Trying out paginated cursortoken variant [UNTESTED]

cursortoken/token.go

@@ -3,12 +3,16 @@ package cursortoken
 import (
 	"encoding/base32"
 	"encoding/json"
-	"go.mongodb.org/mongo-driver/bson/primitive"
 	"gogs.mikescher.com/BlackForestBytes/goext/exerr"
+	"strconv"
 	"strings"
 	"time"
 )
 
+type CursorToken interface {
+	Token() string
+}
+
 type Mode string
 
 const (
@@ -24,97 +28,6 @@ type Extra struct {
 	PageSize  *int
 }
 
-type CursorToken struct {
-	Mode               Mode
-	ValuePrimary       string
-	ValueSecondary     string
-	Direction          SortDirection
-	DirectionSecondary SortDirection
-	PageSize           int
-	Extra              Extra
-}
-
-type cursorTokenSerialize struct {
-	ValuePrimary       *string        `json:"v1,omitempty"`
-	ValueSecondary     *string        `json:"v2,omitempty"`
-	Direction          *SortDirection `json:"dir,omitempty"`
-	DirectionSecondary *SortDirection `json:"dir2,omitempty"`
-	PageSize           *int           `json:"size,omitempty"`
-
-	ExtraTimestamp *time.Time `json:"ts,omitempty"`
-	ExtraId        *string    `json:"id,omitempty"`
-	ExtraPage      *int       `json:"pg,omitempty"`
-	ExtraPageSize  *int       `json:"sz,omitempty"`
-}
-
-func Start() CursorToken {
-	return CursorToken{
-		Mode:               CTMStart,
-		ValuePrimary:       "",
-		ValueSecondary:     "",
-		Direction:          "",
-		DirectionSecondary: "",
-		PageSize:           0,
-		Extra:              Extra{},
-	}
-}
-
-func End() CursorToken {
-	return CursorToken{
-		Mode:               CTMEnd,
-		ValuePrimary:       "",
-		ValueSecondary:     "",
-		Direction:          "",
-		DirectionSecondary: "",
-		PageSize:           0,
-		Extra:              Extra{},
-	}
-}
-
-func (c *CursorToken) Token() string {
-	if c.Mode == CTMStart {
-		return "@start"
-	}
-	if c.Mode == CTMEnd {
-		return "@end"
-	}
-
-	// We kinda manually implement omitempty for the CursorToken here
-	// because omitempty does not work for time.Time and otherwise we would always
-	// get weird time values when decoding a token that initially didn't have an Timestamp set
-	// For this usecase we treat Unix=0 as an empty timestamp
-
-	sertok := cursorTokenSerialize{}
-
-	if c.ValuePrimary != "" {
-		sertok.ValuePrimary = &c.ValuePrimary
-	}
-	if c.ValueSecondary != "" {
-		sertok.ValueSecondary = &c.ValueSecondary
-	}
-	if c.Direction != "" {
-		sertok.Direction = &c.Direction
-	}
-	if c.DirectionSecondary != "" {
-		sertok.DirectionSecondary = &c.DirectionSecondary
-	}
-	if c.PageSize != 0 {
-		sertok.PageSize = &c.PageSize
-	}
-
-	sertok.ExtraTimestamp = c.Extra.Timestamp
-	sertok.ExtraId = c.Extra.Id
-	sertok.ExtraPage = c.Extra.Page
-	sertok.ExtraPageSize = c.Extra.PageSize
-
-	body, err := json.Marshal(sertok)
-	if err != nil {
-		panic(err)
-	}
-
-	return "tok_" + base32.StdEncoding.EncodeToString(body)
-}
-
 func Decode(tok string) (CursorToken, error) {
 	if tok == "" {
 		return Start(), nil
@@ -125,60 +38,56 @@ func Decode(tok string) (CursorToken, error) {
 	if strings.ToLower(tok) == "@end" {
 		return End(), nil
 	}
-
-	if !strings.HasPrefix(tok, "tok_") {
-		return CursorToken{}, exerr.New(exerr.TypeCursorTokenDecode, "could not decode token, missing prefix").Str("token", tok).Build()
+	if strings.ToLower(tok) == "$end" {
+		return PageEnd(), nil
+	}
+	if strings.HasPrefix(tok, "$") && len(tok) > 1 {
+		n, err := strconv.ParseInt(tok[1:], 10, 64)
+		if err != nil {
+			return nil, exerr.Wrap(err, "failed to deserialize token").Str("token", tok).WithType(exerr.TypeCursorTokenDecode).Build()
+		}
+		return Page(int(n)), nil
 	}
 
