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