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api.go
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api.go
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package api
import (
"encoding/json"
"fmt"
"log"
"net/http"
"strconv"
"github.com/dmowcomber/dcc-go/rail"
"github.com/go-chi/chi"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
type API struct {
track *rail.Track
router chi.Router
httpServer *http.Server
}
func New(track *rail.Track, router chi.Router, httpServer *http.Server) *API {
return &API{
track: track,
router: router,
httpServer: httpServer,
}
}
var inflightRequests *prometheus.GaugeVec
func init() {
inflightRequests = prometheus.NewGaugeVec(prometheus.GaugeOpts{
Name: "inflight_http_reqeusts",
}, []string{"endpoint"})
prometheus.MustRegister(inflightRequests)
}
func metricsHandler(rw http.ResponseWriter, req *http.Request) {
promhttp.Handler().ServeHTTP(rw, req)
}
func (a *API) Run() error {
// api group
a.router.Group(func(r chi.Router) {
r.Use(func(next http.Handler) http.Handler {
handler := func(w http.ResponseWriter, r *http.Request) {
inflightRequests.WithLabelValues(r.URL.Path).Inc()
defer inflightRequests.WithLabelValues(r.URL.Path).Dec()
next.ServeHTTP(w, r)
}
return http.HandlerFunc(handler)
})
r.Get("/metrics", metricsHandler)
r.Get("/{address:[0-9]+}/function", a.functionHandler)
r.Get("/{address:[0-9]+}/speed", a.speedDirectionHandler)
r.Get("/{address:[0-9]+}/stop", a.stopHandler)
r.Get("/power", a.powerHandler)
r.Get("/state", a.stateHandler)
})
// web ui routes
assetsDir := http.Dir("./ui/web/assets/")
a.router.Handle("/*", http.FileServer(assetsDir))
err := a.httpServer.ListenAndServe()
if err != nil && err != http.ErrServerClosed {
return fmt.Errorf("unable to run http server: %s", err.Error())
}
return nil
}
type powerResponse struct {
Power bool `json:"power"`
}
type functionsResponse struct {
Functions map[string]bool `json:"functions"`
}
type errorResponse struct {
Error string `json:"error"`
}
func (a *API) powerHandler(w http.ResponseWriter, r *http.Request) {
power, err := a.track.PowerToggle()
if err != nil {
log.Printf("unable to toggle power: %q", err.Error())
w.WriteHeader(http.StatusInternalServerError)
fmt.Fprintf(w, "faile to toggle power: %q", err.Error())
return
}
powerResp := &powerResponse{Power: power}
data, err := json.Marshal(powerResp)
if err != nil {
w.WriteHeader(http.StatusNoContent)
log.Printf("failed to marshal response: %q", err.Error())
return
}
w.WriteHeader(http.StatusOK)
fmt.Fprint(w, string(data))
}
func (a *API) functionHandler(w http.ResponseWriter, r *http.Request) {
address, err := parseAddress(r)
if err != nil {
w.WriteHeader(http.StatusBadRequest)
fmt.Fprintf(w, err.Error())
return
}
functionParam := r.URL.Query().Get("function")
function, err := strconv.ParseUint(functionParam, 10, 32)
if err != nil {
log.Printf("function must be a number: %q", err.Error())
w.WriteHeader(http.StatusBadRequest)
fmt.Fprintf(w, "function must be a number: %q", err.Error())
return
}
funcValue, err := a.track.GetThrottle(address).ToggleFunction(uint(function))
if err != nil {
log.Printf("failed to toggle function: %q", err.Error())
w.WriteHeader(http.StatusInternalServerError)
fmt.Fprintf(w, fmt.Sprintf("failed to toggle function: %q", err.Error()))
return
}
funcResp := &functionsResponse{Functions: map[string]bool{
functionParam: funcValue,
}}
data, err := json.Marshal(funcResp)
if err != nil {
w.WriteHeader(http.StatusNoContent)
log.Printf("failed to marshal response: %q", err.Error())
return
}
w.WriteHeader(http.StatusOK)
fmt.Fprint(w, string(data))
}
// TODO: use json requests data instead of parama. simpler code
// TODO: address middleware
func parseAddress(r *http.Request) (int, error) {
addressParam := chi.URLParam(r, "address")
address, err := strconv.Atoi(addressParam)
if err != nil {
return 0, fmt.Errorf("address must be a number: %q", err.Error())
}
return address, nil
}
func (a *API) speedDirectionHandler(w http.ResponseWriter, r *http.Request) {
address, err := parseAddress(r)
if err != nil {
w.WriteHeader(http.StatusBadRequest)
fmt.Fprintf(w, err.Error())
return
}
speedParam := r.URL.Query().Get("speed")
speed, err := strconv.Atoi(speedParam)
if err != nil {
log.Printf("speed must be a number: %q", err.Error())
// TODO: write json error
w.WriteHeader(http.StatusBadRequest)
fmt.Fprintf(w, "speed must be a number: %q", err.Error())
return
}
// TODO: reuse a lot of this validation logic
forwardParam := r.URL.Query().Get("forward")
forward, err := strconv.ParseBool(forwardParam)
if err != nil {
log.Printf("forward must be a boolean: %q", err.Error())
// TODO: write json error
w.WriteHeader(http.StatusBadRequest)
fmt.Fprintf(w, "forward must be a boolean: %q", err.Error())
return
}
fmt.Fprintf(w, fmt.Sprintf("setting speed to: %d, forward direction: %v", speed, forward))
if forward {
a.track.GetThrottle(address).DirectionForward()
} else {
a.track.GetThrottle(address).DirectionBackward()
}
a.track.GetThrottle(address).SetSpeed(speed)
}
func (a *API) stopHandler(w http.ResponseWriter, r *http.Request) {
address, err := parseAddress(r)
if err != nil {
w.WriteHeader(http.StatusBadRequest)
fmt.Fprintf(w, err.Error())
return
}
err = a.track.GetThrottle(address).Stop()
if err != nil {
errorResp := &errorResponse{
Error: err.Error(),
}
data, _ := json.Marshal(errorResp)
w.WriteHeader(http.StatusInternalServerError)
fmt.Fprint(w, data)
return
}
}
func (a *API) Shutdown() error {
if a.httpServer != nil {
return a.httpServer.Close()
}
return nil
}