wip

src/js/state/Node.test.ts

@@ -3,7 +3,7 @@ import { beforeEach, describe, expect, it, vi } from 'vitest';
 import MemoryAdapter from '@/state/MemoryAdapter.ts';
 import { Callback, Unsubscribe } from '@/state/types.ts';
 
-import Node from './Node';
+import Node, { DIR_VALUE } from './Node';
 
 describe('Node', () => {
   let node;
@@ -100,10 +100,10 @@ describe('Node', () => {
       const node = new Node({ id: 'root', adapters: [new MemoryAdapter()] });
       const mockCallback: Callback = vi.fn();
       const unsubscribe = node.get('chats').map(mockCallback);
-      await node.get('chats').get('someChatId').put({ id: 'someChatId' });
+      await node.get('chats').get('someChatId').get('latest').put({ id: 'messageId', text: 'hi' });
 
       expect(mockCallback).toHaveBeenCalledWith(
-        { id: 'someChatId' },
+        DIR_VALUE,
         'root/chats/someChatId',
         expect.any(Number),
         expect.any(Function),

src/js/state/Node.ts

@@ -12,8 +12,13 @@ type NodeProps = {
   parent?: Node | null;
 };
 
-const DIR_VALUE = '__DIR__';
+export const DIR_VALUE = '__DIR__';
 
+/**
+ * Nodes represent queries into the tree rather than the tree itself. The actual tree data is stored by Adapters.
+ *
+ * Node can be a branch node or a leaf node. Branch nodes have children, leaf nodes have a value (stored in an adapter).
+ */
 export default class Node {
   id: string;
   parent: Node | null;
@@ -21,7 +26,7 @@ export default class Node {
   on_subscriptions = new Map<number, Callback>();
   map_subscriptions = new Map<number, Callback>();
   adapters: Adapter[];
-  counter = 0;
+  private counter = 0;
 
   constructor({ id = '', adapters, parent = null }: NodeProps = {}) {
     this.id = id;
@@ -29,6 +34,10 @@ export default class Node {
     this.adapters = adapters ?? parent?.adapters ?? [new MemoryAdapter(), new LocalForageAdapter()];
   }
 
+  isBranchNode() {
+    return this.children.size > 0;
+  }
+
   /**
    *
    * @param key
@@ -45,8 +54,10 @@ export default class Node {
     return new_node;
   }
 
-  private async putLeaf(value: any, updatedAt: number) {
-    this.children = new Map();
+  private async putValue(value: any, updatedAt: number) {
+    if (value !== DIR_VALUE) {
+      this.children = new Map();
+    }
     const nodeValue: NodeValue = {
       updatedAt,
       value,
@@ -58,11 +69,12 @@ export default class Node {
     await Promise.all(promises);
   }
 
-  private async putBranch(value: Record<string, any>, updatedAt: number) {
+  private async putChildValues(value: Record<string, any>, updatedAt: number) {
     const promises = this.adapters.map((adapter) =>
       adapter.set(this.id, { value: DIR_VALUE, updatedAt }),
     );
     const children = Object.keys(value);
+    // the following probably causes the same callbacks to be fired too many times
     const childPromises = children.map((key) => this.get(key).put(value[key], updatedAt));
     await Promise.all([...promises, ...childPromises]);
   }
@@ -74,51 +86,68 @@ export default class Node {
    */
   async put(value: any, updatedAt = Date.now()) {
     if (typeof value === 'object' && value !== null) {
-      await this.putBranch(value, updatedAt);
+      await this.putChildValues(value, updatedAt);
     } else {
-      await this.putLeaf(value, updatedAt);
+      await this.putValue(value, updatedAt);
     }
 
     if (this.parent) {
-      this.parent.map_subscriptions.forEach((callback) => {
-        callback(value, this.id, updatedAt, () => {});
-      });
+      await this.parent.put(DIR_VALUE, updatedAt);
+      const childName = this.id.split('/').pop()!;
+      if (!this.parent.children.has(childName)) {
+        this.parent.children.set(childName, this);
+      }
+      for (const [id, callback] of this.parent.map_subscriptions) {
+        console.log('calling map callback of ', this.parent.id, ' with ', this.id, value);
+        callback(value, this.id, updatedAt, () => {
+          this.parent?.map_subscriptions.delete(id);
+        });
+      }
     }
   }
 
