Move State struct impl to its own file

src/state.rs

@@ -0,0 +1,118 @@
+use crate::board::Color;
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub struct State {
+    side_to_move: Color,
+    castling_ability: [Castle; 2],
+    en_passant_target_square: Option<usize>,
+    halfmove_clock: u8,
+    fullmove_counter: u8,
+}
+
+impl State {
+    pub const fn new() -> Self {
+        Self {
+            side_to_move: Color::White,
+            castling_ability: [Castle::Both, Castle::Both],
+            en_passant_target_square: None,
+            halfmove_clock: 0,
+            fullmove_counter: 1,
+        }
+    }
+
+    pub const fn load_state(
+        side_to_move: Color,
+        castling_ability: [Castle; 2],
+        en_passant_target_square: Option<usize>,
+        halfmove_clock: u8,
+        fullmove_counter: u8,
+    ) -> Self {
+        Self {
+            side_to_move,
+            castling_ability,
+            en_passant_target_square,
+            halfmove_clock,
+            fullmove_counter,
+        }
+    }
+
+    pub const fn get_en_passant_target_square(&self) -> Option<usize> {
+        self.en_passant_target_square
+    }
+
+    pub fn set_castling_ability(&mut self, color: Color, castle: Castle) {
+        match color {
+            Color::White => self.castling_ability[0] = castle,
+            Color::Black => self.castling_ability[1] = castle,
+        }
+    }
+
+    pub fn update_castling_state_quiet(&mut self, source: usize, color: Color) {
+        self.update_castling_state_capture(source, color);
+
+        match (source, color) {
+            (4, Color::White) => self.set_castling_ability(color, Castle::None),
+            (60, Color::Black) => self.set_castling_ability(color, Castle::None),
+            _ => (),
+        }
+    }
+
+    pub fn update_castling_state_capture(&mut self, target: usize, color: Color) {
+        let (short_square, long_square) = match color {
+            Color::White => (7, 0),
+            Color::Black => (63, 56),
+        };
+
+        if target == short_square {
+            match self.get_castling_ability(color) {
+                Castle::Both => self.set_castling_ability(color, Castle::Long),
+                Castle::Short => self.set_castling_ability(color, Castle::None),
+                _ => (),
+            }
+        }
+
+        if target == long_square {
+            match self.get_castling_ability(color) {
+                Castle::Both => self.set_castling_ability(color, Castle::Short),
+                Castle::Long => self.set_castling_ability(color, Castle::None),
+                _ => (),
+            }
+        }
+    }
+
+    pub fn change_side(&mut self) {
+        self.side_to_move = match self.side_to_move {
+            Color::White => Color::Black,
+            Color::Black => Color::White,
+        }
+    }
+
+    pub const fn next_turn(&self) -> Color {
+        self.side_to_move
+    }
+
+    pub fn set_en_passant_target_square(&mut self, sq: Option<usize>) {
+        self.en_passant_target_square = sq;
+    }
+
+    pub const fn get_castling_ability(&self, color: Color) -> Castle {
+        match color {
+            Color::White => self.castling_ability[0],
+            Color::Black => self.castling_ability[1],
+        }
+    }
+}
+
+impl Default for State {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub enum Castle {
+    Short,
+    Long,
+    Both,
+    None,
+}