Fix code-move things around

src/move-node.js

@@ -1,7 +1,7 @@
 const utils = require('./utils');
 const moveShard = require('./move-shard');
 
-const replaceNodeInStandAloneCouch = async (toNode) => {
+const replaceForSingleNode = async (toNode) => {
   const removedNodes = [];
 
   if (!toNode) {
@@ -17,10 +17,10 @@ const replaceNodeInStandAloneCouch = async (toNode) => {
     const oldNodes = await moveShard.moveShard(shard, toNode);
     removedNodes.push(...oldNodes);
   }
-  return removedNodes;
+  return [...new Set(removedNodes)];
 };
 
-const replaceNodeInClusteredCouch = async (toNode, shardMapJson) => {
+const replaceInCluster = async (toNode, shardMapJson) => {
   const removedNodes = [];
   if (!shardMapJson) {
     throw new Error('Shard map JSON is required for multi-node migration');
@@ -39,26 +39,17 @@ const replaceNodeInClusteredCouch = async (toNode, shardMapJson) => {
   if (!removedNodes.includes(oldNode)) {
     removedNodes.push(oldNode);
   }
-return [...new Set(removedNodes)];
+  return [...new Set(removedNodes)];
 };
 
 const moveNode = async (nodeMap, shardMapJson) => {
   if (typeof nodeMap === 'object') {
-    return await replaceInCluster(nodeMap, shardMapJson);
-  }
-
-  return  await replaceForSingleNode(nodeMap);
-};
-  let removedNodes = [];
-  if (typeof toNode === 'object') {
     // Multi-node migration - replace node in clustered couch
-    removedNodes = await replaceNodeInClusteredCouch(toNode, shardMapJson);
-  } else {
-    // Single node migration - replace node in standalone couch
-    removedNodes = await replaceNodeInStandAloneCouch(toNode);
+    return await replaceInCluster(nodeMap, shardMapJson);
   }
 
-  return [...new Set(removedNodes)];
+  // Single node migration - replace node in standalone couch
+  return  await replaceForSingleNode(nodeMap);
 };
 
 const syncShards = async () => {

src/utils.js

@@ -221,6 +221,35 @@ const getShards = async () => {
   }
 };
 
+/*
+This function creates a mapping of shard ranges to nodes.
+*/
+const getShardMapping = async () => {
+  try {
+    const allDbs = await getDbs();
+    const shardMap = {};
+
+    for (const db of allDbs) {
+      const url = await getUrl(`${db}/_shards`);
+      const shardInfo = await request({ url });
+
+      for (const [shardRange, nodeList] of Object.entries(shardInfo.shards)) {
+        // In n=1 setup, there should be only one node per shard range.
+        // We will have to revisit this if we ever support n>1.
+        if (nodeList.length !== 1) {
+          console.warn(`Unexpected number of nodes for range ${shardRange}: ${nodeList.length}`);
+        }
+        shardMap[shardRange] = nodeList[0];
+      }
+    }
+
+    return JSON.stringify(shardMap);
+  } catch (err) {
+    console.error('Error getting shard mapping:', err);
+    throw new Error('Failed to get shard mapping');
+  }
+};
+
 const getNodes = async () => {
   const membership = await getMembership();
   return membership.all_nodes;
@@ -257,6 +286,7 @@ module.exports = {
   deleteNode,
   syncShards,
   getShards,
+  getShardMapping,
   getNodes,
   getConfig,
   getCouchUrl,