feat: support onRedirect hook (#185)

Co-authored-by: Paul Gascou <paul.gascvail@gmail.com>

Author: pooya parsa

docs/api/auth.md

@@ -124,3 +124,16 @@ export default function({ app }) {
   })
 }
 ```
+
+### `onRedirect(handler)`
+
+ Pre-process URLs before redirect: (`plugins/auth.js`)
+
+ ```js
+export default function({ app }) {
+  app.$auth.onRedirect((to, from) => {
+    console.error(to)
+    // you can optionally change `to` by returning a new value
+  })
+}
+```

lib/core/auth.js

@@ -14,6 +14,9 @@ export default class Auth {
     // Error listeners
     this._errorListeners = []
 
+    // Redirect listeners
+    this._redirectListeners = []
+
     // Storage & State
     options.initialState = { user: null, loggedIn: false }
     const storage = new Storage(ctx, options)
@@ -352,6 +355,9 @@ export default class Auth {
       }
     }
 
+    // Call onRedirect hook
+    to = this.callOnRedirect(to, from) || to
+
     // Prevent infinity redirects
     if (isSameURL(to, from)) {
       return
@@ -368,6 +374,17 @@ export default class Auth {
     }
   }
 
+  onRedirect (listener) {
+    this._redirectListeners.push(listener)
+  }
+
+  callOnRedirect (to, from) {
+    for (const fn of this._redirectListeners) {
+      to = fn(to, from) || to
+    }
+    return to
+  }
+
   hasScope (scope) {
     const userScopes = this.$state.user && getProp(this.$state.user, this.options.scopeKey)