1//go:generate genny -in=connection_template.go -out=gen_bug.go gen "NodeType=string EdgeType=LazyBugEdge ConnectionType=models.BugConnection"
 2//go:generate genny -in=connection_template.go -out=gen_operation.go gen "NodeType=bug.Operation EdgeType=models.OperationEdge ConnectionType=models.OperationConnection"
 3//go:generate genny -in=connection_template.go -out=gen_comment.go gen "NodeType=bug.Comment EdgeType=models.CommentEdge ConnectionType=models.CommentConnection"
 4
 5package connections
 6
 7import (
 8	"encoding/base64"
 9	"fmt"
10	"strconv"
11	"strings"
12)
13
14const cursorPrefix = "cursor:"
15
16type Edge interface {
17	GetCursor() string
18}
19
20// Creates the cursor string from an offset
21func OffsetToCursor(offset int) string {
22	str := fmt.Sprintf("%v%v", cursorPrefix, offset)
23	return base64.StdEncoding.EncodeToString([]byte(str))
24}
25
26// Re-derives the offset from the cursor string.
27func CursorToOffset(cursor string) (int, error) {
28	str := ""
29	b, err := base64.StdEncoding.DecodeString(cursor)
30	if err == nil {
31		str = string(b)
32	}
33	str = strings.Replace(str, cursorPrefix, "", -1)
34	offset, err := strconv.Atoi(str)
35	if err != nil {
36		return 0, fmt.Errorf("Invalid cursor")
37	}
38	return offset, nil
39}