From 6a9f8d3e382682835a7dca8429b78cdef3bbe0d6 Mon Sep 17 00:00:00 2001
From: Ishan Taldekar <taldekar@amazon.com>
Date: Tue, 28 Jan 2025 14:29:16 -0500
Subject: [PATCH] Add ViewRouter POC

---
 .../eclipse/amazonq/views/router/ViewId.java  |  9 ++
 .../amazonq/views/router/ViewRouter.java      | 87 +++++++++++++++++++
 2 files changed, 96 insertions(+)
 create mode 100644 plugin/src/software/aws/toolkits/eclipse/amazonq/views/router/ViewId.java
 create mode 100644 plugin/src/software/aws/toolkits/eclipse/amazonq/views/router/ViewRouter.java

diff --git a/plugin/src/software/aws/toolkits/eclipse/amazonq/views/router/ViewId.java b/plugin/src/software/aws/toolkits/eclipse/amazonq/views/router/ViewId.java
new file mode 100644
index 00000000..8ff6272e
--- /dev/null
+++ b/plugin/src/software/aws/toolkits/eclipse/amazonq/views/router/ViewId.java
@@ -0,0 +1,9 @@
+// Copyright 2024 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package software.aws.toolkits.eclipse.amazonq.views.router;
+
+public enum ViewId {
+    TOOLKIT_LOGIN_VIEW, CHAT_VIEW, DEPENDENCY_MISSING_VIEW, RE_AUTHENTICATE_VIEW, CHAT_ASSET_MISSING_VIEW,
+    CODE_REFERENCE_VIEW, LSP_STARTUP_FAILED_VIEW, LSP_INITIALIZING_VIEW
+}
diff --git a/plugin/src/software/aws/toolkits/eclipse/amazonq/views/router/ViewRouter.java b/plugin/src/software/aws/toolkits/eclipse/amazonq/views/router/ViewRouter.java
new file mode 100644
index 00000000..289b7f0e
--- /dev/null
+++ b/plugin/src/software/aws/toolkits/eclipse/amazonq/views/router/ViewRouter.java
@@ -0,0 +1,87 @@
+// Copyright 2024 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package software.aws.toolkits.eclipse.amazonq.views.router;
+
+import software.aws.toolkits.eclipse.amazonq.broker.api.EventObserver;
+import software.aws.toolkits.eclipse.amazonq.lsp.auth.model.AuthState;
+import software.aws.toolkits.eclipse.amazonq.lsp.manager.LspState;
+import software.aws.toolkits.eclipse.amazonq.plugin.Activator;
+
+public final class ViewRouter {
+
+    private final EventObserver<AuthState> authStateObserver = new EventObserver<>() {
+        @Override
+        public void onEvent(final AuthState newAuthState) {
+            authState = newAuthState;
+            refreshActiveView();
+        }
+    };
+
+    private final EventObserver<LspState> lspStateObserver = new EventObserver<>() {
+        @Override
+        public void onEvent(final LspState newLspState) {
+            lspState = newLspState;
+            refreshActiveView();
+        }
+    };
+
+    private ViewId activeViewId;
+    
+    // this state needs to be maintained to ensure correct resolution in refreshActiveView
+    private LspState lspState;
+    private AuthState authState;
+
+    public ViewRouter() {
+        activeViewId = ViewId.TOOLKIT_LOGIN_VIEW;
+        lspState = null;
+        authState = null;
+
+        Activator.getEventBroker().subscribe(AuthState.class, authStateObserver);
+        Activator.getEventBroker().subscribe(LspState.class, lspStateObserver);
+    }
+
+    private void refreshActiveView() {
+        ViewId newActiveViewId = ViewId.TOOLKIT_LOGIN_VIEW;
+
+        if (isDependencyMissing()) { // TODO: dependency missing check logic needs to be implemented
+            newActiveViewId = ViewId.DEPENDENCY_MISSING_VIEW;
+        } else if (lspState != null) {
+            if (lspState == LspState.FAILED) {
+                newActiveViewId = ViewId.LSP_STARTUP_FAILED_VIEW;
+            } else if (lspState == LspState.PENDING) {
+                newActiveViewId = ViewId.LSP_INITIALIZING_VIEW;
+            }
+        } else if (isChatUIAssetMissing()) { // TODO: chat missing logic needs to be implemented
+            newActiveViewId = ViewId.CHAT_ASSET_MISSING_VIEW;
+        } else if (authState != null) {
+            if (authState.isLoggedOut()) {
+                newActiveViewId = ViewId.TOOLKIT_LOGIN_VIEW;
+            } else if (authState.isExpired()) {
+                newActiveViewId = ViewId.RE_AUTHENTICATE_VIEW;
+            }
+        } else {
+            newActiveViewId = ViewId.CHAT_VIEW;
+        }
+
+        if (activeViewId != newActiveViewId) {
+            activeViewId = newActiveViewId;
+            notifyActiveViewChange();
+        }
+    }
+
+    private void notifyActiveViewChange() {
+        Activator.getEventBroker().post(activeViewId);
+    }
+
+    // TODO: replace with relevant checks
+    private boolean isDependencyMissing() {
+        return false;
+    }
+
+    // TODO: replace with relevant checks
+    private boolean isChatUIAssetMissing() {
+        return false;
+    }
+
+}