update inventory package

2025-11-26 18:22:14 +01:00
parent 7ebbc97e38
commit 28c9a24dac
7 changed files with 567 additions and 25 deletions
@@ -0,0 +1,216 @@
+package inventory
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/redis/go-redis/v9"
+)
+
+type RedisCartReservationService struct {
+	client      *redis.Client
+	luaReserve  *redis.Script
+	luaRelease  *redis.Script
+	luaGetAvail *redis.Script
+}
+
+func NewRedisCartReservationService(client *redis.Client) (*RedisCartReservationService, error) {
+	rdb := client
+
+	// Ping Redis to check connection
+	_, err := rdb.Ping(context.Background()).Result()
+	if err != nil {
+		return nil, err
+	}
+
+	return &RedisCartReservationService{
+		client:      rdb,
+		luaReserve:  redis.NewScript(reserveForCartScript),
+		luaRelease:  redis.NewScript(releaseForCartScript),
+		luaGetAvail: redis.NewScript(getAvailableScript),
+	}, nil
+}
+
+func cartQtyKey(sku SKU, locationID LocationID) string {
+	return fmt.Sprintf("cart_qty:%s:%s", sku, locationID)
+}
+
+func cartExpKey(sku SKU, locationID LocationID) string {
+	return fmt.Sprintf("cart_exp:%s:%s", sku, locationID)
+}
+
+func totalReservedKey(sku SKU, locationID LocationID) string {
+	return fmt.Sprintf("total_reserved:%s:%s", sku, locationID)
+}
+
+func (s *RedisCartReservationService) ReserveForCart(ctx context.Context, req CartReserveRequest) error {
+	keys := []string{
+		getInventoryKey(req.Sku, req.LocationID),
+		cartQtyKey(req.Sku, req.LocationID),
+		cartExpKey(req.Sku, req.LocationID),
+		totalReservedKey(req.Sku, req.LocationID),
+	}
+	args := []interface{}{
+		string(req.CartId),
+		req.Quantity,
+		int64(req.TTL.Seconds()),
+	}
+
+	cmd := s.luaReserve.Run(ctx, s.client, keys, args)
+	if err := cmd.Err(); err != nil {
+		return err
+	}
+	if val, err := cmd.Int(); err != nil {
+		return err
+	} else if val == 0 {
+		return ErrInsufficientInventory
+	}
+	return nil
+}
+
+func (s *RedisCartReservationService) ReleaseForCart(ctx context.Context, sku SKU, locationID LocationID, cartID CartID) error {
+	keys := []string{
+		cartQtyKey(sku, locationID),
+		cartExpKey(sku, locationID),
+		totalReservedKey(sku, locationID),
+	}
+	args := []interface{}{string(cartID)}
+
+	cmd := s.luaRelease.Run(ctx, s.client, keys, args)
+	return cmd.Err()
+}
+
+func (s *RedisCartReservationService) GetReservationExpiry(ctx context.Context, sku SKU, locationID LocationID, cartID CartID) (time.Time, error) {
+	expKey := cartExpKey(sku, locationID)
+	score := s.client.ZScore(ctx, expKey, string(cartID))
+	if err := score.Err(); err != nil {
+		if err == redis.Nil {
+			return time.Time{}, fmt.Errorf("no reservation found for cart %s", cartID)
+		}
+		return time.Time{}, err
+	}
+	expiry := time.Unix(int64(score.Val()), 0)
+	return expiry, nil
+}
+
+func (s *RedisCartReservationService) GetReservationStatus(ctx context.Context, sku SKU, locationID LocationID, cartID CartID) (*ReservationStatus, error) {
+	expiry, err := s.GetReservationExpiry(ctx, sku, locationID, cartID)
+	if err != nil {
+		return nil, err
+	}
+	now := time.Now()
+	if expiry.After(now) {
+		return &ReservationStatus{
