TermInput: Support reorder by drag and drop

asset/css/search-base.less

@@ -40,6 +40,22 @@
     color: var(--search-term-selected-color, @search-term-selected-color);
     font-style: italic;
   }
+
+  [data-drag-initiator] {
+    cursor: grab;
+  }
+
+  .sortable-drag > label {
+    border: 1px dashed var(--search-term-drag-border-color, @search-term-drag-border-color);
+  }
+
+  .sortable-ghost {
+    opacity: .5;
+  }
+}
+
+fieldset:disabled .term-input-area [data-drag-initiator] {
+  cursor: not-allowed;
 }
 
 .invalid-reason {
@@ -198,24 +214,53 @@
   display: flex;
   flex-direction: column-reverse;
 
+  @itemGap: 1px;
+
   > .terms {
-    @gap: 1px;
+    margin-top: @itemGap;
+
+    input {
+      text-overflow: ellipsis;
+    }
+  }
+
+  > div.terms {
     @termsPerRow: 2;
 
     display: flex;
     flex-wrap: wrap;
-    gap: @gap;
-    margin-top: @gap;
+    gap: @itemGap;
 
     label {
       @termWidth: 100%/@termsPerRow;
-      @totalGapWidthPerRow: (@termsPerRow - 1) * @gap;
+      @totalGapWidthPerRow: (@termsPerRow - 1) * @itemGap;
 
       min-width: ~"calc(@{termWidth} - (@{totalGapWidthPerRow} / @{termsPerRow}))";
       flex: 1 1 auto;
+    }
+  }
 
-      input {
-        text-overflow: ellipsis;
+  > ol.terms {
+    padding: 0;
+    margin-bottom: 0;
+    list-style-type: none;
+
+    li:not(:first-child) {
+      margin-top: @itemGap;
+    }
+
+    li {
+      display: flex;
+      align-items: center;
+      gap: .25em;
+
+      > label {
+        flex: 1 1 auto;
+      }
+
+      > [data-drag-initiator]::before {
+        font-size: 1.75em;
+        margin: 0;
       }
     }
   }

asset/css/variables.less

@@ -65,6 +65,7 @@
 @search-term-selected-color: @base-gray-light;
 @search-term-highlighted-bg: @base-primary-bg;
 @search-term-highlighted-color: @default-text-color-inverted;
+@search-term-drag-border-color: @base-gray;
 
 @search-condition-remove-bg: @state-critical;
 @search-condition-remove-color: @default-text-color-inverted;
@@ -160,6 +161,7 @@
     --search-term-selected-color: var(--base-gray);
     --search-term-highlighted-bg: var(--primary-button-bg);
     --search-term-highlighted-color: var(--default-text-color-inverted);
+    --search-term-drag-border-color: var(--base-gray);
 
     --search-condition-remove-bg: var(--base-remove-bg);
     --search-condition-remove-color: var(--default-text-color-inverted);

asset/js/widget/TermInput.js

@@ -1,4 +1,4 @@
-define(["../notjQuery", "BaseInput"], function ($, BaseInput) {
+define(["../notjQuery", "../vendor/Sortable", "BaseInput"], function ($, Sortable, BaseInput) {
 
     "use strict";
 
@@ -7,6 +7,7 @@ define(["../notjQuery", "BaseInput"], function ($, BaseInput) {
             super(input);
 
             this.separator = this.input.dataset.termSeparator || ' ';
+            this.ordered = 'maintainTermOrder' in this.input.dataset;
             this.readOnly = 'readOnlyTerms' in this.input.dataset;
             this.ignoreSpaceUntil = null;
         }
@@ -18,6 +19,16 @@ define(["../notjQuery", "BaseInput"], function ($, BaseInput) {
                 $(this.termContainer).on('click', '[data-index] > input', this.onTermClick, this);
             }
 
+            if (this.ordered) {
+                $(this.termContainer).on('end', this.onDrop, this);
+
+                Sortable.create(this.termContainer, {
+                    scroll: true,
+                    direction: 'vertical',
+                    handle: '[data-drag-initiator]'
+                });
+            }
+
             // TODO: Compatibility only. Remove as soon as possible once Web 2.12 (?) is out.
             //       Or upon any other update which lets Web trigger a real submit upon auto submit.
             $(this.input.form).on('change', 'select.autosubmit', this.onSubmit, this);
@@ -131,6 +142,41 @@ define(["../notjQuery", "BaseInput"], function ($, BaseInput) {
             return quoted.join(this.separator).trim();
         }
 
