import type { IFormatter, FormatterError, OutputFormat } from '../../interfaces/formatter.interface.js';
import type { FeedItem } from '../../interfaces/feed.types.js';
import { TerminalFormatter } from './terminal.formatter.js';
import { JsonFormatter } from './json.formatter.js';

export class Formatter implements IFormatter {
  private terminalFormatter: TerminalFormatter;
  private jsonFormatter: JsonFormatter;

  constructor() {
    this.terminalFormatter = new TerminalFormatter();
    this.jsonFormatter = new JsonFormatter();
  }

  async format(items: FeedItem[], format: OutputFormat): Promise<string> {
    try {
      switch (format) {
        case 'terminal':
          return this.terminalFormatter.format(items);
        case 'json':
          return this.jsonFormatter.format(items);
        case 'html':
          // HTML not implemented yet per requirements
          throw this.createError('UNKNOWN', 'HTML format not implemented');
        default:
          throw this.createError('SERIALIZE_ERROR', `Unknown format: ${format}`);
      }
    } catch (error) {
      if (this.isFormatterError(error)) {
        throw error;
      }
      throw this.createError('UNKNOWN', error instanceof Error ? error.message : 'Unknown error during formatting');
    }
  }

  private createError(code: FormatterError['code'], message: string): FormatterError {
    return { code, message };
  }

  private isFormatterError(error: unknown): error is FormatterError {
    return (
      typeof error === 'object' &&
      error !== null &&
      'code' in error &&
      'message' in error &&
      (error as FormatterError).code !== undefined
    );
  }
}