refactor: RequestBuilder

packages/app/src/System/RequestSplitter.ts

@@ -0,0 +1,43 @@
+import { RawReqFilter } from "@snort/nostr";
+
+export function diffFilters(a: Array<RawReqFilter>, b: Array<RawReqFilter>) {
+  const result: Array<RawReqFilter> = [];
+  let anyChanged = false;
+  for (const [i, bN] of b.entries()) {
+    const prev: Record<string, string | number | string[] | number[] | undefined> = a[i];
+    if (!prev) {
+      result.push(bN);
+      anyChanged = true;
+    } else {
+      // Critical keys changing means the entire filter has changed
+      const criticalKeys = ["since", "until", "limit"];
+      let anyCriticalKeyChanged = false;
+      for (const [k, v] of Object.entries(bN)) {
+        if (Array.isArray(v)) {
+          const prevArray = prev[k] as Array<string | number>;
+          const thisArray = v as Array<string | number>;
+          const added = thisArray.filter(a => !prevArray.includes(a));
+          // support adding new values to array, removing values is ignored since we only care about getting new values
+          result[i] = { ...result[i], [k]: added.length === 0 ? prevArray : added };
+          if (added.length > 0) {
+            anyChanged = true;
+          }
+        } else if (prev[k] !== v) {
+          result[i] = { ...result[i], [k]: v };
+          if (criticalKeys.includes(k)) {
+            anyCriticalKeyChanged = anyChanged = true;
+            break;
+          }
+        }
+      }
+      if (anyCriticalKeyChanged) {
+        result[i] = bN;
+      }
+    }
+  }
+
+  return {
+    filters: result,
+    changed: anyChanged,
+  };
+}