go-cart-actor/message-handler.go

package main

import (
	"fmt"
	"io"

	messages "git.tornberg.me/go-cart-actor/proto"
	"google.golang.org/protobuf/proto"
)

var Handlers = map[uint16]MessageHandler{
	AddRequestType:     &AddRequestHandler{},
	AddItemType:        &AddItemHandler{},
	ChangeQuantityType: &ChangeQuantityHandler{},
	SetDeliveryType:    &SetDeliveryHandler{},
	RemoveItemType:     &RemoveItemHandler{},
	RemoveDeliveryType: &RemoveDeliveryHandler{},
}

func GetMessageHandler(t uint16) (MessageHandler, error) {
	h, ok := Handlers[t]
	if !ok {
		return nil, fmt.Errorf("no handler for type %d", t)
	}
	return h, nil
}

type MessageHandler interface {
	Write(*Message, io.Writer) error
	Read(data []byte) (interface{}, error)
	Is(*Message) bool
}
type TypedMessageHandler struct {
	Type uint16
}

type AddRequestHandler struct {
	TypedMessageHandler
}

func (h *AddRequestHandler) Write(m *Message, w io.Writer) error {
	messageBytes, err := proto.Marshal(m.Content.(*messages.AddRequest))
	if err != nil {
		return err
	}
	w.Write(messageBytes)
	return nil
}

func (h *AddRequestHandler) Read(data []byte) (interface{}, error) {
	msg := &messages.AddRequest{}

	err := proto.Unmarshal(data, msg)
	if err != nil {
		return nil, err
	}
	return msg, nil
}

func (h *AddRequestHandler) Is(m *Message) bool {
	if m.Type != AddRequestType {
		return false
	}
	_, ok := m.Content.(*messages.AddRequest)
	return ok
}

type AddItemHandler struct {
	TypedMessageHandler
}

func (h *AddItemHandler) Write(m *Message, w io.Writer) error {
	messageBytes, err := proto.Marshal(m.Content.(*messages.AddItem))
	if err != nil {
		return err
	}
	w.Write(messageBytes)
	return nil
}

func (h *AddItemHandler) Read(data []byte) (interface{}, error) {
	msg := &messages.AddItem{}

	err := proto.Unmarshal(data, msg)
	if err != nil {
		return nil, err
	}
	return msg, nil
}

func (h *AddItemHandler) Is(m *Message) bool {
	if m.Type != AddItemType {
		return false
	}
	_, ok := m.Content.(*messages.AddItem)
	return ok
}

type ChangeQuantityHandler struct {
	TypedMessageHandler
}

func (h *ChangeQuantityHandler) Write(m *Message, w io.Writer) error {
	messageBytes, err := proto.Marshal(m.Content.(*messages.ChangeQuantity))
	if err != nil {
		return err
	}
	w.Write(messageBytes)
	return nil
}

func (h *ChangeQuantityHandler) Read(data []byte) (interface{}, error) {
	msg := &messages.ChangeQuantity{}

	err := proto.Unmarshal(data, msg)
	if err != nil {
		return nil, err
	}
	return msg, nil
}

func (h *ChangeQuantityHandler) Is(m *Message) bool {
	if m.Type != ChangeQuantityType {
		return false
	}
	_, ok := m.Content.(*messages.ChangeQuantity)
	return ok
}

type SetDeliveryHandler struct {
	TypedMessageHandler
}

func (h *SetDeliveryHandler) Write(m *Message, w io.Writer) error {
	messageBytes, err := proto.Marshal(m.Content.(*messages.SetDelivery))
	if err != nil {
		return err
	}
	w.Write(messageBytes)
	return nil
}

func (h *SetDeliveryHandler) Read(data []byte) (interface{}, error) {
	msg := &messages.SetDelivery{}

	err := proto.Unmarshal(data, msg)
	if err != nil {
		return nil, err
	}
	return msg, nil
}

func (h *SetDeliveryHandler) Is(m *Message) bool {
	if m.Type != ChangeQuantityType {
		return false
	}
	_, ok := m.Content.(*messages.SetDelivery)
	return ok
}

type RemoveItemHandler struct {
	TypedMessageHandler
}

func (h *RemoveItemHandler) Write(m *Message, w io.Writer) error {
	messageBytes, err := proto.Marshal(m.Content.(*messages.RemoveItem))
	if err != nil {
		return err
	}
	w.Write(messageBytes)
	return nil
}

func (h *RemoveItemHandler) Read(data []byte) (interface{}, error) {
	msg := &messages.RemoveItem{}

	err := proto.Unmarshal(data, msg)
	if err != nil {
		return nil, err
	}
	return msg, nil
}

func (h *RemoveItemHandler) Is(m *Message) bool {
	if m.Type != AddItemType {
		return false
	}
	_, ok := m.Content.(*messages.RemoveItem)
	return ok
}

type RemoveDeliveryHandler struct {
	TypedMessageHandler
}

func (h *RemoveDeliveryHandler) Write(m *Message, w io.Writer) error {
	messageBytes, err := proto.Marshal(m.Content.(*messages.RemoveDelivery))
	if err != nil {
		return err
	}
	w.Write(messageBytes)
	return nil
}

func (h *RemoveDeliveryHandler) Read(data []byte) (interface{}, error) {
	msg := &messages.RemoveDelivery{}

	err := proto.Unmarshal(data, msg)
	if err != nil {
		return nil, err
	}
	return msg, nil
}

func (h *RemoveDeliveryHandler) Is(m *Message) bool {
	if m.Type != AddItemType {
		return false
	}
	_, ok := m.Content.(*messages.RemoveDelivery)
	return ok
}