From f843c91284482cea9d3d411fc27aa9f15f279559 Mon Sep 17 00:00:00 2001
From: Elijah Duffy <elijah@thatoneguy.ca>
Date: Thu, 11 Dec 2025 15:20:42 -0800
Subject: [PATCH] add DurationInput component

---
 src/lib/DurationInput.svelte | 300 +++++++++++++++++++++++++++++++++++
 src/lib/TimeInput.svelte     |  71 +++------
 src/lib/index.ts             |   6 +
 src/lib/numeric-utils.ts     |  67 ++++++++
 src/routes/+page.svelte      |  19 ++-
 5 files changed, 408 insertions(+), 55 deletions(-)
 create mode 100644 src/lib/DurationInput.svelte
 create mode 100644 src/lib/numeric-utils.ts

diff --git a/src/lib/DurationInput.svelte b/src/lib/DurationInput.svelte
new file mode 100644
index 0000000..5b5561e
--- /dev/null
+++ b/src/lib/DurationInput.svelte
@@ -0,0 +1,300 @@
+<script lang="ts" module>
+	/**
+	 * formatDuration returns a human readable string for a DateTimeDuration.
+	 *
+	 * @param duration The duration to format, can be null or undefined.
+	 * @param fallback Optional fallback string to return if duration is null or undefined.
+	 *                 If not provided, an empty string will be returned.
+	 *                 If provided, it will be returned when duration is null or undefined.
+	 * @returns The duration in human readable format or the fallback string if undefined.
+	 */
+	export const formatDuration = (
+		duration: DateTimeDuration | null | undefined,
+		fallback?: string
+	): string => {
+		if (!duration) return fallback ?? '';
+		const parts: string[] = [];
+		if (duration.days) parts.push(`${duration.days}d`);
+		if (duration.hours) parts.push(`${duration.hours}h`);
+		if (duration.minutes) parts.push(`${duration.minutes}m`);
+		if (duration.seconds) parts.push(`${duration.seconds}s`);
+		return parts.join(' ');
+	};
+
+	/**
+	 * durationToISO8601 converts a DateTimeDuration to an ISO 8601 duration string.
+	 * @param duration The duration to convert.
+	 * @returns The ISO 8601 duration string.
+	 */
+	export const durationToISO8601 = (duration: DateTimeDuration): string => {
+		let str = 'P';
+		if (duration.days) str += `${duration.days}D`;
+		if (duration.hours || duration.minutes || duration.seconds) str += 'T';
+		if (duration.hours) str += `${duration.hours}H`;
+		if (duration.minutes) str += `${duration.minutes}M`;
+		if (duration.seconds) str += `${duration.seconds}S`;
+		return str;
+	};
+
+	/**
+	 * iso8601ToDuration converts an ISO 8601 duration string to a DateTimeDuration.
+	 * @param str The ISO 8601 duration string.
+	 * @returns The DateTimeDuration object.
+	 */
+	export const iso8601ToDuration = (str: string): DateTimeDuration => {
+		const regex = /^P(?:(\d+)D)?(?:T(?:(\d+)H)?(?:(\d+)M)?(?:(\d+)S)?)?$/;
+		const matches = str.match(regex);
+		if (!matches) {
+			throw new Error('Invalid ISO 8601 duration string');
+		}
+		return {
+			days: matches[1] ? parseInt(matches[1], 10) : 0,
+			hours: matches[2] ? parseInt(matches[2], 10) : 0,
+			minutes: matches[3] ? parseInt(matches[3], 10) : 0,
+			seconds: matches[4] ? parseInt(matches[4], 10) : 0
+		};
+	};
+</script>
+
+<script lang="ts">
+	import type { DateTimeDuration } from '@internationalized/date';
+	import type { ClassValue } from 'svelte/elements';
+	import { FocusManager } from './focus';
+	import { generateIdentifier, prefixZero, targetMust } from './util';
+	import { decrementValue, incrementValue } from './numeric-utils';
+	import Label from './Label.svelte';
+	import { liveValidator, validate } from '@svelte-toolkit/validate';
+	import StyledRawInput from './StyledRawInput.svelte';
+
+	interface Props {
+		/**
+		 * Name of the input for form integration, form will receive ISO 8601
