go-cart-actor/cmd/checkout/utils.go

package main

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"strings"
	"time"

	"git.k6n.net/mats/go-cart-actor/pkg/cart"
	"git.k6n.net/mats/go-cart-actor/pkg/checkout"
	"git.k6n.net/mats/platform/inventory"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/metric"
)

func getOriginalHost(r *http.Request) string {
	proxyHost := r.Header.Get("X-Forwarded-Host")
	if proxyHost != "" {
		return proxyHost
	}
	return r.Host
}

// getScheme resolves the public scheme for building absolute URLs (e.g. Klarna
// merchant_urls). Honors X-Forwarded-Proto set by the edge/dev proxy; defaults
// to https so production (TLS terminated at nginx/ingress, no header) is correct.
func getScheme(r *http.Request) string {
	if proto := r.Header.Get("X-Forwarded-Proto"); proto != "" {
		return proto
	}
	if r.TLS != nil {
		return "https"
	}
	return "https"
}

func getClientIp(r *http.Request) string {
	ip := r.Header.Get("X-Forwarded-For")
	if ip == "" {
		ip = r.RemoteAddr
	}
	return ip
}

func getCurrency(country string) string {
	if country == "no" {
		return "NOK"
	}
	return "SEK"
}

func getLocale(country string) string {
	if country == "no" {
		return "nb-no"
	}
	return "sv-se"
}

// getCountryFromCurrency is the reverse of getCurrency, used by server-to-server
// callbacks (e.g. the Adyen webhook) that carry the settled currency but not the
// shopper's host/country.
func getCountryFromCurrency(currency string) string {
	if strings.EqualFold(currency, "NOK") {
		return "no"
	}
	return "se"
}

func getCountryFromHost(host string) string {
	if strings.Contains(strings.ToLower(host), "-no") {
		return "no"
	}
	if strings.Contains(strings.ToLower(host), "-se") {
		return "se"
	}
	return ""
}

func (a *CheckoutPoolServer) reserveInventory(ctx context.Context, grain *checkout.CheckoutGrain) error {
	if a.reservationPolicy == nil {
		return nil
	}
	for _, item := range grain.CartState.Items {
		if item == nil || !shouldTrackInventory(item) {
			continue
		}
		loc := inventory.LocationID("se")
		if item.StoreId != nil && *item.StoreId != "" {
			loc = inventory.LocationID(*item.StoreId)
		}
		avail, err := a.reservationPolicy.Available(ctx, inventory.SKU(item.Sku), loc)
		if err != nil {
			return fmt.Errorf("inventory check failed for SKU %s: %w", item.Sku, err)
		}
		if int64(item.Quantity) > avail {
			return fmt.Errorf("insufficient inventory for SKU %s: have %d, need %d", item.Sku, avail, item.Quantity)
		}
	}
	return nil
}

const checkoutCookieName = "checkoutid"

func setCheckoutCookie(w http.ResponseWriter, checkoutId checkout.CheckoutId, tls bool) {
	if checkoutId == 0 {
		http.SetCookie(w, &http.Cookie{
			Name:     checkoutCookieName,
			Value:    checkoutId.String(),
			Secure:   tls,
			HttpOnly: true,
			Path:     "/",
			Expires:  time.Unix(0, 0),
			SameSite: http.SameSiteLaxMode,
		})
	} else {
		http.SetCookie(w, &http.Cookie{
			Name:     checkoutCookieName,
			Value:    checkoutId.String(),
			Secure:   tls,
			HttpOnly: true,
			Path:     "/",
			Expires:  time.Now().AddDate(0, 0, 14),
			SameSite: http.SameSiteLaxMode,
		})
	}
}

func CookieCheckoutIdHandler(fn func(w http.ResponseWriter, r *http.Request, checkoutId checkout.CheckoutId) error) func(w http.ResponseWriter, r *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {

		var id checkout.CheckoutId
		cookie, err := r.Cookie(checkoutCookieName)
		if err != nil || cookie.Value == "" {
			w.WriteHeader(http.StatusNotAcceptable)
			return
		} else {
			parsed, ok := cart.ParseCartId(cookie.Value)
			if !ok {
				w.WriteHeader(http.StatusNotAcceptable)
				return
			} else {
				id = parsed
			}
		}

		err = fn(w, r, id)
		if err != nil {
			log.Printf("Server error, not remote error: %v\n", err)
			w.WriteHeader(http.StatusInternalServerError)
			w.Write([]byte(err.Error()))
		}

	}
}

func (s *CheckoutPoolServer) ProxyHandler(fn func(w http.ResponseWriter, r *http.Request, checkoutId checkout.CheckoutId) error) func(w http.ResponseWriter, r *http.Request, checkoutId checkout.CheckoutId) error {
	return func(w http.ResponseWriter, r *http.Request, checkoutId checkout.CheckoutId) error {
		if ownerHost, ok := s.OwnerHost(uint64(checkoutId)); ok {
			ctx, span := tracer.Start(r.Context(), "proxy")
			defer span.End()
			span.SetAttributes(attribute.String("checkoutid", checkoutId.String()))
			hostAttr := attribute.String("other host", ownerHost.Name())
			span.SetAttributes(hostAttr)
			logger.InfoContext(ctx, "checkout proxyed", "result", ownerHost.Name())
			proxyCalls.Add(ctx, 1, metric.WithAttributes(hostAttr))
			handled, err := ownerHost.Proxy(uint64(checkoutId), w, r, nil)

			grainLookups.Inc()
			if err == nil && handled {
				return nil
			}
		}
		_, span := tracer.Start(r.Context(), "own")
		span.SetAttributes(attribute.String("checkoutid", checkoutId.String()))
		defer span.End()
		return fn(w, r, checkoutId)
	}
}