// USAGE
// Require `itoolkitHandler` into the file
// Parameters are an object with arrays
// filters filter out the displayed value when logging, does not modify the actual value
//
// itoolkit.calliPgm(params, program, filters);
//
// params:[Object] An object with keys representing the value's name passed in or returned
//    example: const params = {
//                         name:   ["data", "type"],
//                         number: ["", "6p0"],
//                         yesNo:  ["", "7p2"],
//                        }
//
//         data: [String, Number] The data needs to match the type
//         type: [String] This is a string designating the datatype for the RPG program | Reference the chart below fo more information
//
//         ------------------------------------
//         | Type   | syntax |    eg    | eg  |
//         ------------------------------------
//         ------------------------------------
//         | Number |   npn  | 12345.67 | 7p2 |
//         ------------------------------------
//         | String |    nA  | "hello"  | 5A  |
//         ------------------------------------
//
// program: {name: <programName>, lib: <libraryName.};
//    name: [String] name of the program
//    lib: [String] name of the library the program resides
//
// (optional) filters: {name: callback};
//    name: [String] name of the parameter to modify (Needs to be the same key as in params)
//    callback: [Function] callback to modify the string value of the data being passed in
//      example: {creditCardNumber: ccnum => `XXXX-XXXX-XXXX-${ccnum.slice(-4)}
//

const itoolkit = require('itoolkit');
const logger = require('./config/winston.js');

let conn;
connectitoolkit();

function connectitoolkit() {
  if (!conn) {
    logger.info(`itoolkit setting up DBPool..`);
    try {
      conn = new itoolkit.iConn("*LOCAL", "LOWANG", "ZILLA");
      conn.debug(false);
    } catch (error) {
      logger.error("iConn connection issue: ", error);
    }
  }
  return conn;
}

// Matches "npn" OR "nA"
const validParameterRegex = /\d+A|\d+p\d+/;

exports.calliPgm = function(params, program, filters) {
  logHandler(params, program, filters);
  return new Promise((resolve, reject) => {
    try {
      const conn = connectitoolkit();
      const pgm = new itoolkit.iPgm(program.name, { lib: program.lib });

      Object.values(params).forEach(param => {
        if(!validParameterRegex.test(param[1])) {
          return reject(Error(`Invalid parameter descriptor "${param[1]}" passed to calliPgm, should match "nA" for strings and "npn" for numeric parameters`));
        }

        pgm.addParam(param[0], param[1])
      });

      conn.add(pgm);

      conn.run(xml => {
        const result = itoolkit.xmlToJson(xml)[0];
        if (!result.success) return reject(new Error(xml));
        const formattedData = Object.keys(params).reduce((accumulator, key, index) => {
          accumulator[key] = result.data[index].value;
          return accumulator;
        }, {});
        resolve(formattedData);
      });
    } catch(error) {
      reject(error);
    }
  });
}

// filters is an object with keys of the same name as 'params', and callbacks to modify the displayed value.
function logHandler(params, program, filters={}) {
  // change the value of the parameter to match the return value of the callback
  // This is used to mask stuff like credit card numbers.
  const filtered = Object.entries(filters).reduce((acc, [key, filter]) => {
    acc[key] = [filter(params[key][0]), params[key][1]];
    return acc;
  }, {});

  // Using object spreading to over-write the parameters with the filtered ones
  logger.info(`Calling "${program.lib}.${program.name}" with: ${JSON.stringify({...params, ...filtered}, null, process.env.NODE_ENV === 'development' ? 1 : 0)}`);
}