Add basic state retrieval methods to the game service (#2)

src/services/GameState.service.js

@@ -1,4 +1,10 @@
-import { Player, GridCellState, GameState } from '../module/util.js'
+import { Player, GridCellState, GameState, clone } from '../module/util.js'
+
+// Export a single instance, so it can be shared by all files
+// To use the game state service, you should do:
+// import game_service from './services/GameState.service.js'
+const game_service = new GameStateService()
+export default game_service
 
 /**
  * Singleton service for managing the state of the game.
@@ -41,10 +47,18 @@ export class GameStateService {
 
     /**
      * The current player.
+     * @private
      * @type {string}
      */
     current_player = Player.One
 
+    /**
+     * The current opponent.
+     * @private
+     * @type {string}
+     */
+    current_opponent = Player.Two
+
     /**
      * Construct a new game service. Initialize any internal states.
      */
@@ -64,6 +78,58 @@ export class GameStateService {
         return [this.n_rows, this.n_cols]
     }
 
+    /**
+     * Get the player who is the focus of the current game state.
+     * @return {string}
+     */
+    get_current_player() {
+        return this.current_player
+    }
+
+    /**
+     * Get the player who is NOT the focus of the current game state.
+     * @return {string}
+     */
+    get_current_opponent() {
+        return this.current_opponent
+    }
+
+    /**
+     * Get the state of the current player's board, as it should appear to them.
+     * @return {object[][]}
+     */
+    get_current_player_state() {
+        // The player can see everything about their own board, so just return it.
+        // Return a deep-copy, so internal state can't be modified.
+        return clone(this.player_x_game_board[this.current_player])
+    }
+
+    /**
+     * Get the state of the current opponent's board, as it should appear to the
+     * current player. Note that the current player cannot see "ship" spaces, only
+     * available, damaged, missed, or sunk.
+     * @return {object[][]}
+     */
+    get_current_opponent_state() {
+        // Return a deep-copy, so internal state can't be modified.
+        const state = clone(this.player_x_game_board[this.current_opponent])
+        const hidden_states = [
+            GridCellState.Disabled,
+            GridCellState.Ship,
+        ]
+
+        return state.map(row => {
+            return row.map(cell => {
+                if ( hidden_states.includes(cell.render) ) {
+                    // This is a hidden state, so hide it
+                    cell.render = GridCellState.Available
+                }
+
+                return cell
+            })
+        })
+    }
+
     /**
      * Build an empty structure of grid cells.
      * @return {object[][]}
@@ -79,7 +145,3 @@ export class GameStateService {
         })
     }
 }
-
-// Export a single instance, so it can be shared by all files
-const game_state = new GameStateService()
-export default game_state