+        addRenderedTerm(label) {
+            if (! this.ordered) {
+                return super.addRenderedTerm(label);
+            }
+
+            const listItem = document.createElement('li');
+            listItem.appendChild(label);
+            listItem.appendChild($.render('<i data-drag-initiator class="icon fa-bars fa"></i>'));
+            this.termContainer.appendChild(listItem);
+        }
+
+        insertRenderedTerm(label) {
+            if (! this.ordered) {
+                return super.insertRenderedTerm(label);
+            }
+
+            const termIndex = Number(label.dataset.index);
+            const nextListItemLabel = this.termContainer.querySelector(`[data-index="${ termIndex + 1 }"]`);
+            const nextListItem = nextListItemLabel?.parentNode || null;
+            const listItem = document.createElement('li');
+            listItem.appendChild(label);
+            listItem.appendChild($.render('<i data-drag-initiator class="icon fa-bars fa"></i>'));
+            this.termContainer.insertBefore(listItem, nextListItem);
+
+            return label;
+        }
+
+        removeRenderedTerm(label) {
+            if (! this.ordered) {
+                return super.removeRenderedTerm(label);
+            }
+
+            label.parentNode.remove();
+        }
+
         complete(input, data) {
             data.exclude = this.usedTerms.map(termData => termData.search);
 
@@ -159,6 +205,30 @@ define(["../notjQuery", "BaseInput"], function ($, BaseInput) {
             this.moveFocusForward(termIndex - 1);
         }
 
+        onDrop(event) {
+            if (event.to === event.from && event.newIndex === event.oldIndex) {
+                // The user dropped the term at its previous position
+                return;
+            }
+
+            // The item is the list item, not the term's label
+            const label = event.item.firstChild;
+
+            // Remove the term from the internal map, but not the DOM, as it's been moved already
+            const termData = this.removeTerm(label, false);
+            delete label.dataset.index; // Which is why we have to take it out of the equation for now
+
+            let newIndex = 0; // event.newIndex is intentionally not used, as we have our own indexing
+            if (event.item.previousSibling) {
+                newIndex = Number(event.item.previousSibling.firstChild.dataset.index) + 1;
+            }
+
+            // This is essentially insertTerm() with custom DOM manipulation
+            this.reIndexTerms(newIndex, 1, true); // Free up the new index
+            this.registerTerm(termData, newIndex); // Re-register the term with the new index
+            label.dataset.index = `${ newIndex }`; // Update the DOM, we didn't do that during removal
+        }
+
         onSubmit(event) {
             super.onSubmit(event);
 

src/FormElement/TermInput.php

@@ -40,6 +40,9 @@ class TermInput extends FieldsetElement
     /** @var bool Whether term direction is vertical */
     protected $verticalTermDirection = false;
 
+    /** @var bool Whether term order is significant */
+    protected $ordered = false;
+
     /** @var bool Whether registered terms are read-only */
     protected $readOnly = false;
 
@@ -103,7 +106,31 @@ public function setVerticalTermDirection(bool $state = true): self
      */
     public function getTermDirection(): ?string
     {
-        return $this->verticalTermDirection ? 'vertical' : null;
+        return $this->verticalTermDirection || $this->ordered ? 'vertical' : null;
+    }
+
+    /**
+     * Set whether term order is significant
+     *
+     * @param bool $state
+     *
+     * @return $this
+     */
+    public function setOrdered(bool $state = true): self
+    {
+        $this->ordered = $state;
+
+        return $this;
+    }
+
+    /**
+     * Get whether term order is significant
+     *
+     * @return bool
+     */
+    public function getOrdered(): bool
+    {
+        return $this->ordered;
     }
 
     /**
@@ -442,6 +469,7 @@ public function getValueAttribute()
             'data-with-multi-completion' => true,
             'data-no-auto-submit-on-remove' => true,
             'data-term-direction' => $this->getTermDirection(),
+            'data-maintain-term-order' => $this->getOrdered() && ! $this->getAttribute('disabled')->getValue(),
             'data-read-only-terms' => $this->getReadOnly(),
             'data-data-input' => '#' . $dataInputId,
             'data-term-input' => '#' . $termInputId,

src/FormElement/TermInput/TermContainer.php

@@ -25,6 +25,10 @@ class TermContainer extends BaseHtmlElement
     public function __construct(TermInput $input)
     {
         $this->input = $input;
+
+        if ($input->getOrdered()) {
+            $this->tag = 'ol';
+        }
     }
 
     protected function assemble()
@@ -58,7 +62,16 @@ protected function assemble()
                 );
             }
 
-            $this->addHtml($label);
+            if ($this->tag === 'ol') {
+                $this->addHtml(new HtmlElement(
+                    'li',
+                    null,
+                    $label,
+                    new Icon('bars', ['data-drag-initiator' => true])
+                ));
+            } else {
+                $this->addHtml($label);
+            }
         }
     }
 }