refactor: add composable for core ICIJ/datashare#1528

src/composables/core.js

@@ -0,0 +1,26 @@
+import { getCurrentInstance } from 'vue'
+
+export function useCore() {
+  // `getCurrentInstance` is a Vue Composition API function that gives us access to the current component instance.
+  // This is essential because we need the instance to access global properties like `$core` and `$toast`.
+  const instance = getCurrentInstance()
+
+  // If `getCurrentInstance` is called outside of a Vue component setup function, it will return `null`.
+  // In this case, we throw an error to alert the developer that `useCore` should only be used inside a setup function.
+  if (!instance) {
+    throw new Error('useCore must be called within a Vue component setup function.')
+  }
+
+  // The `instance` object has a `proxy` property, which is the component's public instance.
+  // This `proxy` allows us to access properties like `$core` and `$toast` that are globally provided by the "core" plugin.
+  const { proxy } = instance
+
+  // We return an object with the global `$core` and `$toast` properties.
+  // These properties can then be destructured and used in any component that calls `useCore`.
+  return {
+    // `proxy.$core` gives us access to the global `$core` object provided by the "core" plugin.
+    core: proxy.$core,
+    // `proxy.$toast` gives us access to the global `$toast` object provided by the "core" plugin.
+    toast: proxy.$toast
+  }
+}