From bd27951648706b1ab065fda9976ca69358b9843a Mon Sep 17 00:00:00 2001
From: Maximilian Krambach <maximilian.krambach@intevation.de>
Date: Fri, 17 May 2019 14:46:58 +0200
Subject: [PATCH] drag/Drop multiselect

---
 .../sorting-list/sorting-list.component.html  | 19 ++++-
 .../sorting-list/sorting-list.component.ts    | 75 ++++++++++++++++++-
 .../styles/global-components-style.scss       |  5 ++
 3 files changed, 94 insertions(+), 5 deletions(-)

diff --git a/client/src/app/shared/components/sorting-list/sorting-list.component.html b/client/src/app/shared/components/sorting-list/sorting-list.component.html
index 7da0f16fe..0b13c25c0 100644
--- a/client/src/app/shared/components/sorting-list/sorting-list.component.html
+++ b/client/src/app/shared/components/sorting-list/sorting-list.component.html
@@ -2,18 +2,29 @@
     <div class="line" *ngIf="!array.length">
         <span translate>No data</span>
     </div>
-    <div class="line" *ngFor="let item of array; let i = index" cdkDrag>
-        <div class="section-one backgroundColorLight" cdkDragHandle *ngIf="enable">
+    <div
+        [ngClass]="isSelectedRow(i) ? 'backgroundColorSelected line' : 'backgroundColorLight line'"
+        *ngFor="let item of array; let i = index"
+        cdkDrag
+        (click)="onItemClick($event, i)"
+        (cdkDragStarted)="dragStarted(i)"
+    >
+        <div class="section-one " cdkDragHandle *ngIf="enable">
             <mat-icon>drag_indicator</mat-icon>
         </div>
-        <div class="section-two backgroundColorLight">
+        <div class="section-two">
             <!-- {number}. {item.getTitle()} -->
             <span *ngIf="count">{{ i + 1 }}.&nbsp;</span>
             <span>{{ item.getTitle() }}</span>
         </div>
-        <div class="section-three backgroundColorLight">
+        <div class="section-three">
             <!-- Extra controls slot using implicit template references -->
             <ng-template [ngTemplateOutlet]="templateRef" [ngTemplateOutletContext]="{ $implicit: item }"></ng-template>
         </div>
+        <div class="line" *cdkDragPreview>
+            <div class="spacer.left-10" *ngIf="multiSelectedIndex.length > 0">
+                {{ multiSelectedIndex.length }}&nbsp;<span translate>items selected</span>
+            </div>
+        </div>
     </div>
 </div>
diff --git a/client/src/app/shared/components/sorting-list/sorting-list.component.ts b/client/src/app/shared/components/sorting-list/sorting-list.component.ts
index 7753d4036..8011cb1ae 100644
--- a/client/src/app/shared/components/sorting-list/sorting-list.component.ts
+++ b/client/src/app/shared/components/sorting-list/sorting-list.component.ts
@@ -36,6 +36,12 @@ export class SortingListComponent implements OnInit, OnDestroy {
      */
     public array: Selectable[];
 
+    /**
+     * The index of multiple selected elements. Allows for multiple items to be
+     * selected and then moved
+     */
+    public multiSelectedIndex: number[] = [];
+
     /**
      * Declare the templateRef to coexist between parent in child
      */
@@ -143,12 +149,79 @@ export class SortingListComponent implements OnInit, OnDestroy {
         }
     }
 
+    /**
+     * Handles the start of a dragDrop event and clears multiSelect if the ittem dragged
+     * is not part of the selected items
+     */
+    public dragStarted(index: number): void {
+        if (this.multiSelectedIndex.length && !this.multiSelectedIndex.includes(index)) {
+            this.multiSelectedIndex = [];
+        }
+    }
+
     /**
      * drop event
      * @param event the event
      */
     public drop(event: CdkDragDrop<Selectable[]>): void {
-        moveItemInArray(this.array, event.previousIndex, event.currentIndex);
+        if (this.multiSelectedIndex.length < 2) {
+            moveItemInArray(this.array, event.previousIndex, event.currentIndex);
+        } else {
+            const before: Selectable[] = [];
+            const insertions: Selectable[] = [];
+            const behind: Selectable[] = [];
+            for (let i = 0; i < this.array.length; i++) {
+                if (!this.multiSelectedIndex.includes(i)) {
+                    if (i < event.currentIndex) {
+                        before.push(this.array[i]);
+                    } else if (i > event.currentIndex) {
+                        behind.push(this.array[i]);
+                    } else {
+                        event.currentIndex < 1 ? behind.push(this.array[i]) : before.push(this.array[i]);
+                    }
+                } else {
+                    insertions.push(this.array[i]);
+                }
+            }
+            this.array = [...before, ...insertions, ...behind];
+        }
         this.sortEvent.emit(this.array);
+        this.multiSelectedIndex = [];
+    }
+
+    /**
+     * Handles a click on a row. If the control key is clicked, the element is
+     * added/removed from a multiselect list /(which will be handled on
+     * dropping)
+     *
+     * @param event MouseEvent.
+     * @param indx The index of the row clicked.
+     */
+    public onItemClick(event: MouseEvent, indx: number): void {
+        if (event.ctrlKey) {
+            const ind = this.multiSelectedIndex.findIndex(i => i === indx);
+            if (ind === -1) {
+                this.multiSelectedIndex.push(indx);
+            } else {
+                this.multiSelectedIndex = this.multiSelectedIndex
+                    .slice(0, ind)
+                    .concat(this.multiSelectedIndex.slice(ind + 1));
+            }
+        } else {
+            // deselect all when clicking on an non-selected item
+            if (this.multiSelectedIndex.length && !this.multiSelectedIndex.includes(indx)) {
+                this.multiSelectedIndex = [];
+            }
+        }
+    }
+
+    /**
+     * Checks if the row at the given index is currently selected
+     *
+     * @param index
+     * @returns true if the item is currently selected
+     */
+    public isSelectedRow(index: number): boolean {
+        return this.multiSelectedIndex.includes(index);
     }
 }
diff --git a/client/src/assets/styles/global-components-style.scss b/client/src/assets/styles/global-components-style.scss
index 5c06218a8..080d4c478 100644
--- a/client/src/assets/styles/global-components-style.scss
+++ b/client/src/assets/styles/global-components-style.scss
@@ -80,6 +80,11 @@
         color: mat-color($accent, default-contrast) !important;
     }
 
+    .backgroundColorSelected {
+        background-color: rgba(0, 0, 0, 0.155);
+        color: mat-color($foreground, text) !important;
+    }
+
     .backgroundColorLight {
         background-color: mat-color($background, hover);
         color: mat-color($foreground, text) !important;