// src/config/config-loader.ts
// Loads config from .codewave.config.json - never prompts, requires config file

import fs from 'fs';
import path from 'path';
import { DEFAULT_CONFIG } from './default-config';
import { AppConfig } from './config.interface';

/**
 * Load configuration from file
 * @param configPath Optional path to config file (defaults to .codewave.config.json in cwd)
 * @returns Merged configuration (file + defaults)
 */
export function loadConfig(configPath?: string): AppConfig | null {
  const resolvedPath = configPath || path.resolve(process.cwd(), '.codewave.config.json');

  // Check if config file exists
  if (!fs.existsSync(resolvedPath)) {
    return null; // Config not found - caller should handle
  }

  try {
    const fileContent = fs.readFileSync(resolvedPath, 'utf-8');
    const userConfig: Partial<AppConfig> = JSON.parse(fileContent);

    // Deep merge with defaults
    const merged: AppConfig = {
      apiKeys: { ...DEFAULT_CONFIG.apiKeys, ...(userConfig.apiKeys || {}) },
      llm: { ...DEFAULT_CONFIG.llm, ...(userConfig.llm || {}) },
      agents: { ...DEFAULT_CONFIG.agents, ...(userConfig.agents || {}) },
      output: { ...DEFAULT_CONFIG.output, ...(userConfig.output || {}) },
      tracing: { ...DEFAULT_CONFIG.tracing, ...(userConfig.tracing || {}) },
    };

    return merged;
  } catch (err) {
    throw new Error(
      `Failed to parse config file at ${resolvedPath}: ${err instanceof Error ? err.message : String(err)}`
    );
  }
}

/**
 * Check if config file exists
 */
export function configExists(configPath?: string): boolean {
  const resolvedPath = configPath || path.resolve(process.cwd(), '.codewave.config.json');
  return fs.existsSync(resolvedPath);
}