import { writeFileSync, existsSync } from 'fs';
import { join } from 'path';
import logger from './logger.js';
import config from './config.js';

/**
 * Generates the runtime configuration file (env.js) for the frontend
 * This allows the frontend to receive runtime configuration without rebuilding
 */
export function generateRuntimeConfig(
  frontendPath: string,
  basePath: string
): void {
  try {
    // In dev mode, write to public/env.js (source)
    // In production, write to env.js (dist)
    const isDev = process.env.NODE_ENV !== 'production';
    const envJsPath = isDev
      ? join(frontendPath, 'public', 'env.js')
      : join(frontendPath, 'env.js');

    // Check if frontend directory exists
    if (!existsSync(frontendPath)) {
      logger.warn(
        'Frontend directory not found, skipping runtime config generation',
        {
          frontendPath,
        }
      );
      return;
    }

    // Generate env.js content
    const envConfig = {
      basePath: basePath || '/',
      FRONTEND_API_KEY: config.apiKeys.frontend,
    };

    // eslint-disable-next-line @typescript-eslint/no-unused-vars
    const envJsContent = `// Runtime configuration generated at container startup
// DO NOT EDIT - This file is automatically generated
// eslint-disable-next-line no-undef
window.env = ${JSON.stringify(envConfig, null, 2)};
`;

    // Write env.js file
    writeFileSync(envJsPath, envJsContent, 'utf8');

    logger.info('Runtime configuration generated successfully', {
      envJsPath,
      config: envConfig,
    });
  } catch (error) {
    logger.error('Failed to generate runtime configuration', error as Error, {
      frontendPath,
      basePath,
    });
    // Don't throw - allow server to start even if config generation fails
  }
}