3 files changed, 134 insertions, 0 deletions
diff --git a/src/util.js b/src/util.js
index 4e23d9d..8b85ba7 100644
--- a/src/util.js
+++ b/src/util.js
@@ -14,3 +14,10 @@ export function random_choice(collection, r) {
   const idx = Math.floor(collection.length * r);
   return collection[idx];
 }
+
+
+export function pairs(arr1, arr2) {
+  return arr1
+    .map((x, i) => arr2.map(y => [x, y]))
+    .flat();
+}
diff --git a/src/world/agent.js b/src/world/agent.js
new file mode 100644
index 0000000..7ab501c
--- /dev/null
+++ b/src/world/agent.js
@@ -0,0 +1,83 @@
+import { pairs } from '../util.js';
+
+/* agent structure:
+ * {
+ *   id: string
+ *   net: network
+ *   state: network_state
+ *   x, y: number
+ *   flags: object
+ * }
+ */
+
+/* action structure:
+ * {
+ *   name: string,
+ *   propose: (agent) => proposal[]
+ * }
+ */
+
+
+/* proposal structure
+ * all proposed world and agent changes must be included for the proposed action to be valid
+ * similarly, if any world or agent change creates merge conflicts, the proposal cannot be merged
+ * and must be removed
+ * {
+ *   world_changes: proposal_world_change[]?
+ *   agent_changes: proposal_agent_change[]?
+ * }
+ */
+
+/* proposal_world_change
+ * { 
+ *   x, y: number
+ *   from: string
+ *   to:   string
+ * }
+ */
+
+/* proposal_agent_change
+ * {
+ *   agent_id: string
+ *   x, y: number?
+ *   flags: object?
+ * }
+ */
+
+
+function world_change_conflict(a, b) {
+  if (a.x != b.x) { return [false, false]; }
+  if (a.y != b.y) { return [false, false]; }
+  if (a.to != b.to) { return [true, false]; }
+  // x, y, and to all match -- merge
+  return [false, true];
+}
+
+
+function proposal_conflict_merge(a, b) {
+  const [world_conflict, world_merge] = pairs(a.world_changes, b.world_changes).reduce(
+    (acc, [a, b]) => {
+      const [conflict, merge] = world_change_conflict(a, b);
+      return [acc[0] || conflict, acc[1] || merge];
+    }, 
+    [false, false]
+  )
+  return [world_conflict, world_merge];
+}
+
+
+// merge proposals
+// if two sub-updates conflict, they are both omitted from the final merged proposal
+export function proposal_merge(arr, proposal) {
+  const conflict_merge = arr.map(x => proposal_conflict_merge(x, proposal));
+
+  // if any conflicts are detected then don't merge
+  if (conflict_merge.reduce((acc, [c, m]) => acc || c, false)) {
+    const conflict_free = arr.filter((x, i) => !conflict_merge[i][0]);
+    return conflict_free;
+  } else {
+    // no conflicts, but need to merge identical actions
+    const no_merge = arr.filter((x, i) => !conflict_merge[i][1]);
+    return [...no_merge, proposal];
+  }
+}
diff --git a/src/world/agent.test.js b/src/world/agent.test.js
new file mode 100644
index 0000000..ea64fcb
--- /dev/null
+++ b/src/world/agent.test.js
@@ -0,0 +1,44 @@
+import {
+  proposal_merge,
+} from './agent.js';
+
+
+// --===== proposal conflicts =====--
+
+test("proposals changing different tiles don't conflict", () => {
+  const a = {
+    world_changes: [{ x: 4, y: 3, from: 'empty', to: 'mutable' }],
+  };
+
+  const b = {
+    world_changes: [{ x: 4, y: 4, from: 'empty', to: 'flag' }],
+  };
+
+  expect(proposal_merge([a], b)).toEqual([a, b]);
+});
+
+
+test("proposals changing the same tile to different states conflict", () => {
+  const a = {
+    world_changes: [{ x: 4, y: 3, from: 'empty', to: 'mutable' }],
+  };
+
+  const b = {
+    world_changes: [{ x: 4, y: 3, from: 'empty', to: 'flag' }],
+  };
+
+  expect(proposal_merge([a], b)).toEqual([]);
+});
+
+
+test("proposals changing the same tile to the same state merge to a single proposal", () => {
+  const a = {
+    world_changes: [{ x: 4, y: 3, from: 'empty', to: 'mutable' }],
+  };
+
+  const b = {
+    world_changes: [{ x: 4, y: 3, from: 'empty', to: 'mutable' }],
+  };
+
+  expect(proposal_merge([a], b)).toEqual([a]);
+});