// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements.  See the NOTICE file distributed with
// this work for additional information regarding copyright ownership.
// The ASF licenses this file to You under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with
// the License.  You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package bufreflect

import (
	"context"
	"fmt"
)

import (
	"google.golang.org/protobuf/proto"

	"google.golang.org/protobuf/reflect/protodesc"
	"google.golang.org/protobuf/reflect/protoreflect"

	"google.golang.org/protobuf/types/dynamicpb"
)

import (
	"github.com/apache/dubbo-kubernetes/pkg/bufman/bufpkg/bufimage"
)

// NewMessage returns a new dynamic proto.Message for the fully qualified typeName
// in the bufimage.Image.
func NewMessage(
	ctx context.Context,
	image bufimage.Image,
	typeName string,
) (proto.Message, error) {
	if err := ValidateTypeName(typeName); err != nil {
		return nil, err
	}
	files, err := protodesc.NewFiles(bufimage.ImageToFileDescriptorSet(image))
	if err != nil {
		return nil, err
	}
	descriptor, err := files.FindDescriptorByName(protoreflect.FullName(typeName))
	if err != nil {
		return nil, err
	}
	typedDescriptor, ok := descriptor.(protoreflect.MessageDescriptor)
	if !ok {
		return nil, fmt.Errorf("%q must be a message but is a %T", typeName, descriptor)
	}
	return dynamicpb.NewMessage(typedDescriptor), nil
}

// ValidateTypeName validates that the typeName is well-formed, such that it has one or more
// '.'-delimited package components and no '/' elements.
func ValidateTypeName(typeName string) error {
	if fullName := protoreflect.FullName(typeName); !fullName.IsValid() {
		return fmt.Errorf("%q is not a valid fully qualified type name", fullName)
	}
	return nil
}