Implement tagjoin events

ts/editor/Tag.svelte

@@ -44,6 +44,8 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
         on:focusout={() => (active = false)}
         on:tagupdate={updateTag}
         on:tagadd
+        on:tagjoinprevious
+        on:tagjoinnext
         on:mount={(event) => event.detail.input.focus()}
     />
 {:else}

ts/editor/TagEditor.svelte

@@ -45,6 +45,26 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
         tags = tags;
     }
 
+    function joinWithPreviousTag(index: number): void {
+        if (index === 0) {
+            return;
+        }
+
+        const spliced = tags.splice(index - 1, 1)[0];
+        tags[index - 1].name = spliced.name + tags[index - 1].name;
+        tags = tags;
+    }
+
+    function joinWithNextTag(index: number): void {
+        if (index === tags.length - 1) {
+            return;
+        }
+
+        const spliced = tags.splice(index + 1, 1)[0];
+        tags[index].name = tags[index].name + spliced.name;
+        tags = tags;
+    }
+
     function appendTag(): void {
         const names = tags.map(getName);
         if (!names.includes(newName) && newName.length > 0) {
@@ -54,6 +74,15 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
         newName = "";
     }
+
+    function joinWithLastTag(): void {
+        const popped = tags.pop();
+        tags = tags;
+
+        if (popped) {
+            newName = popped.name + newName;
+        }
+    }
 </script>
 
 <StickyBottom>
@@ -66,6 +95,8 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
                 on:tagupdate={() => checkForDuplicateAt(index)}
                 on:tagadd={() => insertTagAt(index)}
                 on:tagdelete={() => deleteTagAt(index)}
+                on:tagjoinprevious={() => joinWithPreviousTag(index)}
+                on:tagjoinnext={() => joinWithNextTag(index)}
             />
         {/each}
 
@@ -74,6 +105,7 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
             bind:name={newName}
             on:tagupdate={appendTag}
             on:tagadd={appendTag}
+            on:tagjoinprevious={joinWithLastTag}
         />
     </div>
 </StickyBottom>

ts/editor/TagInput.svelte

@@ -27,13 +27,37 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
         /* dropdown.hide(); */
     }
 
+    function onBackspace(event: KeyboardEvent) {
+        if (input.selectionStart === 0 && input.selectionEnd === 0) {
+            dispatch("tagjoinprevious");
+            event.preventDefault();
+        } else if (name.endsWith("::")) {
+            name = name.slice(0, -2);
+            event.preventDefault();
+        }
+    }
+
+    function onDelete(event: KeyboardEvent) {
+        if (
+            input.selectionStart === input.value.length &&
+            input.selectionEnd === input.value.length
+        ) {
+            dispatch("tagjoinnext");
+            event.preventDefault();
+        } else if (name.endsWith("::")) {
+            name = name.slice(0, -2);
+            event.preventDefault();
+        }
+    }
+
     function onKeydown(event: KeyboardEvent): void {
         if (event.code === "Space") {
             name += "::";
             event.preventDefault();
-        } else if (event.code === "Backspace" && name.endsWith("::")) {
-            name = name.slice(0, -2);
-            event.preventDefault();
+        } else if (event.code === "Backspace") {
+            onBackspace(event);
+        } else if (event.code === "Delete") {
+            onDelete(event);
         } else if (event.code === "Enter") {
             onAccept();
             event.preventDefault();