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package http
import (
"encoding/json"
"fmt"
"log"
"net/http"
"net/url"
"path/filepath"
"strconv"
"time"
"github.com/mpolden/atb/cache"
"github.com/mpolden/atb/entur"
)
const (
inbound = "inbound"
outbound = "outbound"
)
// Server represents an Server server.
type Server struct {
Entur *entur.Client
CORS bool
cache *cache.Cache
ttl
}
type ttl struct {
departures time.Duration
stops time.Duration
}
func urlPrefix(r *http.Request) string {
host := r.Host
if host == "" {
host = r.RemoteAddr
}
scheme := "http"
if r.TLS != nil {
scheme = "https"
}
forwardedProto := r.Header["X-Forwarded-Proto"]
if len(forwardedProto) > 0 {
scheme = forwardedProto[0]
}
url := url.URL{Scheme: scheme, Host: host}
return url.String()
}
func filterDepartures(departures []Departure, direction string) []Departure {
switch direction {
case inbound, outbound:
copy := make([]Departure, 0, len(departures))
for _, d := range departures {
towardsCentrum := *d.TowardsCentrum
if direction == inbound && !towardsCentrum {
continue
}
if direction == outbound && towardsCentrum {
continue
}
copy = append(copy, d)
}
return copy
}
return departures
}
func (s *Server) enturDepartures(urlPrefix string, stopID int, direction string) (Departures, bool, error) {
cacheKey := strconv.Itoa(stopID)
cached, hit := s.cache.Get(cacheKey)
var departures Departures
if hit {
departures = cached.(Departures)
} else {
enturDepartures, err := s.Entur.Departures(25, stopID)
if err != nil {
return Departures{}, hit, err
}
departures = convertDepartures(enturDepartures)
departures.URL = fmt.Sprintf("%s/api/v2/departures/%d", urlPrefix, stopID)
s.cache.Set(cacheKey, departures, s.ttl.departures)
}
departures.Departures = filterDepartures(departures.Departures, direction)
return departures, hit, nil
}
func (s *Server) setCacheHeader(w http.ResponseWriter, hit bool) {
v := "MISS"
if hit {
v = "HIT"
}
w.Header().Set("X-Cache", v)
}
// DepartureHandlerV2 is a handler which retrieves departures for a given bus stop through Entur.
func (s *Server) DepartureHandlerV2(w http.ResponseWriter, r *http.Request) (interface{}, *Error) {
stopID, err := strconv.Atoi(filepath.Base(r.URL.Path))
if err != nil {
return nil, &Error{
err: err,
Status: http.StatusBadRequest,
Message: "Invalid stop ID. Use https://stoppested.entur.org/ to find stop IDs.",
}
}
direction := r.URL.Query().Get("direction")
departures, hit, err := s.enturDepartures(urlPrefix(r), stopID, direction)
if err != nil {
return nil, &Error{
err: err,
Status: http.StatusInternalServerError,
Message: "Failed to get departures from Entur",
}
}
s.setCacheHeader(w, hit)
return departures, nil
}
// DefaultHandler lists known URLs.
func (s *Server) DefaultHandler(w http.ResponseWriter, r *http.Request) (interface{}, *Error) {
if r.URL.Path != "/" {
return nil, &Error{Status: http.StatusNotFound, Message: "Resource not found"}
}
prefix := urlPrefix(r)
departuresV2URL := fmt.Sprintf("%s/api/v2/departures", prefix)
return struct {
URLs []string `json:"urls"`
}{
[]string{departuresV2URL},
}, nil
}
// New returns a new Server using given clients to communicate with AtB and Entur. stopTTL and departureTTL control the
// cache TTL bus stops and departures.
func New(entur *entur.Client, stopTTL, departureTTL time.Duration, cors bool) *Server {
cache := cache.New(time.Minute)
return &Server{
Entur: entur,
CORS: cors,
cache: cache,
ttl: ttl{
stops: stopTTL,
departures: departureTTL,
},
}
}
type appHandler func(http.ResponseWriter, *http.Request) (interface{}, *Error)
func (fn appHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
data, e := fn(w, r)
if e != nil { // e is *Error, not os.Error.
if e.err != nil {
log.Print(e.err)
}
out, err := json.Marshal(e)
if err != nil {
// Should never happen
panic(err)
}
w.WriteHeader(e.Status)
w.Write(out)
} else {
out, err := json.Marshal(data)
if err != nil {
panic(err)
}
w.Write(out)
}
}
func requestFilter(next http.Handler, cors bool) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "application/json")
if cors {
w.Header().Set("Access-Control-Allow-Methods", "GET")
w.Header().Set("Access-Control-Allow-Origin", "*")
}
next.ServeHTTP(w, r)
})
}
// Handler returns a root handler for the API.
func (s *Server) Handler() http.Handler {
mux := http.NewServeMux()
mux.Handle("/api/v2/departures", appHandler(s.DepartureHandlerV2))
mux.Handle("/api/v2/departures/", appHandler(s.DepartureHandlerV2))
mux.Handle("/", appHandler(s.DefaultHandler))
return requestFilter(mux, s.CORS)
}
// ListenAndServe listens on the TCP network address addr and serves the API.
func (s *Server) ListenAndServe(addr string) error {
return http.ListenAndServe(addr, s.Handler())
}
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