Fix calculation of total answer statistic of content-group

src/app/components/shared/list-statistic/list-statistic.component.ts

-
 import { Component, Input, OnInit } from '@angular/core';
 import { ContentGroup } from '../../../models/content-group';
 import { ContentService } from '../../../services/http/content.service';
@@ -6,6 +5,7 @@ import { Content } from '../../../models/content';
 import { ContentType } from '../../../models/content-type.enum';
 import { AnswerOption } from '../../../models/answer-option';
 import { ContentChoice } from '../../../models/content-choice';
+
 export class ContentPercents {
   content: Content;
   percent: number;
@@ -19,7 +19,9 @@ export class ContentPercents {
   templateUrl: './list-statistic.component.html',
   styleUrls: ['./list-statistic.component.scss']
 })
+
 export class ListStatisticComponent implements OnInit {
+
   @Input() contentGroup: ContentGroup;
   contents: Content[] = [];
   percents: number[] = [];
@@ -29,33 +31,41 @@ export class ListStatisticComponent implements OnInit {
   totalP = 0;
   correctCounts = 0;
   totalCounts = 0;
+  contentCounter = 0;
+
   constructor(private contentService: ContentService) {
   }
+
   ngOnInit() {
     this.percents = [73, 87, 69, 92, 77];
     this.contentService.getContentChoiceByIds(this.contentGroup.contentIds).subscribe(contents => {
       this.getContents(contents);
     });
   }
+
   getContents(contents: ContentChoice[]) {
     this.contents = contents;
     const length = contents.length;
     this.dataSource = new Array<ContentPercents>(length);
     for (let i = 0; i < length; i++) {
-      this.dataSource[i] = new ContentPercents(null, null );
+      this.dataSource[i] = new ContentPercents(null, 0 );
       this.dataSource[i].content = this.contents[i];
       if (contents[i].format === ContentType.CHOICE) {
         this.contentService.getAnswer(contents[i].id).subscribe(answer => {
-          let percent = this.getCountCorrect(contents[i].options, answer.roundStatistics[0].independentCounts);
+          const percent = this.getCountCorrect(contents[i].options, answer.roundStatistics[0].independentCounts);
           this.dataSource[i].percent = percent;
-          this.totalP += percent;
-          this.total = this.totalP / length;
+          if (percent >= 0) {
+            console.log(percent);
+            this.totalP += percent;
+            this.total = this.totalP / this.contentCounter;
+          }
         });
       } else {
         this.dataSource[i].percent = -1;
       }
     }
   }
+
   getCountCorrect(options: AnswerOption[], indCounts: number[]): number {
     let correctIndex;
     this.correctCounts = 0;
@@ -73,7 +83,12 @@ export class ListStatisticComponent implements OnInit {
       }
       this.totalCounts += indCounts[i];
     }
-    res = ((this.correctCounts / this.totalCounts) * 100);
+    if (this.totalCounts) {
+      res = ((this.correctCounts / this.totalCounts) * 100);
+      this.contentCounter++;
+    } else {
+      res = -1;
+    }
     return res;
   }
 }