package cRpc

import (
	"context"
	"errors"
	"reflect"

	"google.golang.org/grpc/metadata"

	"gitee.com/csingo/cContext"
)

func GrpcHandler[Q, T any](ctx context.Context, app, service, method string, req Q, rsp T) (err error) {
	instance := GetService(app, service)
	if instance == nil {
		return errors.New("rpc 服务异常")
	}

	caller := reflect.ValueOf(instance).MethodByName(method)
	if !caller.IsValid() {
		return errors.New("rpc 服务方法不存在")
	}

	// 读取上下文数据
	newCtx := cContext.New()
	if md, ok := metadata.FromIncomingContext(ctx); ok {
		for k, v := range md {
			var item string
			if len(v) > 0 {
				item = v[0]
			}
			newCtx.Header(k, item)
		}
	}

	responseValues := caller.Call([]reflect.Value{reflect.ValueOf(newCtx), reflect.ValueOf(req)})
	if !responseValues[1].IsNil() {
		return responseValues[1].Interface().(error)
	}

	rsp = responseValues[0].Interface().(T)

	return
}