product_policies.go

product_policies.go

package research

import "fmt"

// ProductPolicies structure
type ProductPolicies []func(product Product) (Product, error)

const maxBSR = 200000

// CreateProductPolicies defines all the product policies
func CreateProductPolicies(estimatedSale *EstimatedSale) *ProductPolicies {
	return &ProductPolicies{
		calculateFbaNetValuePolicy,
		calculateSizePolicy,
		func(p Product) (Product, error) { return estimateSalesPolicy(p, estimatedSale) },
		maximumBSRPolicy,
		containsErrorPolicy,
	}
}

// Apply product policies
func (policies ProductPolicies) Apply(product Product) Product {
	for _, apply := range policies {
		p, err := apply(product)
		if err != nil {
			p.Delete()
			return p
		}
		product = p
	}

	product.Keep()
	return product
}

func calculateFbaNetValuePolicy(p Product) (Product, error) {
	if p.ListingPrice == nil || p.TotalFeesEstimate == nil {
		return p, nil
	}

	value := *p.ListingPrice - *p.TotalFeesEstimate
	p.FbaNetValue = &value
	return p, nil
}

func calculateSizePolicy(p Product) (Product, error) {
	if p.hasDimensions() {
		if packages, ok := mailPackages[*p.Marketplace]; ok {
			for _, size := range packages {
				if size.fits(p) {
					p.SizeID = &size.id
					return p, nil
				}
			}
		}
	}
	p.SizeID = nil
	return p, nil
}

func estimateSalesPolicy(p Product, estimatedSale *EstimatedSale) (Product, error) {
	if p.Bsr == nil || estimatedSale == nil || estimatedSale.Units == nil {
		return p, nil
	}

	p.EstimatedUnits = estimatedSale.Units

	if p.ListingPrice == nil {
		return p, nil
	}

	sales := float32(*p.EstimatedUnits) * *p.ListingPrice
	p.EstimatedSales = &sales
	return p, nil
}

func maximumBSRPolicy(p Product) (Product, error) {
	if p.Bsr != nil && *p.Bsr > maxBSR {
		return p, fmt.Errorf("Product BSR (%d) beyond the maximum (%d)", p.Bsr, maxBSR)
	}
	return p, nil
}

func containsErrorPolicy(p Product) (Product, error) {
	if p.Error != nil {
		return p, fmt.Errorf(*p.Error)
	}
	return p, nil
}