// 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 impl

import (

	"fmt"

	"reflect"

	"strconv"

	"google.golang.org/protobuf/encoding/prototext"

	"google.golang.org/protobuf/internal/errors"

	"google.golang.org/protobuf/proto"

)

// Export is a zero-length named type that exists only to export a set of

// functions that we do not want to appear in godoc.

type Export struct{}

// NewError formats a string according to the format specifier and arguments and

// returns an error that has a "proto" prefix.

func (Export) NewError(f string, x ...interface{}) error {

	return errors.New(f, x...)

}

// enum is any enum type generated by protoc-gen-go

// and must be a named int32 type.

type enum = interface{}

// EnumOf returns the protoreflect.Enum interface over e.

// It returns nil if e is nil.

	switch e := e.(type) {

	case nil:

		return nil

		return e

	default:

		return legacyWrapEnum(reflect.ValueOf(e))

	}

}

// EnumDescriptorOf returns the protoreflect.EnumDescriptor for e.

// It returns nil if e is nil.

	switch e := e.(type) {

	case nil:

		return nil

		return e.Descriptor()

	default:

		return LegacyLoadEnumDesc(reflect.TypeOf(e))

	}

}

// EnumTypeOf returns the protoreflect.EnumType for e.

// It returns nil if e is nil.

	switch e := e.(type) {

	case nil:

		return nil

		return e.Type()

	default:

		return legacyLoadEnumType(reflect.TypeOf(e))

	}

}

// EnumStringOf returns the enum value as a string, either as the name if

// the number is resolvable, or the number formatted as a string.

	ev := ed.Values().ByNumber(n)

	if ev != nil {

		return string(ev.Name())

	}

	return strconv.Itoa(int(n))

}

// message is any message type generated by protoc-gen-go

// and must be a pointer to a named struct type.

type message = interface{}

// legacyMessageWrapper wraps a v2 message as a v1 message.

func (m legacyMessageWrapper) Reset()         { proto.Reset(m.m) }

func (m legacyMessageWrapper) String() string { return Export{}.MessageStringOf(m.m) }

func (m legacyMessageWrapper) ProtoMessage()  {}

// ProtoMessageV1Of converts either a v1 or v2 message to a v1 message.

// It returns nil if m is nil.

	switch mv := m.(type) {

	case nil:

		return nil

		return mv

	case unwrapper:

		return Export{}.ProtoMessageV1Of(mv.protoUnwrap())

		return legacyMessageWrapper{mv}

	default:

		panic(fmt.Sprintf("message %T is neither a v1 or v2 Message", m))

	}

}

	switch mv := m.(type) {

	case nil:

		return nil

		return mv

	case legacyMessageWrapper:

		return mv.m

		return nil

	default:

		panic(fmt.Sprintf("message %T is neither a v1 or v2 Message", m))

	}

}

// ProtoMessageV2Of converts either a v1 or v2 message to a v2 message.

// It returns nil if m is nil.

	if m == nil {

		return nil

	}

	if mv := (Export{}).protoMessageV2Of(m); mv != nil {

		return mv

	}

	return legacyWrapMessage(reflect.ValueOf(m)).Interface()

}

// MessageOf returns the protoreflect.Message interface over m.

// It returns nil if m is nil.

	if m == nil {

		return nil

	}

	if mv := (Export{}).protoMessageV2Of(m); mv != nil {

		return mv.ProtoReflect()

	}

	return legacyWrapMessage(reflect.ValueOf(m))

}

// MessageDescriptorOf returns the protoreflect.MessageDescriptor for m.

// It returns nil if m is nil.

	if m == nil {

		return nil

	}

	if mv := (Export{}).protoMessageV2Of(m); mv != nil {

		return mv.ProtoReflect().Descriptor()

	}

	return LegacyLoadMessageDesc(reflect.TypeOf(m))

}

// MessageTypeOf returns the protoreflect.MessageType for m.

// It returns nil if m is nil.

	if m == nil {

		return nil

	}

	if mv := (Export{}).protoMessageV2Of(m); mv != nil {

		return mv.ProtoReflect().Type()

	}

	return legacyLoadMessageType(reflect.TypeOf(m), "")

}

// MessageStringOf returns the message value as a string,

// which is the message serialized in the protobuf text format.

	return prototext.MarshalOptions{Multiline: false}.Format(m)

}