feat: add server-side pagination sort and search for centers component (#506)

- Add server-side pagination, sort and search for centers component
- Refactor code to meet current guidelines

See: #234

src/app/centers/centers.component.ts

@@ -1,45 +1,132 @@
-import { Component, OnInit, ViewChild, ViewEncapsulation } from '@angular/core';
-import {MatPaginator, MatSort, MatTableDataSource} from '@angular/material';
-import { CentersService } from 'app/centers/centers.service';
-import {DataSource} from '@angular/cdk/collections';
-import { Observable } from 'rxjs';
+/** Angular Imports */
+import { Component, OnInit, ViewChild, AfterViewInit } from '@angular/core';
+import { MatPaginator, MatSort, MatCheckbox } from '@angular/material';
+import { FormControl } from '@angular/forms';
+import { Router, ActivatedRoute } from '@angular/router';
 
+/** rxjs Imports */
+import { merge } from 'rxjs';
+import { tap, startWith, map, distinctUntilChanged, debounceTime} from 'rxjs/operators';
+
+/** Custom Services */
+import { CentersService } from './centers.service';
+
+/** Custom Data Source */
+import { CentersDataSource } from './centers.datasource';
+
+/**
+ * Centers component.
+ */
 @Component({
   selector: 'mifosx-app-centers',
   templateUrl: './centers.component.html',
   styleUrls: ['./centers.component.scss'],
-
 })
-export class CentersComponent implements OnInit {
-  private ELEMENT_DATA: any = undefined;
-  displayedColumns =  ['name', 'accountno', 'externalid', 'status', 'office'];
-  dataSource = new MatTableDataSource();
+export class CentersComponent implements OnInit, AfterViewInit {
+  @ViewChild('showClosedCenters') showClosedCenters: MatCheckbox;
 
+  /** Name form control. */
+  name = new FormControl();
+  /** ExternalId form control. */
+  externalId = new FormControl();
+  /** Columns to be displayed in centers table. */
+  displayedColumns =  ['name', 'accountNo', 'externalId', 'status', 'officeName'];
+  /** Data source for centers table. */
+  dataSource: CentersDataSource;
+  /** Centers filter. */
+  filterCentersBy = [
+    {
+      type: 'name',
+      value: ''
+    },
+    {
+      type: 'externalId',
+      value: ''
+    }
+  ];
+
+  /** Paginator for centers table. */
   @ViewChild(MatPaginator) paginator: MatPaginator;
+  /** Sorter for centers table. */
   @ViewChild(MatSort) sort: MatSort;
-  constructor(private centerService: CentersService) { }
+
+  constructor(private centersService: CentersService) { }
 
   ngOnInit() {
-      this.centerService.getCenters()
-      .subscribe(
-        (res => {
-         console.log(res);
-        // console.log(res.active);
-         res.active = !!res.active;
-         this.dataSource = new MatTableDataSource(res);
-         this.dataSource.paginator = this.paginator;
-         this.dataSource.sort = this.sort;
+    this.getCenters();
+  }
+
+  /**
+   * Subscribes to all search filters:
+   * Name, ExternalId
+   * sort change and page change.
+   */
+  ngAfterViewInit() {
+
+    this.name.valueChanges
+      .pipe(
+        debounceTime(500),
+        distinctUntilChanged(),
+        tap((filterValue) => {
+          this.applyFilter(filterValue, 'name');
         })
-      );
+      )
+      .subscribe();
+
+    this.externalId.valueChanges
+    .pipe(
+      debounceTime(500),
+      distinctUntilChanged(),
+      tap((filterValue) => {
+        this.applyFilter(filterValue, 'externalId');
+      })
+    )
+    .subscribe();
+
+    this.sort.sortChange.subscribe(() => this.paginator.pageIndex = 0);
+
+    merge(this.sort.sortChange, this.paginator.page)
+      .pipe(
+        tap(() => this.loadCentersPage())
+      )
+      .subscribe();
   }
 
+  /**
+   * Reloads page on changing show closed centers checkbox
+   */
+  changeShowClosedCenters() {
+    this.loadCentersPage();
+  }
 
-  applyFilter(filterValue: string) {
-    filterValue = filterValue.trim(); // Remove whitespace
-    filterValue = filterValue.toLowerCase(); // Datasource defaults to lowercase matches
-    this.dataSource.filter = filterValue;
-    if (this.dataSource.paginator) {
-      this.dataSource.paginator.firstPage();
+  /**
+   * Loads a page of centers.
+   */
+  loadCentersPage() {
+    if (!this.sort.direction) {
+      delete this.sort.active;
     }
+    this.dataSource.getCenters(this.filterCentersBy, this.sort.active, this.sort.direction, this.paginator.pageIndex, this.paginator.pageSize, !this.showClosedCenters.checked);
   }
+
+  /**
+   * Filters data in centers table based on passed value and poperty.
+   * @param {string} filterValue Value to filter data.
+   * @param {string} property Property to filter data by.
+   */
+  applyFilter(filterValue: string, property: string) {
+    this.paginator.pageIndex = 0;
+    const findIndex = this.filterCentersBy.findIndex(filter => filter.type === property);
+    this.filterCentersBy[findIndex].value = filterValue;
+    this.loadCentersPage();
+  }
+
+  /**
+   * Initializes the data source for centers table and loads the first page.
+   */
+  getCenters() {
+    this.dataSource = new CentersDataSource(this.centersService);
+    this.dataSource.getCenters(this.filterCentersBy, this.sort.active, this.sort.direction, this.paginator.pageIndex, this.paginator.pageSize);
+  }
+
 }