// Copyright 2019 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 filedesc

import (
	"bytes"
	"fmt"
	"sync"
	"sync/atomic"

	"google.golang.org/protobuf/internal/descfmt"
	"google.golang.org/protobuf/internal/descopts"
	"google.golang.org/protobuf/internal/encoding/defval"
	"google.golang.org/protobuf/internal/pragma"
	pref "google.golang.org/protobuf/reflect/protoreflect"
)

// The types in this file may have a suffix:
//	• L0: Contains fields common to all descriptors (except File) and
//	must be initialized up front.
//	• L1: Contains fields specific to a descriptor and
//	must be initialized up front.
//	• L2: Contains fields that are lazily initialized when constructing
//	from the raw file descriptor. When constructing as a literal, the L2
//	fields must be initialized up front.
//
// The types are exported so that packages like reflect/protodesc can
// directly construct descriptors.

type (
	File struct {
		fileRaw
		L1 FileL1

		once uint32     // atomically set if L2 is valid
		mu   sync.Mutex // protects L2
		L2   *FileL2
	}
	FileL1 struct {
		Syntax  pref.Syntax
		Path    string
		Package pref.FullName

		Enums      Enums
		Messages   Messages
		Extensions Extensions
		Services   Services
	}
	FileL2 struct {
		Options func() pref.ProtoMessage
		Imports FileImports
	}
)

func (fd *File) ParentFile() pref.FileDescriptor { return fd }
func (fd *File) Parent() pref.Descriptor         { return nil }
func (fd *File) Index() int                      { return 0 }
func (fd *File) Syntax() pref.Syntax             { return fd.L1.Syntax }
func (fd *File) Name() pref.Name                 { return fd.L1.Package.Name() }
func (fd *File) FullName() pref.FullName         { return fd.L1.Package }
func (fd *File) IsPlaceholder() bool             { return false }
func (fd *File) Options() pref.ProtoMessage {
	if f := fd.lazyInit().Options; f != nil {
		return f()
	}
	return descopts.File
}
func (fd *File) Path() string                          { return fd.L1.Path }
func (fd *File) Package() pref.FullName                { return fd.L1.Package }
func (fd *File) Imports() pref.FileImports             { return &fd.lazyInit().Imports }
func (fd *File) Enums() pref.EnumDescriptors           { return &fd.L1.Enums }
func (fd *File) Messages() pref.MessageDescriptors     { return &fd.L1.Messages }
func (fd *File) Extensions() pref.ExtensionDescriptors { return &fd.L1.Extensions }
func (fd *File) Services() pref.ServiceDescriptors     { return &fd.L1.Services }
func (fd *File) Format(s fmt.State, r rune)            { descfmt.FormatDesc(s, r, fd) }
func (fd *File) ProtoType(pref.FileDescriptor)         {}
func (fd *File) ProtoInternal(pragma.DoNotImplement)   {}

func (fd *File) lazyInit() *FileL2 {
	if atomic.LoadUint32(&fd.once) == 0 {
		fd.lazyInitOnce()
	}
	return fd.L2
}

func (fd *File) lazyInitOnce() {
	fd.mu.Lock()
	if fd.L2 == nil {
		fd.lazyRawInit() // recursively initializes all L2 structures
	}
	atomic.StoreUint32(&fd.once, 1)
	fd.mu.Unlock()
}

// ProtoLegacyRawDesc is a pseudo-internal API for allowing the v1 code
// to be able to retrieve the raw descriptor.
//
// WARNING: This method is exempt from the compatibility promise and may be
// removed in the future without warning.
func (fd *File) ProtoLegacyRawDesc() []byte {
	return fd.builder.RawDescriptor
}

type (
	Enum struct {
		Base
		L1 EnumL1
		L2 *EnumL2 // protected by fileDesc.once
	}
	EnumL1 struct {
		eagerValues bool // controls whether EnumL2.Values is already populated
	}
	EnumL2 struct {
		Options        func() pref.ProtoMessage
		Values         EnumValues
		ReservedNames  Names
		ReservedRanges EnumRanges
	}

