State Diagrams

// Transition Guards
class TransitionGuards {
  static canRetry(session: ChatSession): boolean {
    return session.retryCount < MAX_RETRIES;
  }
 
  static hasValidAuth(session: ChatSession): boolean {
    return session.user?.isAuthenticated === true;
  }
 
  static hasContext(session: ChatSession): boolean {
    return session.context !== null;
  }
 
  static toolsRequired(message: Message): boolean {
    return message.intent.requiresTools;
  }
}
 
// Transition Actions
class TransitionActions {
  static async onSessionStart(session: ChatSession) {
    session.retryCount = 0;
    await session.loadUserProfile();
    await session.initializeClaude();
  }
 
  static async onMessageReceived(session: ChatSession, message: string) {
    await session.addToHistory(message);
    await session.updateContext();
  }
 
  static async onError(session: ChatSession, error: Error) {
    await session.logError(error);
    await session.notifyUser(error.message);
    session.retryCount++;
  }
}

enum ChatState {
  INACTIVE = 'inactive',
  INITIALIZING = 'initializing',
  ACTIVE = 'active',
  LOADING_CONTEXT = 'loading_context',
  PROCESSING = 'processing',
  TOOL_EXECUTION = 'tool_execution',
  RESPONDING = 'responding',
  IDLE = 'idle',
  ERROR = 'error',
  RECOVERING = 'recovering',
  FAILED = 'failed',
  ENDED = 'ended'
}
 
class ChatSessionStateMachine {
  private state: ChatState = ChatState.INACTIVE;
  private retryCount: number = 0;
  private stateHandlers: Map<ChatState, Function> = new Map();
  private transitionCallbacks: Function[] = [];
 
  constructor(private sessionId: string) {}
 
  registerStateHandler(state: ChatState, handler: Function): void {
    this.stateHandlers.set(state, handler);
  }
 
  async transitionTo(newState: ChatState, event?: string): Promise<void> {
    const oldState = this.state;
 
    // Validate transition
    if (!this.isValidTransition(oldState, newState)) {
      throw new Error(
        `Invalid transition from ${oldState} to ${newState}`
      );
    }
 
    // Execute exit actions
    await this.executeExitActions(oldState);
 
    // Update state
    this.state = newState;
 
    // Execute entry actions
    await this.executeEntryActions(newState);
 
    // Notify callbacks
    for (const callback of this.transitionCallbacks) {
      await callback(oldState, newState, event);
    }
  }
 
  private isValidTransition(from: ChatState, to: ChatState): boolean {
    const validTransitions: Record<ChatState, ChatState[]> = {
      [ChatState.INACTIVE]: [ChatState.INITIALIZING],
      [ChatState.INITIALIZING]: [ChatState.ACTIVE, ChatState.ERROR],
      [ChatState.ACTIVE]: [ChatState.LOADING_CONTEXT, ChatState.IDLE, ChatState.ENDED],
      // ... more transitions
    };
    return validTransitions[from]?.includes(to) ?? false;
  }
}

// app/api/chat/session.ts
const chatSession = new ChatSessionStateMachine('sess_123');
chatSession.registerStateHandler(
  ChatState.PROCESSING,
  handleClaudeProcessing
);
 
await chatSession.transitionTo(ChatState.INITIALIZING)

// Analysis Configuration
const ANALYSIS_CONFIG = {
  cache_ttl: 86400,           // 24 hours
  api_timeout: 5000,          // 5 seconds
  retry_attempts: 3,          // max retries
  retry_delay: 1000,          // 1 second
  score_range: { min: 300, max: 900 },
  bureau_priority: ['equifax', 'transunion'],
  monitoring_interval: 86400000, // 24 hours
};
 
// Credit Factors
enum CreditFactor {
  PAYMENT_HISTORY = 'payment_history',      // 35%
  UTILIZATION = 'credit_utilization',       // 30%
  CREDIT_AGE = 'credit_age',               // 15%
  CREDIT_MIX = 'credit_mix',               // 10%
  NEW_INQUIRIES = 'new_inquiries'          // 10%
}
 
