website refactor

apps/website/lib/auth/LoginFlowController.ts

@@ -0,0 +1,76 @@
+/**
+ * Login Flow Controller
+ * 
+ * Deterministic state machine for authentication flow.
+ * Compliant with docs/architecture/website/LOGIN_FLOW_STATE_MACHINE.md
+ */
+
+import type { SessionViewModel } from '@/lib/view-models/SessionViewModel';
+
+export enum LoginState {
+  UNAUTHENTICATED = "UNAUTHENTICATED",
+  AUTHENTICATED_WITH_PERMISSIONS = "AUTHENTICATED_WITH_PERMISSIONS", 
+  AUTHENTICATED_WITHOUT_PERMISSIONS = "AUTHENTICATED_WITHOUT_PERMISSIONS",
+  POST_AUTH_REDIRECT = "POST_AUTH_REDIRECT"
+}
+
+export type LoginAction = 
+  | { type: 'SHOW_LOGIN_FORM' }
+  | { type: 'REDIRECT'; path: string }
+  | { type: 'SHOW_PERMISSION_ERROR' };
+
+/**
+ * LoginFlowController - Immutable, deterministic state machine
+ * 
+ * Rules:
+ * - Constructed from explicit inputs only
+ * - No side effects
+ * - Pure functions for state transitions
+ * - Side effects (routing) executed outside
+ */
+export class LoginFlowController {
+  // Immutable state
+  private readonly session: SessionViewModel | null;
+  private readonly returnTo: string;
+  
+  // State machine
+  private state: LoginState;
+
+  constructor(session: SessionViewModel | null, returnTo: string) {
+    this.session = session;
+    this.returnTo = returnTo;
+    this.state = this.determineInitialState();
+  }
+
+  private determineInitialState(): LoginState {
+    if (!this.session) return LoginState.UNAUTHENTICATED;
+    if (this.returnTo === '/dashboard') return LoginState.AUTHENTICATED_WITH_PERMISSIONS;
+    return LoginState.AUTHENTICATED_WITHOUT_PERMISSIONS;
+  }
+
+  // Pure function - no side effects
+  getState(): LoginState {
+    return this.state;
+  }
+
+  // Pure function - returns action, does not execute
+  getNextAction(): LoginAction {
+    switch (this.state) {
+      case LoginState.UNAUTHENTICATED:
+        return { type: 'SHOW_LOGIN_FORM' };
+      case LoginState.AUTHENTICATED_WITH_PERMISSIONS:
+        return { type: 'REDIRECT', path: '/dashboard' };
+      case LoginState.AUTHENTICATED_WITHOUT_PERMISSIONS:
+        return { type: 'SHOW_PERMISSION_ERROR' };
+      case LoginState.POST_AUTH_REDIRECT:
+        return { type: 'REDIRECT', path: this.returnTo };
+    }
+  }
+
+  // Transition called after authentication
+  transitionToPostAuth(): void {
+    if (this.session) {
+      this.state = LoginState.POST_AUTH_REDIRECT;
+    }
+  }
+}