	EnumValue struct {
		Base
		L1 EnumValueL1
	}
	EnumValueL1 struct {
		Options func() pref.ProtoMessage
		Number  pref.EnumNumber
	}
)

func (ed *Enum) Options() pref.ProtoMessage {
	if f := ed.lazyInit().Options; f != nil {
		return f()
	}
	return descopts.Enum
}
func (ed *Enum) Values() pref.EnumValueDescriptors {
	if ed.L1.eagerValues {
		return &ed.L2.Values
	}
	return &ed.lazyInit().Values
}
func (ed *Enum) ReservedNames() pref.Names       { return &ed.lazyInit().ReservedNames }
func (ed *Enum) ReservedRanges() pref.EnumRanges { return &ed.lazyInit().ReservedRanges }
func (ed *Enum) Format(s fmt.State, r rune)      { descfmt.FormatDesc(s, r, ed) }
func (ed *Enum) ProtoType(pref.EnumDescriptor)   {}
func (ed *Enum) lazyInit() *EnumL2 {
	ed.L0.ParentFile.lazyInit() // implicitly initializes L2
	return ed.L2
}

func (ed *EnumValue) Options() pref.ProtoMessage {
	if f := ed.L1.Options; f != nil {
		return f()
	}
	return descopts.EnumValue
}
func (ed *EnumValue) Number() pref.EnumNumber            { return ed.L1.Number }
func (ed *EnumValue) Format(s fmt.State, r rune)         { descfmt.FormatDesc(s, r, ed) }
func (ed *EnumValue) ProtoType(pref.EnumValueDescriptor) {}

type (
	Message struct {
		Base
		L1 MessageL1
		L2 *MessageL2 // protected by fileDesc.once
	}
	MessageL1 struct {
		Enums      Enums
		Messages   Messages
		Extensions Extensions
	}
	MessageL2 struct {
		Options               func() pref.ProtoMessage
		IsMapEntry            bool // promoted from google.protobuf.MessageOptions
		IsMessageSet          bool // promoted from google.protobuf.MessageOptions
		Fields                Fields
		Oneofs                Oneofs
		ReservedNames         Names
		ReservedRanges        FieldRanges
		RequiredNumbers       FieldNumbers // must be consistent with Fields.Cardinality
		ExtensionRanges       FieldRanges
		ExtensionRangeOptions []func() pref.ProtoMessage // must be same length as ExtensionRanges
	}

	Field struct {
		Base
		L1 FieldL1
	}
	FieldL1 struct {
		Options         func() pref.ProtoMessage
		Number          pref.FieldNumber
		Cardinality     pref.Cardinality // must be consistent with Message.RequiredNumbers
		Kind            pref.Kind
		JSONName        jsonName
		IsWeak          bool // promoted from google.protobuf.FieldOptions
		HasPacked       bool // promoted from google.protobuf.FieldOptions
		IsPacked        bool // promoted from google.protobuf.FieldOptions
		Default         defaultValue
		ContainingOneof pref.OneofDescriptor // must be consistent with Message.Oneofs.Fields
		Enum            pref.EnumDescriptor
		Message         pref.MessageDescriptor
	}

	Oneof struct {
		Base
		L1 OneofL1
	}
	OneofL1 struct {
		Options func() pref.ProtoMessage
		Fields  OneofFields // must be consistent with Message.Fields.ContainingOneof
	}
)

func (md *Message) Options() pref.ProtoMessage {
	if f := md.lazyInit().Options; f != nil {
		return f()
	}
	return descopts.Message
}
func (md *Message) IsMapEntry() bool                   { return md.lazyInit().IsMapEntry }
func (md *Message) Fields() pref.FieldDescriptors      { return &md.lazyInit().Fields }
func (md *Message) Oneofs() pref.OneofDescriptors      { return &md.lazyInit().Oneofs }
func (md *Message) ReservedNames() pref.Names          { return &md.lazyInit().ReservedNames }
func (md *Message) ReservedRanges() pref.FieldRanges   { return &md.lazyInit().ReservedRanges }
func (md *Message) RequiredNumbers() pref.FieldNumbers { return &md.lazyInit().RequiredNumbers }
func (md *Message) ExtensionRanges() pref.FieldRanges  { return &md.lazyInit().ExtensionRanges }
func (md *Message) ExtensionRangeOptions(i int) pref.ProtoMessage {
	if f := md.lazyInit().ExtensionRangeOptions[i]; f != nil {
		return f()
	}
	return descopts.ExtensionRange
}
func (md *Message) Enums() pref.EnumDescriptors           { return &md.L1.Enums }
func (md *Message) Messages() pref.MessageDescriptors     { return &md.L1.Messages }
func (md *Message) Extensions() pref.ExtensionDescriptors { return &md.L1.Extensions }
func (md *Message) ProtoType(pref.MessageDescriptor)      {}
func (md *Message) Format(s fmt.State, r rune)            { descfmt.FormatDesc(s, r, md) }
func (md *Message) lazyInit() *MessageL2 {
	md.L0.ParentFile.lazyInit() // implicitly initializes L2
	return md.L2
}

