package pgx

import (
	"encoding/hex"
	"fmt"
	"math"
	"strconv"
	"time"
	"unsafe"
)

// PostgreSQL oids for common types
const (
	BoolOid        = 16
	ByteaOid       = 17
	Int8Oid        = 20
	Int2Oid        = 21
	Int4Oid        = 23
	TextOid        = 25
	Float4Oid      = 700
	Float8Oid      = 701
	VarcharOid     = 1043
	DateOid        = 1082
	TimestampOid   = 1114
	TimestampTzOid = 1184
)

// PostgreSQL format codes
const (
	TextFormatCode   = 0
	BinaryFormatCode = 1
)

type SerializationError string

func (e SerializationError) Error() string {
	return string(e)
}

// Scanner is an interface used to decode values from the PostgreSQL server.
type Scanner interface {
	// Scan MUST check r.Type().DataType and r.Type().FormatCode before decoding.
	// It should not assume that it was called on a data type or format that it
	// understands.
	Scan(r *ValueReader) error
}

// Encoder is an interface used to encode values for transmission to the
// PostgreSQL server.
type Encoder interface {
	// Encode writes the value to w.
	//
	// If the value is NULL an int32(-1) should be written.
	//
	// Encode MUST check oid to see if the parameter data type is compatible. If
	// this is not done, the PostgreSQL server may detect the error if the
	// expected data size or format of the encoded data does not match. But if
	// the encoded data is a valid representation of the data type PostgreSQL
	// expects such as date and int4, incorrect data may be stored.
	Encode(w *WriteBuf, oid Oid) error

	// FormatCode returns the format that the encoder writes the value. It must be
	// either pgx.TextFormatCode or pgx.BinaryFormatCode.
	FormatCode() int16
}

// NullFloat32 represents an float4 that may be null.
// NullFloat32 implements the Scanner, TextEncoder, and BinaryEncoder interfaces
// so it may be used both as an argument to Query[Row] and a destination for
// Scan for prepared and unprepared queries.
//
// If Valid is false then the value is NULL.
type NullFloat32 struct {
	Float32 float32
	Valid   bool // Valid is true if Float32 is not NULL
}

func (n *NullFloat32) Scan(vr *ValueReader) error {
	if vr.Type().DataType != Float4Oid {
		return SerializationError(fmt.Sprintf("NullFloat32.Scan cannot decode OID %d", vr.Type().DataType))
	}

	if vr.Len() == -1 {
		n.Float32, n.Valid = 0, false
		return nil
	}
	n.Valid = true
	n.Float32 = decodeFloat4(vr)
	return vr.Err()
}

func (n NullFloat32) FormatCode() int16 { return BinaryFormatCode }

func (n NullFloat32) Encode(w *WriteBuf, oid Oid) error {
	if oid != Float4Oid {
		return SerializationError(fmt.Sprintf("NullFloat32.Encode cannot encode into OID %d", oid))
	}

	if !n.Valid {
		w.WriteInt32(-1)
		return nil
	}

	return encodeFloat4(w, n.Float32)
}

// NullFloat64 represents an float8 that may be null.
// NullFloat64 implements the Scanner, TextEncoder, and BinaryEncoder interfaces
// so it may be used both as an argument to Query[Row] and a destination for
// Scan for prepared and unprepared queries.
//
// If Valid is false then the value is NULL.
type NullFloat64 struct {
	Float64 float64
	Valid   bool // Valid is true if Float64 is not NULL
}

func (n *NullFloat64) Scan(vr *ValueReader) error {
	if vr.Type().DataType != Float8Oid {
		return SerializationError(fmt.Sprintf("NullFloat64.Scan cannot decode OID %d", vr.Type().DataType))
	}

	if vr.Len() == -1 {
		n.Float64, n.Valid = 0, false
		return nil
	}
	n.Valid = true
	n.Float64 = decodeFloat8(vr)
	return vr.Err()
}

func (n NullFloat64) FormatCode() int16 { return BinaryFormatCode }

func (n NullFloat64) Encode(w *WriteBuf, oid Oid) error {
	if oid != Float8Oid {
		return SerializationError(fmt.Sprintf("NullFloat64.EncodeBinary cannot encode into OID %d", oid))
	}

