:docs: Improve PAST labels (#1526)

src/lib/utils/contest.ts

@@ -302,6 +302,10 @@ export const getContestNameLabel = (contestId: string) => {
     return 'TDPC';
   }
 
+  if (contestId.startsWith('past')) {
+    return getPastContestLabel(PAST_TRANSLATIONS, contestId);
+  }
+
   if (contestId === 'practice2') {
     return 'ACL Practice';
   }
@@ -338,6 +342,71 @@ export const getContestNameLabel = (contestId: string) => {
   return contestId.toUpperCase();
 };
 
+/**
+ * A mapping of contest dates to their respective Japanese translations.
+ * Each key represents a date in the format 'YYYYMM', and the corresponding value
+ * is the Japanese translation indicating the contest number.
+ *
+ * Note:
+ * After the 15th contest, the URL includes the number of times the contest has been held
+ *
+ * See:
+ * https://atcoder.jp/contests/archive?ratedType=0&category=50
+ *
+ * Example:
+ * - '201912': ' 第 1 回' (The 1st contest in December 2019)
+ * - '202303': ' 第 14 回' (The 14th contest in March 2023)
+ */
+export const PAST_TRANSLATIONS = {
+  '201912': ' 第 1 回',
+  '202004': ' 第 2 回',
+  '202005': ' 第 3 回',
+  '202010': ' 第 4 回',
+  '202012': ' 第 5 回',
+  '202104': ' 第 6 回',
+  '202107': ' 第 7 回',
+  '202109': ' 第 8 回',
+  '202112': ' 第 9 回',
+  '202203': ' 第 10 回',
+  '202206': ' 第 11 回',
+  '202209': ' 第 12 回',
+  '202212': ' 第 13 回',
+  '202303': ' 第 14 回',
+};
+
+/**
+ * A regular expression to match strings that representing the 15th or later PAST contests.
+ * The string should start with "past" followed by exactly two digits and end with "-open".
+ * The matching is case-insensitive.
+ *
+ * Examples:
+ * - "past15-open" (matches)
+ * - "past16-open" (matches)
+ * - "past99-open" (matches)
+ * - "past1-open" (does not match)
+ */
+const regexForPast = /^past(\d{2})-open$/i;
+
+export function getPastContestLabel(
+  translations: Readonly<ContestLabelTranslations>,
+  contestId: string,
+): string {
+  let label = contestId;
+
+  Object.entries(translations).forEach(([abbrEnglish, japanese]) => {
+    label = label.replace(abbrEnglish, japanese);
+  });
+
+  if (label == contestId) {
+    label = label.replace(regexForPast, (_, round) => {
+      return `PAST 第 ${round} 回-open`;
+    });
+  }
+
+  // Remove suffix
+  return label.replace('-open', '').toUpperCase();
+}
+
 /**
  * Generates a formatted contest label for AtCoder University contests.
  *

src/test/lib/utils/contest.test.ts

@@ -366,18 +366,6 @@ describe('Contest', () => {
         });
       });
 
-      // TODO(#issue): Skipped until notational inconsistencies are resolved.
-      // Current issues:
-      // 1. Contest names use inconsistent formats (e.g., "past201912-open" vs "past17-open")
-      // 2. Need to standardize naming conventions across all contests
-      describe.skip('when contest_id contains past', () => {
-        TestCasesForContestNameLabel.past.forEach(({ name, value }) => {
-          runTests(`${name}`, [value], ({ contestId, expected }: TestCaseForContestNameLabel) => {
-            expect(getContestNameLabel(contestId)).toEqual(expected);
-          });
-        });
-      });
-
       describe('when contest_id is practice2 (ACL practice)', () => {
         TestCasesForContestNameLabel.aclPractice.forEach(({ name, value }) => {
           runTests(`${name}`, [value], ({ contestId, expected }: TestCaseForContestNameLabel) => {
@@ -446,6 +434,18 @@ describe('Contest', () => {
         });
       });
 
+      describe('when contest_id contains past', () => {
+        TestCasesForContestNameAndTaskIndex.past.forEach(({ name, value }) => {
+          runTests(
+            `${name}`,
+            [value],
+            ({ contestId, taskTableIndex, expected }: TestCaseForContestNameAndTaskIndex) => {
+              expect(addContestNameToTaskIndex(contestId, taskTableIndex)).toEqual(expected);
+            },
+          );
+        });
+      });
+
       describe('when contest_id is tessoku-book', () => {
         TestCasesForContestNameAndTaskIndex.tessokuBook.forEach(({ name, value }) => {
           runTests(

src/test/lib/utils/test_cases/contest_name_and_task_index.ts

@@ -1,7 +1,9 @@
 import { createTestCase, zip } from '../../common/test_helpers';
 import {
+  getPastContestLabel,
   getAtCoderUniversityContestLabel,
   getAojContestLabel,
+  PAST_TRANSLATIONS,
   AOJ_COURSES,
 } from '$lib/utils/contest';
 