// IsMessageSet is a pseudo-internal API for checking whether a message
// should serialize in the proto1 message format.
//
// WARNING: This method is exempt from the compatibility promise and may be
// removed in the future without warning.
func (md *Message) IsMessageSet() bool {
	return md.lazyInit().IsMessageSet
}

func (fd *Field) Options() pref.ProtoMessage {
	if f := fd.L1.Options; f != nil {
		return f()
	}
	return descopts.Field
}
func (fd *Field) Number() pref.FieldNumber      { return fd.L1.Number }
func (fd *Field) Cardinality() pref.Cardinality { return fd.L1.Cardinality }
func (fd *Field) Kind() pref.Kind               { return fd.L1.Kind }
func (fd *Field) HasJSONName() bool             { return fd.L1.JSONName.has }
func (fd *Field) JSONName() string              { return fd.L1.JSONName.get(fd) }
func (fd *Field) IsPacked() bool {
	if !fd.L1.HasPacked && fd.L0.ParentFile.L1.Syntax != pref.Proto2 && fd.L1.Cardinality == pref.Repeated {
		switch fd.L1.Kind {
		case pref.StringKind, pref.BytesKind, pref.MessageKind, pref.GroupKind:
		default:
			return true
		}
	}
	return fd.L1.IsPacked
}
func (fd *Field) IsExtension() bool { return false }
func (fd *Field) IsWeak() bool      { return fd.L1.IsWeak }
func (fd *Field) IsList() bool      { return fd.Cardinality() == pref.Repeated && !fd.IsMap() }
func (fd *Field) IsMap() bool       { return fd.Message() != nil && fd.Message().IsMapEntry() }
func (fd *Field) MapKey() pref.FieldDescriptor {
	if !fd.IsMap() {
		return nil
	}
	return fd.Message().Fields().ByNumber(1)
}
func (fd *Field) MapValue() pref.FieldDescriptor {
	if !fd.IsMap() {
		return nil
	}
	return fd.Message().Fields().ByNumber(2)
}
func (fd *Field) HasDefault() bool                           { return fd.L1.Default.has }
func (fd *Field) Default() pref.Value                        { return fd.L1.Default.get(fd) }
func (fd *Field) DefaultEnumValue() pref.EnumValueDescriptor { return fd.L1.Default.enum }
func (fd *Field) ContainingOneof() pref.OneofDescriptor      { return fd.L1.ContainingOneof }
func (fd *Field) ContainingMessage() pref.MessageDescriptor {
	return fd.L0.Parent.(pref.MessageDescriptor)
}
func (fd *Field) Enum() pref.EnumDescriptor       { return fd.L1.Enum }
func (fd *Field) Message() pref.MessageDescriptor { return fd.L1.Message }
func (fd *Field) Format(s fmt.State, r rune)      { descfmt.FormatDesc(s, r, fd) }
func (fd *Field) ProtoType(pref.FieldDescriptor)  {}

func (od *Oneof) Options() pref.ProtoMessage {
	if f := od.L1.Options; f != nil {
		return f()
	}
	return descopts.Oneof
}
func (od *Oneof) Fields() pref.FieldDescriptors  { return &od.L1.Fields }
func (od *Oneof) Format(s fmt.State, r rune)     { descfmt.FormatDesc(s, r, od) }
func (od *Oneof) ProtoType(pref.OneofDescriptor) {}

type (
	Extension struct {
		Base
		L1 ExtensionL1
		L2 *ExtensionL2 // protected by fileDesc.once
	}
	ExtensionL1 struct {
		Number   pref.FieldNumber
		Extendee pref.MessageDescriptor
		Kind     pref.Kind
	}
	ExtensionL2 struct {
		Options     func() pref.ProtoMessage
		Cardinality pref.Cardinality
		JSONName    jsonName
		IsPacked    bool // promoted from google.protobuf.FieldOptions
		Default     defaultValue
		Enum        pref.EnumDescriptor
		Message     pref.MessageDescriptor
	}
)

