package connections import ( "fmt" "github.com/MichaelMure/git-bug/graphql/models" "github.com/cheekybits/genny/generic" ) // NodeType define the node type handled by this relay connection type NodeType generic.Type // EdgeType define the edge type handled by this relay connection type EdgeType generic.Type // ConnectionType define the connection type handled by this relay connection type ConnectionType generic.Type // NodeTypeEdgeMaker define a function that take a NodeType and an offset and // create an Edge. type NodeTypeEdgeMaker func(value NodeType, offset int) Edge // NodeTypeConMaker define a function that create a ConnectionType type NodeTypeConMaker func( edges []EdgeType, nodes []NodeType, info models.PageInfo, totalCount int) (ConnectionType, error) // NodeTypeCon will paginate a source according to the input of a relay connection func NodeTypeCon(source []NodeType, edgeMaker NodeTypeEdgeMaker, conMaker NodeTypeConMaker, input models.ConnectionInput) (ConnectionType, error) { var nodes []NodeType var edges []EdgeType var cursors []string var pageInfo models.PageInfo var totalCount = len(source) emptyCon, _ := conMaker(edges, nodes, pageInfo, 0) offset := 0 if input.After != nil { for i, value := range source { edge := edgeMaker(value, i) if edge.GetCursor() == *input.After { // remove all previous element including the "after" one source = source[i+1:] offset = i + 1 pageInfo.HasPreviousPage = true break } } } if input.Before != nil { for i, value := range source { edge := edgeMaker(value, i+offset) if edge.GetCursor() == *input.Before { // remove all after element including the "before" one pageInfo.HasNextPage = true break } edges = append(edges, edge.(EdgeType)) cursors = append(cursors, edge.GetCursor()) nodes = append(nodes, value) } } else { edges = make([]EdgeType, len(source)) cursors = make([]string, len(source)) nodes = source for i, value := range source { edge := edgeMaker(value, i+offset) edges[i] = edge.(EdgeType) cursors[i] = edge.GetCursor() } } if input.First != nil { if *input.First < 0 { return emptyCon, fmt.Errorf("first less than zero") } if len(edges) > *input.First { // Slice result to be of length first by removing edges from the end edges = edges[:*input.First] cursors = cursors[:*input.First] nodes = nodes[:*input.First] pageInfo.HasNextPage = true } } if input.Last != nil { if *input.Last < 0 { return emptyCon, fmt.Errorf("last less than zero") } if len(edges) > *input.Last { // Slice result to be of length last by removing edges from the start edges = edges[len(edges)-*input.Last:] cursors = cursors[len(cursors)-*input.Last:] nodes = nodes[len(nodes)-*input.Last:] pageInfo.HasPreviousPage = true } } // Fill up pageInfo cursors if len(cursors) > 0 { pageInfo.StartCursor = cursors[0] pageInfo.EndCursor = cursors[len(cursors)-1] } return conMaker(edges, nodes, pageInfo, totalCount) }