Added some display stuff

For errors, and I guess just general displays

I should try extend into colour I think too, just for fun

card_stuffs/src/lib.rs

@@ -1,3 +1,8 @@
+use thiserror::Error;
+use anyhow::Result;
+use std::fmt;
+
+#[derive(PartialEq, Debug)]
 pub enum Suit {
     Heart,
     Diamond,
@@ -5,6 +10,35 @@ pub enum Suit {
     Spade
 }
 
+#[derive(PartialEq, Debug)]
+pub enum Colour {
+    Black,
+    Red,
+}
+
+impl Suit {
+    pub fn colour(&self) -> Colour {
+        match *self {
+            Suit::Heart => Colour::Red,
+            Suit::Diamond => Colour::Red,
+            Suit::Club => Colour::Black,
+            Suit::Spade => Colour::Black,
+        }
+    }
+}
+
+impl fmt::Display for Suit {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Suit::Heart => write!(f, "♥"),
+            Suit::Diamond => write!(f, "♦"),
+            Suit::Club => write!(f, "♣"),
+            Suit::Spade => write!(f, "♠"),
+        }
+    }
+}
+
+#[derive(PartialEq, Debug)]
 pub enum Value {
     Ace,
     Two,
@@ -23,7 +57,8 @@ pub enum Value {
 
 impl Value {
     pub fn indexed_values(&self) -> u8 {
-        match *self {
+        // It might also make sense for Ace to be high... depends on context
+        match self {
             Value::Ace => 1,
             Value::Two => 2,
             Value::Three => 3,
@@ -41,17 +76,64 @@ impl Value {
     }
 }
 
+impl fmt::Display for Value {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Value::Ace => write!(f, "A"),
+            Value::Two => write!(f, "2"),
+            Value::Three => write!(f, "3"),
+            Value::Four => write!(f, "4"),
+            Value::Five => write!(f, "5"),
+            Value::Six => write!(f, "6"),
+            Value::Seven => write!(f, "7"),
+            Value::Eight => write!(f, "8"),
+            Value::Nine => write!(f, "9"),
+            Value::Ten => write!(f, "T"),
+            Value::Jack => write!(f, "J"),
+            Value::Queen => write!(f, "Q"),
+            Value::King => write!(f, "K"),
+        }
+    }
+}
+
+#[derive(PartialEq, Debug)]
 pub struct Card {
     pub suit: Suit,
     pub value: Value,
 }
 
 
-
-pub fn add(left: u64, right: u64) -> u64 {
-    left + right
+impl fmt::Display for Card {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}{}", self.value, self.suit)
+    }
 }
 
+#[derive(Error, Debug)]
+pub enum StackingError {
+    #[error("Trying to stack the same coloured suit")]
+    SameColour,
+    #[error("{0} is not \"next\" to {1}")]
+    NotAdjacent(Card, Card),
+}
+
+impl Card {
+    pub fn can_be_placed_on_top(&self, top: Card) -> bool {
+        // Can't be the same Colour
+        if self.suit.colour() != top.suit.colour() {
+            return false
+        }
+
+        // Needs to be adjascent
+        if self.value == Value::King || self.value.indexed_values() != top.value.indexed_values() + 1 {
+            return false
+        }
+
+        true
+    }
+}
+
+
 #[cfg(test)]
 mod tests {
     use super::*;