// Copyright 2015 The Vanadium 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 vom

// Built-in type Ids
const (
	// Primitive types.
	WireIdBool       = typeId(1)
	WireIdByte       = typeId(2)
	WireIdString     = typeId(3)
	WireIdUint16     = typeId(4)
	WireIdUint32     = typeId(5)
	WireIdUint64     = typeId(6)
	WireIdInt16      = typeId(7)
	WireIdInt32      = typeId(8)
	WireIdInt64      = typeId(9)
	WireIdFloat32    = typeId(10)
	WireIdFloat64    = typeId(11)
	WireIdComplex64  = typeId(12)
	WireIdComplex128 = typeId(13)
	WireIdTypeObject = typeId(14)
	WireIdAny        = typeId(15)
	WireIdInt8       = typeId(16)

	// Other commonly used composites.
	WireIdByteList   = typeId(39)
	WireIdStringList = typeId(40)

	// The first user-defined typeId is 41.
	WireIdFirstUserType = typeId(41)
)

// typeId uniquely identifies a type definition within a vom stream.
type typeId uint64

// The wireType union is used to encode the payload part of each type message,
// using the regular rules for encoding union values.  But unlike our regular
// encoding, the type message for wireType itself (and its fields) are never
// encoded; we need to bootstrap the system.  Thus unlike regular values, the
// ordering of fields within the wire* types cannot be changed.
type wireType union {
	// FIELD INDICES MUST NOT BE CHANGED.
	NamedT    wireNamed    // INDEX = 0
	EnumT     wireEnum     // INDEX = 1
	ArrayT    wireArray    // INDEX = 2
	ListT     wireList     // INDEX = 3
	SetT      wireSet      // INDEX = 4
	MapT      wireMap      // INDEX = 5
	StructT   wireStruct   // INDEX = 6
	UnionT    wireUnion    // INDEX = 7
	OptionalT wireOptional // INDEX = 8
}

// wireNamed represents a type definition for named primitives.
type wireNamed struct {
	Name string
	Base typeId
}

// wireEnum represents an type definition for enum types.
type wireEnum struct {
	Name   string
	Labels []string
}

// wireArray represents an type definition for array types.
type wireArray struct {
	Name string
	Elem typeId
	Len  uint64
}

// wireList represents a type definition for list types.
type wireList struct {
	Name string
	Elem typeId
}

// wireSet represents a type definition for set types.
type wireSet struct {
	Name string
	Key  typeId
}

// wireMap represents a type definition for map types.
type wireMap struct {
	Name string
	Key  typeId
	Elem typeId
}

// wireField represents a field in a struct or union type.
type wireField struct {
	Name string
	Type typeId
}

// wireStruct represents a type definition for struct types.
type wireStruct struct {
	Name   string
	Fields []wireField
}

// wireUnion represents a type definition for union types.
type wireUnion struct {
	Name   string
	Fields []wireField
}

// wireOptional represents an type definition for optional types.
type wireOptional struct {
	Name string
	Elem typeId
}

// Control codes used in VOM wire format
//
//   region 1: 0x80...0xBF (64 entries)
//   region 2: 0xC0...0xDF (32 entries)
//   region 3: 0xE0...0xEF (16 entries)
const (
  WireCtrlNil = byte(0xe0) // Nil in optional or any
  WireCtrlEnd = byte(0xe1) // End of struct or union

  // Control codes for chunked messages.
  // Chunks in multi-chunk messages begin with one of these values.
  // Single-chunk messages do not use these control codes and instead begin with a
  // type id.
  WireCtrlValueFirstChunk = byte(0xe2) // First chunk in a multi-chunk value message
  WireCtrlValueChunk = byte(0xe3) // Continuation of a multi-chunk value message
  WireCtrlValueLastChunk = byte(0xe4) // Final chunk in a multi-chunk value message
  WireCtrlTypeFirstChunk = byte(0xe5) // First chunk in a multi-chunk type message
  WireCtrlTypeChunk = byte(0xe6) // Continuation of a multi-chunk type message
  WireCtrlTypeLastChunk = byte(0xe7) // Final chunk in a multi-chunk type message

  WireCtrlTypeIncomplete = byte(0xe8) // Marks that the type message is incomplete until future messages are received
)