// Improvement Actions
interface ImprovementAction {
  id: string;
  factor: CreditFactor;
  action: string;
  impact: 'high' | 'medium' | 'low';
  timeframe: string;
  difficulty: 'easy' | 'moderate' | 'hard';
}

enum AnalysisState {
  IDLE = 'idle',
  INITIALIZING = 'initializing',
  READY = 'ready',
  FETCHING_SCORE = 'fetching_score',
  CACHE_CHECK = 'cache_check',
  BUREAU_CALL = 'bureau_call',
  SCORE_RETRIEVED = 'score_retrieved',
  FACTOR_ANALYSIS = 'factor_analysis',
  IMPROVEMENT_PLAN = 'improvement_plan',
  RECOMMENDATIONS = 'recommendations',
  COMPLETE = 'complete',
  MONITORING = 'monitoring',
  ERROR = 'error',
  RECOVERY = 'recovery',
  FAILED = 'failed'
}
 
interface AnalysisContext {
  userId: string;
  creditScore?: number;
  factors?: CreditFactorAnalysis;
  plan?: ImprovementPlan;
  recommendations?: Recommendation[];
  errorCount: number;
  cache?: CreditCache;
}
 
class CreditAnalysisStateMachine {
  private state: AnalysisState = AnalysisState.IDLE;
  private context: AnalysisContext;
  private stateHandlers: Map<AnalysisState, Function>;
 
  constructor(userId: string) {
    this.context = {
      userId,
      errorCount: 0
    };
    this.stateHandlers = this.setupHandlers();
  }
 
  async start(): Promise<void> {
    await this.transitionTo(AnalysisState.INITIALIZING);
  }
 
  async analyzeCredit(): Promise<void> {
    if (this.state !== AnalysisState.READY) {
      throw new Error(
        `Cannot analyze in state ${this.state}`
      );
    }
 
    await this.transitionTo(AnalysisState.FETCHING_SCORE);
  }
 
  async transitionTo(newState: AnalysisState): Promise<void> {
    const oldState = this.state;
    this.state = newState;
 
    const handler = this.stateHandlers.get(newState);
    if (handler) {
      try {
        await handler.call(this);
      } catch (error) {
        await this.handleError(error);
      }
    }
  }
 
  private async handleFetchingScore(): Promise<void> {
    // Check cache first
    const cached = await this.context.cache?.get(
      `score:${this.context.userId}`
    );
 
    if (cached) {
      this.context.creditScore = cached.score;
      await this.transitionTo(AnalysisState.SCORE_RETRIEVED);
    } else {
      await this.transitionTo(AnalysisState.BUREAU_CALL);
    }
  }
 
  private async handleFactorAnalysis(): Promise<void> {
    const factors = await analyzeFactors(this.context.creditScore!);
    this.context.factors = factors;
    await this.transitionTo(AnalysisState.IMPROVEMENT_PLAN);
  }
}

// Authentication Configuration
const AUTH_CONFIG = {
  providers: ['email', 'google', 'apple'],
  mfa: {
    enabled: true,
    methods: ['sms', 'totp', 'email']
  },
  session: {
    accessTokenTTL: 3600,      // 1 hour
    refreshTokenTTL: 2592000,  // 30 days
    idleTimeout: 1800,         // 30 minutes
    absoluteTimeout: 86400     // 24 hours
  },
  passwordPolicy: {
    minLength: 12,
    requireUppercase: true,
    requireLowercase: true,
    requireNumbers: true,
    requireSpecialChars: true,
    preventReuse: 5
  }
};
 
// Firebase Auth Integration
interface AuthHandlers {
  async signUp(email: string, password: string): Promise<User> {
    const userCredential = await createUserWithEmailAndPassword(
      auth,
      email,
      password
    );
    await sendEmailVerification(userCredential.user);
    return userCredential.user;
  }
 
  async signIn(email: string, password: string): Promise<User> {
    const userCredential = await signInWithEmailAndPassword(
      auth,
      email,
      password
    );
    
