[#501] Web: Add capability to do a runtime check of the type for the …

…trails types.

projects/web/src/components/submitTrail.tsx

@@ -2,7 +2,7 @@ import * as React from "react";
 import { Link } from "react-router-dom";
 
 import { myGlobals } from "../globals";
-import { UnsignedTrailEntry, SignedTrailEntry } from "../trails";
+import { UnsignedTrailEntry, SignedTrailEntry, isSignedTrailEntryArray} from "../trails";
 
 import { AuthState } from "../auth";
 import { Organisation } from "../org-registry";

projects/web/src/trails.ts

@@ -1,4 +1,9 @@
 import { string } from "prop-types";
+import { isArray } from "util";
+
+export interface SignedTrailEntry extends UnsignedTrailEntry {
+  signature: string;
+}
 
 export interface UnsignedTrailEntry {
   version: number;
@@ -8,6 +13,50 @@ export interface UnsignedTrailEntry {
   previous_signatures : string[];
 }
 
-export interface SignedTrailEntry extends UnsignedTrailEntry {
-  signature: string;
+// Its a real shame that we need to write this explicitly and effectively have to duplicate the type. It would be nice
+// to be able to derrive this directly from the type and if this is possible this should be replaced with that
+// implementation.
+export function isSignedTrailEntryArray(value: any): value is SignedTrailEntry[] {
+  if (isArray(value)) {
+    return value.every(item => isSignedTrailEntry(item));
+  }
+
+  return false;
+}
+
+// Its a real shame that we need to write this explicitly and effectively have to duplicate the type. It would be nice
+// to be able to derrive this directly from the type and if this is possible this should be replaced with that
+// implementation.
+function isSignedTrailEntry(value: any): value is SignedTrailEntry {
+  if (value as SignedTrailEntry) {
+    if (("signature" in value) &&
+        (typeof value.signature === "string")) {
+      return isUnsignedTrailEntry(value);
+    }
+  }
+
+  return false;
+}
+
+// Its a real shame that we need to write this explicitly and effectively have to duplicate the type. It would be nice
+// to be able to derrive this directly from the type and if this is possible this should be replaced with that
+// implementation.
+function isUnsignedTrailEntry(value: any): value is UnsignedTrailEntry {
+  if (value as UnsignedTrailEntry){
+    if (("version" in value) &&
+        (typeof value.version === "number") &&
+        ("timestamp" in value) &&
+        (typeof value.timestamp === "string") &&
+        ("org" in value) &&
+        (typeof value.org === "string") &&
+        ("event_id" in value) &&
+        (typeof value.event_id === "string") &&
+        ("previous_signatures" in value) &&
+        (isArray(value.previous_signatures)) &&
+        (value.previous_signatures.every((signature: any) => typeof signature === "string"))) {
+      return true;
+    }
+  }
+
+  return false;
 }