+		 * formatted string.
+		 */
+		name?: string;
+		/** Label for the input */
+		label?: string;
+		/** Precision for duration input */
+		precision?: { min: componentKey; max: componentKey };
+		/** Bindable DateTimeDuration value */
+		value?: DateTimeDuration | null;
+		/** Bindable formatted duration string, always matches current value and cannot be set */
+		formattedValue?: string;
+		/** Whether the input is required */
+		required?: boolean;
+		/** Message to show when the input is invalid */
+		invalidMessage?: string;
+		/** Whether to use compact styling */
+		compact?: boolean;
+		/** Additional classes are applied to the root container (div element) */
+		class?: ClassValue | null;
+		/** Triggered whenever the duration value is changed by the user */
+		onchange?: (details: { duration: DateTimeDuration | null; formattedDuration: string }) => void;
+	}
+
+	let {
+		name,
+		label,
+		precision = { max: 'minutes', min: 'hours' },
+		value = $bindable(null),
+		formattedValue = $bindable(''),
+		required = false,
+		invalidMessage = 'Please enter a duration',
+		compact,
+		class: classValue,
+		onchange
+	}: Props = $props();
+
+	const COMPONENT_KEYS = ['days', 'hours', 'minutes', 'seconds'] as const;
+	type componentKey = (typeof COMPONENT_KEYS)[number];
+	/** selected components are controlled by min and max precision */
+	let selectedComponents: componentKey[] = $derived.by(() => {
+		const minIndex = COMPONENT_KEYS.indexOf(precision.min);
+		const maxIndex = COMPONENT_KEYS.indexOf(precision.max);
+		if (minIndex === -1 || maxIndex === -1 || minIndex > maxIndex) {
+			throw new Error('Invalid precision settings for DurationInput');
+		}
+		return COMPONENT_KEYS.slice(minIndex, maxIndex + 1);
+	});
+
+	const focusList = new FocusManager();
+	const numericPattern = /^\d*$/;
+	const keydownValidatorOpts = { constrain: true };
+
+	const id = $derived(generateIdentifier('duration-input', name));
+	const values: Record<componentKey, string> = $derived.by(() => {
+		return COMPONENT_KEYS.reduce(
+			(acc, key) => {
+				if (!value || value[key] === 0) {
+					acc[key] = '';
+				} else {
+					acc[key] = prefixZero(value[key]?.toString() || '0');
+				}
+				return acc;
+			},
+			{} as Record<componentKey, string>
+		);
+	});
+	let valid: boolean = $state(true);
+	let hiddenInput: HTMLInputElement;
+
+	/** updateValue updates `value` with the current values from the input fields */
+	const updateValue = (override?: Partial<Record<componentKey, string>>) => {
+		const newValues: Record<componentKey, number> = {
+			days: parseInt(override?.days ?? values.days) || 0,
+			hours: parseInt(override?.hours ?? values.hours) || 0,
+			minutes: parseInt(override?.minutes ?? values.minutes) || 0,
+			seconds: parseInt(override?.seconds ?? values.seconds) || 0
+		};
+
+		let zero = true;
+		for (const key of selectedComponents) {
+			if (newValues[key] !== 0) {
+				zero = false;
+				break;
+			}
+		}
+
+		if (zero) {
+			value = null;
+		} else if (!value) {
+			// Create a new value object if we don't have one yet
+			value = newValues;
+		} else {
+			// Otherwise apply all new values to existing value object
+			for (const [k, v] of Object.entries(newValues)) {
+				value[k as componentKey] = v;
+			}
+		}
+
+		updateHiddenInput();
+		// update formatted value
+		formattedValue = formatDuration(value);
+	};
+
+	/**
+	 * updateHiddenInput pushes the current value to the hidden input in ISO
+	 * 8601 duration format and triggers a keyup event to allow validation to
+	 * detect the change.
+	 */
+	const updateHiddenInput = () => {
+		// TODO: Make sure this formats correctly
