/// <summary>
/// <inheritdoc/>
/// <remarks>
/// This is the appropriate action for <see cref="T:VendingMachine.WaitUserSelectionState"/> i.e. when the machine is ready for the user to select an item.
/// <list type="bullet">
/// <item>
/// <description>
/// Case 1. Checks the total machine inventory and if it is empty, it transitions back to <see cref="T:VendingMachine.SoldOutState"/>.
/// Machine needs a refill.
/// </description>
/// </item>
/// <item>
/// <description>
/// Case 2. Checks if there is sufficient stock of the selected item and transitions the state to <see cref="T:VendingMachine.WaitCoinState"/>.
/// User is in a position to insert the coins.
/// </description>
/// </item>
/// <item>
/// <description>
/// Case 3. If there is no stock left for the selected item it transitions back to <see cref="T:VendingMachine.WaitUserSelectionState"/>.
/// This allows the user to reselect a different item.
/// </description>
/// </item>
/// </list>
/// </remarks>
/// </summary>
/// <param name="itemName">Name of the product</param>
public void SelectItem(string itemName)
{
// Machine's inventory is Zero. Everything is sold out. Make the state transition to the sold out state
if (_machine.TotalItemCount == 0)
{
_machine.State = _machine.GetSoldOutState;
return;
}
// check if the machine has enough stock of the selected item
if (_machine.GetItemCount(itemName) > 0)
{
// tell the machine to update the selected product in transaction
_machine.AddItem(itemName);
_machine.DisplayMessage(string.Format("You selected {0} with a value of {1} ", _machine.SelectedItem.Name, _machine.SelectedItem.Price));
// change the state to "wait for coins".
_machine.State = _machine.GetWaitCoinState;
// display an appropriate message to the user
_machine.DisplayMessage(string.Format("Please insert coins to buy '{0}'", _machine.SelectedItem.Name));
}
else
{
// Sufficient stock is not available. Hence, change the state to wait selection state
// such that the user can select a different drink. Notify this to the user.
_machine.State = _machine.GetUserSelectItemState;
throw new ApplicationException(string.Format("Sorry, '{0}' is not available. Please select a different drink.",
_machine.SelectedItem.Name));
}
}
/// <summary>
/// <inheritdoc/>
/// <remarks>
/// The operation checks if the customer has tendered the correct amount for the selected product.
/// If the customer owes more then it propmpts to enter further amount else the state is changed to
/// <see cref="T:VendingMachine.SoldState"/>
/// </remarks>
/// </summary>
public void InsertCoins()
{
// if balance is negative that means machine needs to return the amount to the customer
if (_machine.CustomerBalance <= 0)
{
_machine.State = _machine.GetSoldState;
}
else
{
_machine.DisplayMessage(string.Format("Balance amount remaining {0}", _machine.CustomerBalance));
}
}
/// <summary>
/// <inheritdoc/>
/// <remarks>
/// Dispenses the changes and sets the state back to user wait selection
/// </remarks>
/// </summary>
public void DispenseChange()
{
var change = _machine.TenderChange();
_machine.DisplayMessage(string.Format("Please collect your change : \n{0}", change));
_machine.State = _machine.GetUserSelectItemState;
}
/// <summary>
/// <inheritdoc/>
/// <remarks>
/// The current state is the <see cref="T:VendingMachine.SoldState"/>. This means that the user has paid.
/// The following scenarios are possible in this case :-
/// <list type="bullet">
/// <item>
/// <description>
/// Case 1. Machine does not have exact change to tender. Hence, refund the user money and set the transition state to
/// <see cref="T:VendingMachine.WaitUserSelectionState"/>
/// </description>
/// </item>
/// <item>
/// <description>
/// Case 2. Everything is fine. Ask the machine to release the drink.
/// </description>
/// </item>
/// <item>
/// <description>
/// Case 3. After releasing the item, check if the machine owes any amount to the user. If yes, then,
/// the state is changed to <see cref="T:VendingMachine.DispenseChangeState"/>
/// </description>
/// </item>
/// <item>
/// <description>
/// Case 4. After releasing the item, checks if the machine has enough inventory and it owes nothing to the user.
/// Transitions the state to <see cref="T:VendingMachine.WaitUserSelectionState"/>
/// </description>
/// </item>
/// <item>
/// <description>
/// Case 5. After releasing the item, check the total inventory count.
/// If its zero, then transition the state to <see cref="T:VendingMachine.SoldOutState"/>
/// </description>
/// </item>
/// </list>
/// </remarks>
/// </summary>
public void DispenseItem()
{
// Machine does not have exact change to tender, hence do not dispense the item
// Change back the state to user selection state, refund the money and show an appropriate message to the user.
if (String.IsNullOrEmpty(_machine.TenderChange()))
{
var refund = _machine.RefundMoney();
_machine.State = _machine.GetUserSelectItemState;
throw new ApplicationException(string.Format("Machine does not have sufficient change. Please tender exact change. Please collect your inserted amount{0}", refund));
}
_machine.ReleaseItem();
_machine.DisplayMessage("Item has been dispensed. Please do not forget to collect it.");
// machine has to refund
if (_machine.CustomerBalance < 0)
{
_machine.State = _machine.GetDispenseChangeState;
}
// Machine has enough products and has nothing to refund back to the user
if (_machine.TotalItemCount > 0 && _machine.CustomerBalance == 0)
{
_machine.State = _machine.GetUserSelectItemState;
}
// Machine is empty. Everything is sold out. Hence, change the state to SoldOut
if (_machine.TotalItemCount == 0)
{
_machine.State = _machine.GetSoldOutState;
throw new ApplicationException("Sorry, the machine is out of stock.");
}
}
/// <summary>
/// <inheritdoc />
/// This can only happen when total item count is zero and machine is in sold out state.
/// User tries to select an item
/// </summary>
public void SelectItem(string itemName)
{
_machine.DisplayMessage("Products are not available. Machine needs a refill.");
}
