-
Notifications
You must be signed in to change notification settings - Fork 27
/
cursor.go
91 lines (75 loc) · 2 KB
/
cursor.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
//
// Copyright 2024 The Chainloop Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package pagination
import (
"encoding/base64"
"errors"
"fmt"
"strings"
"time"
"github.com/google/uuid"
)
type CursorOptions struct {
Cursor *Cursor
Limit int
}
type Cursor struct {
Timestamp *time.Time
ID *uuid.UUID
}
const defaultLimit = 10
func NewCursor(c string, l int) (*CursorOptions, error) {
var cursor *Cursor
var limit = defaultLimit
if c != "" {
time, uuid, err := decodeCursor(c)
if err != nil {
return nil, fmt.Errorf("decoding cursor: %w", err)
}
cursor = &Cursor{Timestamp: time, ID: uuid}
}
if l > 0 {
limit = l
}
return &CursorOptions{
Cursor: cursor,
Limit: limit,
}, nil
}
func decodeCursor(encodedCursor string) (*time.Time, *uuid.UUID, error) {
byt, err := base64.StdEncoding.DecodeString(encodedCursor)
if err != nil {
return nil, nil, err
}
arrStr := strings.Split(string(byt), ",")
if len(arrStr) != 2 {
return nil, nil, errors.New("cursor is invalid")
}
timestamp, err := time.Parse(time.RFC3339Nano, arrStr[0])
if err != nil {
return nil, nil, err
}
rawID := arrStr[1]
uuid, err := uuid.Parse(rawID)
if err != nil {
return nil, nil, err
}
return ×tamp, &uuid, nil
}
// EncodeCursor generates a base64 encoded representation of a timestamp + identifier
func EncodeCursor(t time.Time, uuid uuid.UUID) string {
key := fmt.Sprintf("%s,%s", t.Format(time.RFC3339Nano), uuid)
return base64.StdEncoding.EncodeToString([]byte(key))
}