1package route
2
3import (
4	"net/http"
5
6	"github.com/julienschmidt/httprouter"
7	"golang.org/x/net/context"
8)
9
10type param string
11
12// Param returns param p for the context.
13func Param(ctx context.Context, p string) string {
14	return ctx.Value(param(p)).(string)
15}
16
17// WithParam returns a new context with param p set to v.
18func WithParam(ctx context.Context, p, v string) context.Context {
19	return context.WithValue(ctx, param(p), v)
20}
21
22// Router wraps httprouter.Router and adds support for prefixed sub-routers,
23// per-request context injections and instrumentation.
24type Router struct {
25	rtr    *httprouter.Router
26	prefix string
27	instrh func(handlerName string, handler http.HandlerFunc) http.HandlerFunc
28}
29
30// New returns a new Router.
31func New() *Router {
32	return &Router{
33		rtr: httprouter.New(),
34	}
35}
36
37// WithInstrumentation returns a router with instrumentation support.
38func (r *Router) WithInstrumentation(instrh func(handlerName string, handler http.HandlerFunc) http.HandlerFunc) *Router {
39	return &Router{rtr: r.rtr, prefix: r.prefix, instrh: instrh}
40}
41
42// WithPrefix returns a router that prefixes all registered routes with prefix.
43func (r *Router) WithPrefix(prefix string) *Router {
44	return &Router{rtr: r.rtr, prefix: r.prefix + prefix, instrh: r.instrh}
45}
46
47// handle turns a HandlerFunc into an httprouter.Handle.
48func (r *Router) handle(handlerName string, h http.HandlerFunc) httprouter.Handle {
49	if r.instrh != nil {
50		// This needs to be outside the closure to avoid data race when reading and writing to 'h'.
51		h = r.instrh(handlerName, h)
52	}
53	return func(w http.ResponseWriter, req *http.Request, params httprouter.Params) {
54		ctx, cancel := context.WithCancel(req.Context())
55		defer cancel()
56
57		for _, p := range params {
58			ctx = context.WithValue(ctx, param(p.Key), p.Value)
59		}
60		h(w, req.WithContext(ctx))
61	}
62}
63
64// Get registers a new GET route.
65func (r *Router) Get(path string, h http.HandlerFunc) {
66	r.rtr.GET(r.prefix+path, r.handle(path, h))
67}
68
69// Options registers a new OPTIONS route.
70func (r *Router) Options(path string, h http.HandlerFunc) {
71	r.rtr.OPTIONS(r.prefix+path, r.handle(path, h))
72}
73
74// Del registers a new DELETE route.
75func (r *Router) Del(path string, h http.HandlerFunc) {
76	r.rtr.DELETE(r.prefix+path, r.handle(path, h))
77}
78
79// Put registers a new PUT route.
80func (r *Router) Put(path string, h http.HandlerFunc) {
81	r.rtr.PUT(r.prefix+path, r.handle(path, h))
82}
83
84// Post registers a new POST route.
85func (r *Router) Post(path string, h http.HandlerFunc) {
86	r.rtr.POST(r.prefix+path, r.handle(path, h))
87}
88
89// Redirect takes an absolute path and sends an internal HTTP redirect for it,
90// prefixed by the router's path prefix. Note that this method does not include
91// functionality for handling relative paths or full URL redirects.
92func (r *Router) Redirect(w http.ResponseWriter, req *http.Request, path string, code int) {
93	http.Redirect(w, req, r.prefix+path, code)
94}
95
96// ServeHTTP implements http.Handler.
97func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
98	r.rtr.ServeHTTP(w, req)
99}
100
101// FileServe returns a new http.HandlerFunc that serves files from dir.
102// Using routes must provide the *filepath parameter.
103func FileServe(dir string) http.HandlerFunc {
104	fs := http.FileServer(http.Dir(dir))
105
106	return func(w http.ResponseWriter, r *http.Request) {
107		r.URL.Path = Param(r.Context(), "filepath")
108		fs.ServeHTTP(w, r)
109	}
110}
111