	if !n.Valid {
		w.WriteInt32(-1)
		return nil
	}

	return encodeFloat8(w, n.Float64)
}

// NullString represents an string that may be null. NullString implements
// the Scanner and TextEncoder interfaces so it may be used both as an
// argument to Query[Row] and a destination for Scan for prepared and
// unprepared queries.
//
// If Valid is false then the value is NULL.
type NullString struct {
	String string
	Valid  bool // Valid is true if Int64 is not NULL
}

func (s *NullString) Scan(vr *ValueReader) error {
	// Not checking oid as so we can scan anything into into a NullString - may revisit this decision later

	if vr.Len() == -1 {
		s.String, s.Valid = "", false
		return nil
	}

	s.Valid = true
	s.String = decodeText(vr)
	return vr.Err()
}

func (n NullString) FormatCode() int16 { return TextFormatCode }

func (s NullString) Encode(w *WriteBuf, oid Oid) error {
	if !s.Valid {
		w.WriteInt32(-1)
		return nil
	}

	return encodeText(w, s.String)
}

// NullInt16 represents an smallint that may be null.
// NullInt16 implements the Scanner, TextEncoder, and BinaryEncoder interfaces
// so it may be used both as an argument to Query[Row] and a destination for
// Scan for prepared and unprepared queries.
//
// If Valid is false then the value is NULL.
type NullInt16 struct {
	Int16 int16
	Valid bool // Valid is true if Int16 is not NULL
}

func (n *NullInt16) Scan(vr *ValueReader) error {
	if vr.Type().DataType != Int2Oid {
		return SerializationError(fmt.Sprintf("NullInt16.Scan cannot decode OID %d", vr.Type().DataType))
	}

	if vr.Len() == -1 {
		n.Int16, n.Valid = 0, false
		return nil
	}
	n.Valid = true
	n.Int16 = decodeInt2(vr)
	return vr.Err()
}

func (n NullInt16) FormatCode() int16 { return BinaryFormatCode }

func (n NullInt16) Encode(w *WriteBuf, oid Oid) error {
	if oid != Int2Oid {
		return SerializationError(fmt.Sprintf("NullInt16.Encode cannot encode into OID %d", oid))
	}

	if !n.Valid {
		w.WriteInt32(-1)
		return nil
	}

	return encodeInt2(w, n.Int16)
}

// NullInt32 represents an integer that may be null.
// NullInt32 implements the Scanner, TextEncoder, and BinaryEncoder interfaces
// so it may be used both as an argument to Query[Row] and a destination for
// Scan for prepared and unprepared queries.
//
// If Valid is false then the value is NULL.
type NullInt32 struct {
	Int32 int32
	Valid bool // Valid is true if Int64 is not NULL
}

func (n *NullInt32) Scan(vr *ValueReader) error {
	if vr.Type().DataType != Int4Oid {
		return SerializationError(fmt.Sprintf("NullInt32.Scan cannot decode OID %d", vr.Type().DataType))
	}

	if vr.Len() == -1 {
		n.Int32, n.Valid = 0, false
		return nil
	}
	n.Valid = true
	n.Int32 = decodeInt4(vr)
	return vr.Err()
}

func (n NullInt32) FormatCode() int16 { return BinaryFormatCode }

func (n NullInt32) Encode(w *WriteBuf, oid Oid) error {
	if oid != Int4Oid {
		return SerializationError(fmt.Sprintf("NullInt32.Encode cannot encode into OID %d", oid))
	}

	if !n.Valid {
		w.WriteInt32(-1)
		return nil
	}

	return encodeInt4(w, n.Int32)
}

// NullInt64 represents an bigint that may be null.
// NullInt64 implements the Scanner, TextEncoder, and BinaryEncoder interfaces
// so it may be used both as an argument to Query[Row] and a destination for
// Scan for prepared and unprepared queries.
//
// If Valid is false then the value is NULL.
type NullInt64 struct {
	Int64 int64
	Valid bool // Valid is true if Int64 is not NULL
}

func (n *NullInt64) Scan(vr *ValueReader) error {
	if vr.Type().DataType != Int8Oid {
		return SerializationError(fmt.Sprintf("NullInt64.Scan cannot decode OID %d", vr.Type().DataType))
	}

