district-politics/projects/speech-statistics/src/app/auth/administration/factions/factions.component.ts

import {Component, OnInit} from '@angular/core';
import {Faction} from './faction';
import {AngularFireDatabase, SnapshotAction} from '@angular/fire/compat/database';
import {Observable} from 'rxjs';
import {map} from 'rxjs/operators';

@Component({
  selector: 'app-factions',
  templateUrl: './factions.component.html',
  styleUrls: ['./factions.component.scss']
})
export class FactionsComponent implements OnInit {
  public factions: Observable<SnapshotAction<Faction>[]> = new Observable<SnapshotAction<Faction>[]>();

  constructor(private database: AngularFireDatabase) { }

  ngOnInit(): void {
    const factionRef = this.database.list<Faction>('factions');
    this.factions = factionRef.snapshotChanges().pipe(
      map(results => {
        return results.sort(FactionsComponent.sortDescending)
      })
    );
  }

  public addFaction(name: string, size: string): void {
    const factionRef = this.database.list<Faction>('factions');
    factionRef.push({
      name: name,
      size: +size
    })
  }

  public deleteFaction(key: string|null): void {
    const factionRef = this.database.list<Faction>('factions');
    if (key != null) {
      factionRef.remove(key);
    }
  }

  private static sortDescending(factionA: SnapshotAction<Faction>, factionB: SnapshotAction<Faction>): number {
    const factionAValue = factionA.payload.val();
    const factionBValue = factionB.payload.val();

    if (factionAValue == null || factionBValue == null) {
      return 0;
    }

    if (factionAValue.size < factionBValue.size) {
      return 1;
    }
    if (factionAValue.size > factionBValue.size) {
      return -1;
    }

    return 0;
  }
}