+			Active:        true,
+			RemainingTime: expiry.Sub(now),
+		}, nil
+	}
+	return &ReservationStatus{
+		Active:        false,
+		RemainingTime: 0,
+	}, nil
+}
+
+func (s *RedisCartReservationService) GetAvailableInventory(ctx context.Context, sku SKU, locationID LocationID) (int64, error) {
+	keys := []string{
+		getInventoryKey(sku, locationID),
+		cartQtyKey(sku, locationID),
+		cartExpKey(sku, locationID),
+		totalReservedKey(sku, locationID),
+	}
+
+	cmd := s.luaGetAvail.Run(ctx, s.client, keys)
+	if err := cmd.Err(); err != nil {
+		return 0, err
+	}
+	return cmd.Int64()
+}
+
+const reserveForCartScript = `
+local inventory_key = KEYS[1]
+local qty_key = KEYS[2]
+local exp_key = KEYS[3]
+local total_reserved_key = KEYS[4]
+local cart = ARGV[1]
+local req_qty = tonumber(ARGV[2])
+local ttl = tonumber(ARGV[3])
+
+-- Get current time in seconds
+local current_time = redis.call('TIME')[1]
+
+-- Clean expired reservations
+local expired_carts = redis.call('ZRANGEBYSCORE', exp_key, 0, current_time)
+local expired_qty_sum = 0
+for _, exp_cart in ipairs(expired_carts) do
+    local qty = redis.call('HGET', qty_key, exp_cart)
+    if qty then
+        expired_qty_sum = expired_qty_sum + tonumber(qty)
+    end
+    redis.call('HDEL', qty_key, exp_cart)
+    redis.call('ZREM', exp_key, exp_cart)
+end
+if expired_qty_sum > 0 then
+    redis.call('DECRBY', total_reserved_key, expired_qty_sum)
+end
+
+-- Get total_reserved
+local total_reserved = tonumber(redis.call('GET', total_reserved_key) or 0)
+
+-- Get inventory
+local inventory = tonumber(redis.call('GET', inventory_key) or 0)
+
+-- Check if enough available
+if inventory - total_reserved >= req_qty then
+    redis.call('HSET', qty_key, cart, req_qty)
+    redis.call('ZADD', exp_key, current_time + ttl, cart)
+    redis.call('INCRBY', total_reserved_key, req_qty)
+    return 1
+else
+    return 0
+end
+`
+
+const releaseForCartScript = `
+local qty_key = KEYS[1]
+local exp_key = KEYS[2]
+local total_reserved_key = KEYS[3]
+local cart = ARGV[1]
+
+local qty = redis.call('HGET', qty_key, cart)
+if qty then
+    redis.call('DECRBY', total_reserved_key, tonumber(qty))
+end
+redis.call('HDEL', qty_key, cart)
+redis.call('ZREM', exp_key, cart)
+return 1
+`
+
+const getAvailableScript = `
+local inventory_key = KEYS[1]
+local qty_key = KEYS[2]
+local exp_key = KEYS[3]
+local total_reserved_key = KEYS[4]
+
+-- Get current time
+local current_time = redis.call('TIME')[1]
+
+-- Clean expired
+local expired_carts = redis.call('ZRANGEBYSCORE', exp_key, 0, current_time)
+local expired_qty_sum = 0
+for _, exp_cart in ipairs(expired_carts) do
+    local qty = redis.call('HGET', qty_key, exp_cart)
+    if qty then
+        expired_qty_sum = expired_qty_sum + tonumber(qty)
+    end
+    redis.call('HDEL', qty_key, exp_cart)
+    redis.call('ZREM', exp_key, exp_cart)
+end
+if expired_qty_sum > 0 then
+    redis.call('DECRBY', total_reserved_key, expired_qty_sum)
+end
+
+local total_reserved = tonumber(redis.call('GET', total_reserved_key) or 0)
+local inventory = tonumber(redis.call('GET', inventory_key) or 0)
+return inventory - total_reserved
+`