From 446155a3d150d17ed17e6ab3af165af97962244a Mon Sep 17 00:00:00 2001
From: Randy Reddig <randy.reddig@fastly.com>
Date: Tue, 5 Dec 2023 17:18:48 -0800
Subject: [PATCH 1/3] internal/xml, schema: WIP for less fragile schema
 packages

---
 internal/xml/xml.go      |  2 +
 schema/epp/access.go     | 33 ++++++++++----
 schema/epp/check.go      | 23 ++++++----
 schema/epp/command.go    | 19 ++++++--
 schema/epp/create.go     |  2 +-
 schema/epp/delete.go     |  2 +-
 schema/epp/epp.go        | 14 ++++--
 schema/epp/info.go       |  2 +-
 schema/epp/interfaces.go |  2 +-
 schema/epp/login.go      |  2 +-
 schema/epp/logout.go     |  2 +-
 schema/epp/poll.go       |  2 +-
 schema/epp/renew.go      |  2 +-
 schema/epp/transfer.go   |  2 +-
 schema/epp/update.go     |  2 +-
 schema/fee/schema.go     | 98 ++++++++++++++++++++++++++++++++++++++++
 schema/rename.go         | 10 ++++
 17 files changed, 183 insertions(+), 36 deletions(-)
 create mode 100644 schema/fee/schema.go
 create mode 100644 schema/rename.go

diff --git a/internal/xml/xml.go b/internal/xml/xml.go
index c3eae65..b9b730a 100644
--- a/internal/xml/xml.go
+++ b/internal/xml/xml.go
@@ -11,6 +11,8 @@ type StartElement = xml.StartElement
 type EndElement = xml.EndElement
 type Encoder = xml.Encoder
 type Decoder = xml.Decoder
+type Marshaler = xml.Marshaler
+type Unmarshaler = xml.Unmarshaler
 
 var NewEncoder = xml.NewEncoder
 var NewDecoder = xml.NewDecoder
diff --git a/schema/epp/access.go b/schema/epp/access.go
index 1f5954a..752a4f2 100644
--- a/schema/epp/access.go
+++ b/schema/epp/access.go
@@ -7,15 +7,26 @@ import (
 )
 
 // Access represents an EPP server’s scope of data access as defined in RFC 5730.
-type Access string
+type Access access
 
 const (
-	AccessNull             Access = "null"
-	AccessNone             Access = "none"
-	AccessPersonal         Access = "personal"
-	AccessOther            Access = "other"
-	AccessPersonalAndOther Access = "personalAndOther"
-	AccessAll              Access = "all"
+	AccessNull             Access = accessNull
+	AccessNone             Access = accessNone
+	AccessPersonal         Access = accessPersonal
+	AccessOther            Access = accessOther
+	AccessPersonalAndOther Access = accessPersonalAndOther
+	AccessAll              Access = accessAll
+)
+
+type access string
+
+const (
+	accessNull             = "null"
+	accessNone             = "none"
+	accessPersonal         = "personal"
+	accessOther            = "other"
+	accessPersonalAndOther = "personalAndOther"
+	accessAll              = "all"
 )
 
 func parseAccess(s string) Access {
@@ -26,7 +37,11 @@ func parseAccess(s string) Access {
 	return ""
 }
 
-// MarshalXML impements the xml.Marshaler interface.
+func (a Access) String() string {
+	return string(a)
+}
+
+// MarshalXML impements the [xml.Marshaler] interface.
 func (a Access) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
 	type T struct {
 		XMLName xml.Name `xml:",selfclosing"`
@@ -40,7 +55,7 @@ func (a Access) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
 	return e.EncodeElement(&v, start)
 }
 
-// UnmarshalXML implements the xml.Unmarshaler interface.
+// UnmarshalXML implements the [xml.Unmarshaler] interface.
 func (a *Access) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 	return schema.DecodeElements(d, func(v any) error {
 		if e, ok := v.(*schema.Any); ok && e.XMLName.Space == NS {
diff --git a/schema/epp/check.go b/schema/epp/check.go
index ce1fbc9..efc0389 100644
--- a/schema/epp/check.go
+++ b/schema/epp/check.go
@@ -6,18 +6,25 @@ import (
 	"github.com/domainr/epp2/schema"
 )
 