+		hiddenInput.value = value ? durationToISO8601(value) : '';
+		hiddenInput.dispatchEvent(new KeyboardEvent('keyup'));
+		onchange?.({ duration: value, formattedDuration: formattedValue });
+		console.log('updated hidden input', hiddenInput.value);
+	};
+
+	/**
+	 * buildEventHandlers generates a fairly generic onkeydown and onblur
+	 * handler pair for a given component key. Start is always 0, max is
+	 * unset for all keys. No special handling per key.
+	 */
+	const buildEventHandlers = (key: componentKey) => {
+		return {
+			onkeydown: (e: KeyboardEvent) => {
+				const target = targetMust<HTMLInputElement>(e);
+
+				if (e.key === 'ArrowUp') {
+					incrementValue(target, { start: 0 });
+				} else if (e.key === 'ArrowDown') {
+					decrementValue(target, { start: 0 });
+				} else {
+					return;
+				}
+
+				updateValue({ [key]: target.value });
+				e.preventDefault();
+			},
+			onblur: (e: FocusEvent) => {
+				const target = targetMust<HTMLInputElement>(e);
+				updateValue({ [key]: target.value });
+			}
+		};
+	};
+
+	/** component definitions */
+	const components: Record<
+		componentKey,
+		{
+			pattern: RegExp;
+			onkeydown?: (e: KeyboardEvent) => void;
+			oninput?: (e: Event) => void;
+			onblur?: (e: FocusEvent) => void;
+			divider?: string;
+			placeholder?: string;
+		}
+	> = {
+		days: {
+			pattern: numericPattern,
+			...buildEventHandlers('days')
+		},
+		hours: {
+			pattern: numericPattern,
+			divider: ':',
+			placeholder: '0',
+			...buildEventHandlers('hours')
+		},
+		minutes: {
+			pattern: numericPattern,
+			divider: ':',
+			placeholder: '0',
+			...buildEventHandlers('minutes')
+		},
+		seconds: {
+			pattern: numericPattern,
+			placeholder: '0',
+			...buildEventHandlers('seconds')
+		}
+	};
+</script>
+
+<div class={classValue}>
+	{#if label}
+		<Label for={id}>{label}</Label>
+	{/if}
+
+	<!-- Hidden input stores the selected duration in ISO 8601 format -->
+	<input
+		type="hidden"
+		{id}
+		{name}
+		use:validate={{ required, autovalOnInvalid: true }}
+		onvalidate={(e) => (valid = e.detail.valid)}
+		bind:this={hiddenInput}
+	/>
+
+	<div class="flex items-start">
+		{#each selectedComponents as componentKey[] as key, index}
+			{@const opts = components[key]}
+			{@const partID = generateIdentifier('duration-input-part', key)}
+			<div class="flex flex-col items-center">
+				<StyledRawInput
+					id={partID}
+					class={[
+						'text-center text-xl focus:placeholder:text-transparent',
+						compact ? 'h-9 w-16! placeholder:text-base' : 'h-16 w-24!'
+					]}
+					value={values[key]}
+					inputmode="numeric"
+					pattern="[0-9]*"
+					placeholder={opts.placeholder}
+					validate={{ pattern: opts.pattern }}
+					use={(n) => liveValidator(n, keydownValidatorOpts)}
+					onkeydown={opts.onkeydown}
+					oninput={opts.oninput}
+					onblur={opts.onblur}
+					{@attach focusList.input({ selectAll: true })}
+				/>
+
+				<Label for={partID} class={['capitalize', compact && '-mt-0.5']}>{key}</Label>
+			</div>
+
+			{#if opts.divider && index < selectedComponents.length - 1}
+				<span class={[compact ? 'mx-1 text-2xl' : 'mx-2 mt-3 text-3xl']}>
+					{opts.divider}
+				</span>
+			{/if}
+		{/each}
+	</div>
+</div>
diff --git a/src/lib/TimeInput.svelte b/src/lib/TimeInput.svelte
index 974ce40..0fc43df 100644
--- a/src/lib/TimeInput.svelte
+++ b/src/lib/TimeInput.svelte
@@ -23,17 +23,31 @@
 	import { generateIdentifier, prefixZero, targetMust } from './util';
 	import { FocusManager } from './focus';
 	import { Time } from '@internationalized/date';
+	import { incrementValue, decrementValue } from './numeric-utils';
 
