Implement pawn promotion

[matheusmosca]

The promotion event happens when a pawn reaches the last row (white player) or the first row (black player).

• The player should see a modal asking for a piece to replace his pawn
• A pawn can only be replaced by a queen, a rook, a bishop, or a knight (with the player's color)
• The player has to choose one piece to replace

[nyc4m]

Can I work on this one ? 😄

[nyc4m]

Before adding a modal I think the code might need some rearranging, because when using a modal, you need to make the game "wait" for the player to make his choice, and currently the code is not designed to wait on something. I think it would be useful to create an other issue to adapt the code first 😄

[nyc4m]

sorry to answer just now, i've been a bit busy these days

[matheusmosca]

No problem, I've been busy these days too. Could you describe better which adaption it would be? I created this repo when I get started with TypeScript, that is why my code doesn't look so good though.

But I think the modal isn't dependent on the game progress, might there is a way to create a function which observes if a pawn can be promoted, then open a modal and handle the promotion event. In that approach, the logic wouldn't be on the piece's logic.

But I may be wrong, thanks for your suggestion! 😄