	if vr.Len() == -1 {
		n.Int64, n.Valid = 0, false
		return nil
	}
	n.Valid = true
	n.Int64 = decodeInt8(vr)
	return vr.Err()
}

func (n NullInt64) FormatCode() int16 { return BinaryFormatCode }

func (n NullInt64) Encode(w *WriteBuf, oid Oid) error {
	if oid != Int8Oid {
		return SerializationError(fmt.Sprintf("NullInt64.Encode cannot encode into OID %d", oid))
	}

	if !n.Valid {
		w.WriteInt32(-1)
		return nil
	}

	return encodeInt8(w, n.Int64)
}

// NullBool represents an bool that may be null.
// NullBool implements the Scanner, TextEncoder, and BinaryEncoder interfaces
// so it may be used both as an argument to Query[Row] and a destination for
// Scan for prepared and unprepared queries.
//
// If Valid is false then the value is NULL.
type NullBool struct {
	Bool  bool
	Valid bool // Valid is true if Bool is not NULL
}

func (n *NullBool) Scan(vr *ValueReader) error {
	if vr.Type().DataType != BoolOid {
		return SerializationError(fmt.Sprintf("NullBool.Scan cannot decode OID %d", vr.Type().DataType))
	}

	if vr.Len() == -1 {
		n.Bool, n.Valid = false, false
		return nil
	}
	n.Valid = true
	n.Bool = decodeBool(vr)
	return vr.Err()
}

func (n NullBool) FormatCode() int16 { return BinaryFormatCode }

func (n NullBool) Encode(w *WriteBuf, oid Oid) error {
	if oid != BoolOid {
		return SerializationError(fmt.Sprintf("NullBool.Encode cannot encode into OID %d", oid))
	}

	if !n.Valid {
		w.WriteInt32(-1)
		return nil
	}

	return encodeBool(w, n.Bool)
}

// NullTime represents an bigint that may be null.
// NullTime implements the Scanner, TextEncoder, and BinaryEncoder interfaces
// so it may be used both as an argument to Query[Row] and a destination for
// Scan for prepared and unprepared queries.
//
// If Valid is false then the value is NULL.
type NullTime struct {
	Time  time.Time
	Valid bool // Valid is true if Time is not NULL
}

func (n *NullTime) Scan(vr *ValueReader) error {
	if vr.Type().DataType != TimestampTzOid {
		return SerializationError(fmt.Sprintf("NullTime.Scan cannot decode OID %d", vr.Type().DataType))
	}

	if vr.Len() == -1 {
		n.Time, n.Valid = time.Time{}, false
		return nil
	}

	n.Valid = true
	n.Time = decodeTimestampTz(vr)

	return vr.Err()
}

func (n NullTime) FormatCode() int16 { return BinaryFormatCode }

func (n NullTime) Encode(w *WriteBuf, oid Oid) error {
	if oid != TimestampTzOid {
		return SerializationError(fmt.Sprintf("NullTime.Encode cannot encode into OID %d", oid))
	}

	if !n.Valid {
		w.WriteInt32(-1)
		return nil
	}

	return encodeTimestampTz(w, n.Time)
}

func decodeBool(vr *ValueReader) bool {
	if vr.Len() == -1 {
		vr.Fatal(ProtocolError("Cannot decode null into bool"))
		return false
	}

	switch vr.Type().FormatCode {
	case TextFormatCode:
		s := vr.ReadString(vr.Len())
		switch s {
		case "t":
			return true
		case "f":
			return false
		default:
			vr.Fatal(ProtocolError(fmt.Sprintf("Received invalid bool: %v", s)))
			return false
		}
	case BinaryFormatCode:
		if vr.Len() != 1 {
			vr.Fatal(ProtocolError(fmt.Sprintf("Received an invalid size for an bool: %d", vr.Len())))
			return false
		}
		b := vr.ReadByte()
		return b != 0
	default:
		vr.Fatal(ProtocolError(fmt.Sprintf("Unknown field description format code: %v", vr.Type().FormatCode)))
		return false
	}
}

func encodeBool(w *WriteBuf, value interface{}) error {
	v, ok := value.(bool)
	if !ok {
		return fmt.Errorf("Expected bool, received %T", value)
	}

