package handler

import (
	"git.noahlan.cn/noahlan/ntool-biz/nmodbus/protocol"
	"git.noahlan.cn/noahlan/ntool-biz/nmodbus/serialize"
)

// ReadDiscreteInputs 读离散输入 功能码 0x02
type ReadDiscreteInputs struct {
	fnCode uint8
}

func NewReadDiscreteInputs(fnCode uint8) FunctionHandler {
	return &ReadDiscreteInputs{fnCode: fnCode}
}

func (r *ReadDiscreteInputs) FnCode() uint8 {
	return r.fnCode
}

// Function 读离散输入 功能码 0x02
func (r *ReadDiscreteInputs) Function(s *Handler, req protocol.Packet, resp protocol.Packet) *protocol.MError {
	register, numRegs, endRegister := serialize.RegisterAddressAndNumber(req.GetBody())
	if endRegister > 65535 {
		resp.SetBody([]byte{})
		return &protocol.IllegalDataAddress
	}
	dataSize := numRegs / 8
	if (numRegs % 8) != 0 {
		dataSize++
	}
	data := make([]byte, 1+dataSize)
	data[0] = byte(dataSize)

	dataMgr := s.DataManager(req.GetAddress())
	discreteInputs := dataMgr.ReadDiscreteInputs(register, endRegister)

	for i, value := range discreteInputs {
		if value != 0 {
			shift := uint(i) % 8
			data[1+i/8] |= byte(1 << shift)
		}
	}

	s.HandleLogic(r.fnCode, req, register, numRegs, data)

	resp.SetBody(data)
	return &protocol.Success
}