From b565eb72c1ca8ec647b85e5e42159c7d4f6ea4fb Mon Sep 17 00:00:00 2001
From: Anders Mikkelsen <andersgm@outlook.dk>
Date: Mon, 6 Feb 2023 09:18:15 +0100
Subject: [PATCH] warning on undefined controller or action

---
 src/core/application.ts                               |  7 +++++++
 src/core/binding_observer.ts                          |  8 ++++++++
 src/core/context.ts                                   |  6 ++++++
 src/core/router.ts                                    | 11 +++++++++--
 src/mutation-observers/value_list_observer.ts         |  5 ++++-
 .../mutation-observers/value_list_observer_tests.ts   |  4 ++++
 6 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/src/core/application.ts b/src/core/application.ts
index b8b92715..3831d03b 100644
--- a/src/core/application.ts
+++ b/src/core/application.ts
@@ -15,6 +15,7 @@ export class Application implements ErrorHandler {
   readonly actionDescriptorFilters: ActionDescriptorFilters
   logger: Logger = console
   debug = false
+  warnings = true
 
   static start(element?: Element, schema?: Schema): Application {
     const application = new this(element, schema)
@@ -90,6 +91,12 @@ export class Application implements ErrorHandler {
     window.onerror?.(message, "", 0, 0, error)
   }
 
+  handleWarning(warning: string, message: string, detail: object) {
+    if (this.warnings) {
+      this.logger.warn(`%s\n\n%s\n\n%o`, message, warning, detail)
+    }
+  }
+
   // Debug logging
 
   logDebugActivity = (identifier: string, functionName: string, detail: object = {}): void => {
diff --git a/src/core/binding_observer.ts b/src/core/binding_observer.ts
index 62cc8355..32b77006 100644
--- a/src/core/binding_observer.ts
+++ b/src/core/binding_observer.ts
@@ -92,4 +92,12 @@ export class BindingObserver implements ValueListObserverDelegate<Action> {
   elementUnmatchedValue(element: Element, action: Action) {
     this.disconnectAction(action)
   }
+
+  elementMatchedNoValue(element: Element, token: Token) {
+    this.context.handleWarning(
+      `Element references undefined action ${token.content}`,
+      `Warning connecting action ${token.content}`,
+      { element, action: token.content }
+    )
+  }
 }
diff --git a/src/core/context.ts b/src/core/context.ts
index e1187add..3a17f087 100644
--- a/src/core/context.ts
+++ b/src/core/context.ts
@@ -101,6 +101,12 @@ export class Context implements ErrorHandler, TargetObserverDelegate, OutletObse
     this.application.handleError(error, `Error ${message}`, detail)
   }
 
+  handleWarning(warning: string, message: string, detail: object = {}) {
+    const { identifier, controller, element } = this
+    detail = Object.assign({ identifier, controller, element }, detail)
+    this.application.handleWarning(warning, `Warning ${message}`, detail)
+  }
+
   // Debug logging
 
   logDebugActivity = (functionName: string, detail: object = {}): void => {
diff --git a/src/core/router.ts b/src/core/router.ts
index c06e5e57..a4bda3c4 100644
--- a/src/core/router.ts
+++ b/src/core/router.ts
@@ -88,10 +88,17 @@ export class Router implements ScopeObserverDelegate {
   }
 
   scopeConnected(scope: Scope) {
-    this.scopesByIdentifier.add(scope.identifier, scope)
-    const module = this.modulesByIdentifier.get(scope.identifier)
+    const { element, identifier } = scope
+    this.scopesByIdentifier.add(identifier, scope)
+    const module = this.modulesByIdentifier.get(identifier)
     if (module) {
       module.connectContextForScope(scope)
+    } else {
+      this.application.handleWarning(
+        `Element references undefined controller ${identifier}`,
+        `Warning connecting controller ${identifier}`,
+        { identifier, element }
+      )
     }
   }
 
diff --git a/src/mutation-observers/value_list_observer.ts b/src/mutation-observers/value_list_observer.ts
index 35cd214a..8d986bb4 100644
--- a/src/mutation-observers/value_list_observer.ts
+++ b/src/mutation-observers/value_list_observer.ts
@@ -3,6 +3,7 @@ import { Token, TokenListObserver, TokenListObserverDelegate } from "./token_lis
 export interface ValueListObserverDelegate<T> {
   parseValueForToken(token: Token): T | undefined
   elementMatchedValue(element: Element, value: T): void
+  elementMatchedNoValue(element: Element, token: Token): void
   elementUnmatchedValue(element: Element, value: T): void
 }
 
@@ -50,10 +51,12 @@ export class ValueListObserver<T> implements TokenListObserverDelegate {
 
   tokenMatched(token: Token) {
     const { element } = token
-    const { value } = this.fetchParseResultForToken(token)
+    const { error, value } = this.fetchParseResultForToken(token)
     if (value) {
       this.fetchValuesByTokenForElement(element).set(token, value)
       this.delegate.elementMatchedValue(element, value)
+    } else if (error) {
+      this.delegate.elementMatchedNoValue(element, token)
     }
   }
 
diff --git a/src/tests/modules/mutation-observers/value_list_observer_tests.ts b/src/tests/modules/mutation-observers/value_list_observer_tests.ts
index 1a4b1517..11295196 100644
--- a/src/tests/modules/mutation-observers/value_list_observer_tests.ts
+++ b/src/tests/modules/mutation-observers/value_list_observer_tests.ts
@@ -100,4 +100,8 @@ export default class ValueListObserverTests extends ObserverTestCase implements
   elementUnmatchedValue(element: Element, value: Value) {
     this.recordCall("elementUnmatchedValue", element, value.id, value.token.content)
   }
+
+  elementMatchedNoValue(element: Element, token: Token) {
+    this.recordCall("elementMatchedNoValue", element, token)
+  }
 }