Add Naive Game Rules (#11)

* Add components for tracking points

* Add methods to create new entities

* Adds nodes for points

* Add system to detect points

* Adds system to detect a winner

* Add system to render points and winner

* Add points required to win to config

* Add it all to the engine

* Add mention of points to changelog

1 files changed, 104 insertions, 0 deletions

diff --git a/lib/systems/detect_winner.js b/lib/systems/detect_winner.js
new file mode 100644
index 0000000..e7fbd76
--- /dev/null
+++ b/lib/systems/detect_winner.js
@@ -0,0 +1,104 @@
+import { System } from '@serpentity/serpentity';
+
+import WinnerNode from '../nodes/winner';
+import PointsNode from '../nodes/points';
+
+import Config from '../config';
+
+/**
+ * Handles finding the winner
+ *
+ * @extends {external:Serpentity.System}
+ * @class DetectWinnerSystem
+ * @param {object} config a configuration object to extend.
+ */
+export default class DetectWinnerSystem extends System {
+
+  constructor(config = {}) {
+
+    super();
+
+    /**
+     * The collection of points keepers
+     *
+     * @property {external:Serpentity.NodeCollection} pointsKeepers
+     * @instance
+     * @memberof DetectWinnerSystem
+     */
+    this.pointsKeepers = null;
+
+    /**
+     * The collection of winner keepers
+     *
+     * @property {external:Serpentity.NodeCollection} winnerKeepers
+     * @instance
+     * @memberof DetectWinnerSystem
+     */
+    this.winnerKeepers = null;
+  }
+
+  /**
+   * Initializes system when added. Requests points and winner keepers
+   *
+   * @function added
+   * @memberof DetectWinnerSystem
+   * @instance
+   * @param {external:Serpentity.Engine} engine the serpentity engine to
+   * which we are getting added
+   */
+  added(engine) {
+
+    this.pointsKeepers = engine.getNodes(PointsNode);
+    this.winnerKeepers = engine.getNodes(WinnerNode);
+  }
+
+  /**
+   * Clears system resources when removed.
+   *
+   * @function removed
+   * @instance
+   * @memberof DetectWinnerSystem
+   */
+  removed() {
+
+    this.pointsKeepers = null;
+    this.winnerKeepers = null;
+  }
+
+  /**
+   * Runs on every update of the loop. Checks if someone won
+   *
+   * @function update
+   * @instance
+   * @param {Number} currentFrameDuration the duration of the current
+   * frame
+   * @memberof DetectWinnerSystem
+   */
+  update(currentFrameDuration) {
+
+    let winner = null;
+
+    for (const pointsKeeper of this.pointsKeepers) {
+      for (const pointsCandidate of Object.keys(pointsKeeper.points)) {
+        if (pointsKeeper.points[pointsCandidate] >= Config.maxPoints) {
+          winner = pointsCandidate;
+          break;
+        }
+      }
+    }
+
+    if (!winner) {
+      return;
+    }
+
+    for (const winnerKeeper of this.winnerKeepers) {
+
+      // Only one winner, another system should reset
+      if (!winnerKeeper.winner.winner) {
+        winnerKeeper.winner.winner = winner;
+      }
+
+    }
+  }
+};
+