const { SerialPort } = require('serialport');
const config = require('../config/config');
const logger = require('../logger');

function createAstmSerialConnector(options = {}) {
  let port;
  let messageHandler = async () => {};
  let errorHandler = (err) => logger.error({ err }, 'astm connector error');
  const serialPath = options.port || options.comPort || config.connectors.astmSerialPath;
  const baudRate = Number(options.baudRate || config.connectors.astmSerialBaudRate);
  const dataBits = Number(options.dataBits || config.connectors.astmSerialDataBits);
  const stopBits = Number(options.stopBits || config.connectors.astmSerialStopBits);
  const parity = options.parity || config.connectors.astmSerialParity;
  const instrumentId = options.instrument_id || null;

  function processBufferedLines(state) {
    const lines = state.buffer.split(/\r?\n/);
    state.buffer = lines.pop() || '';
    lines
      .map((line) => line.trim())
      .filter(Boolean)
      .forEach((line) => {
        messageHandler({
          payload: line,
          context: {
            connector: 'astm-serial',
            instrument_id: instrumentId,
            comPort: serialPath,
            baudRate,
            dataBits,
            stopBits,
            parity
          }
        }).catch(errorHandler);
      });
  }

  return {
    name: () => 'astm-serial',
    type: () => 'astm-serial',
    async start() {
      const state = { buffer: '' };
      port = new SerialPort({
        path: serialPath,
        baudRate,
        dataBits,
        stopBits,
        parity,
        autoOpen: false
      });

      port.on('data', (chunk) => {
        state.buffer += chunk.toString('utf8');
        if (state.buffer.includes('\n')) {
          processBufferedLines(state);
        }
      });
      port.on('error', (err) => errorHandler(err));

      return new Promise((resolve, reject) => {
        port.open((err) => {
          if (err) {
            errorHandler(err);
            return reject(err);
          }
          logger.info({
            instrument_id: instrumentId,
            comPort: serialPath,
            baudRate,
            dataBits,
            stopBits,
            parity
          }, 'astm serial connector opened');
          resolve();
        });
      });
    },
    async stop() {
      if (!port) return;

      if (!port.isOpen) {
        port.removeAllListeners();
        port = null;
        return;
      }

      return new Promise((resolve, reject) => {
        port.close((err) => {
          if (err) return reject(err);
          port.removeAllListeners();
          port = null;
          resolve();
        });
      });
    },
    health() {
      return {
        status: port && port.isOpen ? 'up' : 'down',
        instrument_id: instrumentId,
        comPort: serialPath,
        baudRate
      };
    },
    onMessage(handler) {
      messageHandler = handler;
    },
    onError(handler) {
      errorHandler = handler;
    }
  };
}

module.exports = { createAstmSerialConnector };