5 files changed, 370 insertions, 0 deletions
diff --git a/graphql/connections/connection_template.go b/graphql/connections/connection_template.go
new file mode 100644
index 00000000..3dfaca8f
--- /dev/null
+++ b/graphql/connections/connection_template.go
@@ -0,0 +1,82 @@
+package connections
+
+import (
+	"fmt"
+	"github.com/MichaelMure/git-bug/graphql/models"
+	"github.com/cheekybits/genny/generic"
+)
+
+type NodeType generic.Type
+type EdgeType generic.Type
+type ConnectionType generic.Type
+
+type NodeTypeEdger func(value NodeType, offset int) Edge
+type NodeTypeConMaker func(edges []EdgeType, info models.PageInfo, totalCount int) ConnectionType
+
+func NodeTypeCon(source []NodeType, edger NodeTypeEdger, conMaker NodeTypeConMaker, input models.ConnectionInput) (ConnectionType, error) {
+	var edges []EdgeType
+	var pageInfo models.PageInfo
+
+	emptyCon := conMaker(edges, pageInfo, 0)
+
+	offset := 0
+
+	if input.After != nil {
+		for i, value := range source {
+			edge := edger(value, i)
+			if edge.GetCursor() == *input.After {
+				// remove all previous element including the "after" one
+				source = source[i+1:]
+				offset = i + 1
+				break
+			}
+		}
+	}
+
+	if input.Before != nil {
+		for i, value := range source {
+			edge := edger(value, i+offset)
+
+			if edge.GetCursor() == *input.Before {
+				// remove all after element including the "before" one
+				break
+			}
+
+			edges = append(edges, edge.(EdgeType))
+		}
+	} else {
+		edges = make([]EdgeType, len(source))
+
+		for i, value := range source {
+			edges[i] = edger(value, i+offset).(EdgeType)
+		}
+	}
+
+	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]
+			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:]
+			pageInfo.HasPreviousPage = true
+		}
+	}
+
+	con := conMaker(edges, pageInfo, len(source))
+
+	return con, nil
+}
diff --git a/graphql/connections/connections.go b/graphql/connections/connections.go
new file mode 100644
index 00000000..145bfbbe
--- /dev/null
+++ b/graphql/connections/connections.go
@@ -0,0 +1,39 @@
+//go:generate genny -in=connection_template.go -out=gen_bug.go gen "NodeType=bug.Snapshot EdgeType=models.BugEdge ConnectionType=models.BugConnection"
+//go:generate genny -in=connection_template.go -out=gen_operation.go gen "NodeType=bug.Operation EdgeType=models.OperationEdge ConnectionType=models.OperationConnection"
+//go:generate genny -in=connection_template.go -out=gen_comment.go gen "NodeType=bug.Comment EdgeType=models.CommentEdge ConnectionType=models.CommentConnection"
+
+package connections
+
+import (
+	"encoding/base64"
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+const cursorPrefix = "cursor:"
+
+type Edge interface {
+	GetCursor() string
+}
+
+// Creates the cursor string from an offset
+func OffsetToCursor(offset int) string {
+	str := fmt.Sprintf("%v%v", cursorPrefix, offset)
+	return base64.StdEncoding.EncodeToString([]byte(str))
+}
+
+// Re-derives the offset from the cursor string.
+func CursorToOffset(cursor string) (int, error) {
+	str := ""
+	b, err := base64.StdEncoding.DecodeString(cursor)
+	if err == nil {
+		str = string(b)
+	}
+	str = strings.Replace(str, cursorPrefix, "", -1)
+	offset, err := strconv.Atoi(str)
+	if err != nil {
+		return 0, fmt.Errorf("Invalid cursor")
+	}
+	return offset, nil
+}
diff --git a/graphql/connections/gen_bug.go b/graphql/connections/gen_bug.go
new file mode 100644
index 00000000..b43d5c11
--- /dev/null
+++ b/graphql/connections/gen_bug.go
@@ -0,0 +1,83 @@
+// This file was automatically generated by genny.
+// Any changes will be lost if this file is regenerated.
