Add halving countdown widget to main dashboard

frontend/src/app/components/difficulty/difficulty.component.html

@@ -1,7 +1,15 @@
-<div *ngIf="showTitle" class="main-title" i18n="dashboard.difficulty-adjustment">Difficulty Adjustment</div>
+<div *ngIf="showTitle && mode === 'difficulty'" class="main-title" i18n="dashboard.difficulty-adjustment">Difficulty Adjustment</div>
+<div *ngIf="showTitle && mode === 'halving'" class="main-title" i18n="dashboard.halving-countdown">Halving Countdown</div>
 <div class="card-wrapper">
   <div class="card">
-    <div class="card-body more-padding">
+    <div class="widget-toggler">
+      <a href="" (click)="setMode('difficulty')" class="toggler-option"
+        [ngClass]="{'inactive': mode === 'difficulty'}"><small i18n="statistics.average-small">difficulty</small></a>
+      <span style="color: #ffffff66; font-size: 8px"> | </span>
+      <a href="" (click)="setMode('halving')" class="toggler-option"
+        [ngClass]="{'inactive': mode === 'halving'}"><small i18n="statistics.median-small">halving</small></a>
+    </div>
+    <div *ngIf="mode === 'difficulty'; else halving" class="card-body more-padding">
       <div class="difficulty-adjustment-container" *ngIf="(isLoadingWebSocket$ | async) === false && (difficultyEpoch$ | async) as epochData; else loadingDifficulty">
         <div class="epoch-progress">
           <svg #epochSvg class="epoch-blocks" height="22px" width="100%" viewBox="0 0 224 9" shape-rendering="crispEdges" preserveAspectRatio="none">
@@ -76,6 +84,52 @@
   </div>
 </div>
 
+<ng-template #halving>
+  <div class="card-body more-padding">
+    <div class="difficulty-adjustment-container halving" *ngIf="(isLoadingWebSocket$ | async) === false && (difficultyEpoch$ | async) as epochData; else loadingDifficulty">
+      <div class="halving-progress">
+        <div class="background"></div>
+        <div class="remaining" [style]="{ left: ((210000 - epochData.blocksUntilHalving) / 2100).toFixed(2) + '%' }"></div>
+        <div class="label">
+          {{ ((210000 - epochData.blocksUntilHalving) / 2100).toFixed(2) }}%
+        </div>
+      </div>
+      <div class="difficulty-stats">
+        <div class="item">
+          <div class="card-text bigger">
+            <app-btc [satoshis]="312500000"></app-btc>
+          </div>
+          <div class="symbol">
+            <span i18n="difficulty-box.new-subsidy">New subsidy</span>
+          </div>
+        </div>
+        <div class="item">
+          <div class="card-text">
+            {{ epochData.blocksUntilHalving | number }}
+          </div>
+          <div class="symbol">
+            <span *ngIf="epochData.blocksUntilHalving > 1" i18n="shared.blocks-remaining">Blocks remaining</span>
+            <span *ngIf="epochData.blocksUntilHalving === 1" i18n="shared.block-remaining">Block remaining</span>
+          </div>
+        </div>
+        <div class="item">
+          <div class="card-text" i18n-ngbTooltip="mining.average-fee" placement="bottom">
+            <span>{{ epochData.timeUntilHalving | date }}</span>
+          </div>
+          <div class="symbol" *ngIf="epochData.blocksUntilHalving === 1; else approxTime">
+            <app-time kind="until" [time]="epochData.adjustedTimeAvg + now" [fastRender]="false" [fixedRender]="true" [precision]="1" minUnit="minute"></app-time>
+          </div>
+          <ng-template #approxTime>
+            <div class="symbol">
+              <app-time kind="until" [time]="epochData.timeUntilHalving" [fastRender]="false" [fixedRender]="true" [precision]="0" [numUnits]="2" [units]="['year', 'day', 'hour', 'minute']"></app-time>
+            </div>
+          </ng-template>
+        </div>
+      </div>
+    </div>
+  </div>
+</ng-template>
+
 <ng-template #loadingDifficulty>
   <div class="epoch-progress">
     <div class="skeleton-loader"></div>

frontend/src/app/components/difficulty/difficulty.component.scss

@@ -168,7 +168,7 @@
   white-space: nowrap;
 }
 
-.epoch-progress {
+.epoch-progress, .halving-progress {
   width: 100%;
   height: 22px;
   margin-bottom: 12px;
@@ -213,3 +213,42 @@
 .blocks-behind {
   color: #D81B60;
 }
+
+.halving-progress {
+  position: relative;
+  .background, .remaining {
+    position: absolute;
+    top: 0;
+    bottom: 0;
+    height: 100%;
+  }
+  .background {
+    background: linear-gradient(to right, #105fb0, #9339f4);
+    left: 0;
+    right: 0;
+  }
+  .remaining {
+    background: #2d3348;
+    right: 0;
+  }
+  .label {
+    position: relative;
+    margin: auto;
+  }
+}
+
+.widget-toggler {
+  font-size: 12px;
+  position: absolute;
+  top: -20px;
+  right: 3px;
+  text-align: right;
+}
+
+.toggler-option {
+  text-decoration: none;
+}
+
+.inactive {
+  color: #ffffff66;
+}

frontend/src/app/components/difficulty/difficulty.component.ts

@@ -51,6 +51,10 @@ export class DifficultyComponent implements OnInit {
   isLoadingWebSocket$: Observable<boolean>;
   difficultyEpoch$: Observable<EpochProgress>;
 
+  mode: 'difficulty' | 'halving' = 'difficulty';
+  userSelectedMode: boolean = false;
+
+  now: number = Date.now();
   epochStart: number;
   currentHeight: number;
   currentIndex: number;
@@ -101,6 +105,11 @@ export class DifficultyComponent implements OnInit {
         const timeUntilHalving = new Date().getTime() + (blocksUntilHalving * 600000);
         const newEpochStart = Math.floor(this.stateService.latestBlockHeight / EPOCH_BLOCK_LENGTH) * EPOCH_BLOCK_LENGTH;
         const newExpectedHeight = Math.floor(newEpochStart + da.expectedBlocks);
+        this.now = new Date().getTime();
+
+        if (blocksUntilHalving < da.remainingBlocks && !this.userSelectedMode) {
+          this.mode = 'halving';
+        }
 
         if (newEpochStart !== this.epochStart || newExpectedHeight !== this.expectedHeight || this.currentHeight !== this.stateService.latestBlockHeight) {
           this.epochStart = newEpochStart;
@@ -194,6 +203,12 @@ export class DifficultyComponent implements OnInit {
     return shapes;
   }
 
+  setMode(mode: 'difficulty' | 'halving'): boolean {
+    this.mode = mode;
+    this.userSelectedMode = true;
+    return false;
+  }
+
   @HostListener('pointerdown', ['$event'])
   onPointerDown(event): void {
     if (this.epochSvgElement?.nativeElement?.contains(event.target)) {