2 files changed, 53 insertions, 2 deletions
diff --git a/src/simulation/actions.js b/src/simulation/actions.js
index e389518..62a8395 100644
--- a/src/simulation/actions.js
+++ b/src/simulation/actions.js
@@ -137,7 +137,29 @@ const pretend_frozen = {
 };
 
 
+const unfreeze = {
+  size: 1,
+  propose: (world, agent, head) => {
+    if (head[0] < threshold) { return []; }
+    else {
+      const dx = { n: 0, e: 1, s: 0, w: -1 }[agent.flags.orientation];
+      const dy = { n: -1, e: 0, s: 1, w: 0 }[agent.flags.orientation];
+      const target = world.agents.filter(
+        a => a.x === agent.x+dx && a.y === agent.y+dy
+      )[0];
+      if (target === undefined) { return []; }
+      return [
+        { agent_changes: [{
+          agent_id: target.id,
+          flags: { frozen: false, emit: [0, 1, 0, 0, 0, 0, 0, 0] },
+        }]}
+      ];
+    }
+  },
+};
+
+
 export const actions = [
   move_forward, move_backward, turn_left, turn_right, 
-  place, trigger, pretend_frozen,
+  place, trigger, pretend_frozen, unfreeze,
 ];
diff --git a/src/simulation/actions.test.js b/src/simulation/actions.test.js
index 43ad23c..c5f35be 100644
--- a/src/simulation/actions.test.js
+++ b/src/simulation/actions.test.js
@@ -7,7 +7,7 @@ const [
   move_forward, move_backward, 
   turn_left, turn_right,
   place, trigger,
-  pretend_frozen,
+  pretend_frozen, unfreeze,
   ...rest
 ] = actions;
 
@@ -217,3 +217,32 @@ test("pretend frozen", () => {
     }]
   }]);
 });
+
+
+test("unfreeze", () => {
+  const agent1 = { id: 0, x: 0, y: 0, flags: { orientation: 'n' } };
+  const agent2 = { id: 1, x: 0,  y: -1 };
+  const agent3 = { id: 10, x: -1, y: 0 };
+  const agents = [ agent1, agent2, agent3 ];
+
+  expect(unfreeze.propose({agents}, agent1, [1])).toEqual([{
+    agent_changes: [{
+      agent_id: 1,
+      flags: { frozen: false, emit: [ 0, 1, 0, 0, 0, 0, 0, 0 ] },
+    }]
+  }]);
+
+  agent1.flags.orientation = 'w';
+
+  expect(unfreeze.propose({agents}, agent1, [1])).toEqual([{
+    agent_changes: [{
+      agent_id: 10,
+      flags: { frozen: false, emit: [ 0, 1, 0, 0, 0, 0, 0, 0 ] },
+    }]
+  }]);
+
+  agent1.flags.orientation = 's';
+  expect(unfreeze.propose({agents}, agent1, [1])).toEqual([]);
+
+  expect(unfreeze.propose({agents}, agent1, [0])).toEqual([]);
+});