goext/cursortoken/tokenKeySort.go

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) IsEnd() bool {
	return c.Mode == CTMEnd
}

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
	}
}