Connection

model/connection.go

@@ -0,0 +1,93 @@
+package model
+
+import (
+	"encoding/json"
+	"fmt"
+	"git.beejay.kim/Craft/Api/connection"
+	"github.com/samber/lo"
+	"math"
+)
+
+type Connection[T connection.Cursor] struct {
+	Nodes    []T       `json:"nodes"`
+	PageInfo *PageInfo `json:"page_info"`
+}
+
+func (c *Connection[T]) Reverse() {
+	c.Nodes = lo.Reverse[T](c.Nodes)
+}
+
+func (c *Connection[T]) Grain(after, before *string) error {
+	if after != nil && before != nil {
+		return fmt.Errorf("illegal agruments: only one of `after` and `before` can be used at a time")
+	}
+
+	if len(c.Nodes) == 0 {
+		c.PageInfo = &PageInfo{}
+		return nil
+	}
+
+	edges := lo.FlatMap[T, string](c.Nodes, func(item T, _ int) []string {
+		return []string{item.Cursor()}
+	})
+
+	c.PageInfo = &PageInfo{
+		Total:       len(edges),
+		StartCursor: lo.ToPtr(edges[0]),
+		EndCursor:   lo.ToPtr(edges[(len(edges) - 1)]),
+	}
+
+	if after != nil {
+		if idx := lo.IndexOf(edges, *after); idx != -1 {
+			c.Nodes = lo.Slice[T](c.Nodes, idx+1, math.MaxUint32)
+		}
+	}
+
+	if before != nil {
+		if idx := lo.IndexOf(edges, *before); idx != -1 {
+			c.Nodes = lo.Subset[T](c.Nodes, -idx, math.MaxUint32)
+		}
+	}
+
+	return nil
+}
+
+func (c *Connection[T]) Slice(first, last *int) error {
+	if first != nil && last != nil {
+		return fmt.Errorf("illegal agruments: only one of `first` and `last` can be used at a time")
+	}
+
+	if first != nil {
+		c.Nodes = lo.Slice[T](c.Nodes, 0, *first)
+	}
+
+	if last != nil {
+		c.Nodes = lo.Subset[T](c.Nodes, -*last, math.MaxUint32)
+	}
+
+	if len(c.Nodes) < 1 {
+		c.PageInfo.HasPreviousPage = c.PageInfo.StartCursor != nil
+		c.PageInfo.HasNextPage = c.PageInfo.EndCursor != nil
+		c.PageInfo.StartCursor = nil
+		c.PageInfo.EndCursor = nil
+	} else {
+		c.PageInfo.HasPreviousPage = !(*c.PageInfo.StartCursor == c.Nodes[0].Cursor())
+		c.PageInfo.HasNextPage = !(*c.PageInfo.EndCursor == c.Nodes[len(c.Nodes)-1].Cursor())
+		c.PageInfo.StartCursor = lo.ToPtr(c.Nodes[0].Cursor())
+		c.PageInfo.EndCursor = lo.ToPtr(c.Nodes[len(c.Nodes)-1].Cursor())
+	}
+
+	return nil
+}
+
+func (c Connection[T]) Marshal() ([]byte, error) {
+	return json.Marshal(c.Nodes)
+}
+
+func (c *Connection[T]) Unmarshal(data []byte) error {
+	return json.Unmarshal(data, &c.Nodes)
+}
+
+func (c Connection[T]) Key() string {
+	return fmt.Sprintf("connection-nodes-%s", "match")
+}