Initial commit

Author: hachibu

.gitignore

@@ -128,3 +128,5 @@ dist
 .yarn/build-state.yml
 .yarn/install-state.gz
 .pnp.*
+
+# datelata

README.md

@@ -1 +1,54 @@
-# datelta
+# Datelta (Date + Delta = Datelta)
+
+CLI tool to diff dates.
+
+## Quick Start
+
+- Install [Deno](https://docs.deno.com/runtime/manual/#install-deno)
+- Run `deno task install`
+- Run `datelta --start "Jan 1, 1990" | jq`
+
+## Usage
+
+Time between start date and end date.
+
+```
+datelta --start "jan 10, 1990 12:30:01" --end "feb 2002" | jq
+```
+
+```json
+{
+  "years": 12,
+  "months": 0,
+  "days": 24,
+  "hours": 11,
+  "minutes": 29,
+  "seconds": 59,
+  "milliseconds": 0
+}
+```
+
+Time since start date.
+
+```
+datelta --start "mar 2006" | jq
+```
+
+```json
+{
+  "years": 17,
+  "months": 7,
+  "days": 28,
+  "hours": 19,
+  "minutes": 42,
+  "seconds": 36,
+  "milliseconds": 428
+}
+```
+
+## Commands
+
+| Task                | Description                      |
+| ------------------- | -------------------------------- |
+| deno task install   | Install datelta as an executable |
+| deno task uninstall | Uninstall datelta                |

deno.json

@@ -0,0 +1,7 @@
+{
+  "tasks": {
+    "dev": "deno run --watch src/main.ts",
+    "install": "deno install -f --name datelta src/main.ts",
+    "uninstall": "deno uninstall datelta"
+  }
+}

deno.lock

@@ -0,0 +1,25 @@
+import { toUTC, floorDivMod, floorMod } from "./util.ts";
+
+export interface DateDiff {
+  years: number;
+  months: number;
+  days: number;
+  hours: number;
+  minutes: number;
+  seconds: number;
+  milliseconds: number;
+}
+
+export function dateDiff(start: Date, end: Date): DateDiff {
+  const diffMilliseconds = toUTC(end) - toUTC(start);
+  const millisecondsPerDay = 1000 * 60 * 60 * 24;
+  const diffDays = diffMilliseconds / millisecondsPerDay;
+  const [years, yearsRem] = floorDivMod(diffDays, 365);
+  const [months, monthsRem] = floorDivMod(yearsRem, 30);
+  const [days, daysRem] = floorMod(monthsRem);
+  const [hours, hoursRem] = floorMod(daysRem * 24);
+  const [minutes, minutesRem] = floorMod(hoursRem * 60);
+  const [seconds, secondsRem] = floorMod(minutesRem * 60);
+  const [milliseconds] = floorMod(secondsRem * 1000);
+  return { years, months, days, hours, minutes, seconds, milliseconds };
+}

src/lib.ts

@@ -0,0 +1,46 @@
+import { dateDiff } from "./lib.ts";
+import { parse } from "https://deno.land/std@0.202.0/flags/mod.ts";
+
+const version = "v0.0.1";
+const help = `Usage: datelta [OPTIONS]
+
+Options:
+          --start     Start date
+          --end       End date
+      -h, --help      Print help
+      -V, --version   Print version`;
+
+function main() {
+  const flags = parse(Deno.args, {
+    boolean: ["help", "h", "version", "V"],
+    string: ["start", "s", "end", "e"],
+    default: { color: true },
+  });
+
+  if (flags.help || flags.h) {
+    return console.log(help);
+  } else if (flags.version || flags.V) {
+    return console.log(version);
+  }
+
+  let startDate, endDate;
+
+  if (flags.start) {
+    startDate = new Date(flags.start);
+    endDate = new Date();
+  }
+  if (flags.start && flags.end) {
+    startDate = new Date(flags.start);
+    endDate = new Date(flags.end);
+  }
+
+  if (!startDate) {
+    console.error("Error: Start date is required.");
+  } else if (startDate && endDate) {
+    console.log(JSON.stringify(dateDiff(startDate, endDate)));
+  }
+}
+
+if (import.meta.main) {
+  main();
+}

src/main.ts

@@ -0,0 +1,29 @@
+export function toUTC(date: Date): number {
+  return Date.UTC(
+    date.getFullYear(),
+    date.getMonth(),
+    date.getDate(),
+    date.getHours(),
+    date.getMinutes(),
+    date.getSeconds(),
+    date.getMilliseconds()
+  );
+}
+
+export function floorDivMod(
+  n: number,
+  m: number
+): [quotient: number, remainder: number] {
+  const q = Math.floor(n / m);
+  const r = n % m;
+  return [q, r];
+}
+
+export function floorMod(n: number): [quotient: number, remainder: number] {
+  if (n === 0) {
+    return [0, 0];
+  }
+  const q = Math.floor(n);
+  const r = n % q;
+  return [q, r];
+}