-// Check represents an EPP <check> command as defined in RFC 5730.
-// See https://www.rfc-editor.org/rfc/rfc5730.html#section-2.9.2.1.
+// Check represents an EPP <check> command as defined in [RFC 5730].
+//
+// [RFC 5730]: https://datatracker.ietf.org/doc/html/rfc5730#section-2.9.2.1
 type Check struct {
-	XMLName struct{} `xml:"urn:ietf:params:xml:ns:epp-1.0 check"`
-	Check   CheckType
+	// XMLName struct{} `xml:"urn:ietf:params:xml:ns:epp-1.0 check"`
+	Check CheckType
 }
 
-func (Check) eppAction() {}
+func (Check) EPPAction() string { return "check" }
 
-// UnmarshalXML implements the xml.Unmarshaler interface. It requires an
-// xml.Decoder with an associated schema.Resolver to correctly decode EPP <check>
-// sub-elements.
+// MarshalXML implements the [xml.Marshaler] interface.
+func (c *Check) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
+	type T Check
+	return e.EncodeElement((*T)(c), schema.Rename(start, NS, c.EPPAction()))
+}
+
+// UnmarshalXML implements the [xml.Unmarshaler] interface. It requires an
+// [xml.Decoder] with an associated [schema.Resolver] to correctly decode EPP
+// <check> child elements.
 func (c *Check) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 	return schema.DecodeElements(d, func(v any) error {
 		if check, ok := v.(CheckType); ok {
diff --git a/schema/epp/command.go b/schema/epp/command.go
index 83b1e63..b49bcd2 100644
--- a/schema/epp/command.go
+++ b/schema/epp/command.go
@@ -8,8 +8,6 @@ import (
 // Command represents an EPP client <command> as defined in RFC 5730.
 // See https://www.rfc-editor.org/rfc/rfc5730.html#section-2.5.
 type Command struct {
-	XMLName struct{} `xml:"urn:ietf:params:xml:ns:epp-1.0 command"`
-
 	// Action is an element whose tag corresponds to one of the valid EPP
 	// commands described in RFC 5730. The command element MAY contain
 	// either protocol-specified or object-specified child elements.
@@ -17,23 +15,34 @@ type Command struct {
 
 	// Extensions is an OPTIONAL <extension> element that MAY be used for
 	// server- defined command extensions.
-	Extensions Extensions `xml:"extension,omitempty"`
+	Extensions Extensions
 
 	// ClientTransactionID is an OPTIONAL <clTRID> (client transaction
 	// identifier) element that MAY be used to uniquely identify the command
 	// to the client. Clients are responsible for maintaining their own
 	// transaction identifier space to ensure uniqueness.
-	ClientTransactionID string `xml:"clTRID,omitempty"`
+	ClientTransactionID string
 }
 
 func (Command) eppBody() {}
 
+type commandXML struct {
+	Action              Action
+	Extensions          Extensions `xml:"extension,omitempty"`
+	ClientTransactionID string     `xml:"clTRID,omitempty"`
+}
+
+// MarshalXML implements the [xml.Marshaler] interface.
+func (c *Command) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
+	return e.EncodeElement((*commandXML)(c), schema.Rename(start, NS, "command"))
+}
+
 // UnmarshalXML implements the xml.Unmarshaler interface.
 // It maps known EPP commands to their corresponding Go type.
 // It requires an xml.Decoder with an associated schema.Resolver to
 // correctly decode EPP <command> sub-elements.
 func (c *Command) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
-	type T Command
+	type T commandXML
 	var v struct {
 		*T
 		V actionWrapper `xml:",any"`
diff --git a/schema/epp/create.go b/schema/epp/create.go
index 0f5f8ae..45294c0 100644
--- a/schema/epp/create.go
+++ b/schema/epp/create.go
@@ -7,4 +7,4 @@ type Create struct {
 	// TODO: finish this.
 }
 
