Implement get_moves command on rs

Issue #1

rs/src/ui.rs

@@ -25,17 +25,47 @@ impl std::fmt::Display for board::Piece {
     }
 }
 
+trait GridAxisIO: std::fmt::Display
+where
+    Self: GridAxis,
+{
+    const ALL_CHARS: [char; 8];
+    fn parse(c: char) -> Result<Self, ()> {
+        let index = Self::ALL_CHARS.iter().position(|p| p == &c).ok_or(())?;
+        Ok(Self::ALL_VALUES[index].clone())
+    }
+}
+
+impl GridAxisIO for board::Rank {
+    const ALL_CHARS: [char; 8] = ['1', '2', '3', '4', '5', '6', '7', '8'];
+}
+
 impl std::fmt::Display for board::Rank {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        const ALL_CHARS: [char; 8] = ['1', '2', '3', '4', '5', '6', '7', '8'];
-        write!(f, "{}", ALL_CHARS[self.get_index() as usize])
+        write!(f, "{}", Self::ALL_CHARS[self.get_index() as usize])
     }
 }
 
+impl GridAxisIO for board::File {
+    const ALL_CHARS: [char; 8] = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'];
+}
+
 impl std::fmt::Display for board::File {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        const ALL_CHARS: [char; 8] = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'];
-        write!(f, "{}", ALL_CHARS[self.get_index() as usize])
+        write!(f, "{}", Self::ALL_CHARS[self.get_index() as usize])
+    }
+}
+
+impl board::Position {
+    fn parse(s: &str) -> Result<Self, ()> {
+        let mut chars = s.chars();
+        let file = board::File::parse(chars.next().ok_or(())?)?;
+        let rank = board::Rank::parse(chars.next().ok_or(())?)?;
+        if chars.next().is_none() {
+            Ok(board::Position::new(rank, file))
+        } else {
+            Err(())
+        }
     }
 }
 
@@ -74,6 +104,22 @@ impl Ui {
             Ok(result)
         }
     }
+    fn get_moves(&self, args: &[&str]) -> Result<String, String> {
+        if args.len() != 1 {
+            return Err("get_moves takes 1 arg".to_owned());
+        };
+        let position = board::Position::parse(args[0])
+            .map_err(|_| format!("Error parsing position {}", args[0]))?;
+        match self.board.get_legal_moves(&position) {
+            None => {
+                let error = format!("No moves possible from {}", position);
+                Err(error)
+            }
+            Some(positions) => {
+                Ok(positions.iter().map(|pos| format!("{}", pos)).collect())
+            }
+        }
+    }
     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
@@ -81,6 +127,7 @@ impl Ui {
         let args: Vec<&str> = cmd.collect();
         match cmd_type {
             "get_state" => self.get_state(&args),
+            "get_moves" => self.get_moves(&args),
             "" => Err("No command given".to_owned()),
             _ => Err("Invalid command".to_owned()),
         }