1package connections
2
3import (
4 "fmt"
5
6 "github.com/cheekybits/genny/generic"
7
8 "github.com/git-bug/git-bug/api/graphql/models"
9)
10
11// Name define the name of the connection
12type Name generic.Type
13
14// NodeType define the node type handled by this relay connection
15type NodeType generic.Type
16
17// EdgeType define the edge type handled by this relay connection
18type EdgeType generic.Type
19
20// ConnectionType define the connection type handled by this relay connection
21type ConnectionType generic.Type
22
23// NameEdgeMaker define a function that take a NodeType and an offset and
24// create an Edge.
25type NameEdgeMaker func(value NodeType, offset int) Edge
26
27// NameConMaker define a function that create a ConnectionType
28type NameConMaker func(
29 edges []*EdgeType,
30 nodes []NodeType,
31 info *models.PageInfo,
32 totalCount int) (*ConnectionType, error)
33
34// NameCon will paginate a source according to the input of a relay connection
35func NameCon(source []NodeType, edgeMaker NameEdgeMaker, conMaker NameConMaker, input models.ConnectionInput) (*ConnectionType, error) {
36 var nodes []NodeType
37 var edges []*EdgeType
38 var cursors []string
39 var pageInfo = &models.PageInfo{}
40 var totalCount = len(source)
41
42 emptyCon, _ := conMaker(edges, nodes, pageInfo, 0)
43
44 offset := 0
45
46 if input.After != nil {
47 for i, value := range source {
48 edge := edgeMaker(value, i)
49 if edge.GetCursor() == *input.After {
50 // remove all previous element including the "after" one
51 source = source[i+1:]
52 offset = i + 1
53 pageInfo.HasPreviousPage = true
54 break
55 }
56 }
57 }
58
59 if input.Before != nil {
60 for i, value := range source {
61 edge := edgeMaker(value, i+offset)
62
63 if edge.GetCursor() == *input.Before {
64 // remove all after element including the "before" one
65 pageInfo.HasNextPage = true
66 break
67 }
68
69 e := edge.(EdgeType)
70 edges = append(edges, &e)
71 cursors = append(cursors, edge.GetCursor())
72 nodes = append(nodes, value)
73 }
74 } else {
75 edges = make([]*EdgeType, len(source))
76 cursors = make([]string, len(source))
77 nodes = source
78
79 for i, value := range source {
80 edge := edgeMaker(value, i+offset)
81 e := edge.(EdgeType)
82 edges[i] = &e
83 cursors[i] = edge.GetCursor()
84 }
85 }
86
87 if input.First != nil {
88 if *input.First < 0 {
89 return emptyCon, fmt.Errorf("first less than zero")
90 }
91
92 if len(edges) > *input.First {
93 // Slice result to be of length first by removing edges from the end
94 edges = edges[:*input.First]
95 cursors = cursors[:*input.First]
96 nodes = nodes[:*input.First]
97 pageInfo.HasNextPage = true
98 }
99 }
100
101 if input.Last != nil {
102 if *input.Last < 0 {
103 return emptyCon, fmt.Errorf("last less than zero")
104 }
105
106 if len(edges) > *input.Last {
107 // Slice result to be of length last by removing edges from the start
108 edges = edges[len(edges)-*input.Last:]
109 cursors = cursors[len(cursors)-*input.Last:]
110 nodes = nodes[len(nodes)-*input.Last:]
111 pageInfo.HasPreviousPage = true
112 }
113 }
114
115 // Fill up pageInfo cursors
116 if len(cursors) > 0 {
117 pageInfo.StartCursor = cursors[0]
118 pageInfo.EndCursor = cursors[len(cursors)-1]
119 }
120
121 return conMaker(edges, nodes, pageInfo, totalCount)
122}