Implement make_move function on engine

rs/src/board.rs

@@ -205,19 +205,25 @@ pub struct Board {
 }
 
 impl Board {
-    pub fn get_at(&self, position: &Position) -> Option<&Piece> {
+    fn get_at(&self, position: &Position) -> Option<&Piece> {
         self.state.get(position)
     }
-    pub fn set_at(
-        &mut self,
-        position: Position,
-        piece_or_empty: Option<Piece>,
-    ) {
+    fn set_at(&mut self, position: Position, piece_or_empty: Option<Piece>) {
         match piece_or_empty {
             Some(piece) => self.state.insert(position, piece),
             None => self.state.remove(&position),
         };
     }
+    fn move_from_to(
+        &mut self,
+        source: &Position,
+        target: Position,
+    ) -> Result<(), ()> {
+        let (_, piece) = self.state.remove_entry(source).ok_or(())?;
+        self.set_at(target, Some(piece));
+        Ok(())
+    }
+
     pub fn new() -> Board {
         Board {
             state: Default::default(),
@@ -255,4 +261,16 @@ impl Board {
             });
         Some(valid_moves.chain(valid_captures).collect())
     }
+    pub fn make_move(
+        &mut self,
+        source: &Position,
+        target: Position,
+    ) -> Result<(), ()> {
+        if !self.get_legal_moves(source).ok_or(())?.contains(&target) {
+            Err(())
+        } else {
+            // We checked that there is a piece at source in get_legal_moves
+            self.move_from_to(source, target)
+        }
+    }
 }

rs/src/ui.rs

@@ -120,6 +120,21 @@ impl Ui {
             }
         }
     }
+    fn make_move(&mut self, args: &[&str]) -> Result<String, String> {
+        if args.len() != 2 {
+            return Err("make_move takes 2 args".to_owned());
+        };
+        let source = board::Position::parse(args[0])
+            .map_err(|_| format!("Error parsing source {}", args[0]))?;
+        let target = board::Position::parse(args[1])
+            .map_err(|_| format!("Error parsing target {}", args[1]))?;
+        match self.board.make_move(&source, target) {
+            Err(()) => {
+                Err(format!("Move not possible {}-{}", args[0], args[1]))
+            }
+            Ok(()) => Ok(self.board.to_string()),
+        }
+    }
     fn handle_command(&mut self, s: &str) -> Result<String, String> {
         let mut cmd = s.split(',');
         // There will be at least an empty string => otherwise panic
@@ -128,6 +143,7 @@ impl Ui {
         match cmd_type {
             "get_state" => self.get_state(&args),
             "get_moves" => self.get_moves(&args),
+            "make_move" => self.make_move(&args),
             "" => Err("No command given".to_owned()),
             _ => Err("Invalid command".to_owned()),
         }