From bf759c72831c19992ffee657fabc8a8e6ed97ef4 Mon Sep 17 00:00:00 2001
From: Zoe <git@zoe-codez.xyz>
Date: Sat, 23 Mar 2024 07:56:07 -0500
Subject: [PATCH] entity previous state

---
 package-lock.json                          |  4 ++--
 package.json                               |  2 +-
 src/extensions/entity-manager.extension.ts | 19 +++++++++++++++++--
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/package-lock.json b/package-lock.json
index 4ce7e84..4e48fea 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@digital-alchemy/hass",
-  "version": "0.3.3",
+  "version": "0.3.5",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@digital-alchemy/hass",
-      "version": "0.3.3",
+      "version": "0.3.5",
       "license": "MIT",
       "dependencies": {
         "@digital-alchemy/core": "^0.3.6",
diff --git a/package.json b/package.json
index 0b7bfa9..5e1fb39 100644
--- a/package.json
+++ b/package.json
@@ -2,7 +2,7 @@
   "name": "@digital-alchemy/hass",
   "repository": "https://github.com/Digital-Alchemy-TS/hass",
   "homepage": "https://docs.digital-alchemy.app/Hass",
-  "version": "0.3.4",
+  "version": "0.3.5",
   "scripts": {
     "build": "rm -rf dist/; tsc",
     "lint": "eslint src",
diff --git a/src/extensions/entity-manager.extension.ts b/src/extensions/entity-manager.extension.ts
index d12b18e..275d5b6 100644
--- a/src/extensions/entity-manager.extension.ts
+++ b/src/extensions/entity-manager.extension.ts
@@ -32,18 +32,28 @@ export type ByIdProxy<ENTITY_ID extends PICK_ENTITY> =
      * Run callback
      */
     onUpdate: (
-      callback: (state: NonNullable<ENTITY_STATE<ENTITY_ID>>) => TBlackHole,
+      callback: (
+        new_state: NonNullable<ENTITY_STATE<ENTITY_ID>>,
+        old_state: NonNullable<ENTITY_STATE<ENTITY_ID>>,
+      ) => TBlackHole,
     ) => void;
     /**
      * Run callback once, for next update
      */
     once: (
-      callback: (state: NonNullable<ENTITY_STATE<ENTITY_ID>>) => TBlackHole,
+      callback: (
+        new_state: NonNullable<ENTITY_STATE<ENTITY_ID>>,
+        old_state: NonNullable<ENTITY_STATE<ENTITY_ID>>,
+      ) => TBlackHole,
     ) => void;
     /**
      * Will resolve with the next state of the next value. No time limit
      */
     nextState: () => Promise<ENTITY_STATE<ENTITY_ID>>;
+    /**
+     * Access the immediate previous entity state
+     */
+    previous: ENTITY_STATE<ENTITY_ID>;
   };
 
 const MAX_ATTEMPTS = 50;
@@ -65,6 +75,7 @@ export function EntityManager({
     Record<ALL_DOMAINS, Record<string, ENTITY_STATE<PICK_ENTITY>>>
   >;
   const ENTITY_PROXIES = new Map<PICK_ENTITY, ByIdProxy<PICK_ENTITY>>();
+  const PREVIOUS_STATE = new Map<PICK_ENTITY, ENTITY_STATE<PICK_ENTITY>>();
   let lastRefresh: Dayjs;
 
   // * Local event emitter for coordination of socket events
@@ -136,6 +147,9 @@ export function EntityManager({
             if (property === "entity_id") {
               return entity_id;
             }
+            if (property === "previous") {
+              return PREVIOUS_STATE.get(entity_id);
+            }
             if (property === "nextState") {
               return new Promise<ENTITY_STATE<ENTITY_ID>>(done => {
                 event.once(entity_id, (entity: ENTITY_STATE<ENTITY_ID>) =>
@@ -285,6 +299,7 @@ export function EntityManager({
     new_state: ENTITY_STATE<ENTITY>,
     old_state: ENTITY_STATE<ENTITY>,
   ) {
+    PREVIOUS_STATE.set(entity_id, old_state);
     if (new_state === null) {
       logger.warn(
         { name: EntityUpdateReceiver },