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/** * BaseThemeService * * DESIGN PATTERNS: * - Abstract base class for theme listing services * - Template method pattern for extensible theme extraction * - Strategy pattern allowing different theme source implementations * * CODING STANDARDS: * - Abstract classes define interface contracts for subclasses * - Protected methods allow subclass customization * - Use async/await for all I/O operations * - Throw descriptive errors with context * * AVOID: * - Direct instantiation of abstract class * - Source-specific logic in base class * - Synchronous file operations */ import { promises as fs } from 'node:fs'; import type { AvailableThemesResult, ThemeServiceConfig } from './types'; /** * Abstract base class for theme listing services. * * Subclasses must implement the `listThemes` method to provide * source-specific theme extraction logic (CSS files, JSON configs, etc.). * * @example * ```typescript * class MyCustomThemeService extends BaseThemeService { * async listThemes(): Promise<AvailableThemesResult> { * // Custom theme extraction logic * } * } * ``` */ export abstract class BaseThemeService { protected config: ThemeServiceConfig; /** * Creates a new theme service instance * @param config - Theme service configuration */ constructor(config: ThemeServiceConfig) { this.config = config; } /** * List available themes from the configured source. * * Subclasses must implement this method to provide source-specific * theme extraction logic (e.g., CSS class selectors, JSON files). * * @returns Promise resolving to available themes result * @throws Error if themes cannot be loaded */ abstract listThemes(): Promise<AvailableThemesResult>; /** * Get the source identifier for this service * @returns Source identifier string (e.g., 'css-file', 'json-config', 'custom') */ abstract getSourceId(): 'css-file' | 'json-config' | 'custom'; /** * Validate that a file path exists and is readable. * Can be overridden by subclasses for custom validation. * * @param filePath - Path to validate * @throws Error if path is invalid or unreadable */ protected async validatePath(filePath: string): Promise<void> { try { await fs.access(filePath); } catch { throw new Error(`File not found or not readable: ${filePath}`); } } }