func (xd *Extension) Options() pref.ProtoMessage {
	if f := xd.lazyInit().Options; f != nil {
		return f()
	}
	return descopts.Field
}
func (xd *Extension) Number() pref.FieldNumber                   { return xd.L1.Number }
func (xd *Extension) Cardinality() pref.Cardinality              { return xd.lazyInit().Cardinality }
func (xd *Extension) Kind() pref.Kind                            { return xd.L1.Kind }
func (xd *Extension) HasJSONName() bool                          { return xd.lazyInit().JSONName.has }
func (xd *Extension) JSONName() string                           { return xd.lazyInit().JSONName.get(xd) }
func (xd *Extension) IsPacked() bool                             { return xd.lazyInit().IsPacked }
func (xd *Extension) IsExtension() bool                          { return true }
func (xd *Extension) IsWeak() bool                               { return false }
func (xd *Extension) IsList() bool                               { return xd.Cardinality() == pref.Repeated }
func (xd *Extension) IsMap() bool                                { return false }
func (xd *Extension) MapKey() pref.FieldDescriptor               { return nil }
func (xd *Extension) MapValue() pref.FieldDescriptor             { return nil }
func (xd *Extension) HasDefault() bool                           { return xd.lazyInit().Default.has }
func (xd *Extension) Default() pref.Value                        { return xd.lazyInit().Default.get(xd) }
func (xd *Extension) DefaultEnumValue() pref.EnumValueDescriptor { return xd.lazyInit().Default.enum }
func (xd *Extension) ContainingOneof() pref.OneofDescriptor      { return nil }
func (xd *Extension) ContainingMessage() pref.MessageDescriptor  { return xd.L1.Extendee }
func (xd *Extension) Enum() pref.EnumDescriptor                  { return xd.lazyInit().Enum }
func (xd *Extension) Message() pref.MessageDescriptor            { return xd.lazyInit().Message }
func (xd *Extension) Format(s fmt.State, r rune)                 { descfmt.FormatDesc(s, r, xd) }
func (xd *Extension) ProtoType(pref.FieldDescriptor)             {}
func (xd *Extension) ProtoInternal(pragma.DoNotImplement)        {}
func (xd *Extension) lazyInit() *ExtensionL2 {
	xd.L0.ParentFile.lazyInit() // implicitly initializes L2
	return xd.L2
}

type (
	Service struct {
		Base
		L1 ServiceL1
		L2 *ServiceL2 // protected by fileDesc.once
	}
	ServiceL1 struct{}
	ServiceL2 struct {
		Options func() pref.ProtoMessage
		Methods Methods
	}

	Method struct {
		Base
		L1 MethodL1
	}
	MethodL1 struct {
		Options           func() pref.ProtoMessage
		Input             pref.MessageDescriptor
		Output            pref.MessageDescriptor
		IsStreamingClient bool
		IsStreamingServer bool
	}
)

func (sd *Service) Options() pref.ProtoMessage {
	if f := sd.lazyInit().Options; f != nil {
		return f()
	}
	return descopts.Service
}
func (sd *Service) Methods() pref.MethodDescriptors     { return &sd.lazyInit().Methods }
func (sd *Service) Format(s fmt.State, r rune)          { descfmt.FormatDesc(s, r, sd) }
func (sd *Service) ProtoType(pref.ServiceDescriptor)    {}
func (sd *Service) ProtoInternal(pragma.DoNotImplement) {}
func (sd *Service) lazyInit() *ServiceL2 {
	sd.L0.ParentFile.lazyInit() // implicitly initializes L2
	return sd.L2
}

func (md *Method) Options() pref.ProtoMessage {
	if f := md.L1.Options; f != nil {
		return f()
	}
	return descopts.Method
}
func (md *Method) Input() pref.MessageDescriptor       { return md.L1.Input }
func (md *Method) Output() pref.MessageDescriptor      { return md.L1.Output }
func (md *Method) IsStreamingClient() bool             { return md.L1.IsStreamingClient }
func (md *Method) IsStreamingServer() bool             { return md.L1.IsStreamingServer }
func (md *Method) Format(s fmt.State, r rune)          { descfmt.FormatDesc(s, r, md) }
func (md *Method) ProtoType(pref.MethodDescriptor)     {}
func (md *Method) ProtoInternal(pragma.DoNotImplement) {}

