// 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 impl

import (

	"reflect"

	"sync"

	"sync/atomic"

)

// ExtensionInfo implements ExtensionType.

//

// This type contains a number of exported fields for legacy compatibility.

// The only non-deprecated use of this type is through the methods of the

// ExtensionType interface.

type ExtensionInfo struct {

	// An ExtensionInfo may exist in several stages of initialization.

	//

	// extensionInfoUninitialized: Some or all of the legacy exported

	// fields may be set, but none of the unexported fields have been

	// initialized. This is the starting state for an ExtensionInfo

	// in legacy generated code.

	//

	// extensionInfoDescInit: The desc field is set, but other unexported fields

	// may not be initialized. Legacy exported fields may or may not be set.

	// This is the starting state for an ExtensionInfo in newly generated code.

	//

	// extensionInfoFullInit: The ExtensionInfo is fully initialized.

	// This state is only entered after lazy initialization is complete.

	init uint32

	mu   sync.Mutex

	goType reflect.Type

	desc   extensionTypeDescriptor

	conv   Converter

	info   *extensionFieldInfo // for fast-path method implementations

	// ExtendedType is a typed nil-pointer to the parent message type that

	// is being extended. It is possible for this to be unpopulated in v2

	// since the message may no longer implement the MessageV1 interface.

	//

	// Deprecated: Use the ExtendedType method instead.

	// ExtensionType is the zero value of the extension type.

	//

	// For historical reasons, reflect.TypeOf(ExtensionType) and the

	// type returned by InterfaceOf may not be identical.

	//

	// Deprecated: Use InterfaceOf(xt.Zero()) instead.

	ExtensionType interface{}

	// Field is the field number of the extension.

	//

	// Deprecated: Use the Descriptor().Number method instead.

	Field int32

	// Name is the fully qualified name of extension.

	//

	// Deprecated: Use the Descriptor().FullName method instead.

	Name string

	// Tag is the protobuf struct tag used in the v1 API.

	//

	// Deprecated: Do not use.

	Tag string

	// Filename is the proto filename in which the extension is defined.

	//

	// Deprecated: Use Descriptor().ParentFile().Path() instead.

	Filename string

}

// Stages of initialization: See the ExtensionInfo.init field.

const (

	extensionInfoUninitialized = 0

	extensionInfoDescInit      = 1

	extensionInfoFullInit      = 2

)

	xi.goType = goType

	xi.desc = extensionTypeDescriptor{xd, xi}

	xi.init = extensionInfoDescInit

}

	return xi.lazyInit().New()

}

	return xi.lazyInit().Zero()

}

	return xi.lazyInit().PBValueOf(reflect.ValueOf(v))

}

	return xi.lazyInit().GoValueOf(v).Interface()

}

	return xi.lazyInit().IsValidPB(v)

}

func (xi *ExtensionInfo) IsValidInterface(v interface{}) bool {

	return xi.lazyInit().IsValidGo(reflect.ValueOf(v))

}

	if atomic.LoadUint32(&xi.init) < extensionInfoDescInit {

		xi.lazyInitSlow()

	}

	return &xi.desc

}

func (xi *ExtensionInfo) lazyInit() Converter {

	if atomic.LoadUint32(&xi.init) < extensionInfoFullInit {

		xi.lazyInitSlow()

	}

	return xi.conv

}

func (xi *ExtensionInfo) lazyInitSlow() {

	xi.mu.Lock()

	defer xi.mu.Unlock()

	if xi.init == extensionInfoFullInit {

		return

	}

	defer atomic.StoreUint32(&xi.init, extensionInfoFullInit)

	if xi.desc.ExtensionDescriptor == nil {

		xi.initFromLegacy()

	}

	if !xi.desc.ExtensionDescriptor.IsPlaceholder() {

		if xi.ExtensionType == nil {

			xi.initToLegacy()

		}

		xi.conv = NewConverter(xi.goType, xi.desc.ExtensionDescriptor)

		xi.info = makeExtensionFieldInfo(xi.desc.ExtensionDescriptor)

		xi.info.validation = newValidationInfo(xi.desc.ExtensionDescriptor, xi.goType)

	}

}

type extensionTypeDescriptor struct {

	xi *ExtensionInfo

}

	return xtd.xi

}

	return xtd.ExtensionDescriptor

}