carlos / todomvc-bakeoff Public

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1	// Package ref is the bakeoff's reference fixture: a minimal, in-memory
2	// implementation of CONTRACT.md used only to prove the behaviour suite and
3	// the harness before any builder starts. It is not a contestant, and
4	// builders never see it.
5	package ref
6
7	import (
8	"crypto/rand"
9	_ "embed"
10	"encoding/hex"
11	"html/template"
12	"log"
13	"net/http"
14	"path/filepath"
15	"strconv"
16	"strings"
17	"sync"
18	)
19
20	//go:embed page.html.tmpl
21	var pageSrc string
22
23	//go:embed app.js
24	var appJS []byte
25
26	var page = template.Must(template.New("page").Parse(pageSrc))
27
28	const cookieName = "todo"
29
30	type item struct {
31	ID int
32	Title string
33	Completed bool
34	}
35
36	type list struct {
37	next int
38	items []item
39	}
40
41	type app struct {
42	origin string
43	shared string
44	mu sync.Mutex
45	lists map[string]*list
46	}
47
48	// NewApp returns the reference app's handler. origin is the app's own
49	// origin for the Origin check; shared is the directory holding base.css
50	// and index.css.
51	func NewApp(origin, shared string) http.Handler {
52	a := &app{origin: origin, shared: shared, lists: map[string]*list{}}
53	mux := http.NewServeMux()
54	mux.HandleFunc("GET /healthz", func(w http.ResponseWriter, _ *http.Request) { w.Write([]byte("ok")) })
55	mux.HandleFunc("GET /api/version", func(w http.ResponseWriter, _ *http.Request) { w.Write([]byte("refapp")) })
56	mux.HandleFunc("GET /static/{file}", a.static)
57	mux.HandleFunc("GET /{$}", a.show("all"))
58	mux.HandleFunc("GET /active", a.show("active"))
59	mux.HandleFunc("GET /completed", a.show("completed"))
60	mux.HandleFunc("POST /todos", a.act(func(l *list, r *http.Request) int {
61	if t := strings.TrimSpace(r.FormValue("title")); t != "" {
62	l.next++
63	l.items = append(l.items, item{ID: l.next, Title: t})
64	}
65	return 0
66	}))
67	mux.HandleFunc("POST /todos/toggle-all", a.act(func(l *list, _ *http.Request) int {
68	all := true
69	for _, it := range l.items {
70	all = all && it.Completed
71	}
72	for i := range l.items {
73	l.items[i].Completed = !all
74	}
75	return 0
76	}))
77	mux.HandleFunc("POST /todos/clear-completed", a.act(func(l *list, _ *http.Request) int {
78	kept := l.items[:0]
79	for _, it := range l.items {
80	if !it.Completed {
81	kept = append(kept, it)
82	}
83	}
84	l.items = kept
85	return 0
86	}))
87	mux.HandleFunc("POST /todos/{id}/{op}", a.act(func(l *list, r *http.Request) int {
88	i := l.find(r.PathValue("id"))
89	if i < 0 {
90	return http.StatusNotFound
91	}
92	switch r.PathValue("op") {
93	case "toggle":
94	l.items[i].Completed = !l.items[i].Completed
95	case "edit":
96	if t := strings.TrimSpace(r.FormValue("title")); t != "" {
97	l.items[i].Title = t
98	} else {
99	l.items = append(l.items[:i], l.items[i+1:]...)
100	}
101	case "destroy":
102	l.items = append(l.items[:i], l.items[i+1:]...)
103	default:
104	return http.StatusNotFound
105	}
106	return 0
107	}))
108	return mux
109	}
110
111	func (l *list) find(id string) int {
112	n, err := strconv.Atoi(id)
113	if err != nil {
114	return -1
115	}
116	for i, it := range l.items {
117	if it.ID == n {
118	return i
119	}
120	}
121	return -1
122	}
123
124	func (a *app) static(w http.ResponseWriter, r *http.Request) {
125	switch f := r.PathValue("file"); f {
126	case "base.css", "index.css":
127	w.Header().Set("Content-Type", "text/css; charset=utf-8")
128	http.ServeFile(w, r, filepath.Join(a.shared, f))
129	case "app.js":
130	w.Header().Set("Content-Type", "text/javascript; charset=utf-8")
131	w.Write(appJS)
132	default:
133	http.NotFound(w, r)
134	}
135	}
136
137	// listFor returns the caller's list, minting a fresh one (and its cookie)
138	// when the cookie is missing or unknown. Caller holds a.mu.
139	func (a *app) listFor(w http.ResponseWriter, r *http.Request) *list {
140	if c, err := r.Cookie(cookieName); err == nil {
141	if l, ok := a.lists[c.Value]; ok {
142	return l
143	}
144	}
145	b := make([]byte, 16)
146	rand.Read(b)
147	key := hex.EncodeToString(b)
148	l := &list{}
149	a.lists[key] = l
150	http.SetCookie(w, &http.Cookie{Name: cookieName, Value: key, Path: "/", HttpOnly: true,
151	SameSite: http.SameSiteLaxMode, Secure: strings.HasPrefix(a.origin, "https://")})
152	return l
153	}
154
155	func filterPath(f string) string {
156	switch f {
157	case "active", "completed":
158	return "/" + f
159	}
160	return "/"
161	}
162
163	func (a *app) act(f func(*list, *http.Request) int) http.HandlerFunc {
164	return func(w http.ResponseWriter, r *http.Request) {
165	if o := r.Header.Get("Origin"); o != "" && o != a.origin {
166	http.Error(w, "cross-site request refused", http.StatusForbidden)
167	return
168	}
169	r.ParseForm()
170	a.mu.Lock()
171	status := f(a.listFor(w, r), r)
172	a.mu.Unlock()
173	if status != 0 {
174	http.Error(w, http.StatusText(status), status)
175	return
176	}
177	filter := r.FormValue("filter")
178	if r.Header.Get("X-Requested-With") == "fetch" {
179	a.render(w, r, filter)
180	return
181	}
182	http.Redirect(w, r, filterPath(filter), http.StatusSeeOther)
183	}
184	}
185
186	func (a *app) show(filter string) http.HandlerFunc {
187	return func(w http.ResponseWriter, r *http.Request) { a.render(w, r, filter) }
188	}
189
190	type view struct {
191	Filter, Path string
192	Items []item
193	Total, Left, Done int
194	AllDone bool
195	EditID int
196	}
197
198	func (a *app) render(w http.ResponseWriter, r *http.Request, filter string) {
199	if filter != "active" && filter != "completed" {
200	filter = "all"
201	}
202	a.mu.Lock()
203	l := a.listFor(w, r)
204	v := view{Filter: filter, Path: filterPath(filter), Total: len(l.items)}
205	for _, it := range l.items {
206	if it.Completed {
207	v.Done++
208	} else {
209	v.Left++
210	}
211	if filter == "all" || (filter == "completed") == it.Completed {
212	v.Items = append(v.Items, it)
213	}
214	}
215	a.mu.Unlock()
216	v.AllDone = v.Total > 0 && v.Left == 0
217	v.EditID, _ = strconv.Atoi(r.URL.Query().Get("edit"))
218	w.Header().Set("Content-Type", "text/html; charset=utf-8")
219	if err := page.Execute(w, v); err != nil {
220	log.Print(err)
221	}
222	}
223