From d68ee3fb7455254fff89bca4db6da60abc1bf4b0 Mon Sep 17 00:00:00 2001
From: Franck Royer <franck@status.im>
Date: Mon, 12 Jul 2021 13:11:43 +1000
Subject: [PATCH] New `peers` and `randomPeer` methods to return available
 peers

---
 CHANGELOG.md                     |  2 ++
 src/lib/select_peer.ts           | 22 +++++++++++++---------
 src/lib/waku_light_push/index.ts | 22 ++++++++++++++++++++--
 src/lib/waku_store/index.ts      | 22 ++++++++++++++++++++--
 4 files changed, 55 insertions(+), 13 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index dfdd696bcd..4fe694decb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Keep alive feature that pings host regularly, reducing the chance of connections being dropped due to idle.
   Can be disabled or default frequency (10s) can be changed when calling `Waku.create`.
 - New `lib/utils` module for easy, dependency-less hex/bytes conversions.
+- New `peers` and `randomPeer` methods on `WakuStore` and `WakuLightPush` to have a better idea of available peers;
+  Note that it does not check whether Waku node is currently connected to said peers.
 
 ### Changed
 - **Breaking**: Auto select peer if none provided for store and light push protocols.
diff --git a/src/lib/select_peer.ts b/src/lib/select_peer.ts
index 8e01850ec6..c509236bba 100644
--- a/src/lib/select_peer.ts
+++ b/src/lib/select_peer.ts
@@ -5,14 +5,18 @@ import { Peer } from 'libp2p/src/peer-store';
  * Returns a pseudo-random peer that supports the given protocol.
  * Useful for protocols such as store and light push
  */
-export function selectRandomPeer(
-  libp2p: Libp2p,
-  protocol: string
-): Peer | undefined {
-  const allPeers = Array.from(libp2p.peerStore.peers.values());
-  const size = allPeers.length;
-  const peers = allPeers.filter((peer) => peer.protocols.includes(protocol));
+export function selectRandomPeer(peers: Peer[]): Peer | undefined {
   if (peers.length === 0) return;
-  const index = Math.round(Math.random() * (size - 1));
-  return allPeers[index];
+
+  const index = Math.round(Math.random() * (peers.length - 1));
+  return peers[index];
+}
+
+/**
+ * Returns the list of peers that supports the given protocol.
+ */
+export function getPeersForProtocol(libp2p: Libp2p, protocol: string): Peer[] {
+  return Array.from(libp2p.peerStore.peers.values()).filter((peer) =>
+    peer.protocols.includes(protocol)
+  );
 }
diff --git a/src/lib/waku_light_push/index.ts b/src/lib/waku_light_push/index.ts
index 88551756de..f46155514c 100644
--- a/src/lib/waku_light_push/index.ts
+++ b/src/lib/waku_light_push/index.ts
@@ -2,10 +2,11 @@ import concat from 'it-concat';
 import lp from 'it-length-prefixed';
 import pipe from 'it-pipe';
 import Libp2p from 'libp2p';
+import { Peer } from 'libp2p/src/peer-store';
 import PeerId from 'peer-id';
 
 import { PushResponse } from '../../proto/waku/v2/light_push';
-import { selectRandomPeer } from '../select_peer';
+import { getPeersForProtocol, selectRandomPeer } from '../select_peer';
 import { WakuMessage } from '../waku_message';
 import { DefaultPubsubTopic } from '../waku_relay';
 
@@ -54,7 +55,7 @@ export class WakuLightPush {
       peer = this.libp2p.peerStore.get(opts.peerId);
       if (!peer) throw 'Peer is unknown';
     } else {
-      peer = selectRandomPeer(this.libp2p, LightPushCodec);
+      peer = this.randomPeer;
     }
     if (!peer) throw 'No peer available';
     if (!peer.protocols.includes(LightPushCodec))
@@ -93,4 +94,21 @@ export class WakuLightPush {
     }
     return null;
   }
+
+  /**
+   * Returns known peers from the address book (`libp2p.peerStore`) that support
+   * light push protocol. Waku may or  may not be currently connected to these peers.
+   */
+  get peers(): Peer[] {
+    return getPeersForProtocol(this.libp2p, LightPushCodec);
+  }
+
+  /**
+   * Returns a random peer that supports light push protocol from the address
+   * book (`libp2p.peerStore`). Waku may or  may not be currently connected to
+   * this peer.
+   */
+  get randomPeer(): Peer | undefined {
+    return selectRandomPeer(this.peers);
+  }
 }
diff --git a/src/lib/waku_store/index.ts b/src/lib/waku_store/index.ts
index c0cbe65bf1..242482cdbd 100644
--- a/src/lib/waku_store/index.ts
+++ b/src/lib/waku_store/index.ts
@@ -2,9 +2,10 @@ import concat from 'it-concat';
 import lp from 'it-length-prefixed';
 import pipe from 'it-pipe';
 import Libp2p from 'libp2p';
+import { Peer } from 'libp2p/src/peer-store';
 import PeerId from 'peer-id';
 
-import { selectRandomPeer } from '../select_peer';
+import { getPeersForProtocol, selectRandomPeer } from '../select_peer';
 import { WakuMessage } from '../waku_message';
 import { DefaultPubsubTopic } from '../waku_relay';
 
@@ -76,7 +77,7 @@ export class WakuStore {
       peer = this.libp2p.peerStore.get(opts.peerId);
       if (!peer) throw 'Peer is unknown';
     } else {
-      peer = selectRandomPeer(this.libp2p, StoreCodec);
+      peer = this.randomPeer;
     }
     if (!peer) throw 'No peer available';
     if (!peer.protocols.includes(StoreCodec))
@@ -164,4 +165,21 @@ export class WakuStore {
       }
     }
   }
+
+  /**
+   * Returns known peers from the address book (`libp2p.peerStore`) that support
+   * store protocol. Waku may or  may not be currently connected to these peers.
+   */
+  get peers(): Peer[] {
+    return getPeersForProtocol(this.libp2p, StoreCodec);
+  }
+
+  /**
+   * Returns a random peer that supports store protocol from the address
+   * book (`libp2p.peerStore`). Waku may or  may not be currently connected to
+   * this peer.
+   */
+  get randomPeer(): Peer | undefined {
+    return selectRandomPeer(this.peers);
+  }
 }