@@ -81,6 +83,70 @@ export const typical90 = [
   }),
 ];
 
+const generatePastTestCases = (
+  contestIds: string[],
+  taskIndices: string[],
+): { name: string; value: TestCaseForContestNameAndTaskIndex }[] => {
+  return zip(contestIds, taskIndices).map(([contestId, taskIndex]) => {
+    const testCase = createTestCaseForContestNameAndTaskIndex(`PAST, ${contestId} ${taskIndex}`)({
+      contestId: `${contestId}`,
+      taskTableIndex: `${taskIndex}`,
+      expected: `${getPastContestLabel(PAST_TRANSLATIONS, contestId)} - ${taskIndex}`,
+    });
+
+    return testCase;
+  });
+};
+
+const PAST_TEST_DATA = {
+  // 1st
+  'past201912-open': {
+    contestId: 'past201904',
+    tasks: ['A', 'B', 'C', 'M', 'N', 'O'],
+  },
+  // 2nd
+  'past202004-open': {
+    contestId: 'past202004-open',
+    tasks: ['A', 'B', 'C', 'M', 'N', 'O'],
+  },
+  // 3rd
+  'past202005-open': {
+    contestId: 'past202005-open',
+    tasks: ['A', 'B', 'C', 'M', 'N', 'O'],
+  },
+  // 9th
+  'past202112-open': {
+    contestId: 'past202203-open',
+    tasks: ['A', 'B', 'C', 'M', 'N', 'O'],
+  },
+  // 10th
+  'past202203-open': {
+    contestId: 'past202203-open',
+    tasks: ['A', 'B', 'C', 'M', 'N', 'O'],
+  },
+  // 14th
+  'past202303-open': {
+    contestId: 'past202303-open',
+    tasks: ['A', 'B', 'C', 'M', 'N', 'O'],
+  },
+  'past15-open': {
+    contestId: 'past15-open',
+    tasks: ['A', 'B', 'C', 'M', 'N', 'O'],
+  },
+  'past16-open': {
+    contestId: 'past16-open',
+    tasks: ['A', 'B', 'C', 'M', 'N', 'O'],
+  },
+  'past17-open': {
+    contestId: 'past17-open',
+    tasks: ['A', 'B', 'C', 'M', 'N', 'O'],
+  },
+};
+
+export const past = Object.entries(PAST_TEST_DATA).flatMap(([contestId, tasks]) =>
+  generatePastTestCases(Array(tasks.tasks.length).fill(contestId), tasks.tasks),
+);
+
 export const tessokuBook = [
   createTestCaseForContestNameAndTaskIndex('Tessoku Book, Task A01')({
     contestId: 'tessoku-book',

src/test/lib/utils/test_cases/contest_name_labels.ts

@@ -21,42 +21,6 @@ export const tdpc = [
   }),
 ];
 
-// Note: Not yet implemented, because notational distortion needs to be corrected for each contest.
-export const past = [
-  createTestCaseForContestNameLabel('PAST 17th')({
-    contestId: 'past17-open',
-    expected: '',
-  }),
-  createTestCaseForContestNameLabel('PAST 16th')({
-    contestId: 'past16-open',
-    expected: '',
-  }),
-  createTestCaseForContestNameLabel('PAST 15th')({
-    contestId: 'past15-open',
-    expected: '',
-  }),
-  createTestCaseForContestNameLabel('PAST 14th')({
-    contestId: 'past202303-open',
-    expected: '',
-  }),
-  createTestCaseForContestNameLabel('PAST 13th')({
-    contestId: 'past202212-open',
-    expected: '',
-  }),
-  createTestCaseForContestNameLabel('PAST 3rd')({
-    contestId: 'past202005-open',
-    expected: '',
-  }),
-  createTestCaseForContestNameLabel('PAST 2nd')({
-    contestId: 'past202004-open',
-    expected: '',
-  }),
-  createTestCaseForContestNameLabel('PAST 1st')({
-    contestId: 'past201912-open',
-    expected: '',
-  }),
-];
-
 export const aclPractice = [
   createTestCaseForContestNameLabel('ACL Practice')({
     contestId: 'practice2',