import { get, has } from 'lodash-es';

/**
 * Match simple variables, like `$foo`
 */
const simpleVariableRegex = /(?!\\\$)\$(\w+)/g;

/**
 * Match wrapped variables, like `${foo.bar}`
 */
const wrappedVariableRegex = /(?!\\\$)\${([^}]+)}/g;

const processVariable = (
  data: Record<string, unknown>,
  _matchedText: string,
  varName: string,
): string => {
  if (has(data, varName)) {
    return `${get(data, varName)}`;
  }
  throw new Error(
    `Invalid template variable: ${JSON.stringify(
      varName,
    )}. Please use \\$ if this is not a variable.`,
  );
};

const processTemplate = (template: string | null, data: Record<string, unknown>): string => {
  if (!template) {
    return '';
  }
  if (!template.includes('$')) {
    return template;
  }
  // Replace any vars (excluding `\$`) with their data
  const replacerFn = processVariable.bind(null, data);
  return template
    .replace(simpleVariableRegex, replacerFn)
    .replace(wrappedVariableRegex, replacerFn);
};

export { processTemplate };