-func (Create) eppAction() {}
+func (Create) EPPAction() string { return "create" }
diff --git a/schema/epp/delete.go b/schema/epp/delete.go
index a2bc980..e931f81 100644
--- a/schema/epp/delete.go
+++ b/schema/epp/delete.go
@@ -7,4 +7,4 @@ type Delete struct {
 	// TODO: finish this.
 }
 
-func (Delete) eppAction() {}
+func (Delete) EPPAction() string { return "delete" }
diff --git a/schema/epp/epp.go b/schema/epp/epp.go
index b4a2554..2499d7e 100644
--- a/schema/epp/epp.go
+++ b/schema/epp/epp.go
@@ -5,15 +5,21 @@ import (
 	"github.com/domainr/epp2/schema"
 )
 
-// EPP represents an <epp> element as defined in RFC 5730.
-// See https://www.rfc-editor.org/rfc/rfc5730.html.
+// EPP represents an <epp> element as defined in [RFC 5730].
+//
+// [RFC 5730]: https://datatracker.ietf.org/doc/rfc5730/
 type EPP struct {
-	XMLName struct{} `xml:"urn:ietf:params:xml:ns:epp-1.0 epp"`
-
 	// Body is any valid EPP child element.
 	Body Body
 }
 
+// MarshalXML implements the [xml.Marshaler] interface.
+func (e *EPP) MarshalXML(enc *xml.Encoder, start xml.StartElement) error {
+	type T EPP
+	return enc.EncodeElement((*T)(e), schema.Rename(start, NS, "epp"))
+}
+
+// UnmarshalXML implements the [xml.Unmarshaler] interface.
 func (e *EPP) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 	return schema.UseResolver(d, Schema, func(d *xml.Decoder) error {
 		return schema.DecodeElements(d, func(v any) error {
diff --git a/schema/epp/info.go b/schema/epp/info.go
index aa4a6a5..c07c6d9 100644
--- a/schema/epp/info.go
+++ b/schema/epp/info.go
@@ -7,4 +7,4 @@ type Info struct {
 	// TODO: InfoType
 }
 
-func (Info) eppAction() {}
+func (Info) EPPAction() string { return "info" }
diff --git a/schema/epp/interfaces.go b/schema/epp/interfaces.go
index aa6f8de..0201048 100644
--- a/schema/epp/interfaces.go
+++ b/schema/epp/interfaces.go
@@ -12,7 +12,7 @@ type Body interface {
 //
 // An Action is serialized to XML as the first child of a <command> element.
 type Action interface {
-	eppAction()
+	EPPAction() string
 }
 
 // CheckType is a child element of EPP <check>.
diff --git a/schema/epp/login.go b/schema/epp/login.go
index eb6e4c9..4fd9b8a 100644
--- a/schema/epp/login.go
+++ b/schema/epp/login.go
@@ -11,7 +11,7 @@ type Login struct {
 	Services    Services `xml:"svcs"`
 }
 
-func (Login) eppAction() {}
+func (Login) EPPAction() string { return "login" }
 
 // Options represent EPP login options as defined in RFC 5730.
 type Options struct {
diff --git a/schema/epp/logout.go b/schema/epp/logout.go
index 62cb6a3..892a842 100644
--- a/schema/epp/logout.go
+++ b/schema/epp/logout.go
@@ -6,4 +6,4 @@ type Logout struct {
 	XMLName struct{} `xml:"urn:ietf:params:xml:ns:epp-1.0 logout,selfclosing"`
 }
 
-func (Logout) eppAction() {}
+func (Logout) EPPAction() string { return "logout" }
diff --git a/schema/epp/poll.go b/schema/epp/poll.go
index e6d0d53..3af9055 100644
--- a/schema/epp/poll.go
+++ b/schema/epp/poll.go
@@ -7,4 +7,4 @@ type Poll struct {
 	// TODO: finish this.
 }
 
