From 1a308eadf53fe2ffbc6a36e2ad13d29f213f1925 Mon Sep 17 00:00:00 2001
From: Chris Wanstrath <chris@ozmm.org>
Date: Tue, 9 Dec 2025 08:35:39 -0800
Subject: [PATCH] [prelude] add `date` functions

---
 src/prelude/date.ts            |  12 +++
 src/prelude/index.ts           |   2 +
 src/prelude/tests/date.test.ts | 170 +++++++++++++++++++++++++++++++++
 3 files changed, 184 insertions(+)
 create mode 100644 src/prelude/date.ts
 create mode 100644 src/prelude/tests/date.test.ts

diff --git a/src/prelude/date.ts b/src/prelude/date.ts
new file mode 100644
index 0000000..dda92ef
--- /dev/null
+++ b/src/prelude/date.ts
@@ -0,0 +1,12 @@
+export const date = {
+  now: () => Date.now(),
+  year: (time: number) => (new Date(time)).getFullYear(),
+  month: (time: number) => (new Date(time)).getMonth(),
+  date: (time: number) => (new Date(time)).getDate(),
+  hour: (time: number) => (new Date(time)).getHours(),
+  minute: (time: number) => (new Date(time)).getMinutes(),
+  second: (time: number) => (new Date(time)).getSeconds(),
+  ms: (time: number) => (new Date(time)).getMilliseconds(),
+  new: (year: number, month: number, day: number, hour = 0, minute = 0, second = 0, ms = 0) =>
+    new Date(year, month, day, hour, minute, second, ms).getTime()
+}
\ No newline at end of file
diff --git a/src/prelude/index.ts b/src/prelude/index.ts
index 2a01236..d69cfc4 100644
--- a/src/prelude/index.ts
+++ b/src/prelude/index.ts
@@ -6,6 +6,7 @@ import {
   extractParamInfo, isWrapped, getOriginalFunction,
 } from 'reefvm'
 
+import { date } from './date'
 import { dict } from './dict'
 import { fs } from './fs'
 import { json } from './json'
@@ -16,6 +17,7 @@ import { str } from './str'
 import { types } from './types'
 
 export const globals: Record<string, any> = {
+  date,
   dict,
   fs,
   json,
diff --git a/src/prelude/tests/date.test.ts b/src/prelude/tests/date.test.ts
new file mode 100644
index 0000000..9a2f4a5
--- /dev/null
+++ b/src/prelude/tests/date.test.ts
@@ -0,0 +1,170 @@
+import { expect, describe, test } from 'bun:test'
+
+describe('date', () => {
+  test('date.now returns current timestamp', () => {
+    expect(`date.now | number?`).toEvaluateTo(true)
+
+    expect(`(date.now) > 1577836800000`).toEvaluateTo(true)
+  })
+
+  test('date.new creates timestamp from components', () => {
+    expect(`
+      t = date.new 2024 0 1 12 0 0 500
+      [
+        (date.year t)
+        (date.month t)
+        (date.date t)
+        (date.hour t)
+        (date.minute t)
+        (date.second t)
+        (date.ms t)
+      ]
+    `).toEvaluateTo([2024, 0, 1, 12, 0, 0, 500])
+  })
+
+  test('date.new with minimal arguments', () => {
+    expect(`
+      t = date.new 2024 5 15
+      [
+        (date.year t)
+        (date.month t)
+        (date.date t)
+        (date.hour t)
+        (date.minute t)
+        (date.second t)
+        (date.ms t)
+      ]
+    `).toEvaluateTo([2024, 5, 15, 0, 0, 0, 0])
+  })
+
+  test('date.year extracts year', () => {
+    expect(`
+      t = date.new 2024 0 1
+      date.year t
+    `).toEvaluateTo(2024)
+
+    expect(`
+      t = date.new 1999 11 31
+      date.year t
+    `).toEvaluateTo(1999)
+  })
+
+  test('date.month extracts month (0-indexed)', () => {
+    // January = 0, December = 11
+    expect(`
+      jan = date.new 2024 0 1
+      dec = date.new 2024 11 31
+      [(date.month jan) (date.month dec)]
+    `).toEvaluateTo([0, 11])
+  })
+
+  test('date.date extracts day of month', () => {
+    expect(`
+      t = date.new 2024 5 15
+      date.date t
+    `).toEvaluateTo(15)
+
+    expect(`
+      date.new 2024 0 1 | date.date
+    `).toEvaluateTo(1)
+  })
+
+  test('date.hour extracts hour', () => {
+    expect(`
+      t = date.new 2024 0 1 14 30 45
+      date.hour t
+    `).toEvaluateTo(14)
+
+    expect(`
+      t = date.new 2024 0 1 0 0 0
+      date.hour t
+    `).toEvaluateTo(0)
+  })
+
+  test('date.minute extracts minute', () => {
+    expect(`
+      t = date.new 2024 0 1 14 30 45
+      date.minute t
+    `).toEvaluateTo(30)
+  })
+
+  test('date.second extracts second', () => {
+    expect(`
+      t = date.new 2024 0 1 14 30 45
+      date.second t
+    `).toEvaluateTo(45)
+  })
+
+  test('date.ms extracts milliseconds', () => {
+    expect(`
+      t = date.new 2024 0 1 14 30 45 250
+      date.ms t
+    `).toEvaluateTo(250)
+  })
+
+  test('round-trip: create and extract components', () => {
+    expect(`
+      t = date.new 2024 6 4 15 30 45 123
+      year = date.year t
+      month = date.month t
+      day = date.date t
+      hour = date.hour t
+      min = date.minute t
+      sec = date.second t
+      ms = date.ms t
+      [year month day hour min sec ms]
+    `).toEvaluateTo([2024, 6, 4, 15, 30, 45, 123])
+  })
+
+  test('edge cases - midnight', () => {
+    expect(`
+      t = date.new 2024 0 1 0 0 0 0
+      [
+        (date.hour t)
+        (date.minute t)
+        (date.second t)
+        (date.ms t)
+      ]
+    `).toEvaluateTo([0, 0, 0, 0])
+  })
+
+  test('edge cases - end of day', () => {
+    expect(`
+      t = date.new 2024 0 1 23 59 59 999
+      [
+        (date.hour t)
+        (date.minute t)
+        (date.second t)
+        (date.ms t)
+      ]
+    `).toEvaluateTo([23, 59, 59, 999])
+  })
+
+  test('edge cases - leap year', () => {
+    expect(`
+      t = date.new 2024 1 29
+      [
+        (date.year t)
+        (date.month t)
+        (date.date t)
+      ]
+    `).toEvaluateTo([2024, 1, 29])
+  })
+
+  test('combining date functions with arithmetic', () => {
+    expect(`
+      t = date.new 2024 5 15 10 30 0
+      next-hour = date.new 2024 5 15 11 30 0
+      (date.hour next-hour) - (date.hour t)
+    `).toEvaluateTo(1)
+  })
+
+  test('using date.now in calculations', () => {
+    // Check that date.now is in the past compared to a future timestamp
+    expect(`
+      now = (date.now)
+      future = date.new 2030 0 1
+      future > now
+    `).toEvaluateTo(true)
+  })
+})
\ No newline at end of file