From 4c38940ff56568dfed451a6a18b2b9adc12d75d1 Mon Sep 17 00:00:00 2001
From: zkldi <notzkldi@zkldi.com>
Date: Wed, 9 Jun 2021 15:25:02 +0100
Subject: [PATCH] add CreateGoalID

---
 server/src/lib/achievables/goals.ts | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/server/src/lib/achievables/goals.ts b/server/src/lib/achievables/goals.ts
index 90db764a7..1629722dd 100644
--- a/server/src/lib/achievables/goals.ts
+++ b/server/src/lib/achievables/goals.ts
@@ -4,6 +4,7 @@ import db from "../../external/mongo/db";
 import { KtLogger } from "../logger/logger";
 import { GetFolderChartIDs } from "../../utils/folder";
 import { FilterQuery } from "mongodb";
+import fjsh from "fast-json-stable-hash";
 
 export interface EvaluatedGoalReturn {
     achieved: boolean;
@@ -13,6 +14,21 @@ export interface EvaluatedGoalReturn {
     outOfHuman: string;
 }
 
+/**
+ * Creates a goalID from a goals charts and criteria.
+ *
+ * This uses FJSH to stable-stringify the charts and criteria,
+ * then hashes that string under sha256.
+ *
+ * @note We could do better here, by converting criteria
+ * to 'similar' criteria - like 100% resolving to 1million score
+ * but that proves very complex to implement when it comes
+ * to multiple games.
+ */
+export function CreateGoalID(charts: GoalDocument["charts"], criteria: GoalDocument["criteria"]) {
+    return fjsh.hash({ charts, criteria }, "sha256");
+}
+
 export async function EvaluateGoalForUser(
     goal: GoalDocument,
     userID: integer,