text-processing-utils/src/errors/error-handler.ts

import { TextProcessingError } from './text-error.js';

export interface ErrorHandlerOptions {
  maxRetries?: number;
  retryDelay?: number;
  exponentialBackoff?: boolean;
  onError?: (error: Error) => void;
  // NO FALLBACKS - fail fast per CLAUDE.md
  throwOnFatal?: boolean;
}

export class ErrorHandler {
  private readonly retryCount = new Map<string, number>();

  constructor(private readonly options: ErrorHandlerOptions = {}) {}

  async handle<T>(operation: () => Promise<T>, context?: string): Promise<T> {
    const maxRetries = this.options.maxRetries || 3;
    const retryKey = context || 'default';

    let lastError: Error | undefined;

    for (let attempt = 0; attempt <= maxRetries; attempt++) {
      try {
        const result = await operation();

        this.retryCount.delete(retryKey);

        return result;
      } catch (error) {
        lastError = error as Error;

        if (this.options.onError) {
          this.options.onError(lastError);
        }

        if (this.isFatalError(lastError)) {
          if (this.options.throwOnFatal !== false) {
            throw lastError;
          }

          break;
        }

        if (attempt < maxRetries) {
          const delay = this.calculateDelay(attempt);

          await this.sleep(delay);
          this.retryCount.set(retryKey, attempt + 1);
        }
      }
    }

    // NO FALLBACKS - fail fast per CLAUDE.md
    throw lastError || new Error('Operation failed');
  }

  handleSync<T>(operation: () => T, _context?: string): T {
    try {
      return operation();
    } catch (error) {
      if (this.options.onError) {
        this.options.onError(error as Error);
      }

      if (this.isFatalError(error as Error) && this.options.throwOnFatal !== false) {
        throw error;
      }

      // NO FALLBACKS - fail fast per CLAUDE.md
      throw error;
    }
  }

  private isFatalError(error: Error): boolean {
    // Determine if error is non-recoverable
    if (error instanceof TextProcessingError) {
      const fatalCodes = ['VALIDATION_ERROR', 'PARSE_ERROR', 'TEMPLATE_ERROR'];

      return fatalCodes.includes(error.code || '');
    }

    // Check for common fatal errors
    return (
      error.name === 'TypeError' || error.name === 'ReferenceError' || error.name === 'SyntaxError'
    );
  }

  private calculateDelay(attempt: number): number {
    const baseDelay = this.options.retryDelay || 1000;

    if (this.options.exponentialBackoff) {
      return baseDelay * Math.pow(2, attempt);
    }

    return baseDelay;
  }

  private sleep(ms: number): Promise<void> {
    return new Promise((resolve) => setTimeout(resolve, ms));
  }

  // eslint-disable-next-line @typescript-eslint/no-explicit-any -- Generic function wrapper requires any
  wrap<T extends (...args: any[]) => any>(fn: T, context?: string): T {
    return ((...args: Parameters<T>) => {
      if (fn.constructor.name === 'AsyncFunction') {
        return this.handle(() => fn(...args), context);
      }

      return this.handleSync(() => fn(...args), context);
    }) as T;
  }

  static createRetryable<T>(fn: () => Promise<T>, options?: ErrorHandlerOptions): () => Promise<T> {
    const handler = new ErrorHandler(options);

    return () => handler.handle(fn);
  }

  // REMOVED withFallback - NO FALLBACKS per CLAUDE.md
  // If operation fails, it should fail fast and loud

  static async withTimeout<T>(
    fn: () => Promise<T>,
    timeout: number,
    timeoutError?: Error,
  ): Promise<T> {
    const timeoutPromise = new Promise<never>((_, reject) => {
      setTimeout(() => {
        reject(timeoutError || new Error(`Operation timed out after ${timeout}ms`));
      }, timeout);
    });

    return Promise.race([fn(), timeoutPromise]);
  }

  getRetryCount(context?: string): number {
    return this.retryCount.get(context || 'default') || 0;
  }

  resetRetryCount(context?: string): void {
    if (context) {
      this.retryCount.delete(context);
    } else {
      this.retryCount.clear();
    }
  }
}

interface ErrorEntry {
  error: Error;
  context?: unknown;
  timestamp: Date;
}

// eslint-disable-next-line @typescript-eslint/no-explicit-any -- Error constructor type requires any
type ErrorConstructor<T extends Error> = new (...args: any[]) => T;

export class ErrorAggregator {
  private errors: ErrorEntry[] = [];

  add(error: Error, context?: unknown): void {
    this.errors.push({
      error,
      context,
      timestamp: new Date(),
    });
  }

  getErrors(): ErrorEntry[] {
    return [...this.errors];
  }

  getErrorsByType<T extends Error>(type: ErrorConstructor<T>): T[] {
    return this.errors.filter((e) => e.error instanceof type).map((e) => e.error as T);
  }

  hasErrors(): boolean {
    return this.errors.length > 0;
  }

  hasErrorType<T extends Error>(type: ErrorConstructor<T>): boolean {
    return this.errors.some((e) => e.error instanceof type);
  }

  clear(): void {
    this.errors = [];
  }

  throwIfErrors(): void {
    if (this.errors.length === 0) {
      return;
    }

    if (this.errors.length === 1) {
      throw this.errors[0].error;
    }

    const aggregateError = new AggregateError(
      this.errors.map((e) => e.error),
      `${this.errors.length} errors occurred`,
    );

    throw aggregateError;
  }

  getSummary(): string {
    const errorCounts = new Map<string, number>();

    for (const { error } of this.errors) {
      const name = error.name || 'Unknown';

      errorCounts.set(name, (errorCounts.get(name) || 0) + 1);
    }

    const summary: string[] = [];

    for (const [name, count] of errorCounts) {
      summary.push(`${name}: ${count}`);
    }

    return summary.join(', ');
  }
}