Reset history when changing edit mode

src/panels/lovelace/ha-panel-lovelace.ts

@@ -324,6 +324,8 @@ export class LovelacePanel extends LitElement {
       urlPath: this.urlPath,
       editMode: this.lovelace ? this.lovelace.editMode : false,
       locale: this.hass!.locale,
+      configHistory: this.lovelace ? this.lovelace.configHistory : [config],
+      configHistoryIndex: this.lovelace ? this.lovelace.configHistoryIndex : 0,
       enableFullEditMode: () => {
         if (!editorLoaded) {
           editorLoaded = true;
@@ -343,7 +345,11 @@ export class LovelacePanel extends LitElement {
         }
 
         if (!editMode || this.lovelace!.mode !== "generated") {
-          this._updateLovelace({ editMode });
+          this._updateLovelace({
+            editMode,
+            configHistory: [this.lovelace!.config],
+            configHistoryIndex: 0,
+          });
           return;
         }
 
@@ -358,6 +364,8 @@ export class LovelacePanel extends LitElement {
           config: previousConfig,
           rawConfig: previousRawConfig,
           mode: previousMode,
+          configHistory: previousConfigHistory,
+          configHistoryIndex: previousConfigHistoryIndex,
         } = this.lovelace!;
         newConfig = this._checkLovelaceConfig(newConfig);
         let conf: LovelaceConfig;
@@ -372,11 +380,22 @@ export class LovelacePanel extends LitElement {
           conf = newConfig;
         }
         try {
+          const newConfigHistory = [...previousConfigHistory];
+          let newConfigHistoryIndex = previousConfigHistoryIndex;
+
+          if (previousConfigHistoryIndex !== 0) {
+            newConfigHistory.splice(0, previousConfigHistoryIndex);
+            newConfigHistoryIndex = 0;
+          }
+          newConfigHistory.unshift(newConfig);
+
           // Optimistic update
           this._updateLovelace({
             config: conf,
             rawConfig: newConfig,
             mode: "storage",
+            configHistory: newConfigHistory,
+            configHistoryIndex: newConfigHistoryIndex,
           });
           this._ignoreNextUpdateEvent = true;
           await saveConfig(this.hass!, urlPath, newConfig);
@@ -388,6 +407,7 @@ export class LovelacePanel extends LitElement {
             config: previousConfig,
             rawConfig: previousRawConfig,
             mode: previousMode,
+            configHistory: previousConfigHistory,
           });
           throw err;
         }
@@ -427,6 +447,57 @@ export class LovelacePanel extends LitElement {
           throw err;
         }
       },
+      restoreConfigFromHistory: async (
+        configHistoryIndex: number
+      ): Promise<void> => {
+        const {
+          configHistory,
+          configHistoryIndex: previousConfigHistoryIndex,
+          config: previousConfig,
+          rawConfig: previousRawConfig,
+        } = this.lovelace!;
+
+        if (
+          previousConfigHistoryIndex === configHistoryIndex ||
+          configHistoryIndex < 0 ||
+          configHistoryIndex >= configHistory.length
+        ) {
+          return;
+        }
+
+        let conf: LovelaceConfig;
+        const newConfig = configHistory[configHistoryIndex];
+
+        if (newConfig.strategy) {
+          conf = await generateLovelaceDashboardStrategy({
+            config: newConfig,
+            hass: this.hass!,
+            narrow: this.narrow,
+          });
+        } else {
+          conf = newConfig;
+        }
+        try {
+          // Optimistic update
+          this._updateLovelace({
+            config: conf,
+            rawConfig: newConfig,
+            configHistoryIndex: configHistoryIndex,
+          });
+          this._ignoreNextUpdateEvent = true;
+          await saveConfig(this.hass!, urlPath, newConfig);
+        } catch (err: any) {
+          // eslint-disable-next-line
+          console.error(err);
+          // Rollback the optimistic update
+          this._updateLovelace({
+            config: previousConfig,
+            rawConfig: previousRawConfig,
+            configHistoryIndex: previousConfigHistoryIndex,
+          });
+          throw err;
+        }
+      },
     };
   }
 

src/panels/lovelace/hui-root.ts

@@ -12,8 +12,10 @@ import {
   mdiMagnify,
   mdiPencil,
   mdiPlus,
+  mdiRedo,
   mdiRefresh,
   mdiShape,
+  mdiUndo,
   mdiViewDashboard,
 } from "@mdi/js";
 import "@polymer/paper-tabs/paper-tab";
@@ -106,12 +108,31 @@ class HUIRoot extends LitElement {
     );
   }
 
+  private _undo() {
+    if (this.lovelace) {
+      this.lovelace.restoreConfigFromHistory(
+        this.lovelace.configHistoryIndex + 1
+      );
+    }
+  }
+
+  private _redo() {
+    if (this.lovelace) {
+      this.lovelace.restoreConfigFromHistory(
+        this.lovelace.configHistoryIndex - 1
+      );
+    }
+  }
+
   protected render(): TemplateResult {
     const views = this.lovelace?.config.views ?? [];
 
     const curViewConfig =
       typeof this._curView === "number" ? views[this._curView] : undefined;
 
+    const historyTotal = this.lovelace?.configHistory.length ?? 0 - 1;
+    const historyIndex = this.lovelace?.configHistoryIndex ?? 0;
+
     return html`
       <div
         class=${classMap({
@@ -144,6 +165,18 @@ class HUIRoot extends LitElement {
                       )}
                       @click=${this._editModeDisable}
                     ></mwc-button>
+                    <ha-icon-button
+                      label="Undo"
+                      .path=${mdiUndo}
+                      .disabled=${historyIndex + 1 >= historyTotal}
+                      @click=${this._undo}
+                    ></ha-icon-button>
+                    <ha-icon-button
+                      label="Redo"
+                      .path=${mdiRedo}
+                      .disabled=${historyIndex === 0}
+                      @click=${this._redo}
+                    ></ha-icon-button>
                     <a
                       href=${documentationUrl(this.hass, "/dashboards/")}
                       rel="noreferrer"

src/panels/lovelace/types.ts

@@ -32,6 +32,9 @@ export interface Lovelace {
   setEditMode: (editMode: boolean) => void;
   saveConfig: (newConfig: LovelaceConfig) => Promise<void>;
   deleteConfig: () => Promise<void>;
+  configHistory: LovelaceConfig[];
+  configHistoryIndex: number;
+  restoreConfigFromHistory: (index: number) => Promise<void>;
 }
 
 export interface LovelaceBadge extends HTMLElement {