Change sequence renumbering behaviour.

By default, change just the number of the sequence
being edited. It is checked for conflict with other
planned sequences but not with anything already acquired.

If the user ticks the ‘shift all’ checkbox, then all
planned sequences are shifted by the same amount.

lib/www/client/source/src/views/Plan.vue

@@ -58,6 +58,11 @@
                   single-line
                 >
                 </v-text-field>
+                <v-checkbox
+                  v-model="shiftAll"
+                  class="mt-0"
+                  label="Shift all planned sequences"
+                ></v-checkbox>
               </template>
             </v-edit-dialog>
           </template>
@@ -320,6 +325,7 @@ export default {
       queuedReload: false,
 
       plannerConfig: null,
+      shiftAll: false, // Shift all sequences checkbox
       
       // Context menu stuff
       contextMenuShow: false,
@@ -355,7 +361,11 @@ export default {
             await this.shiftTimesAfter(item, delta);
             await this.saveItem({sequence: item.sequence, key: 'ts1', value: ts1});
           } else if (oldVal.key == "sequence") {
-            await this.shiftSequences(oldVal.value-item.sequence);
+            if (this.shiftAll) {
+              await this.shiftSequences(oldVal.value-item.sequence);
+            } else {
+              await this.shiftSequence(item, oldVal.value);
+            }
           } else if (item[oldVal.key] != oldVal.value) {
             if (await this.saveItem(oldVal)) {
               item[oldVal.key] = oldVal.value;
@@ -449,6 +459,38 @@ export default {
       }
     },
 
+    async shiftSequence (item, newSequence) {
+
+      if (item.sequence == newSequence) {
+        // Nothing to do
+        return;
+      }
+
+      const conflict = this.items.find(i => i.sequence == newSequence)
+      if (conflict) {
+        this.showSnack([`Sequence ${newSequence} already exists`, "error"]);
+      } else {
+        // Cannot do this check at the moment as we would have to load the list of sequences.
+        // TODO We will do this after refactoring.
+        /*
+        if (this.sequences.find(i => i.sequence == newSequence)) {
+          this.showSnack([`Sequence ${newSequence} conflicts with a line that's already been acquired`, "warning"]);
+        }
+        */
+
+        const url = `/project/${this.$route.params.project}/plan/${item.sequence}`;
+        const init = {
+          method: "PATCH",
+          headers: {"Content-Type": "application/json"},
+          body: {
+            sequence: newSequence,
+            name: null
+          } // Setting name to null causes it to be regenerated
+        }
+        await this.api([url, init]);
+      }
+    },
+
     async shiftTimesAfter(item, delta) {
       const pos = this.items.indexOf(item)+1;
       if (pos != 0) {
@@ -546,7 +588,7 @@ export default {
         : item;
     },
 
-    ...mapActions(["api"])
+    ...mapActions(["api", "showSnack"])
   },
 
   async mounted () {