refactor(server/api): prelude helpers (requireUser/requireURLUUID/decodeBody); migrate admin_users.go (A2 1/N)

internal/api/prelude.go

@@ -0,0 +1,50 @@
+package api
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/jackc/pgx/v5/pgtype"
+
+	"git.fabledsword.com/bvandeusen/minstrel/internal/apierror"
+	"git.fabledsword.com/bvandeusen/minstrel/internal/auth"
+	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
+)
+
+// requireUser returns the authenticated user from request context. On
+// missing context, writes a 401 envelope and returns ok=false; the
+// caller MUST return immediately on ok=false. Defensive belt against
+// middleware bypass — handlers using this don't need a separate check.
+func requireUser(w http.ResponseWriter, r *http.Request) (dbq.User, bool) {
+	user, ok := auth.UserFromContext(r.Context())
+	if !ok {
+		writeErr(w, apierror.Unauthorized("auth_required", ""))
+		return dbq.User{}, false
+	}
+	return user, true
+}
+
+// requireURLUUID parses the chi URL parameter named key as a UUID. On
+// invalid input, writes a 400 envelope and returns ok=false; the caller
+// MUST return immediately on ok=false.
+func requireURLUUID(w http.ResponseWriter, r *http.Request, key string) (pgtype.UUID, bool) {
+	id, ok := parseUUID(chi.URLParam(r, key))
+	if !ok {
+		writeErr(w, apierror.BadRequest("invalid_id", ""))
+		return id, false
+	}
+	return id, true
+}
+
+// decodeBody decodes the request body as JSON into out. On decode
+// failure, writes a 400 envelope and returns false; the caller MUST
+// return immediately on false. Out parameter pattern (rather than
+// returning T) keeps the type explicit at the call site.
+func decodeBody[T any](w http.ResponseWriter, r *http.Request, out *T) bool {
+	if err := json.NewDecoder(r.Body).Decode(out); err != nil {
+		writeErr(w, apierror.BadRequest("invalid_body", ""))
+		return false
+	}
+	return true
+}