WGPS progress tracking

src/wgps/events.ts

@@ -0,0 +1,11 @@
+export class WgpsStatusEvent
+  extends CustomEvent<{ remaining: number; all: number }> {
+  constructor(remaining: number, all: number) {
+    super("status", {
+      detail: {
+        remaining,
+        all,
+      },
+    });
+  }
+}

src/wgps/range_counter.ts

@@ -0,0 +1,27 @@
+import { WillowError } from "../errors.ts";
+import { COVERS_NONE } from "./types.ts";
+
+export class RangeCounter {
+  private count = 0n;
+  private inProgress = new Set<bigint>();
+
+  getNext() {
+    this.inProgress.add(this.count);
+    return this.count++;
+  }
+
+  done(covers: bigint | typeof COVERS_NONE) {
+    if (covers !== COVERS_NONE) {
+      if (!this.inProgress.delete(covers)) {
+        throw new WillowError("Answered range without request");
+      }
+    }
+  }
+
+  info() {
+    return {
+      remaining: BigInt(this.inProgress.size),
+      all: this.count,
+    };
+  }
+}