Product/graphql/helper/page_info.go

package helper

import (
	"github.com/gshopify/service-wrapper/interfaces"
	"github.com/gshopify/service-wrapper/model"
	"gshopper.com/gshopify/products/graphql/generated"
)

func NewPageInfo[T interfaces.Node](src []T, namespace model.Gid, first T, last T) *generated.PageInfo {
	var (
		size = len(src)
		info = &generated.PageInfo{}
	)

	if size == 0 {
		return info
	}

	if c, err := model.NewSimpleCursor(src[0].GetID(), namespace); err == nil {
		info.StartCursor = c.String()
	}

	if c, err := model.NewSimpleCursor(src[size-1].GetID(), namespace); err == nil {
		info.EndCursor = c.String()
	}

	info.HasPreviousPage = first.GetID() != src[0].GetID()
	info.HasNextPage = info.StartCursor == info.EndCursor || last.GetID() != src[size-1].GetID()
	return info
}