	w.WriteInt32(1)

	var n byte
	if v {
		n = 1
	}

	w.WriteByte(n)

	return nil
}

func decodeInt8(vr *ValueReader) int64 {
	if vr.Len() == -1 {
		vr.Fatal(ProtocolError("Cannot decode null into int64"))
		return 0
	}

	if vr.Type().DataType != Int8Oid {
		vr.Fatal(ProtocolError(fmt.Sprintf("Expected type oid %v but received type oid %v", Int8Oid, vr.Type().DataType)))
		return 0
	}

	switch vr.Type().FormatCode {
	case TextFormatCode:
		s := vr.ReadString(vr.Len())
		n, err := strconv.ParseInt(s, 10, 64)
		if err != nil {
			vr.Fatal(ProtocolError(fmt.Sprintf("Received invalid int8: %v", s)))
			return 0
		}
		return n
	case BinaryFormatCode:
		if vr.Len() != 8 {
			vr.Fatal(ProtocolError(fmt.Sprintf("Received an invalid size for an int8: %d", vr.Len())))
			return 0
		}
		return vr.ReadInt64()
	default:
		vr.Fatal(ProtocolError(fmt.Sprintf("Unknown field description format code: %v", vr.Type().FormatCode)))
		return 0
	}
}

func encodeInt8(w *WriteBuf, value interface{}) error {
	var v int64
	switch value := value.(type) {
	case int8:
		v = int64(value)
	case uint8:
		v = int64(value)
	case int16:
		v = int64(value)
	case uint16:
		v = int64(value)
	case int32:
		v = int64(value)
	case uint32:
		v = int64(value)
	case int64:
		v = int64(value)
	case uint64:
		if value > math.MaxInt64 {
			return fmt.Errorf("uint64 %d is larger than max int64 %d", value, math.MaxInt64)
		}
		v = int64(value)
	case int:
		v = int64(value)
	default:
		return fmt.Errorf("Expected integer representable in int64, received %T %v", value, value)
	}

	w.WriteInt32(8)
	w.WriteInt64(v)

	return nil
}

func decodeInt2(vr *ValueReader) int16 {
	if vr.Len() == -1 {
		vr.Fatal(ProtocolError("Cannot decode null into int16"))
		return 0
	}

	if vr.Type().DataType != Int2Oid {
		vr.Fatal(ProtocolError(fmt.Sprintf("Expected type oid %v but received type oid %v", Int2Oid, vr.Type().DataType)))
		return 0
	}

	switch vr.Type().FormatCode {
	case TextFormatCode:
		s := vr.ReadString(vr.Len())
		n, err := strconv.ParseInt(s, 10, 16)
		if err != nil {
			vr.Fatal(ProtocolError(fmt.Sprintf("Received invalid int2: %v", s)))
			return 0
		}
		return int16(n)
	case BinaryFormatCode:
		if vr.Len() != 2 {
			vr.Fatal(ProtocolError(fmt.Sprintf("Received an invalid size for an int2: %d", vr.Len())))
			return 0
		}
		return vr.ReadInt16()
	default:
		vr.Fatal(ProtocolError(fmt.Sprintf("Unknown field description format code: %v", vr.Type().FormatCode)))
		return 0
	}
}

func encodeInt2(w *WriteBuf, value interface{}) error {
	var v int16
	switch value := value.(type) {
	case int8:
		v = int16(value)
	case uint8:
		v = int16(value)
	case int16:
		v = int16(value)
	case uint16:
		if value > math.MaxInt16 {
			return fmt.Errorf("%T %d is larger than max int16 %d", value, value, math.MaxInt16)
		}
		v = int16(value)
	case int32:
		if value > math.MaxInt16 {
			return fmt.Errorf("%T %d is larger than max int16 %d", value, value, math.MaxInt16)
		}
		v = int16(value)
	case uint32:
		if value > math.MaxInt16 {
			return fmt.Errorf("%T %d is larger than max int16 %d", value, value, math.MaxInt16)
		}
		v = int16(value)
	case int64:
		if value > math.MaxInt16 {
			return fmt.Errorf("%T %d is larger than max int16 %d", value, value, math.MaxInt16)
		}
		v = int16(value)
	case uint64:
		if value > math.MaxInt16 {
			return fmt.Errorf("%T %d is larger than max int16 %d", value, value, math.MaxInt16)
		}
		v = int16(value)
	case int:
		if value > math.MaxInt16 {
			return fmt.Errorf("%T %d is larger than max int16 %d", value, value, math.MaxInt16)
		}
		v = int16(value)
	default:
		return fmt.Errorf("Expected integer representable in int16, received %T %v", value, value)
	}