    // Check if MFA is required
    if (userCredential.user.multiFactor.enrolledFactors.length > 0) {
      // Trigger MFA flow
      return this.requireMFA(userCredential.user);
    }
    
    return userCredential.user;
  }
 
  async refreshSession(refreshToken: string): Promise<string> {
    const response = await fetch('/api/auth/refresh', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ refreshToken })
    });
    
    if (!response.ok) {
      throw new Error('Session refresh failed');
    }
    
    const { accessToken } = await response.json();
    return accessToken;
  }
}

enum AuthState {
  UNAUTHENTICATED = 'unauthenticated',
  SIGNING_UP = 'signing_up',
  VERIFYING = 'verifying',
  PROFILE_SETUP = 'profile_setup',
  CREDIT_CONSENT = 'credit_consent',
  LOGGING_IN = 'logging_in',
  MFA_REQUIRED = 'mfa_required',
  AUTHENTICATED = 'authenticated',
  SESSION_ACTIVE = 'session_active',
  SESSION_REFRESH = 'session_refresh',
  LOGGING_OUT = 'logging_out'
}
 
interface AuthContext {
  user?: User;
  session?: Session;
  mfaChallenge?: MFAChallenge;
  errorCount: number;
  lastActivity: Date;
}
 
class AuthenticationStateMachine {
  private state: AuthState = AuthState.UNAUTHENTICATED;
  private context: AuthContext = { errorCount: 0, lastActivity: new Date() };
  private stateHandlers: Map<AuthState, Function>;
  private firebase: Auth;
 
  constructor() {
    this.firebase = getAuth();
    this.stateHandlers = this.setupHandlers();
    this.monitorSession();
  }
 
  async signUp(email: string, password: string): Promise<void> {
    if (this.state !== AuthState.UNAUTHENTICATED) {
      throw new Error('Already authenticated');
    }
 
    await this.transitionTo(AuthState.SIGNING_UP);
    
    try {
      const userCredential = await createUserWithEmailAndPassword(
        this.firebase,
        email,
        password
      );
      
      this.context.user = userCredential.user;
      await sendEmailVerification(userCredential.user);
      await this.transitionTo(AuthState.VERIFYING);
    } catch (error) {
      await this.handleAuthError(error);
    }
  }
 
  async signIn(email: string, password: string): Promise<void> {
    await this.transitionTo(AuthState.LOGGING_IN);
    
    try {
      const userCredential = await signInWithEmailAndPassword(
        this.firebase,
        email,
        password
      );
      
      if (userCredential.user.multiFactor.enrolledFactors.length > 0) {
        await this.transitionTo(AuthState.MFA_REQUIRED);
      } else {
        await this.createSession(userCredential.user);
      }
    } catch (error) {
      await this.handleAuthError(error);
    }
  }
 
  private async createSession(user: User): Promise<void> {
    const idToken = await user.getIdToken();
    
    const response = await fetch('/api/auth/session', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ idToken })
    });
    
    if (response.ok) {
      const session = await response.json();
      this.context.session = session;
      await this.transitionTo(AuthState.AUTHENTICATED);
      await this.transitionTo(AuthState.SESSION_ACTIVE);
    } else {
      throw new Error('Session creation failed');
    }
  }
 
  private monitorSession(): void {
    setInterval(async () => {
      if (this.state === AuthState.SESSION_ACTIVE) {
        const now = Date.now();
        const sessionAge = now - this.context.session!.createdAt;
        const idleTime = now - this.context.lastActivity.getTime();
        
        if (idleTime > AUTH_CONFIG.session.idleTimeout * 1000) {
          await this.signOut();
        } else if (sessionAge > AUTH_CONFIG.session.accessTokenTTL * 900) {
          await this.transitionTo(AuthState.SESSION_REFRESH);
        }
      }
    }, 60000); // Check every minute
  }
}