management server listener (#17)

Reviewed-on: #17
Co-authored-by: David Ashby <delta.mu.alpha@gmail.com>
Co-committed-by: David Ashby <delta.mu.alpha@gmail.com>

cmd/serve/api.go

@@ -0,0 +1,179 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/fs"
+	"log"
+	"net/http"
+
+	"git.yetaga.in/alazyreader/library/media"
+	"tailscale.com/client/tailscale"
+)
+
+type Router struct {
+	static  fs.FS
+	lib     Library
+	rcol    RecordCollection
+	query   Query
+	ts      *tailscale.LocalClient
+	isAdmin bool
+}
+
+type path map[string]func()
+
+func (h path) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if f, ok := h[r.Method]; ok {
+		f()
+		return
+	}
+	writeJSONerror(w, "method not supported", http.StatusMethodNotAllowed)
+}
+
+func writeJSONerror(w http.ResponseWriter, err string, status int) {
+	log.Println(err)
+	writeJSON(w, struct{ Status, Reason string }{Status: "error", Reason: err}, status)
+}
+
+func writeJSON(w http.ResponseWriter, b any, status int) {
+	bytes, err := json.Marshal(b)
+	if err != nil {
+		writeJSONerror(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.WriteHeader(status)
+	w.Write(bytes)
+	w.Write([]byte("\n"))
+}
+
+func (router *Router) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	switch r.URL.Path {
+	case "/api/mode":
+		path{
+			http.MethodGet: func() {
+				writeJSON(w, struct{ Admin bool }{Admin: router.isAdmin}, http.StatusOK)
+			},
+		}.ServeHTTP(w, r)
+	case "/api/whoami":
+		if !router.isAdmin {
+			http.NotFoundHandler().ServeHTTP(w, r)
+			return
+		}
+		path{
+			http.MethodGet: func() { getWhoAmI(router.ts, w, r) },
+		}.ServeHTTP(w, r)
+	case "/api/records":
+		path{
+			http.MethodGet: func() { getRecords(router.rcol, w, r) },
+		}.ServeHTTP(w, r)
+	case "/api/books":
+		p := path{
+			http.MethodGet: func() { getBooks(router.lib, w, r) },
+		}
+		if router.isAdmin {
+			p[http.MethodPost] = func() { addBook(router.lib, w, r) }
+			p[http.MethodDelete] = func() { deleteBook(router.lib, w, r) }
+		}
+		p.ServeHTTP(w, r)
+	case "/api/query":
+		if !router.isAdmin {
+			http.NotFoundHandler().ServeHTTP(w, r)
+			return
+		}
+		path{
+			http.MethodPost: func() { lookupBook(router.query, w, r) },
+		}.ServeHTTP(w, r)
+	default:
+		static(router.static).ServeHTTP(w, r)
+	}
+}
+
+func getBooks(l Library, w http.ResponseWriter, r *http.Request) {
+	books, err := l.GetAllBooks(r.Context())
+	if err != nil {
+		writeJSONerror(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	writeJSON(w, books, http.StatusOK)
+}
+
+func addBook(l Library, w http.ResponseWriter, r *http.Request) {
+	book, err := ReadBody[media.Book](r.Body)
+	if err != nil {
+		writeJSONerror(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	if err = l.AddBook(r.Context(), book); err != nil {
+		writeJSONerror(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	w.WriteHeader(http.StatusAccepted)
+}
+
+func deleteBook(l Library, w http.ResponseWriter, r *http.Request) {
+	book, err := ReadBody[media.Book](r.Body)
+	if err != nil {
+		writeJSONerror(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	if err = l.DeleteBook(r.Context(), book); err != nil {
+		writeJSONerror(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	w.WriteHeader(http.StatusAccepted)
+}
+
+func getRecords(l RecordCollection, w http.ResponseWriter, r *http.Request) {
+	records, err := l.GetAllRecords(r.Context())
+	if err != nil {
+		writeJSONerror(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	writeJSON(w, records, http.StatusOK)
+}
+
+func getWhoAmI(ts *tailscale.LocalClient, w http.ResponseWriter, r *http.Request) {
+	whois, err := ts.WhoIs(r.Context(), r.RemoteAddr)
+	if err != nil {
+		writeJSONerror(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	writeJSON(w, whois.UserProfile, http.StatusOK)
+}
+
+func lookupBook(query Query, w http.ResponseWriter, r *http.Request) {
+	req, err := ReadBody[media.Book](r.Body)
+	if err != nil {
+		writeJSONerror(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	book, err := query.GetByISBN(req.ISBN13)
+	if err != nil {
+		writeJSONerror(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	writeJSON(w, book, http.StatusOK)
+}
+
+func static(f fs.FS) http.Handler {
+	return http.FileServer(http.FS(f))
+}
+
+func ReadBody[T any](r io.ReadCloser) (*T, error) {
+	t := new(T)
+	if r == nil {
+		return t, fmt.Errorf("no body provided")
+	}
+	defer r.Close()
+	b, err := io.ReadAll(r)
+	if err != nil {
+		return t, fmt.Errorf("error reading body: %w", err)
+	}
+	err = json.Unmarshal(b, t)
+	if err != nil {
+		return t, fmt.Errorf("error reading body: %w", err)
+	}
+	return t, nil
+}