gocommon/wshandler/api_handler.go

package wshandler

import (
	"encoding/json"
	"io"
	"reflect"
	"unsafe"

	"repositories.action2quare.com/ayo/gocommon/logger"
)

const (
	ClientConnected    = "ClientConnected"
	ClientDisconnected = "ClientDisconnected"
)

type apiFuncType func(ApiCallContext)

type WebsocketApiHandler struct {
	methods     map[string]apiFuncType
	connfunc    apiFuncType
	disconnfunc apiFuncType
}

type ApiCallContext struct {
	CallBy    *Sender
	Arguments []any
}

func MakeWebsocketApiHandler[T any](receiver *T, receiverName string) WebsocketApiHandler {
	methods := make(map[string]apiFuncType)

	tp := reflect.TypeOf(receiver)
	if len(receiverName) == 0 {
		receiverName = tp.Elem().Name()
	}

	var connfunc apiFuncType
	var disconnfunc apiFuncType

	for i := 0; i < tp.NumMethod(); i++ {
		method := tp.Method(i)
		if method.Type.NumIn() != 2 {
			continue
		}

		if method.Type.In(0) != tp {
			continue
		}

		if method.Type.In(1) != reflect.TypeOf((*ApiCallContext)(nil)).Elem() {
			continue
		}

		funcptr := method.Func.Pointer()
		p1 := unsafe.Pointer(&funcptr)
		p2 := unsafe.Pointer(&p1)
		testfunc := (*func(*T, ApiCallContext))(p2)

		if method.Name == ClientConnected {
			connfunc = func(ctx ApiCallContext) {
				(*testfunc)(receiver, ctx)
			}
		} else if method.Name == ClientDisconnected {
			disconnfunc = func(ctx ApiCallContext) {
				(*testfunc)(receiver, ctx)
			}
		} else {
			methods[receiverName+"."+method.Name] = func(ctx ApiCallContext) {
				(*testfunc)(receiver, ctx)
			}
		}
	}

	return WebsocketApiHandler{
		methods:     methods,
		connfunc:    connfunc,
		disconnfunc: disconnfunc,
	}
}

type WebsocketApiBroker struct {
	methods      map[string]apiFuncType
	connFuncs    []apiFuncType
	disconnFuncs []apiFuncType
}

func (hc *WebsocketApiBroker) AddHandler(receiver WebsocketApiHandler) {
	if hc.methods == nil {
		hc.methods = make(map[string]apiFuncType)
	}

	for k, v := range receiver.methods {
		logger.Println("http api registered :", k)
		hc.methods[k] = v
	}

	if receiver.connfunc != nil {
		hc.connFuncs = append(hc.connFuncs, receiver.connfunc)
	}

	if receiver.disconnfunc != nil {
		// disconnfunc은 역순
		hc.disconnFuncs = append([]apiFuncType{receiver.disconnfunc}, hc.disconnFuncs...)
	}
}

func (hc *WebsocketApiBroker) Call(callby *Sender, funcname string, r io.Reader) {
	if funcname == ClientConnected {
		for _, v := range hc.connFuncs {
			v(ApiCallContext{
				CallBy:    callby,
				Arguments: nil,
			})
		}
	} else if funcname == ClientDisconnected {
		for _, v := range hc.disconnFuncs {
			v(ApiCallContext{
				CallBy:    callby,
				Arguments: nil,
			})
		}
	} else if found := hc.methods[funcname]; found != nil {
		var args []any
		if r != nil {
			dec := json.NewDecoder(r)
			if err := dec.Decode(&args); err != nil {
				logger.Println("WebsocketApiBroker.Call failed. decode returns err :", err)
			}
		}

		found(ApiCallContext{
			CallBy:    callby,
			Arguments: args,
		})
	} else {
		logger.Println("api is not found :", funcname)
	}
}