From bf01ec0d0321d2eafd5ae579278898a71da7d68e Mon Sep 17 00:00:00 2001
From: Sebastien DUMETZ <s.dumetz@holusion.com>
Date: Tue, 9 Jan 2024 09:42:45 +0100
Subject: [PATCH] some further refining work

---
 source/server/utils/merge/index.ts    |  9 ++++--
 source/server/utils/merge/pointers.ts | 46 +++++++++++++--------------
 2 files changed, 30 insertions(+), 25 deletions(-)

diff --git a/source/server/utils/merge/index.ts b/source/server/utils/merge/index.ts
index 9c8efadc..4176db1e 100644
--- a/source/server/utils/merge/index.ts
+++ b/source/server/utils/merge/index.ts
@@ -14,13 +14,18 @@ export {
 
 /**
  * like `diff()` but dereferences a document's pointers first to make a cleaner diff
- * @returns 
+ * @see diff
  */
 export function diffDoc(from:IDocument,to:IDocument){
   return diff( toPointers(from), toPointers(to));
 }
 
-
+/**
+ * like `apply()` but dereferences a document's pointers first to make a cleaner diff, then re-references the result
+ * @see apply
+ * @see fromPointers
+ * @see toPointers
+ */
 export function applyDoc(from:IDocument, diff:Diff<DerefDocument>){
   return fromPointers(apply(toPointers(from), diff));
 }
diff --git a/source/server/utils/merge/pointers.ts b/source/server/utils/merge/pointers.ts
index e7a055bc..d2ababe5 100644
--- a/source/server/utils/merge/pointers.ts
+++ b/source/server/utils/merge/pointers.ts
@@ -5,10 +5,14 @@ import { ISetup } from "../schema/setup.js";
 import { DerefDocument, DerefNode, DerefScene } from "./types.js";
 
 
+type DocumentCollections = keyof Omit<IDocument, "asset"|"scene">;
 
 /**
  * Dereference all indexed values into pointers in a SVX document
  * It effectively forgets about all unreachable nodes (scenes, setups, etc...).
+ * 
+ * It's something of an emulation of what DPO-voyager does when building a scene graph from a document.
+ * See CVScene.ts and CVNode.ts in voyager. 
  */
 export function toPointers(src :IDocument) :DerefDocument {
   const nodes = src.nodes?.map(iNode=>{
@@ -72,8 +76,10 @@ export function toPointers(src :IDocument) :DerefDocument {
 
 export function fromPointers({asset, scene} :DerefDocument): IDocument{
 
-
-  let collections = {
+  //The output document
+  let document :Required<IDocument> = {
+    asset,
+    scene: -1,
     "scenes": [] as IScene[],
     "nodes": [] as INode[],
     "cameras": [] as ICamera[],
@@ -81,8 +87,7 @@ export function fromPointers({asset, scene} :DerefDocument): IDocument{
     "models": [] as IModel[],
     "metas": [] as IMeta[],
     "setups": [] as ISetup[],
-    
-  } as const;
+  };
 
 
   function appendScene(scene :DerefScene){
@@ -96,12 +101,12 @@ export function fromPointers({asset, scene} :DerefDocument): IDocument{
     for(let key of ["setup", "meta"] as const){
       const value = scene[key];
       if(!value) continue;
-      let colKey = key+"s" as keyof typeof collections;
-      const idx = collections[colKey].length;
-      collections[colKey].push(value as any);
+      let colKey = key+"s" as DocumentCollections;
+      const idx = document[colKey]!.length;
+      document[colKey]!.push(value as any);
       iScene[key] = idx as any;
     }
-    return collections.scenes.push(iScene) - 1;
+    return document.scenes.push(iScene) - 1;
   }
 
   function appendNode(node :DerefNode){
@@ -110,7 +115,7 @@ export function fromPointers({asset, scene} :DerefDocument): IDocument{
     if(node.name) iNode.name = node.name;
 
     //Push to collection before appending children because that's a more "natural" order to have
-    const idx = collections.nodes.push(iNode) - 1;
+    const idx = document.nodes.push(iNode) - 1;
 
     if(node.children?.length){
       iNode.children = node.children.map((child)=>appendNode(child));
@@ -125,28 +130,23 @@ export function fromPointers({asset, scene} :DerefDocument): IDocument{
     for(let key of ["camera", "light", "model", "meta"] as const){
       const value = node[key];
       if(!value) continue;
-      let colKey = key+"s" as keyof typeof collections;
-      const idx = collections[colKey].length;
-      collections[colKey].push(value as any);
+      let colKey = key+"s" as DocumentCollections;
+      const idx = document[colKey].length;
+      document[colKey].push(value as any);
       iNode[key] = idx as any;
     }
     return idx;
   }  
 
 
-  let sceneIndex = appendScene(scene);
+  document.scene = appendScene(scene);
 
 
-  let out :IDocument = {
-    asset,
-    scene: sceneIndex,
-    ...collections,
-  };
-
-  for(let key in out){
-    let v = out[key as keyof typeof out];
-    if(typeof v === "undefined" || (Array.isArray(v) && v.length == 0)) delete out[key as keyof typeof out];
+  //Remove empty collections
+  for(let key in document){
+    let v = document[key as keyof typeof document];
+    if(typeof v === "undefined" || (Array.isArray(v) && v.length == 0)) delete document[key as keyof typeof document];
   }
 
-  return out;
+  return document;
 }
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