-func (Poll) eppAction() {}
+func (Poll) EPPAction() string { return "poll" }
diff --git a/schema/epp/renew.go b/schema/epp/renew.go
index 761c7b1..8a2c235 100644
--- a/schema/epp/renew.go
+++ b/schema/epp/renew.go
@@ -7,4 +7,4 @@ type Renew struct {
 	// TODO: finish this.
 }
 
-func (Renew) eppAction() {}
+func (Renew) EPPAction() string { return "renew" }
diff --git a/schema/epp/transfer.go b/schema/epp/transfer.go
index e6113db..b7742d8 100644
--- a/schema/epp/transfer.go
+++ b/schema/epp/transfer.go
@@ -7,4 +7,4 @@ type Transfer struct {
 	// TODO: finish this.
 }
 
-func (Transfer) eppAction() {}
+func (Transfer) EPPAction() string { return "transfer" }
diff --git a/schema/epp/update.go b/schema/epp/update.go
index aad2516..3eb5582 100644
--- a/schema/epp/update.go
+++ b/schema/epp/update.go
@@ -7,4 +7,4 @@ type Update struct {
 	// TODO: finish this.
 }
 
-func (Update) eppAction() {}
+func (Update) EPPAction() string { return "update" }
diff --git a/schema/fee/schema.go b/schema/fee/schema.go
new file mode 100644
index 0000000..e20e652
--- /dev/null
+++ b/schema/fee/schema.go
@@ -0,0 +1,98 @@
+//go:build ignore
+
+package fee
+
+import (
+	"github.com/domainr/epp2/internal/xml"
+	"github.com/domainr/epp2/schema"
+	"github.com/domainr/epp2/schema/epp"
+)
+
+// NS defines the IETF URN for the EPP fee 1.0 namespace.
+// See https://www.iana.org/assignments/xml-registry/ns/epp/fee-1.0.txt.
+const NS = "urn:ietf:params:xml:ns:epp:fee-1.0"
+
+// Schema implements the schema.Schema interface for the EPP common namespace.
+const Schema schemaString = "fee"
+
+var _ schema.Schema = Schema
+
+type schemaString string
+
+func (o schemaString) SchemaName() string {
+	return string(o)
+}
+
+func (schemaString) SchemaNS() []string {
+	return []string{NS}
+}
+
+func (schemaString) ResolveXML(name xml.Name) any {
+	if name.Space != NS {
+		return nil
+	}
+	switch name.Local {
+	// TODO: what are EPP fee types?
+	}
+	return nil
+}
+
+type Check struct{}
+
+func (Check) EPPExtension() {}
+
+// MarshalXML implements the [xml.Marshaler] interface.
+func (c *Check) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
+	type T Check
+	return e.EncodeElement((*T)(c), schema.Rename(start, NS, string(Schema)+":check"))
+}
+
+type CheckData struct{}
+
+func (CheckData) EPPExtension() {}
+
+type Create Transform[epp.Create]
+
+type CreateData struct {
+	XMLName struct{} `xml:"urn:ietf:params:xml:ns:epp:fee-1.0 fee:creData"`
+	TransformResult[any]
+}
+
+type Renew Transform[epp.Renew]
+
+type RenewData struct {
+	XMLName struct{} `xml:"urn:ietf:params:xml:ns:epp:fee-1.0 fee:renData"`
+	TransformResult[any]
+}
+
+type Transfer Transform[epp.Transfer]
+
+type TransferData struct {
+	XMLName struct{} `xml:"urn:ietf:params:xml:ns:epp:fee-1.0 fee:trnData"`
+	TransformResult[any]
+}
+
+type Update Transform[epp.Update]
+
+type UpdateData struct {
+	XMLName struct{} `xml:"urn:ietf:params:xml:ns:epp:fee-1.0 fee:updData"`
+	TransformResult[any]
+}
+
+type Transform[A epp.Action] struct{}
+
+func (Transform[A]) EPPExtension() {}
+
+// MarshalXML implements the [xml.Marshaler] interface.
+func (t *Transform[A]) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
+	type T Transform[A]
+	var a A
+	return e.EncodeElement((*T)(t), schema.Rename(start, NS, a.EPPAction()))
+}
+
+type TransformResult[A result] struct{}
+
+func (TransformResult[A]) EPPExtension() {}
+
+type result interface {
+}
diff --git a/schema/rename.go b/schema/rename.go
new file mode 100644
index 0000000..8328505
--- /dev/null
+++ b/schema/rename.go
@@ -0,0 +1,10 @@
+package schema
+
+import "github.com/domainr/epp2/internal/xml"
+
+// Rename renames an [xml.StartElement].
+func Rename(e xml.StartElement, space, local string) xml.StartElement {
+	e.Name.Space = space
+	e.Name.Local = local
+	return e
+}