-	body, err := base32.StdEncoding.DecodeString(tok[len("tok_"):])
-	if err != nil {
-		return CursorToken{}, err
-	}
+	if strings.HasPrefix(tok, "tok_") {
 
-	var tokenDeserialize cursorTokenSerialize
-	err = json.Unmarshal(body, &tokenDeserialize)
-	if err != nil {
-		return CursorToken{}, exerr.Wrap(err, "failed to deserialize token").Str("token", tok).Build()
-	}
+		body, err := base32.StdEncoding.DecodeString(tok[len("tok_"):])
+		if err != nil {
+			return nil, err
+		}
 
-	token := CursorToken{Mode: CTMNormal}
+		var tokenDeserialize cursorTokenKeySortSerialize
+		err = json.Unmarshal(body, &tokenDeserialize)
+		if err != nil {
+			return nil, exerr.Wrap(err, "failed to deserialize token").Str("token", tok).WithType(exerr.TypeCursorTokenDecode).Build()
+		}
 
-	if tokenDeserialize.ValuePrimary != nil {
-		token.ValuePrimary = *tokenDeserialize.ValuePrimary
-	}
-	if tokenDeserialize.ValueSecondary != nil {
-		token.ValueSecondary = *tokenDeserialize.ValueSecondary
-	}
-	if tokenDeserialize.Direction != nil {
-		token.Direction = *tokenDeserialize.Direction
-	}
-	if tokenDeserialize.DirectionSecondary != nil {
-		token.DirectionSecondary = *tokenDeserialize.DirectionSecondary
-	}
-	if tokenDeserialize.PageSize != nil {
-		token.PageSize = *tokenDeserialize.PageSize
-	}
+		token := CTKeySort{Mode: CTMNormal}
 
-	token.Extra.Timestamp = tokenDeserialize.ExtraTimestamp
-	token.Extra.Id = tokenDeserialize.ExtraId
-	token.Extra.Page = tokenDeserialize.ExtraPage
-	token.Extra.PageSize = tokenDeserialize.ExtraPageSize
+		if tokenDeserialize.ValuePrimary != nil {
+			token.ValuePrimary = *tokenDeserialize.ValuePrimary
+		}
+		if tokenDeserialize.ValueSecondary != nil {
+			token.ValueSecondary = *tokenDeserialize.ValueSecondary
+		}
+		if tokenDeserialize.Direction != nil {
+			token.Direction = *tokenDeserialize.Direction
+		}
+		if tokenDeserialize.DirectionSecondary != nil {
+			token.DirectionSecondary = *tokenDeserialize.DirectionSecondary
+		}
+		if tokenDeserialize.PageSize != nil {
+			token.PageSize = *tokenDeserialize.PageSize
+		}
 
-	return token, nil
-}
+		token.Extra.Timestamp = tokenDeserialize.ExtraTimestamp
+		token.Extra.Id = tokenDeserialize.ExtraId
+		token.Extra.Page = tokenDeserialize.ExtraPage
+		token.Extra.PageSize = tokenDeserialize.ExtraPageSize
+
+		return token, nil
 
-func (c *CursorToken) ValuePrimaryObjectId() (primitive.ObjectID, bool) {
-	if oid, err := primitive.ObjectIDFromHex(c.ValuePrimary); err == nil {
-		return oid, true
 	} else {
-		return primitive.ObjectID{}, false
-	}
-}
-
-func (c *CursorToken) ValueSecondaryObjectId() (primitive.ObjectID, bool) {
-	if oid, err := primitive.ObjectIDFromHex(c.ValueSecondary); err == nil {
-		return oid, true
-	} else {
-		return primitive.ObjectID{}, false
+		return nil, exerr.New(exerr.TypeCursorTokenDecode, "could not decode token, missing/unknown prefix").Str("token", tok).Build()
 	}
 }