 	interface Props {
+		/**
+		 * Name of the input for form integration, form will receive ISO 8601
+		 * formatted string.
+		 */
 		name?: string;
+		/** Label for the input */
 		label?: string;
+		/** Bindable Time value */
 		value?: Time | null;
+		/** Bindable formatted time string, always matches current value and cannot be set */
 		formattedValue?: string;
+		/** Whether the input is required */
 		required?: boolean;
+		/** Message to show when the input is invalid */
 		invalidMessage?: string;
+		/** Controls visibility for a confirmation text below the input */
 		showConfirm?: boolean;
+		/** Whether to use compact styling */
 		compact?: boolean;
+		/** Class is applied to the root container (div element) */
 		class?: ClassValue | null | undefined;
+		/** Triggered whenever the time value is changed by the user */
 		onchange?: (details: { time: Time | null; formattedTime: string }) => void;
 	}
 
@@ -95,55 +109,6 @@
 		}
 	};
 
-	/**
-	 * incrementValue increments the value of the input by 1
-	 * @param input The input element to increment
-	 * @param max The maximum value of the input
-	 * @param start The starting value of the input
-	 * @returns true if the value was incremented, false if it looped back to 0
-	 */
-	const incrementValue = (input: HTMLInputElement, max: number, start: number): boolean => {
-		if (input.value.length === 0) {
-			input.value = start.toString();
-			return true;
-		}
-
-		const value = parseInt(input.value);
-		if (value === max) {
-			input.value = start.toString();
-			return false;
-		} else if (value > max) {
-			input.value = (value - max).toString();
-			return false;
-		} else {
-			input.value = (value + 1).toString();
-			return true;
-		}
-	};
-
-	/**
-	 * decrementValue decrements the value of the input by 1
-	 * @param input The input element to decrement
-	 * @param max The maximum value of the input
-	 * @param start The starting value of the input
-	 * @returns true if the value was decremented, false if it looped back to max
-	 */
-	const decrementValue = (input: HTMLInputElement, max: number, start: number): boolean => {
-		if (input.value.length === 0) {
-			input.value = max.toString();
-			return true;
-		}
-
-		const value = parseInt(input.value);
-		if (value <= start) {
-			input.value = max.toString();
-			return false;
-		} else {
-			input.value = (value - 1).toString();
-			return true;
-		}
-	};
-
 	/**
 	 * updateValue updates `value` with the current time in 24-hour format.
 	 * If any component is invalid or blank, it sets `value` to an empty string.
@@ -216,10 +181,10 @@
 				}
 
 				if (e.key === 'ArrowUp') {
-					incrementValue(target, 12, 1);
+					incrementValue(target, { max: 12, start: 1 });
 					if (target.value === '12') toggleAMPM();
 				} else if (e.key === 'ArrowDown') {
-					decrementValue(target, 12, 1);
+					decrementValue(target, { max: 12, start: 1 });
 					if (target.value === '11') toggleAMPM();
 				} else {
 					return;
@@ -248,9 +213,9 @@
 				const target = targetMust<HTMLInputElement>(e);
 