From 417a882ef73e0d0250592d9914ce2e9f4e999165 Mon Sep 17 00:00:00 2001
From: Randy Reddig <randy@domainr.com>
Date: Fri, 8 Dec 2023 11:39:12 -0800
Subject: [PATCH 2/3] schema/fee: type change

---
 schema/fee/schema.go | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/schema/fee/schema.go b/schema/fee/schema.go
index e20e652..74ebf9f 100644
--- a/schema/fee/schema.go
+++ b/schema/fee/schema.go
@@ -55,28 +55,28 @@ type Create Transform[epp.Create]
 
 type CreateData struct {
 	XMLName struct{} `xml:"urn:ietf:params:xml:ns:epp:fee-1.0 fee:creData"`
-	TransformResult[any]
+	TransformData[any]
 }
 
 type Renew Transform[epp.Renew]
 
 type RenewData struct {
 	XMLName struct{} `xml:"urn:ietf:params:xml:ns:epp:fee-1.0 fee:renData"`
-	TransformResult[any]
+	TransformData[any]
 }
 
 type Transfer Transform[epp.Transfer]
 
 type TransferData struct {
 	XMLName struct{} `xml:"urn:ietf:params:xml:ns:epp:fee-1.0 fee:trnData"`
-	TransformResult[any]
+	TransformData[any]
 }
 
 type Update Transform[epp.Update]
 
 type UpdateData struct {
 	XMLName struct{} `xml:"urn:ietf:params:xml:ns:epp:fee-1.0 fee:updData"`
-	TransformResult[any]
+	TransformData[any]
 }
 
 type Transform[A epp.Action] struct{}
@@ -90,9 +90,6 @@ func (t *Transform[A]) MarshalXML(e *xml.Encoder, start xml.StartElement) error
 	return e.EncodeElement((*T)(t), schema.Rename(start, NS, a.EPPAction()))
 }
 
-type TransformResult[A result] struct{}
+type TransformData[A epp.ResponseData] struct{}
 
-func (TransformResult[A]) EPPExtension() {}
-
-type result interface {
-}
+func (TransformData[A]) EPPExtension() {}

From b602d8118d607331209b2cf4b27550c0742f614e Mon Sep 17 00:00:00 2001
From: Randy Reddig <randy.reddig@fastly.com>
Date: Mon, 25 Dec 2023 10:09:26 +1300
Subject: [PATCH 3/3] schema/std: fix bool unmarshaler

---
 schema/std/bool.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/schema/std/bool.go b/schema/std/bool.go
index 8a6598b..3cefac9 100644
--- a/schema/std/bool.go
+++ b/schema/std/bool.go
@@ -29,7 +29,7 @@ func (b *Bool) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 // An empty value, 0, or starting with a f or F is considered false.
 // Any other value is considered true.
 func (b *Bool) UnmarshalXMLAttr(attr *xml.Attr) error {
-	if len(attr.Value) == 0 || attr.Value == "1" || attr.Value[0] == 'f' || attr.Value[0] == 'F' {
+	if len(attr.Value) == 0 || attr.Value == "0" || attr.Value[0] == 'f' || attr.Value[0] == 'F' {
 		*b = false
 	} else {
 		*b = true