62 lines
2.1 KiB
Go
62 lines
2.1 KiB
Go
package main
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import (
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"fmt"
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messages "git.tornberg.me/go-cart-actor/pkg/messages"
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)
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// mutation_add_request.go
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//
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// Registers the AddRequest mutation. This mutation is a higher-level intent
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// (add by SKU + quantity) which may translate into either:
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// - Increasing quantity of an existing line (same SKU), OR
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// - Creating a new item by performing a product lookup (via getItemData inside CartGrain.AddItem)
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//
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// Behavior:
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// - Validates non-empty SKU and quantity > 0
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// - If an item with the SKU already exists: increments its quantity
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// - Else delegates to CartGrain.AddItem (which itself produces an AddItem mutation)
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// - Totals recalculated automatically (WithTotals)
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//
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// NOTE:
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// - This handler purposely avoids duplicating the detailed AddItem logic;
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// it reuses CartGrain.AddItem which then flows through the AddItem mutation
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// registry handler.
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// - Double total recalculation can occur (AddItem has WithTotals too), but
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// is acceptable for clarity. Optimize later if needed.
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//
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// Potential future improvements:
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// - Stock validation before increasing quantity
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// - Reservation logic or concurrency guards around stock updates
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// - Coupon / pricing rules applied conditionally during add-by-sku
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func init() {
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RegisterMutation[messages.AddRequest](
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"AddRequest",
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func(g *CartGrain, m *messages.AddRequest) error {
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if m == nil {
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return fmt.Errorf("AddRequest: nil payload")
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}
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if m.Sku == "" {
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return fmt.Errorf("AddRequest: sku is empty")
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}
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if m.Quantity < 1 {
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return fmt.Errorf("AddRequest: invalid quantity %d", m.Quantity)
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}
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// Existing line: accumulate quantity only.
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if existing, found := g.FindItemWithSku(m.Sku); found {
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existing.Quantity += int(m.Quantity)
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return nil
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}
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// New line: delegate to higher-level AddItem flow (product lookup).
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// We intentionally ignore the returned *CartGrain; registry will
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// do totals again after this handler returns (harmless).
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_, err := g.AddItem(m.Sku, int(m.Quantity), m.Country, m.StoreId)
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return err
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},
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WithTotals(),
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)
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}
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