REFACTOR: Support bundling our admin section as an ember addon

app/assets/javascripts/admin/addon/controllers/admin-customize-themes-edit.js

@@ -0,0 +1,68 @@
+import I18n from "I18n";
+import Controller from "@ember/controller";
+import { url } from "discourse/lib/computed";
+import discourseComputed from "discourse-common/utils/decorators";
+
+export default Controller.extend({
+  section: null,
+  currentTarget: 0,
+  maximized: false,
+  previewUrl: url("model.id", "/admin/themes/%@/preview"),
+  showAdvanced: false,
+  editRouteName: "adminCustomizeThemes.edit",
+  showRouteName: "adminCustomizeThemes.show",
+
+  setTargetName: function (name) {
+    const target = this.get("model.targets").find((t) => t.name === name);
+    this.set("currentTarget", target && target.id);
+  },
+
+  @discourseComputed("currentTarget")
+  currentTargetName(id) {
+    const target = this.get("model.targets").find(
+      (t) => t.id === parseInt(id, 10)
+    );
+    return target && target.name;
+  },
+
+  @discourseComputed("model.isSaving")
+  saveButtonText(isSaving) {
+    return isSaving ? I18n.t("saving") : I18n.t("admin.customize.save");
+  },
+
+  @discourseComputed("model.changed", "model.isSaving")
+  saveDisabled(changed, isSaving) {
+    return !changed || isSaving;
+  },
+
+  actions: {
+    save() {
+      this.set("saving", true);
+      this.model.saveChanges("theme_fields").finally(() => {
+        this.set("saving", false);
+      });
+    },
+
+    fieldAdded(target, name) {
+      this.replaceRoute(this.editRouteName, this.get("model.id"), target, name);
+    },
+
+    onlyOverriddenChanged(onlyShowOverridden) {
+      if (onlyShowOverridden) {
+        if (!this.model.hasEdited(this.currentTargetName, this.fieldName)) {
+          let firstTarget = this.get("model.targets").find((t) => t.edited);
+          let firstField = this.get(`model.fields.${firstTarget.name}`).find(
+            (f) => f.edited
+          );
+
+          this.replaceRoute(
+            this.editRouteName,
+            this.get("model.id"),
+            firstTarget.name,
+            firstField.name
+          );
+        }
+      }
+    },
+  },
+});