import failWithError from './failWithError';
import IOption from './IOption';

const fail = failWithError.bind(null, '');

export default function initState(spec: { [key: string]: IOption }) {
  //The parsed arguments that are returned by this function
  const outputArgs: { [key: string]: string } = {};

  //Create a lookup table to find a long option when given the short option, and to check if all required options are set
  const shortToLongLookup: { [key: string]: string } = {};
  const requiredOptions: { [key: string]: boolean } = {};
  for (const longOption in spec) {
    if (spec.hasOwnProperty(longOption)) {
      if (longOption === '') {
        fail(`The long option may not be an empty string. This is a bug in the source code of the script that you tried to call.`);
      }
      if (!longOption.match(/^[a-z0-9]+(-[a-z0-9]+)*$/)) {
        fail(`The long option "${longOption}" must only contain alpha-numeric characters, optionally separated by hyphens. This is a bug in the source code of the script that you tried to call.`);
      }

      const shortOption = spec[longOption].short;
      if (shortOption !== undefined && shortOption !== '') {
        if (shortOption.length > 1) {
          fail(`Short options must only be one character long but the short option "${shortOption}" for "${longOption}" was ${shortOption.length} characters long. This is a bug in the source code of the script that you tried to call.`);
        }
        shortToLongLookup[shortOption] = longOption;
      }

      //If a default value is given, use the default value (it can be overridden later), otherwise mark argument as being required
      const defaultValue = spec[longOption].default;
      if (defaultValue !== undefined) {
        outputArgs[longOption] = defaultValue;
      } else {
        requiredOptions[longOption] = false;
      }
    }
  }

  const usage = `./${process.argv[1].substr(process.argv[1].lastIndexOf('/') + 1)} [options]\nOPTIONS\n${
    Object.entries(spec).map(([key, {default: defaultValue, short, description}]) => (
      `  ${(defaultValue === undefined) ? '' : '['}${(short !== undefined && short !== '') ? `-${short}, ` : ''}--${key} <value>${(defaultValue === undefined) ? '' : `], defaults to "${defaultValue}"`}${(description !== undefined && description !== '') ? `\n      ${description}` : ''}`
      )).join('\n')
  }`;

  const failFunction = failWithError.bind(null, usage);

  return { outputArgs, shortToLongLookup, requiredOptions, failFunction };
}