use Inventory.Base.InventoryInterface;
use Inventory.Base.PartsInventory;

Inventory/PartsInventory -> InventoryInterface {
    String<> partNames.set(<>);
    Integer<> partQuantities.set(<>);
    Decimal<> partPrices.set(<>);

    +fn on_create() -> [Null] {
        // inventory initialized
    }

    +fn on_destroy() -> [Null] {
        my.partNames.set(<>);
        my.partQuantities.set(<>);
        my.partPrices.set(<>);
    }

    -fn findPartIndex(partName:String) -> [Integer] {
        Integer idx.set(-1);
        my.partNames.each(name, i -> {
            if (name.eq(partName)) {
                idx.set(i);
            }
        });
        rtn idx;
    }

    +fn addPart(partName:String, quantity:Integer, price:Decimal) -> [Boolean] {
        Integer i.set(my.findPartIndex(partName));
        if (i.gte(0)) {
            Integer current.set(my.partQuantities.get(i));
            my.partQuantities.remove(i);
            my.partQuantities.add(current.add(quantity));
            my.partPrices.remove(i);
            my.partPrices.add(price);
            rtn True;
        } else {
            my.partNames.add(partName);
            my.partQuantities.add(quantity);
            my.partPrices.add(price);
            rtn True;
        }
    }

    +fn removePart(partName:String, quantity:Integer) -> [Boolean] {
        Integer i.set(my.findPartIndex(partName));
        if (i.lt(0)) { rtn False; }

        Integer current.set(my.partQuantities.get(i));
        if (current.lt(quantity)) { rtn False; }

        if (current.eq(quantity)) {
            my.partNames.remove(i);
            my.partQuantities.remove(i);
            my.partPrices.remove(i);
        } else {
            my.partQuantities.remove(i);
            my.partQuantities.add(current.subtract(quantity));
        }
        rtn True;
    }

    +fn getPartPrice(partName:String) -> [Decimal] {
        Integer i.set(my.findPartIndex(partName));
        if (i.lt(0)) { rtn 0; }
        rtn my.partPrices.get(i);
    }

    +fn getTotalInventoryValue() -> [Decimal] {
        Decimal total.set(0);
        my.partNames.each(name, i -> {
            Decimal value.set(my.partQuantities.get(i).multiply(my.partPrices.get(i)));
            total.set(total.add(value));
        });
        rtn total;
    }

    +fn getPartDetails(partName:String) -> [String] {
        Integer i.set(my.findPartIndex(partName));
        if (i.lt(0)) { rtn ["Part not found"]; }
        String details.set(
            partName
            .concat(" — Qty: ")
            .concat(my.partQuantities.get(i).format())
            .concat(", Price: $")
            .concat(my.partPrices.get(i).format())
        );
        rtn [details];
    }

    -fn ensureNonNegative(quantity:Integer) -> [Boolean] {
        if (quantity.lt(0)) { rtn False; }
        rtn True;
    }

    fn audit_sample() {
        // protected (no prefix) example: internal audit routine callable within package
        String report.set("Inventory count: ".concat(my.partNames.length().format()));
        rtn report;
    }
}