const config = require('./conf/transformConfig.json');
const functionsConfig = require('./conf/functionsConfig.json');
const loadedFunctions = {};

Object.keys(functionsConfig).forEach(funcName => {
  loadedFunctions[funcName] = require(functionsConfig[funcName]);
});

function resolveField(source, fieldConfig) {
  let result = null;

  if (typeof fieldConfig === 'string' || typeof fieldConfig === 'boolean' || typeof fieldConfig === 'number') {
    return fieldConfig;
  }

  if (fieldConfig.from && source.hasOwnProperty(fieldConfig.from)) {
    result = source[fieldConfig.from];
  }

  if (result === null && fieldConfig.fallback) {
    result = source[fieldConfig.fallback];
  }

  if (fieldConfig.template) {
    result = fieldConfig.template.replace(/\$\{(.*?)\}/g, (match, key) => source[key] || '');
  }

  if (fieldConfig.func && typeof loadedFunctions[fieldConfig.func] === 'function') {
    result = loadedFunctions[fieldConfig.func](fieldConfig.params || {});
  }

  return result;
}

function convertToGiteaFormat(originalData) {
  const result = {};
  Object.keys(config.fields).forEach((key) => {
    result[key] = resolveField(originalData, config.fields[key]);
  });
  return result;
}

module.exports = { convertToGiteaFormat };