	w.WriteInt32(2)
	w.WriteInt16(v)

	return nil
}

func decodeInt4(vr *ValueReader) int32 {
	if vr.Len() == -1 {
		vr.Fatal(ProtocolError("Cannot decode null into int32"))
		return 0
	}

	if vr.Type().DataType != Int4Oid {
		vr.Fatal(ProtocolError(fmt.Sprintf("Expected type oid %v but received type oid %v", Int4Oid, vr.Type().DataType)))
		return 0
	}

	switch vr.Type().FormatCode {
	case TextFormatCode:
		s := vr.ReadString(vr.Len())
		n, err := strconv.ParseInt(s, 10, 32)
		if err != nil {
			vr.Fatal(ProtocolError(fmt.Sprintf("Received invalid int4: %v", s)))
		}
		return int32(n)
	case BinaryFormatCode:
		if vr.Len() != 4 {
			vr.Fatal(ProtocolError(fmt.Sprintf("Received an invalid size for an int4: %d", vr.Len())))
			return 0
		}
		return vr.ReadInt32()
	default:
		vr.Fatal(ProtocolError(fmt.Sprintf("Unknown field description format code: %v", vr.Type().FormatCode)))
		return 0
	}
}

func encodeInt4(w *WriteBuf, value interface{}) error {
	var v int32
	switch value := value.(type) {
	case int8:
		v = int32(value)
	case uint8:
		v = int32(value)
	case int16:
		v = int32(value)
	case uint16:
		v = int32(value)
	case int32:
		v = int32(value)
	case uint32:
		if value > math.MaxInt32 {
			return fmt.Errorf("%T %d is larger than max int64 %d", value, value, math.MaxInt32)
		}
		v = int32(value)
	case int64:
		if value > math.MaxInt32 {
			return fmt.Errorf("%T %d is larger than max int64 %d", value, value, math.MaxInt32)
		}
		v = int32(value)
	case uint64:
		if value > math.MaxInt32 {
			return fmt.Errorf("%T %d is larger than max int64 %d", value, value, math.MaxInt32)
		}
		v = int32(value)
	case int:
		if value > math.MaxInt32 {
			return fmt.Errorf("%T %d is larger than max int64 %d", value, value, math.MaxInt32)
		}
		v = int32(value)
	default:
		return fmt.Errorf("Expected integer representable in int32, received %T %v", value, value)
	}

	w.WriteInt32(4)
	w.WriteInt32(v)

	return nil
}

func decodeFloat4(vr *ValueReader) float32 {
	if vr.Len() == -1 {
		vr.Fatal(ProtocolError("Cannot decode null into float32"))
		return 0
	}

	switch vr.Type().FormatCode {
	case TextFormatCode:
		s := vr.ReadString(vr.Len())
		n, err := strconv.ParseFloat(s, 32)
		if err != nil {
			vr.Fatal(ProtocolError(fmt.Sprintf("Received invalid float4: %v", s)))
			return 0
		}
		return float32(n)
	case BinaryFormatCode:
		if vr.Len() != 4 {
			vr.Fatal(ProtocolError(fmt.Sprintf("Received an invalid size for an float4: %d", vr.Len())))
			return 0
		}

		i := vr.ReadInt32()
		p := unsafe.Pointer(&i)
		return *(*float32)(p)
	default:
		vr.Fatal(ProtocolError(fmt.Sprintf("Unknown field description format code: %v", vr.Type().FormatCode)))
		return 0
	}
}

func encodeFloat4(w *WriteBuf, value interface{}) error {
	var v float32
	switch value := value.(type) {
	case float32:
		v = float32(value)
	case float64:
		if value > math.MaxFloat32 {
			return fmt.Errorf("%T %f is larger than max float32 %f", value, math.MaxFloat32)
		}
		v = float32(value)
	default:
		return fmt.Errorf("Expected float representable in float32, received %T %v", value, value)
	}