+// see https://github.com/cheekybits/genny
+
+package connections
+
+import (
+	"fmt"
+
+	"github.com/MichaelMure/git-bug/bug"
+	"github.com/MichaelMure/git-bug/graphql/models"
+)
+
+type BugSnapshotEdger func(value bug.Snapshot, offset int) Edge
+type BugSnapshotConMaker func(edges []models.BugEdge, info models.PageInfo, totalCount int) models.BugConnection
+
+func BugSnapshotCon(source []bug.Snapshot, edger BugSnapshotEdger, conMaker BugSnapshotConMaker, input models.ConnectionInput) (models.BugConnection, error) {
+	var edges []models.BugEdge
+	var pageInfo models.PageInfo
+
+	emptyCon := conMaker(edges, pageInfo, 0)
+
+	offset := 0
+
+	if input.After != nil {
+		for i, value := range source {
+			edge := edger(value, i)
+			if edge.GetCursor() == *input.After {
+				// remove all previous element including the "after" one
+				source = source[i+1:]
+				offset = i + 1
+				break
+			}
+		}
+	}
+
+	if input.Before != nil {
+		for i, value := range source {
+			edge := edger(value, i+offset)
+
+			if edge.GetCursor() == *input.Before {
+				// remove all after element including the "before" one
+				break
+			}
+
+			edges = append(edges, edge.(models.BugEdge))
+		}
+	} else {
+		edges = make([]models.BugEdge, len(source))
+
+		for i, value := range source {
+			edges[i] = edger(value, i+offset).(models.BugEdge)
+		}
+	}
+
+	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]
+			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:]
+			pageInfo.HasPreviousPage = true
+		}
+	}
+
+	con := conMaker(edges, pageInfo, len(source))
+
+	return con, nil
+}
diff --git a/graphql/connections/gen_comment.go b/graphql/connections/gen_comment.go
new file mode 100644
index 00000000..dfcce42a
--- /dev/null
+++ b/graphql/connections/gen_comment.go
@@ -0,0 +1,83 @@
+// This file was automatically generated by genny.
+// Any changes will be lost if this file is regenerated.
+// see https://github.com/cheekybits/genny
+
+package connections
+
+import (
+	"fmt"
+
+	"github.com/MichaelMure/git-bug/bug"
+	"github.com/MichaelMure/git-bug/graphql/models"
+)
+
+type BugCommentEdger func(value bug.Comment, offset int) Edge
+type BugCommentConMaker func(edges []models.CommentEdge, info models.PageInfo, totalCount int) models.CommentConnection
+
+func BugCommentCon(source []bug.Comment, edger BugCommentEdger, conMaker BugCommentConMaker, input models.ConnectionInput) (models.CommentConnection, error) {
+	var edges []models.CommentEdge
+	var pageInfo models.PageInfo
+
+	emptyCon := conMaker(edges, pageInfo, 0)
+
+	offset := 0
+
+	if input.After != nil {
+		for i, value := range source {
+			edge := edger(value, i)
+			if edge.GetCursor() == *input.After {
+				// remove all previous element including the "after" one
+				source = source[i+1:]
+				offset = i + 1
+				break
+			}
+		}
+	}
+
+	if input.Before != nil {
+		for i, value := range source {
+			edge := edger(value, i+offset)
+
+			if edge.GetCursor() == *input.Before {
+				// remove all after element including the "before" one
+				break
+			}
+
+			edges = append(edges, edge.(models.CommentEdge))
+		}
+	} else {
+		edges = make([]models.CommentEdge, len(source))
+
+		for i, value := range source {
+			edges[i] = edger(value, i+offset).(models.CommentEdge)
+		}
+	}
+
+	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]
+			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:]
+			pageInfo.HasPreviousPage = true
+		}
+	}
+
+	con := conMaker(edges, pageInfo, len(source))
+
+	return con, nil
+}
diff --git a/graphql/connections/gen_operation.go b/graphql/connections/gen_operation.go
new file mode 100644
index 00000000..32cee97a
--- /dev/null
+++ b/graphql/connections/gen_operation.go
@@ -0,0 +1,83 @@
+// This file was automatically generated by genny.
+// Any changes will be lost if this file is regenerated.
+// see https://github.com/cheekybits/genny
+
+package connections
+
+import (
+	"fmt"
+
+	"github.com/MichaelMure/git-bug/bug"
+	"github.com/MichaelMure/git-bug/graphql/models"
+)
+
+type BugOperationEdger func(value bug.Operation, offset int) Edge
+type BugOperationConMaker func(edges []models.OperationEdge, info models.PageInfo, totalCount int) models.OperationConnection
+
+func BugOperationCon(source []bug.Operation, edger BugOperationEdger, conMaker BugOperationConMaker, input models.ConnectionInput) (models.OperationConnection, error) {
+	var edges []models.OperationEdge
+	var pageInfo models.PageInfo
+
+	emptyCon := conMaker(edges, pageInfo, 0)
+
+	offset := 0
+
+	if input.After != nil {
+		for i, value := range source {
+			edge := edger(value, i)
+			if edge.GetCursor() == *input.After {
+				// remove all previous element including the "after" one
+				source = source[i+1:]
+				offset = i + 1
+				break
+			}
+		}
+	}
+
+	if input.Before != nil {
+		for i, value := range source {
+			edge := edger(value, i+offset)
+
+			if edge.GetCursor() == *input.Before {
+				// remove all after element including the "before" one
+				break
+			}
+
+			edges = append(edges, edge.(models.OperationEdge))
+		}
+	} else {
+		edges = make([]models.OperationEdge, len(source))
+
+		for i, value := range source {
+			edges[i] = edger(value, i+offset).(models.OperationEdge)
+		}
+	}
+
+	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]
+			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:]
+			pageInfo.HasPreviousPage = true
+		}
+	}
+
+	con := conMaker(edges, pageInfo, len(source))
+
+	return con, nil
+}