Product/graphql/helper/product_variant.go

package helper

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

func NewProductVariantConnection(src []*generated.ProductVariant,
	after *string, before *string, first *int, last *int, reverse *bool, sortKey *generated.ProductVariantSortKeys) (*generated.ProductVariantConnection, error) {

	var (
		connection = &generated.ProductVariantConnection{}
		err        error
	)

	if len(src) == 0 {
		return connection, nil
	}

	if sortKey != nil && sortKey.IsValid() {
		sort.Slice(src[:], func(i, j int) bool {

			switch *sortKey {
			case generated.ProductVariantSortKeysID:
				return src[i].ID < src[j].ID
			case generated.ProductVariantSortKeysTitle:
				return src[i].Title < src[j].Title
			case generated.ProductVariantSortKeysSku:
				var isku, jsku string

				if src[i].Sku != nil {
					isku = *src[i].Sku
				}

				if src[j].Sku != nil {
					jsku = *src[j].Sku
				}

				return isku < jsku
			case generated.ProductVariantSortKeysPosition:
				return ExtractMetaPosition(model.GidVariant, src[i].Metafields) <
					ExtractMetaPosition(model.GidVariant, src[j].Metafields)
			case generated.ProductVariantSortKeysRelevance: // TODO:
			}

			return false
		})
	}

	if reverse != nil && *reverse {
		src = fun.Reverse(src)
	}

	connection.Nodes = src[:]
	connection.Nodes = fun.First(connection.Nodes, first)
	connection.Nodes = fun.Last(connection.Nodes, last)

	connection.Nodes, err = fun.WithCursor(connection.Nodes, after, model.GidVariant, true)
	if err != nil {
		return nil, fmt.Errorf("illegal cursor: %s", *after)
	}

	connection.Nodes, err = fun.WithCursor(connection.Nodes, before, model.GidVariant, false)
	if err != nil {
		return nil, fmt.Errorf("illegal cursor: %s", *before)
	}

	connection.PageInfo = model.NewPageInfo(connection.Nodes, model.GidVariant, src[0], src[len(src)-1])

	// Edges
	for i := range connection.Nodes {
		e := &generated.ProductVariantEdge{
			Node: connection.Nodes[i],
		}

		if c, err := model.NewCursor(e.Node.ID, model.GidVariant); err == nil {
			e.Cursor = *c.String()
		}

		connection.Edges = append(connection.Edges, e)
	}

	return connection, nil
}