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In this video we'll write the logic to handle a user interacting with the Tableau!

0:01
Just one user action remaining and don't worry, we saved the best for last.

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When we tap on a tab row pile just like with the foundation pile,

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we need to be able to tell which pile it is.

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But with the tableau pile, we also need to know which card was tapped in the pile.

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So we'll need to include both of those as its parameters.

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Right above our play card function, let's create our tableau tab function.

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Fun onTableauTap.

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And for the first parameter, let's pass an tableauIndex, which is an Int.

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And for the second parameter, let's pass in cardIndex, which is also an Int.

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Next, we need to figure out which tableauPile we're talking about.

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So it's type val tableauPile and

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set it equal to tableauPiles at index tableauIndex.

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And now that we've got our tableauPile Let's make sure it's not empty.

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If tableauPile.cards.size is greater than 0 and

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if our pile isn't empty, we need to get the card or

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cards that the player is trying to move.

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So let's create a new variable named cards and

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set it equal to tableauPile.cards.subList,

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and then let's use F1 on Mac or

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Ctrl+Q on Windows to check out the quick documentation.

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So the sublist function returns a mutable list of the portion of this

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list between the specified fromIndex, inclusive and toIndex, exclusive.

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So let's pass an card index cardindex for

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the fromIndex and for the toIndex,

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let's pass in tableauPile.cards.lastIndex + 1.

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Since the toIndex is exclusive, meaning, it doesn't include this index and our

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list, we need to add one more to make sure that our sublist includes the last card.

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And by the way, lastIndex here is what's known as an extension property.

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It's just like an extension function, except instead of a function,

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it's a property.

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And if we use Cmd or Ctrl+B to jump to the declaration,

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we can see that it's an extension property on the list object and

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it's just equal to the size of our list 1.

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How convenient.

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Back in our tableauPile.

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Now that we've got the cards were interested in just like

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with the other functions, we need to try and play them.

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And if we can play them, then we need to go ahead and

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remove them from this tableauPile.

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So let's type if playCards pass in our

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cards list and then add brackets.

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And if we played the cards successfully, let's remove them from our tableauPile.

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TableauPile.removeCards and pass in the cardIndex.

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Next, let's use Alt+Enter to create the play cards function.

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And inside this function,

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let's start by handling the case where there's only one card in the list.

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When there's only one card in the list,

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we can just pass that card along to the play card function and call it a day.

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So, let's start with if cards.size is equal to 1.

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And if it is,

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let's return the result of passing that card into our playCard function.

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Awesome, that takes care of that case.

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All that's left is the case where we're trying to move multiple cards from one

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tableauPile to another.

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To handle this, let's start with an L statement.

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And then just like we did with our playCard function,

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let's try adding those cards to each of our tableauPiles to try and find a match.

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In fact, let's just copy this tableauPiles loop from our playCard function and

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paste it up here into our else block.

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Then instead of passing an mutableListof(card),

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let's just pass in the cards parameter.

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Finally, if we make it to the end of the function without finding a match,

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then we need to return false.

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We did it.

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Not only does our model contain all the objects we need,

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but now it also contains all the logic we need to tie those objects together.

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At this point, we're pretty much done with our game.

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Remember, we're saving the UI for another course.

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So at this point, all we've got left is the presenter and the view and

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we'll finish those up in the next video.
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