package modbusx

import (
	"encoding/binary"
	"sync/atomic"
)

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

func Write(ipAddr string, address uint16, value int) (err error) {
	var bytesVal []byte
	if value <= 1<<16 {
		uint16ToBytes(uint16(value))
	} else {
		bytesVal = intToBytes(value)
	}
	cli := getModbusConnection(ipAddr)
	_, err = cli.WriteMultipleRegisters(address, uint16(len(bytesVal)), bytesVal)
	dealErr(err, ipAddr)
	return err
}

func uint16ToBytes(value uint16) []byte {
	// 创建一个长度为2的字节切片
	bytes := make([]byte, 2)

	// 将 uint16 的值写入字节切片，可以选择使用大端或小端字节序
	bytes[0] = byte(value >> 8) // 获取高8位
	bytes[1] = byte(value)      // 获取低8位

	return bytes
}

func intToBytes(value int) []byte {
	// 创建一个长度为4的字节切片，用于存储 int 值
	bytes := make([]byte, 4)

	// 使用 binary 包将 int 值转换为字节切片
	binary.BigEndian.PutUint32(bytes, uint32(value))

	return bytes
}

func dealErr(err error, ipAddr string) {
	if err != nil {
		unsetModbusConnection(ipAddr)       //失败则删除缓存的连接
		FailureRemainingOpportunitiesDecr() //减少失败剩余机会
	} else {
		FailureRemainingOpportunitiesReset() //重置失败剩余机会
	}
}

var connectionStatus atomic.Bool

var failureRemainingOpportunities atomic.Int64

const (
	defaultFailureRemainingOpportunities = 20
)

func IsConnect() bool {
	return connectionStatus.Load()
}

func FailureRemainingOpportunitiesDecr() {
	newValue := failureRemainingOpportunities.Add(-1)
	if newValue <= 0 {
		connectionStatus.Store(false)
	}
	return
}

func FailureRemainingOpportunitiesReset() {
	if failureRemainingOpportunities.Load() < defaultFailureRemainingOpportunities {
		failureRemainingOpportunities.Store(defaultFailureRemainingOpportunities)
	}
	if connectionStatus.Load() == false {
		connectionStatus.Store(true)
	}
	return
}