 				if (e.key === 'ArrowUp') {
-					incrementValue(target, 59, 0);
+					incrementValue(target, { max: 59, start: 0 });
 				} else if (e.key === 'ArrowDown') {
-					decrementValue(target, 59, 0);
+					decrementValue(target, { max: 59, start: 0 });
 				} else {
 					return;
 				}
diff --git a/src/lib/index.ts b/src/lib/index.ts
index 96a2fac..461f10f 100644
--- a/src/lib/index.ts
+++ b/src/lib/index.ts
@@ -6,6 +6,12 @@ export { default as Checkbox, type CheckboxState } from './Checkbox.svelte';
 export { default as Combobox, type ComboboxOption } from './Combobox.svelte';
 export { default as DateInput } from './DateInput.svelte';
 export { default as Dialog, type DialogAPI, type DialogControlOpts } from './Dialog.svelte';
+export {
+	default as DurationInput,
+	formatDuration,
+	durationToISO8601,
+	iso8601ToDuration
+} from './DurationInput.svelte';
 export { default as ErrorBox } from './ErrorBox.svelte';
 export { default as FramelessButton } from './FramelessButton.svelte';
 export { default as InjectGoogleMaps } from './InjectGoogleMaps.svelte';
diff --git a/src/lib/numeric-utils.ts b/src/lib/numeric-utils.ts
new file mode 100644
index 0000000..5a5e3b8
--- /dev/null
+++ b/src/lib/numeric-utils.ts
@@ -0,0 +1,67 @@
+/**
+ * numeric-utils.ts
+ * Utility functions for numeric input manipulation.
+ */
+
+/**
+ * incrementValue increments the value of the input by 1
+ * @param input The input element to increment
+ * @param max The maximum value of the input
+ * @param start The starting value of the input
+ * @returns true if the value was incremented, false if it looped back to 0
+ */
+export const incrementValue = (
+	input: HTMLInputElement,
+	opts: { max?: number; start: number }
+): boolean => {
+	if (input.value.length === 0) {
+		input.value = opts.start.toString();
+		return true;
+	}
+
+	const value = parseInt(input.value);
+	if (value === opts.max) {
+		input.value = opts.start.toString();
+		return false;
+	} else if (opts.max && value > opts.max) {
+		input.value = (value - opts.max).toString();
+		return false;
+	} else {
+		input.value = (value + 1).toString();
+		return true;
+	}
+};
+
+/**
+ * decrementValue decrements the value of the input by 1
+ * @param input The input element to decrement
+ * @param max The maximum value of the input
+ * @param start The starting value of the input
+ * @returns true if the value was decremented, false if it looped back to max
+ */
+export const decrementValue = (
+	input: HTMLInputElement,
+	opts: { max?: number; start: number }
+): boolean => {
+	const setToMax = (): boolean => {
+		if (opts.max) {
+			input.value = opts.max.toString();
+			return true;
+		} else {
+			input.value = '0';
+			return false;
+		}
+	};
+
+	if (input.value.length === 0) {
+		return setToMax();
+	}
+
+	const value = parseInt(input.value);
+	if (value <= opts.start) {
+		return !setToMax();
+	} else {
+		input.value = (value - 1).toString();
+		return true;
+	}
+};
diff --git a/src/routes/+page.svelte b/src/routes/+page.svelte
index 51b01f8..c905127 100644
--- a/src/routes/+page.svelte
+++ b/src/routes/+page.svelte
@@ -1,5 +1,10 @@
 <script lang="ts">
-	import { CalendarDate, today, getLocalTimeZone } from '@internationalized/date';
+	import {
+		CalendarDate,
+		today,
+		getLocalTimeZone,
+		type TimeDuration
+	} from '@internationalized/date';
 	import Button from '$lib/Button.svelte';
 	import ActionSelect from '$lib/ActionSelect.svelte';
 	import Checkbox, { type CheckboxState } from '$lib/Checkbox.svelte';
@@ -33,6 +38,7 @@
 	import { onMount, type Component } from 'svelte';
 	import ErrorBox from '$lib/ErrorBox.svelte';
 	import TextareaInput from '$lib/TextareaInput.svelte';
+	import DurationInput, { formatDuration } from '$lib/DurationInput.svelte';
 
 	// Lazy-load heavy components
 	let PhoneInput = createLazyComponent(() => import('$lib/PhoneInput.svelte'));
@@ -60,6 +66,7 @@
 		{ value: 'complex', label: 'Complex item' }
 	]);
 	let timeValue = $state<Time | null>(null);
+	let durationValue = $state<TimeDuration | null>(null);
 
 	const toolbar = new Toolbar();
 	const fontGroup = toolbar.group();
@@ -286,11 +293,18 @@
 </div>
 
 <div class="component">
-	<p class="title">Time Input</p>
+	<p class="title">Time & Duration Input</p>
 
 	<InputGroup class="gap-8">
 		<TimeInput label="Regular time input" name="example-time-input" />
 		<TimeInput label="Compact time" compact bind:value={timeValue} />
+		<DurationInput
+			label="Duration input"
+			name="example-duration-input"
+			precision={{ min: 'hours', max: 'seconds' }}
+			bind:value={durationValue}
+		/>
+		<DurationInput label="Compact duration" compact />
 	</InputGroup>
 	<InputGroup>
 		<p>Selected time is {formatTime(timeValue, 'undefined')} ({timeValue?.toString()})</p>
@@ -301,6 +315,7 @@
 		>
 			Set 3:00 PM
 		</Button>
+		<p>Precise duration is {formatDuration(durationValue)}</p>
 	</InputGroup>
 </div>