import { readFileSync } from 'fs';
import { parse } from 'yaml';
import { configSchema, type Config } from './schema.js';

function expandEnvVars(value: string): string {
  return value.replace(/\$\{([^}]+)\}/g, (_, envVar) => {
    const envValue = process.env[envVar];
    if (envValue === undefined) {
      throw new Error(`Environment variable ${envVar} is not set`);
    }
    return envValue;
  });
}

function expandEnvVarsInObject(obj: unknown): unknown {
  if (typeof obj === 'string') {
    return expandEnvVars(obj);
  }
  if (Array.isArray(obj)) {
    return obj.map(expandEnvVarsInObject);
  }
  if (obj !== null && typeof obj === 'object') {
    const result: Record<string, unknown> = {};
    for (const [key, value] of Object.entries(obj)) {
      result[key] = expandEnvVarsInObject(value);
    }
    return result;
  }
  return obj;
}

export function loadConfig(configPath: string): Config {
  const rawContent = readFileSync(configPath, 'utf-8');
  const rawConfig = parse(rawContent);
  const expandedConfig = expandEnvVarsInObject(rawConfig);
  return configSchema.parse(expandedConfig);
}