+  doBranchNodeCallback(callback: Callback) {
+    const aggregated: Record<string, any> = {};
+    const keys = Array.from(this.children.keys());
+    const total = keys.length;
+    let count = 0;
+
+    keys.forEach((key) => {
+      this.children.get(key)?.once((childValue) => {
+        aggregated[key] = childValue;
+        count++;
+
+        if (count === total) {
+          callback(aggregated, this.id, Date.now(), () => {});
+        }
+      });
+    });
+  }
+
+  // note to self: may be problematic that on behaves differently for leaf and branch nodes
   /**
    * Subscribe to a value
    * @param callback
    */
-  on(callback: Callback): Unsubscribe {
+  on(callback: Callback, returnIfUndefined: boolean = false): Unsubscribe {
     let latest: NodeValue | null = null;
     const cb = (value, path, updatedAt, unsubscribe) => {
       if (value !== DIR_VALUE && (latest === null || latest.updatedAt < value.updatedAt)) {
-        latest = { value, updatedAt };
-        callback(value, path, updatedAt, unsubscribe);
+        if (value !== undefined || returnIfUndefined) {
+          latest = { value, updatedAt };
+          callback(value, path, updatedAt, unsubscribe);
+        }
         // TODO send to other adapters? or PubSub which decides where to send?
       }
     };
     const subId = this.counter++;
     this.on_subscriptions.set(subId, cb);
+
+    // if it's not a dir, adapters will call the callback directly
     const adapterSubs = this.adapters.map((adapter) => adapter.get(this.id, cb));
 
-    if (this.children.size > 0) {
-      const aggregated: Record<string, any> = {};
-      const keys = Array.from(this.children.keys());
-      const total = keys.length;
-      let count = 0;
-
-      keys.forEach((key) => {
-        this.children.get(key)?.once((childValue) => {
-          aggregated[key] = childValue;
-          count++;
-
-          if (count === total) {
-            callback(aggregated, this.id, Date.now(), () => {});
-          }
-        });
-      });
+    if (this.isBranchNode()) {
+      this.doBranchNodeCallback(callback);
     }
 
     const unsubscribe = () => {
@@ -137,7 +166,7 @@ export default class Node {
     this.map_subscriptions.set(id, callback);
     const unsubscribe = () => this.map_subscriptions.delete(id);
     for (const child of this.children.values()) {
-      child.once(callback, unsubscribe);
+      child.once(callback, false, unsubscribe);
     }
     return unsubscribe;
   }
@@ -147,7 +176,7 @@ export default class Node {
    * @param callback
    * @param unsubscribe
    */
-  once(callback?: Callback, unsubscribe?: Unsubscribe): Promise<any> {
+  once(callback?: Callback, returnIfUndefined = false, unsubscribe?: Unsubscribe): Promise<any> {
     return new Promise((resolve) => {
       const cb = (value, updatedAt, path, unsub) => {
         if (unsubscribe) {
@@ -157,7 +186,7 @@ export default class Node {
         callback?.(value, updatedAt, path, unsub);
         unsub();
       };
-      this.on(cb);
+      this.on(cb, returnIfUndefined);
     });
   }
 }

src/js/state/types.ts

@@ -12,4 +12,5 @@ export type Callback = (
 export abstract class Adapter {
   abstract get(path: string, callback: Callback): Unsubscribe;
   abstract set(path: string, data: NodeValue): Promise<void>;
+  // abstract list(path: string, callback: Callback): Unsubscribe; ?
 }