Add pie chart and rewrite the pool ranking component

frontend/src/app/services/mining.service.ts

@@ -0,0 +1,44 @@
+import { Injectable } from '@angular/core';
+import { Observable } from 'rxjs';
+import { map } from 'rxjs/operators';
+import { MiningStats, PoolsStats } from '../interfaces/node-api.interface';
+import { ApiService } from '../services/api.service';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class MiningService {
+
+  constructor(
+    private apiService: ApiService,
+  ) { }
+
+  public getMiningStats(interval: string): Observable<MiningStats> {
+    return this.apiService.listPools$(interval).pipe(
+      map(pools => this.generateMiningStats(pools))
+    );
+  }
+
+  private generateMiningStats(stats: PoolsStats) : MiningStats {
+    const totalEmptyBlock = Object.values(stats.pools).reduce((prev, cur) => {
+      return prev + cur.emptyBlocks;
+    }, 0);
+    const totalEmptyBlockRatio = (totalEmptyBlock / stats.blockCount * 100).toFixed(2);
+    const poolsStats = stats.pools.map((poolStat) => {
+      return {
+        share: (poolStat.blockCount / stats.blockCount * 100).toFixed(2),
+        lastEstimatedHashrate: (poolStat.blockCount / stats.blockCount * stats.lastEstimatedHashrate / Math.pow(10, 15)).toFixed(2),
+        emptyBlockRatio: (poolStat.emptyBlocks / poolStat.blockCount * 100).toFixed(2),
+        ...poolStat
+      }
+    });
+
+    return {
+      lastEstimatedHashrate: (stats.lastEstimatedHashrate / Math.pow(10, 15)).toFixed(2),
+      blockCount: stats.blockCount,
+      totalEmptyBlock: totalEmptyBlock,
+      totalEmptyBlockRatio: totalEmptyBlockRatio,
+      pools: poolsStats,
+    };
+  }
+}