	w.WriteInt32(4)

	p := unsafe.Pointer(&v)
	w.WriteInt32(*(*int32)(p))

	return nil
}

func decodeFloat8(vr *ValueReader) float64 {
	if vr.Len() == -1 {
		vr.Fatal(ProtocolError("Cannot decode null into float64"))
		return 0
	}

	switch vr.Type().FormatCode {
	case TextFormatCode:
		s := vr.ReadString(vr.Len())
		v, err := strconv.ParseFloat(s, 64)
		if err != nil {
			vr.Fatal(ProtocolError(fmt.Sprintf("Received invalid float8: %v", s)))
			return 0
		}
		return v
	case BinaryFormatCode:
		if vr.Len() != 8 {
			vr.Fatal(ProtocolError(fmt.Sprintf("Received an invalid size for an float8: %d", vr.Len())))
			return 0
		}

		i := vr.ReadInt64()
		p := unsafe.Pointer(&i)
		return *(*float64)(p)
	default:
		vr.Fatal(ProtocolError(fmt.Sprintf("Unknown field description format code: %v", vr.Type().FormatCode)))
		return 0
	}
}

func encodeFloat8(w *WriteBuf, value interface{}) error {
	var v float64
	switch value := value.(type) {
	case float32:
		v = float64(value)
	case float64:
		v = float64(value)
	default:
		return fmt.Errorf("Expected float representable in float64, received %T %v", value, value)
	}

	w.WriteInt32(8)

	p := unsafe.Pointer(&v)
	w.WriteInt64(*(*int64)(p))

	return nil
}

func decodeText(vr *ValueReader) string {
	if vr.Len() == -1 {
		vr.Fatal(ProtocolError("Cannot decode null into string"))
		return ""
	}

	return vr.ReadString(vr.Len())
}

func encodeText(w *WriteBuf, value interface{}) error {
	s, ok := value.(string)
	if !ok {
		return fmt.Errorf("Expected string, received %T", value)
	}

	w.WriteInt32(int32(len(s)))
	w.WriteBytes([]byte(s))

	return nil
}

func decodeBytea(vr *ValueReader) []byte {
	if vr.Len() == -1 {
		return nil
	}

	switch vr.Type().FormatCode {
	case TextFormatCode:
		s := vr.ReadString(vr.Len())
		b, err := hex.DecodeString(s[2:])
		if err != nil {
			vr.Fatal(ProtocolError(fmt.Sprintf("Can't decode byte array: %v - %v", err, s)))
			return nil
		}
		return b
	case BinaryFormatCode:
		return vr.ReadBytes(vr.Len())
	default:
		vr.Fatal(ProtocolError(fmt.Sprintf("Unknown field description format code: %v", vr.Type().FormatCode)))
		return nil
	}
}

func encodeBytea(w *WriteBuf, value interface{}) error {
	b, ok := value.([]byte)
	if !ok {
		return fmt.Errorf("Expected []byte, received %T", value)
	}

	w.WriteInt32(int32(len(b)))
	w.WriteBytes(b)

	return nil
}

func decodeDate(vr *ValueReader) time.Time {
	var zeroTime time.Time

	if vr.Len() == -1 {
		vr.Fatal(ProtocolError("Cannot decode null into time.Time"))
		return zeroTime
	}

	if vr.Type().DataType != DateOid {
		vr.Fatal(ProtocolError(fmt.Sprintf("Expected type oid %v but received type oid %v", DateOid, vr.Type().DataType)))
		return zeroTime
	}

	switch vr.Type().FormatCode {
	case TextFormatCode:
		s := vr.ReadString(vr.Len())
		t, err := time.ParseInLocation("2006-01-02", s, time.Local)
		if err != nil {
			vr.Fatal(ProtocolError(fmt.Sprintf("Can't decode date: %v", s)))
			return zeroTime
		}
		return t
	case BinaryFormatCode:
		if vr.Len() != 4 {
			vr.Fatal(ProtocolError(fmt.Sprintf("Received an invalid size for an date: %d", vr.Len())))
		}
		dayOffset := vr.ReadInt32()
		return time.Date(2000, 1, int(1+dayOffset), 0, 0, 0, 0, time.Local)
	default:
		vr.Fatal(ProtocolError(fmt.Sprintf("Unknown field description format code: %v", vr.Type().FormatCode)))
		return zeroTime
	}
}