// Surrogate files are can be used to create standalone descriptors
// where the syntax is only information derived from the parent file.
var (
	SurrogateProto2 = &File{L1: FileL1{Syntax: pref.Proto2}, L2: &FileL2{}}
	SurrogateProto3 = &File{L1: FileL1{Syntax: pref.Proto3}, L2: &FileL2{}}
)

type (
	Base struct {
		L0 BaseL0
	}
	BaseL0 struct {
		FullName   pref.FullName // must be populated
		ParentFile *File         // must be populated
		Parent     pref.Descriptor
		Index      int
	}
)

func (d *Base) Name() pref.Name         { return d.L0.FullName.Name() }
func (d *Base) FullName() pref.FullName { return d.L0.FullName }
func (d *Base) ParentFile() pref.FileDescriptor {
	if d.L0.ParentFile == SurrogateProto2 || d.L0.ParentFile == SurrogateProto3 {
		return nil // surrogate files are not real parents
	}
	return d.L0.ParentFile
}
func (d *Base) Parent() pref.Descriptor             { return d.L0.Parent }
func (d *Base) Index() int                          { return d.L0.Index }
func (d *Base) Syntax() pref.Syntax                 { return d.L0.ParentFile.Syntax() }
func (d *Base) IsPlaceholder() bool                 { return false }
func (d *Base) ProtoInternal(pragma.DoNotImplement) {}

func JSONName(s string) jsonName {
	return jsonName{has: true, name: s}
}

type jsonName struct {
	has  bool
	once sync.Once
	name string
}

func (js *jsonName) get(fd pref.FieldDescriptor) string {
	if !js.has {
		js.once.Do(func() {
			js.name = makeJSONName(fd.Name())
		})
	}
	return js.name
}

// makeJSONName creates a JSON name from the protobuf short name.
func makeJSONName(s pref.Name) string {
	var b []byte
	var wasUnderscore bool
	for i := 0; i < len(s); i++ { // proto identifiers are always ASCII
		c := s[i]
		if c != '_' {
			isLower := 'a' <= c && c <= 'z'
			if wasUnderscore && isLower {
				c -= 'a' - 'A'
			}
			b = append(b, c)
		}
		wasUnderscore = c == '_'
	}
	return string(b)
}

func DefaultValue(v pref.Value, ev pref.EnumValueDescriptor) defaultValue {
	dv := defaultValue{has: v.IsValid(), val: v, enum: ev}
	if b, ok := v.Interface().([]byte); ok {
		// Store a copy of the default bytes, so that we can detect
		// accidental mutations of the original value.
		dv.bytes = append([]byte(nil), b...)
	}
	return dv
}

func unmarshalDefault(b []byte, k pref.Kind, pf *File, ed pref.EnumDescriptor) defaultValue {
	var evs pref.EnumValueDescriptors
	if k == pref.EnumKind {
		// If the enum is declared within the same file, be careful not to
		// blindly call the Values method, lest we bind ourselves in a deadlock.
		if ed, ok := ed.(*Enum); ok && ed.L0.ParentFile == pf {
			evs = &ed.L2.Values
		} else {
			evs = ed.Values()
		}
	}

	v, ev, err := defval.Unmarshal(string(b), k, evs, defval.Descriptor)
	if err != nil {
		panic(err)
	}
	return DefaultValue(v, ev)
}

type defaultValue struct {
	has   bool
	val   pref.Value
	enum  pref.EnumValueDescriptor
	bytes []byte
}

func (dv *defaultValue) get(fd pref.FieldDescriptor) pref.Value {
	// Return the zero value as the default if unpopulated.
	if !dv.has {
		if fd.Cardinality() == pref.Repeated {
			return pref.Value{}
		}
		switch fd.Kind() {
		case pref.BoolKind:
			return pref.ValueOf(false)
		case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind:
			return pref.ValueOf(int32(0))
		case pref.Int64Kind, pref.Sint64Kind, pref.Sfixed64Kind:
			return pref.ValueOf(int64(0))
		case pref.Uint32Kind, pref.Fixed32Kind:
			return pref.ValueOf(uint32(0))
		case pref.Uint64Kind, pref.Fixed64Kind:
			return pref.ValueOf(uint64(0))
		case pref.FloatKind:
			return pref.ValueOf(float32(0))
		case pref.DoubleKind:
			return pref.ValueOf(float64(0))
		case pref.StringKind:
			return pref.ValueOf(string(""))
		case pref.BytesKind:
			return pref.ValueOf([]byte(nil))
		case pref.EnumKind:
			return pref.ValueOf(fd.Enum().Values().Get(0).Number())
		}
	}

	if len(dv.bytes) > 0 && !bytes.Equal(dv.bytes, dv.val.Bytes()) {
		// TODO: Avoid panic if we're running with the race detector
		// and instead spawn a goroutine that periodically resets
		// this value back to the original to induce a race.
		panic("detected mutation on the default bytes")
	}
	return dv.val
}