cursortoken/tokenKeySort.go

@@ -0,0 +1,128 @@
+package cursortoken
+
+import (
+	"encoding/base32"
+	"encoding/json"
+	"go.mongodb.org/mongo-driver/bson/primitive"
+	"time"
+)
+
+type CTKeySort struct {
+	Mode               Mode
+	ValuePrimary       string
+	ValueSecondary     string
+	Direction          SortDirection
+	DirectionSecondary SortDirection
+	PageSize           int
+	Extra              Extra
+}
+
+type cursorTokenKeySortSerialize struct {
+	ValuePrimary       *string        `json:"v1,omitempty"`
+	ValueSecondary     *string        `json:"v2,omitempty"`
+	Direction          *SortDirection `json:"dir,omitempty"`
+	DirectionSecondary *SortDirection `json:"dir2,omitempty"`
+	PageSize           *int           `json:"size,omitempty"`
+
+	ExtraTimestamp *time.Time `json:"ts,omitempty"`
+	ExtraId        *string    `json:"id,omitempty"`
+	ExtraPage      *int       `json:"pg,omitempty"`
+	ExtraPageSize  *int       `json:"sz,omitempty"`
+}
+
+func NewKeySortToken(valuePrimary string, valueSecondary string, direction SortDirection, directionSecondary SortDirection, pageSize int, extra Extra) CursorToken {
+	return CTKeySort{
+		Mode:               CTMNormal,
+		ValuePrimary:       valuePrimary,
+		ValueSecondary:     valueSecondary,
+		Direction:          direction,
+		DirectionSecondary: directionSecondary,
+		PageSize:           pageSize,
+		Extra:              extra,
+	}
+}
+
+func Start() CursorToken {
+	return CTKeySort{
+		Mode:               CTMStart,
+		ValuePrimary:       "",
+		ValueSecondary:     "",
+		Direction:          "",
+		DirectionSecondary: "",
+		PageSize:           0,
+		Extra:              Extra{},
+	}
+}
+
+func End() CursorToken {
+	return CTKeySort{
+		Mode:               CTMEnd,
+		ValuePrimary:       "",
+		ValueSecondary:     "",
+		Direction:          "",
+		DirectionSecondary: "",
+		PageSize:           0,
+		Extra:              Extra{},
+	}
+}
+
+func (c CTKeySort) Token() string {
+
+	if c.Mode == CTMStart {
+		return "@start"
+	}
+	if c.Mode == CTMEnd {
+		return "@end"
+	}
+
+	// We kinda manually implement omitempty for the CursorToken here
+	// because omitempty does not work for time.Time and otherwise we would always
+	// get weird time values when decoding a token that initially didn't have an Timestamp set
+	// For this usecase we treat Unix=0 as an empty timestamp
+
+	sertok := cursorTokenKeySortSerialize{}
+
+	if c.ValuePrimary != "" {
+		sertok.ValuePrimary = &c.ValuePrimary
+	}
+	if c.ValueSecondary != "" {
+		sertok.ValueSecondary = &c.ValueSecondary
+	}
+	if c.Direction != "" {
+		sertok.Direction = &c.Direction
+	}
+	if c.DirectionSecondary != "" {
+		sertok.DirectionSecondary = &c.DirectionSecondary
+	}
+	if c.PageSize != 0 {
+		sertok.PageSize = &c.PageSize
+	}
+
+	sertok.ExtraTimestamp = c.Extra.Timestamp
+	sertok.ExtraId = c.Extra.Id
+	sertok.ExtraPage = c.Extra.Page
+	sertok.ExtraPageSize = c.Extra.PageSize
+
+	body, err := json.Marshal(sertok)
+	if err != nil {
+		panic(err)
+	}
+
+	return "tok_" + base32.StdEncoding.EncodeToString(body)
+}
+
+func (c CTKeySort) valuePrimaryObjectId() (primitive.ObjectID, bool) {
+	if oid, err := primitive.ObjectIDFromHex(c.ValuePrimary); err == nil {
+		return oid, true
+	} else {
+		return primitive.ObjectID{}, false
+	}
+}
+
+func (c CTKeySort) valueSecondaryObjectId() (primitive.ObjectID, bool) {
+	if oid, err := primitive.ObjectIDFromHex(c.ValueSecondary); err == nil {
+		return oid, true
+	} else {
+		return primitive.ObjectID{}, false
+	}
+}

cursortoken/tokenPaginate.go

@@ -0,0 +1,33 @@
+package cursortoken
+
+import "strconv"
+
+type CTPaginated struct {
+	Mode Mode
+	Page int
+}
+
+func Page(p int) CursorToken {
+	return CTPaginated{
+		Mode: CTMNormal,
+		Page: p,
+	}
+}
+
+func PageEnd() CursorToken {
+	return CTPaginated{
+		Mode: CTMEnd,
+		Page: 0,
+	}
+}
+
+func (c CTPaginated) Token() string {
+	if c.Mode == CTMStart {
+		return "$1"
+	}
+	if c.Mode == CTMEnd {
+		return "$end"
+	}
+
+	return "$" + strconv.Itoa(c.Page)
+}