Set Age Restrictions on library with a slider (#468)

* Adding groups logic and restrictions

* Cleaning up some redundant code

* hastily made translations

* Linter issues

* More linting

* PR comments

* Covering other APIs with age filters per comment

* Add ages to age ratings

* Making the linter happy

---------

Co-authored-by: Robert Clabough <robert@clabough.tech>

server/utils/ageRatings.ts

@@ -5,64 +5,71 @@ import { AgeRatingOrganization } from "~/prisma/client/enums";
  * will be to normalize to these ratings. Admins of course can override and set a separate rating if needed.
  *
  * These will change, but historically very infrequently.
+ *
+ * Each rating has a `value` (the string stored in the database) and an `age` (the minimum age for that rating).
  */
 
+interface RatingDef {
+  readonly value: string;
+  readonly age: number;
+}
+
 export const ESRBRating = {
-  EC: "EC",
-  E: "E",
-  E10: "E10",
-  T: "T",
-  M: "M",
-  AO: "AO",
+  EC: { value: "EC", age: 3 },
+  E: { value: "E", age: 6 },
+  E10: { value: "E10", age: 10 },
+  T: { value: "T", age: 13 },
+  M: { value: "M", age: 17 },
+  AO: { value: "AO", age: 18 },
 } as const;
 
 export const PEGIRating = {
-  "3": "3",
-  "7": "7",
-  "12": "12",
-  "16": "16",
-  "18": "18",
+  "3": { value: "3", age: 3 },
+  "7": { value: "7", age: 7 },
+  "12": { value: "12", age: 12 },
+  "16": { value: "16", age: 16 },
+  "18": { value: "18", age: 18 },
 } as const;
 
 export const CEROrating = {
-  A: "A",
-  B: "B",
-  C: "C",
-  D: "D",
-  Z: "Z",
+  A: { value: "A", age: 0 },
+  B: { value: "B", age: 12 },
+  C: { value: "C", age: 15 },
+  D: { value: "D", age: 17 },
+  Z: { value: "Z", age: 18 },
 } as const;
 
 export const USKRating = {
-  "0": "0",
-  "6": "6",
-  "12": "12",
-  "16": "16",
-  "18": "18",
+  "0": { value: "0", age: 0 },
+  "6": { value: "6", age: 6 },
+  "12": { value: "12", age: 12 },
+  "16": { value: "16", age: 16 },
+  "18": { value: "18", age: 18 },
 } as const;
 
 export const GRACRating = {
-  ALL: "ALL",
-  "12": "12",
-  "15": "15",
-  "18": "18",
+  ALL: { value: "ALL", age: 0 },
+  "12": { value: "12", age: 12 },
+  "15": { value: "15", age: 15 },
+  "18": { value: "18", age: 18 },
 } as const;
 
 export const ClassIndRating = {
-  L: "L",
-  "10": "10",
-  "12": "12",
-  "14": "14",
-  "16": "16",
-  "18": "18",
+  L: { value: "L", age: 0 },
+  "10": { value: "10", age: 10 },
+  "12": { value: "12", age: 12 },
+  "14": { value: "14", age: 14 },
+  "16": { value: "16", age: 16 },
+  "18": { value: "18", age: 18 },
 } as const;
 
 export const ACBRating = {
-  G: "G",
-  PG: "PG",
-  M: "M",
-  MA15: "MA15",
-  R18: "R18",
-  RC: "RC",
+  G: { value: "G", age: 0 },
+  PG: { value: "PG", age: 8 },
+  M: { value: "M", age: 15 },
+  MA15: { value: "MA15", age: 15 },
+  R18: { value: "R18", age: 18 },
+  RC: { value: "RC", age: 18 },
 } as const;
 
 export const RATINGS_FOR_ORGANIZATION = {
@@ -73,8 +80,62 @@ export const RATINGS_FOR_ORGANIZATION = {
   [AgeRatingOrganization.GRAC]: GRACRating,
   [AgeRatingOrganization.ClassInd]: ClassIndRating,
   [AgeRatingOrganization.ACB]: ACBRating,
-} as const satisfies Record<AgeRatingOrganization, Record<string, string>>;
+} as const satisfies Record<AgeRatingOrganization, Record<string, RatingDef>>;
 
 export function getAvailableRatings(org: AgeRatingOrganization): string[] {
-  return Object.values(RATINGS_FOR_ORGANIZATION[org]);
+  return Object.values(RATINGS_FOR_ORGANIZATION[org]).map((r) => r.value);
+}
+
+/**
+ * Given a maximum allowed age, returns all org:rating pairs that exceed it (should be banned).
+ */
+export function getBannedRatingsForMaxAge(
+  maxAge: number,
+): Array<{ organization: AgeRatingOrganization; rating: string }> {
+  const banned: Array<{ organization: AgeRatingOrganization; rating: string }> =
+    [];
+  for (const org of Object.values(AgeRatingOrganization)) {
+    const ratings = RATINGS_FOR_ORGANIZATION[org];
+    for (const def of Object.values(ratings)) {
+      if (def.age > maxAge) {
+        banned.push({ organization: org, rating: def.value });
+      }
+    }
+  }
+  return banned;
+}
+
+/**
+ * Given a set of banned ratings, infer what max age slider position would produce them.
+ * Returns null if the set doesn't match any clean slider threshold (manual overrides).
+ */
+export function inferMaxAgeFromBannedRatings(
+  banned: Array<{ organization: string; rating: string }>,
+): number | null {
+  if (banned.length === 0) return 18;
+
+  // Try each possible age and check if the banned set matches exactly
+  const possibleAges = new Set<number>();
+  for (const orgRatings of Object.values(RATINGS_FOR_ORGANIZATION)) {
+    for (const def of Object.values(orgRatings)) {
+      possibleAges.add(def.age);
+    }
+  }
+
+  const bannedSet = new Set(banned.map((b) => `${b.organization}:${b.rating}`));
+
+  for (const age of Array.from(possibleAges).sort((a, b) => b - a)) {
+    const expected = getBannedRatingsForMaxAge(age);
+    const expectedSet = new Set(
+      expected.map((e) => `${e.organization}:${e.rating}`),
+    );
+    if (
+      expectedSet.size === bannedSet.size &&
+      [...expectedSet].every((e) => bannedSet.has(e))
+    ) {
+      return age;
+    }
+  }
+
+  return null;
 }