package modbusx

import (
	"encoding/binary"
)

func Read(ipAddr string, address uint16, quantity uint16) (data []byte, err error) {
	address--
	cli := getModbusConnection(ipAddr)
	data, err = cli.ReadHoldingRegisters(address, quantity)
	dealErr(err, ipAddr)
	if err != nil {
		cli = getModbusConnection(ipAddr)
		data, err = cli.ReadHoldingRegisters(address, quantity)
		dealErr(err, ipAddr)
	}
	return
}

func Write(ipAddr string, address uint16, value int, endian string, length int) (err error) {
	address--
	var bytesVal []byte
	bytesVal = intToBytes(value, endian, length)
	cli := getModbusConnection(ipAddr)
	_, err = cli.WriteMultipleRegisters(address, uint16(len(bytesVal)), bytesVal)
	dealErr(err, ipAddr)
	return err
}

func intToBytes(value int, endian string, length int) (data []byte) {
	if endian == "mix" {
		data = make([]byte, 0, 4)
		highVal := value / (1 << 16)
		highBts := make([]byte, 2)
		binary.BigEndian.PutUint16(highBts, uint16(highVal))
		lowValue := value % (1 << 16)
		lowBts := make([]byte, 2)
		binary.BigEndian.PutUint16(lowBts, uint16(lowValue))
		data = append(data, lowBts...)
		data = append(data, highBts...)
	} else {
		if length == 1 {
			data = make([]byte, 2)
			if endian == "big" {
				binary.BigEndian.PutUint16(data, uint16(value))
			} else {
				binary.LittleEndian.PutUint16(data, uint16(value))
			}
		} else {
			data = make([]byte, 4)
			if endian == "big" {
				binary.BigEndian.PutUint32(data, uint32(value))
			} else {
				binary.LittleEndian.PutUint32(data, uint32(value))
			}
		}
	}
	return
}

func dealErr(err error, ipAddr string) {
	if err != nil {
		unsetModbusConnection(ipAddr) //失败则删除缓存的连接
	}
}