// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package prototype

import (
	"fmt"

	pragma "github.com/golang/protobuf/v2/internal/pragma"
	pfmt "github.com/golang/protobuf/v2/internal/typefmt"
	pref "github.com/golang/protobuf/v2/reflect/protoreflect"
)

var (
	emptyFiles      fileImports
	emptyMessages   messages
	emptyFields     fields
	emptyOneofs     oneofs
	emptyNumbers    numbers
	emptyRanges     ranges
	emptyEnums      enums
	emptyEnumValues enumValues
	emptyExtensions extensions
	emptyServices   services
)

type placeholderName pref.FullName

func (t placeholderName) Parent() (pref.Descriptor, bool)       { return nil, false }
func (t placeholderName) Index() int                            { return 0 }
func (t placeholderName) Syntax() pref.Syntax                   { return 0 }
func (t placeholderName) Name() pref.Name                       { return pref.FullName(t).Name() }
func (t placeholderName) FullName() pref.FullName               { return pref.FullName(t) }
func (t placeholderName) IsPlaceholder() bool                   { return true }
func (t placeholderName) DescriptorProto() (pref.Message, bool) { return nil, false }
func (t placeholderName) ProtoInternal(pragma.DoNotImplement)   {}

type placeholderFile struct {
	path string
	placeholderName
}

func (t placeholderFile) Options() pref.ProtoMessage                     { return optionTypes.File }
func (t placeholderFile) Path() string                                   { return t.path }
func (t placeholderFile) Package() pref.FullName                         { return t.FullName() }
func (t placeholderFile) Imports() pref.FileImports                      { return &emptyFiles }
func (t placeholderFile) Messages() pref.MessageDescriptors              { return &emptyMessages }
func (t placeholderFile) Enums() pref.EnumDescriptors                    { return &emptyEnums }
func (t placeholderFile) Extensions() pref.ExtensionDescriptors          { return &emptyExtensions }
func (t placeholderFile) Services() pref.ServiceDescriptors              { return &emptyServices }
func (t placeholderFile) DescriptorByName(pref.FullName) pref.Descriptor { return nil }
func (t placeholderFile) Format(s fmt.State, r rune)                     { pfmt.FormatDesc(s, r, t) }
func (t placeholderFile) ProtoType(pref.FileDescriptor)                  {}

type placeholderMessage struct {
	placeholderName
}

func (t placeholderMessage) Options() pref.ProtoMessage            { return optionTypes.Message }
func (t placeholderMessage) IsMapEntry() bool                      { return false }
func (t placeholderMessage) Fields() pref.FieldDescriptors         { return &emptyFields }
func (t placeholderMessage) Oneofs() pref.OneofDescriptors         { return &emptyOneofs }
func (t placeholderMessage) RequiredNumbers() pref.FieldNumbers    { return &emptyNumbers }
func (t placeholderMessage) ExtensionRanges() pref.FieldRanges     { return &emptyRanges }
func (t placeholderMessage) Messages() pref.MessageDescriptors     { return &emptyMessages }
func (t placeholderMessage) Enums() pref.EnumDescriptors           { return &emptyEnums }
func (t placeholderMessage) Extensions() pref.ExtensionDescriptors { return &emptyExtensions }
func (t placeholderMessage) Format(s fmt.State, r rune)            { pfmt.FormatDesc(s, r, t) }
func (t placeholderMessage) ProtoType(pref.MessageDescriptor)      {}

type placeholderEnum struct {
	placeholderName
}

func (t placeholderEnum) Options() pref.ProtoMessage        { return optionTypes.Enum }
func (t placeholderEnum) Values() pref.EnumValueDescriptors { return &emptyEnumValues }
func (t placeholderEnum) Format(s fmt.State, r rune)        { pfmt.FormatDesc(s, r, t) }
func (t placeholderEnum) ProtoType(pref.EnumDescriptor)     {}