109 lines
4.7 KiB
Go
109 lines
4.7 KiB
Go
package main
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import (
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messages "git.k6n.net/mats/go-cart-actor/proto/cart"
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"git.k6n.net/mats/platform/catalog"
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)
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// taxClassToBp maps the canonical TaxClass string identifiers published on
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// catalog.Projection to basis-points-of-a-percent (rate × 100) — the single
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// platform-wide rate scale used by AddItem.Tax (int32 basis points), the
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// mutation registry, and the tax.Provider Compute formula.
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//
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// Values reflect the standard tariff names used by the Nordic configuration.
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// Per-country / per-tenant numeric resolution (e.g. Finland 25.5%, Ireland
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// 13.5%) is delegated to platform/tax and is a follow-up: this static map
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// gets the common case right (2500 / 1200 / 600 / 0) and lets the cache path
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// ship while the platform/tax lookup is wired into the cart pool server.
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var taxClassToBp = map[string]int{
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"standard": 2500,
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"reduced": 1200, // common reduced rate (e.g. SE/NO food)
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"lowered": 600, // super-reduced
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"zero": 0, // zero-rated (export, healthcare, ...)
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"exempt": 0, // similarly untaxed, separate nominal class
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}
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// resolveTaxBp returns the basis-point rate for a TaxClass string, falling
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// back to platform "standard" (25%) when the class is unrecognised. The
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// default matches the grain's existing behaviour (AddItem falls back to 2500
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// when m.Tax == 0 — see pkg/cart/mutation_add_item.go).
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func resolveTaxBp(class string) int {
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if bp, ok := taxClassToBp[class]; ok {
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return bp
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}
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return 2500
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}
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// ApplyProjectionOverlay overlays the cache's authoritative catalog facts onto
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// an AddItem message that was just produced by a PRODUCT_BASE_URL HTTP fetch.
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//
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// Authoritative-from-cache fields (these WIN over the HTTP-fetched value when
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// both are present, because the bus is the live stream):
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//
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// Price (bus has post-class-overrides; product service has static)
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// Tax (TaxClass → bp via resolveTaxBp; only when TaxClass is set —
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// an empty TaxClass means the producer didn't classify,
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// so we leave the HTTP-fetched rate intact rather than
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// quietly swapping in a default 2500 and miscategorising)
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// Title (canonical, post-trim)
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// Image (canonical)
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// ItemID (positive bus values override HTTP; zero is the
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// documented "no id" signal, so a tombstone's zero or an
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// unbus-fed cache value won't clobber a real HTTP id.)
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// InventoryTracked (only flips to true; false is the zero value in proto
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// and may be unset on the wire, so we don't second-guess)
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// DropShip (only flips to true; same reasoning)
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//
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// The HTTP-fetched values remain authoritative for fields the cache does not
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// carry: SellerId / SellerName (marketplace split), Stock (per docs/inventory-
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// shape.md stock is queried synchronously from inventory, not cached),
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// OrgPrice / Discount (not yet on the projection schema), and the dynamic
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// ExtraJson product data (configurator options — width/height used by
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// accessory child-pricing).
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//
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// Now that ItemID round-trips from the bus, a future "cache-only" build path
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// (skipping PRODUCT_BASE_URL entirely for known SKUs) is unblocked — the
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// only fields left HTTP-only in that future path are Sellers, Stock, OrgPrice
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// and configurator extras, none of which affect line dedup.
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//
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// Tombstoned SKUs (catalog.projection_published with deleted=true) → the
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// caller checks idx.IsDeleted(sku) before this helper and short-circuits.
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func ApplyProjectionOverlay(msg *messages.AddItem, p catalog.Projection) {
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if msg == nil {
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return
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}
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// Price: positive bus values override HTTP. A zero PriceIncVat is treated
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// as "no value" rather than "free".
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if p.PriceIncVat.Int64() > 0 {
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msg.Price = p.PriceIncVat.Int64()
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}
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// Tax: only override when the bus has classified the SKU. An empty TaxClass
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// means the producer had nothing to say about VAT; the HTTP rate is more
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// trustworthy in that case than a guessed 2500.
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if p.TaxClass != "" {
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msg.Tax = int32(resolveTaxBp(p.TaxClass))
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}
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// ItemId: positive bus values override HTTP. Zero means the producer
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// didn't publish an id (some sources have no integer id) — we leave the
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// HTTP-fetched id intact in that case rather than zeroing out a real id.
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if p.ItemID != 0 {
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msg.ItemId = p.ItemID
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}
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// Display fields: only override if non-empty so the HTTP-fanned value
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// remains in place when the cache hasn't populated them yet.
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if p.Title != "" {
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msg.Name = p.Title
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}
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if p.Image != "" {
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msg.Image = p.Image
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}
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// Flags: only flip to true (positive boolean signals). A false is the
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// proto-zero value and not worth overriding.
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if p.InventoryTracked {
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msg.InventoryTracked = true
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}
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if p.DropShip {
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msg.DropShip = true
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}
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}
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