91 lines
2.9 KiB
Go
91 lines
2.9 KiB
Go
package cart
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import (
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"context"
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"fmt"
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"log"
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cart_messages "git.k6n.net/mats/go-cart-actor/proto/cart"
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)
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// mutation_change_quantity.go
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//
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// Registers the ChangeQuantity mutation.
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//
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// Behavior:
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// - Locates an item by its cart-local line item Id (not source item_id).
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// - If requested quantity <= 0 the line AND any descendants are
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// removed via the shared RemoveItem cascade (transitive parent→child).
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// - Otherwise the line's Quantity is updated and direct children are
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// rescaled proportionally so a "2 of this + 2 of each accessory"
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// bundle stays internally consistent when the parent becomes 3.
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// - Totals are recalculated (WithTotals).
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//
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// Error handling:
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// - Returns an error if the item Id is not found.
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// - Returns an error if payload is nil (defensive).
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//
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// Concurrency:
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// - Uses the grain's RW-safe mutation pattern: we mutate in place under
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// the grain's implicit expectation that higher layers control access.
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// (If strict locking is required around every mutation, wrap logic in
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// an explicit g.mu.Lock()/Unlock(), but current model mirrors prior code.)
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func (c *CartMutationContext) ChangeQuantity(g *CartGrain, m *cart_messages.ChangeQuantity) error {
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if m == nil {
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return fmt.Errorf("ChangeQuantity: nil payload")
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}
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ctx := context.Background()
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foundIndex := -1
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for i, it := range g.Items {
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if it.Id == uint32(m.Id) {
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foundIndex = i
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break
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}
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}
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if foundIndex == -1 {
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return fmt.Errorf("ChangeQuantity: item id %d not found", m.Id)
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}
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if m.Quantity <= 0 {
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// Setting a parent line to 0 means "remove it AND its accessories".
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// Delegate to RemoveItem so the cascade logic in one place stays
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// the source of truth for descendant cleanup + reservation
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// release — otherwise we'd duplicate the transitive cascade here.
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return c.RemoveItem(g, &cart_messages.RemoveItem{Id: m.Id})
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}
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item := g.Items[foundIndex]
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if item == nil {
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return fmt.Errorf("ChangeQuantity: item id %d not found", m.Id)
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}
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oldQty := item.Quantity
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if g.Type == cart_messages.CartType_REGULAR && c.UseReservations(item) {
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if item.ReservationEndTime != nil {
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err := c.ReleaseItem(ctx, g.Id, item.Sku, item.StoreId)
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if err != nil {
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log.Printf("unable to release reservation for %s in location: %v", item.Sku, item.StoreId)
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}
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}
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endTime, err := c.ReserveItem(ctx, g.Id, item.Sku, item.StoreId, uint16(m.Quantity))
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if err != nil {
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return err
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}
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item.ReservationEndTime = endTime
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}
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item.Quantity = uint16(m.Quantity)
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// Rescale any direct child lines proportionally so accessories stay
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// in sync with their parent. Descends recursively into grandchildren
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// via CascadeChildQuantities itself. Skipped when the target itself
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// is a child line — direct qty edits on a child are treated as
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// explicit user intent and don't propagate further.
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if item.ParentId == nil {
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c.CascadeChildQuantities(ctx, g, item.Id, oldQty, item.Quantity)
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}
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g.UpdateTotals()
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return nil
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}
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