'use strict';

const Stampit = require('stampit');
const Put     = require('put');

module.exports = Stampit()
    .init(function () {
        const FC = 5;

        let init = () => this.addResponseHandler(FC, onResponse);

        let onResponse = (unitId, pdu, cb) => {
            const fc            = pdu.readUInt8(0);
            const outputAddress = pdu.readUInt16BE(1);
            const outputValue   = pdu.readUInt16BE(3);

            let resp = {
                unitId:         unitId,
                fc:             fc,
                outputAddress:  outputAddress,
                outputValue:    outputValue === 0x0000 ? false : (outputValue === 0xFF00 ? true : undefined)
            };

            if (fc !== FC) {
                cb(`WriteSingleCoil: Invalid FC ${fc}`);
            } else {
                cb(null, resp);
            }
        };

        this.writeSingleCoil = (unitId, address, value) => {
            return new Promise((resolve, reject) => {
                const payload = (value instanceof Buffer) ? (value.readUInt8(0) > 0) : value;
                const pdu     = Put().word8be(FC).word16be(address).word16be(payload ? 0xff00 : 0x0000);

                this.queueRequest(unitId, FC, pdu.buffer(), (err, resp) => {
                    if (err) {
                        reject(err);
                    } else {
                        resolve(resp);
                    }
                });
            });
        };

        init();
    });