivesEnabled(true)
log.Fatal(srv.ListenAndServe())
}