/// <summary>
/// <inheritdoc/>
/// <remarks>
/// User can wish to do an <see cref="M:VendingMachine.IState.EjectCoin"/> action in the <see cref="T:VendingMachine.WaitCoinState"/>. For ex: User inserted 10P but total price of the item is 20P.
/// So, instead of continuing, he may as well decide to cancel the transaction and get the refund back.
/// </remarks>
/// </summary>
public void EjectCoin()
{
var refund = _machine.RefundMoney();
_machine.DisplayMessage(string.Format("Transaction has been cancelled. Please collect the refund{0}.", refund));
_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/>
/// <remarks>
/// If the user performs an Insert Coin action in SoldOut state then refund back the money
/// </remarks>
/// </summary>
public void InsertCoins()
{
_machine.RefundMoney();
throw new ApplicationException("Machine is empty. Please take back your money.");
}
/// <summary>
/// <inheritdoc/>
/// <remarks>
/// When the machine is in <see cref="T:VendingMachine.WaitUserSelectionState"/>, user may try to perform the <see cref="M:VendingMachine.IState.InsertCoins"/> action.
/// In such a situation, the state will signal the machine to refund the coins.
/// No state transition will happen. The state of the machine remains unaltered.
/// User is presented with a message saying the product selection needs to happen first.
/// Alternatively,
/// </remarks>
/// </summary>
public void InsertCoins()
{
// return the inserted money from the user as the state is not appropriate to accept coins
_machine.RefundMoney();
throw new ApplicationException("Please select a product first. Collect back your money.");
}
