feat: sort nodes based on distance and weight (#26)

* feat: sort nodes based on distance and weight

* make sorting a pure func

* fix

Author: AmeanAsad

src/client.js

@@ -10,6 +10,8 @@ import { getJWT } from './utils/jwt.js'
 import { parseUrl, addHttpPrefix } from './utils/url.js'
 import { isBrowserContext } from './utils/runtime.js'
 
+const MAX_NODE_WEIGHT = 100
+
 export class Saturn {
   static nodesListKey = 'saturn-nodes'
   /**
@@ -369,6 +371,29 @@ export class Saturn {
     }
   }
 
+  _sortNodes (nodes) {
+    // Determine the maximum distance for normalization
+    const maxDistance = Math.max(...nodes.map(node => node.distance))
+
+    // These weights determine how important each factor is in determining
+    const distanceImportanceFactor = 0.8
+    const weightImportanceFactor = 1 - distanceImportanceFactor
+
+    return nodes.slice().sort((a, b) => {
+      const normalizedDistanceA = a.distance / maxDistance
+      const normalizedDistanceB = b.distance / maxDistance
+      const normalizedWeightA = a.weight / MAX_NODE_WEIGHT
+      const normalizedWeightB = b.weight / MAX_NODE_WEIGHT
+
+      const metricA =
+        distanceImportanceFactor * normalizedDistanceA - weightImportanceFactor * normalizedWeightA
+      const metricB =
+        distanceImportanceFactor * normalizedDistanceB - weightImportanceFactor * normalizedWeightB
+
+      return metricA - metricB
+    })
+  }
+
   async _loadNodes (opts) {
     let origin = opts.orchURL
 
@@ -407,6 +432,7 @@ export class Saturn {
     }
     // we always want to update from the orchestrator regardless.
     nodes = await orchNodesListPromise
+    nodes = this._sortNodes(nodes)
     this.nodes = nodes
     this.storage?.set(Saturn.nodesListKey, nodes)
   }

test/test-utils.js

@@ -36,7 +36,7 @@ export function generateNodes (count, originDomain) {
     const nodeIp = `node${i}`
     const node = {
       ip: nodeIp,
-      weight: i,
+      weight: 50,
       distance: 100,
       url: `https://${nodeIp}.${originDomain}`
     }