97 lines
2.8 KiB
Go
97 lines
2.8 KiB
Go
package main
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import (
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"fmt"
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"slices"
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messages "git.tornberg.me/go-cart-actor/pkg/messages"
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)
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// mutation_set_delivery.go
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//
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// Registers the SetDelivery mutation.
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//
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// Semantics (mirrors legacy switch logic):
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// - If the payload specifies an explicit list of item IDs (payload.Items):
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// - Each referenced cart line must exist.
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// - None of the referenced items may already belong to a delivery.
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// - Only those items are associated with the new delivery.
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// - If payload.Items is empty:
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// - All items currently without any delivery are associated with the new delivery.
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// - A new delivery line is created with:
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// - Auto-incremented delivery ID (cart-local)
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// - Provider from payload
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// - Fixed price (currently hard-coded: 4900 minor units) – adjust as needed
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// - Optional PickupPoint copied from payload
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// - Cart totals are recalculated (WithTotals)
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//
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// Error cases:
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// - Referenced item does not exist
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// - Referenced item already has a delivery
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// - No items qualify (resulting association set empty) -> returns error (prevents creating empty delivery)
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//
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// Concurrency:
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// - Uses g.mu to protect lastDeliveryId increment and append to Deliveries slice.
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// Item scans are read-only and performed outside the lock for simplicity;
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// if stricter guarantees are needed, widen the lock section.
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//
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// Future extension points:
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// - Variable delivery pricing (based on weight, distance, provider, etc.)
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// - Validation of provider codes
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// - Multi-currency delivery pricing
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func SetDelivery(g *CartGrain, m *messages.SetDelivery) error {
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if m == nil {
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return fmt.Errorf("SetDelivery: nil payload")
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}
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if m.Provider == "" {
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return fmt.Errorf("SetDelivery: provider is empty")
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}
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withDelivery := g.ItemsWithDelivery()
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targetItems := make([]int, 0)
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if len(m.Items) == 0 {
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// Use every item currently without a delivery
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targetItems = append(targetItems, g.ItemsWithoutDelivery()...)
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} else {
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// Validate explicit list
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for _, id64 := range m.Items {
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id := int(id64)
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found := false
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for _, it := range g.Items {
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if it.Id == id {
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found = true
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break
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}
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}
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if !found {
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return fmt.Errorf("SetDelivery: item id %d not found", id)
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}
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if slices.Contains(withDelivery, id) {
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return fmt.Errorf("SetDelivery: item id %d already has a delivery", id)
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}
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targetItems = append(targetItems, id)
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}
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}
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if len(targetItems) == 0 {
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return fmt.Errorf("SetDelivery: no eligible items to attach")
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}
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// Append new delivery
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g.mu.Lock()
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g.lastDeliveryId++
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newId := g.lastDeliveryId
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g.Deliveries = append(g.Deliveries, &CartDelivery{
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Id: newId,
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Provider: m.Provider,
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PickupPoint: m.PickupPoint,
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Price: 4900, // TODO: externalize pricing
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Items: targetItems,
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})
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g.mu.Unlock()
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return nil
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}
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