func encodeDate(w *WriteBuf, value interface{}) error {
	t, ok := value.(time.Time)
	if !ok {
		return fmt.Errorf("Expected time.Time, received %T", value)
	}

	s := t.Format("2006-01-02")
	return encodeText(w, s)
}

const microsecFromUnixEpochToY2K = 946684800 * 1000000

func decodeTimestampTz(vr *ValueReader) time.Time {
	var zeroTime time.Time

	if vr.Len() == -1 {
		vr.Fatal(ProtocolError("Cannot decode null into time.Time"))
		return zeroTime
	}

	if vr.Type().DataType != TimestampTzOid {
		vr.Fatal(ProtocolError(fmt.Sprintf("Expected type oid %v but received type oid %v", TimestampTzOid, vr.Type().DataType)))
		return zeroTime
	}

	switch vr.Type().FormatCode {
	case TextFormatCode:
		s := vr.ReadString(vr.Len())
		t, err := time.Parse("2006-01-02 15:04:05.999999-07", s)
		if err != nil {
			vr.Fatal(ProtocolError(fmt.Sprintf("Can't decode timestamptz: %v - %v", err, s)))
			return zeroTime
		}
		return t
	case BinaryFormatCode:
		if vr.Len() != 8 {
			vr.Fatal(ProtocolError(fmt.Sprintf("Received an invalid size for an timestamptz: %d", vr.Len())))
		}
		microsecSinceY2K := vr.ReadInt64()
		microsecSinceUnixEpoch := microsecFromUnixEpochToY2K + microsecSinceY2K
		return time.Unix(microsecSinceUnixEpoch/1000000, (microsecSinceUnixEpoch%1000000)*1000)
	default:
		vr.Fatal(ProtocolError(fmt.Sprintf("Unknown field description format code: %v", vr.Type().FormatCode)))
		return zeroTime
	}
}

func encodeTimestampTz(w *WriteBuf, value interface{}) error {
	t, ok := value.(time.Time)
	if !ok {
		return fmt.Errorf("Expected time.Time, received %T", value)
	}

	microsecSinceUnixEpoch := t.Unix()*1000000 + int64(t.Nanosecond())/1000
	microsecSinceY2K := microsecSinceUnixEpoch - microsecFromUnixEpochToY2K

	w.WriteInt32(8)
	w.WriteInt64(microsecSinceY2K)

	return nil
}

func decodeTimestamp(vr *ValueReader) time.Time {
	var zeroTime time.Time

	if vr.Len() == -1 {
		vr.Fatal(ProtocolError("Cannot decode null into timestamp"))
		return zeroTime
	}

	if vr.Type().DataType != TimestampOid {
		vr.Fatal(ProtocolError(fmt.Sprintf("Expected type oid %v but received type oid %v", TimestampOid, vr.Type().DataType)))
		return zeroTime
	}

	switch vr.Type().FormatCode {
	case TextFormatCode:
		s := vr.ReadString(vr.Len())
		t, err := time.ParseInLocation("2006-01-02 15:04:05.999999", s, time.Local)
		if err != nil {
			vr.Fatal(ProtocolError(fmt.Sprintf("Can't decode timestamp: %v - %v", err, s)))
			return zeroTime
		}
		return t
	case BinaryFormatCode:
		vr.Fatal(ProtocolError("Can't decode binary timestamp"))
		return zeroTime
	default:
		vr.Fatal(ProtocolError(fmt.Sprintf("Unknown field description format code: %v", vr.Type().FormatCode)))
		return zeroTime
	}
}

func encodeTimestamp(w *WriteBuf, value interface{}) error {
	t, ok := value.(time.Time)
	if !ok {
		return fmt.Errorf("Expected time.Time, received %T", value)
	}

	s := t.Format("2006-01-02 15:04:05.999999")
	return encodeText(w, s)

	return nil
}