feat: add REST API for flashcards (/api/v1/flashcards/*)

api.go

@@ -0,0 +1,82 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strconv"
+	"strings"
+
+	"go.uber.org/zap"
+)
+
+func registerAPI(mux *http.ServeMux, sqlite *sqliteStore, logger *zap.Logger) {
+	mux.HandleFunc("/api/v1/flashcards", func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet {
+			http.Error(w, `{"error":"method not allowed"}`, http.StatusMethodNotAllowed)
+			return
+		}
+
+		ids, err := sqlite.listAllPublicIDs(r.Context())
+		if err != nil {
+			logger.Error("list flashcards", zap.Error(err))
+			http.Error(w, `{"error":"internal error"}`, http.StatusInternalServerError)
+			return
+		}
+
+		urls := make([]string, 0, len(ids))
+		for _, id := range ids {
+			urls = append(urls, fmt.Sprintf("/api/v1/flashcards/%d", id))
+		}
+
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(map[string][]string{"flashcards": urls})
+	})
+
+	mux.HandleFunc("/api/v1/flashcards/", func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet {
+			http.Error(w, `{"error":"method not allowed"}`, http.StatusMethodNotAllowed)
+			return
+		}
+
+		segments := strings.Split(strings.TrimPrefix(r.URL.Path, "/api/v1/flashcards/"), "/")
+		if len(segments) == 0 || segments[0] == "" {
+			http.Error(w, `{"error":"not found"}`, http.StatusNotFound)
+			return
+		}
+
+		publicID, err := strconv.ParseInt(segments[0], 10, 64)
+		if err != nil {
+			http.Error(w, `{"error":"invalid id"}`, http.StatusBadRequest)
+			return
+		}
+
+		if len(segments) >= 2 && segments[1] != "" {
+			version, err := strconv.Atoi(segments[1])
+			if err != nil {
+				http.Error(w, `{"error":"invalid version"}`, http.StatusBadRequest)
+				return
+			}
+			e, err := sqlite.getByPublicIDAndVersion(r.Context(), publicID, version)
+			writeEntry(w, e, err)
+			return
+		}
+
+		e, err := sqlite.getLatestByPublicID(r.Context(), publicID)
+		writeEntry(w, e, err)
+	})
+}
+
+func writeEntry(w http.ResponseWriter, e *entry, err error) {
+	if err != nil {
+		http.Error(w, `{"error":"internal error"}`, http.StatusInternalServerError)
+		return
+	}
+	if e == nil {
+		http.Error(w, `{"error":"not found"}`, http.StatusNotFound)
+		return
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(e)
+}