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src/lib/components/ui/calendar/calendar-caption.svelte

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+<script lang="ts">
+	import type { ComponentProps } from "svelte";
+	import type Calendar from "./calendar.svelte";
+	import CalendarMonthSelect from "./calendar-month-select.svelte";
+	import CalendarYearSelect from "./calendar-year-select.svelte";
+	import { DateFormatter, getLocalTimeZone, type DateValue } from "@internationalized/date";
+
+	let {
+		captionLayout,
+		months,
+		monthFormat,
+		years,
+		yearFormat,
+		month,
+		locale,
+		placeholder = $bindable(),
+		monthIndex = 0,
+	}: {
+		captionLayout: ComponentProps<typeof Calendar>["captionLayout"];
+		months: ComponentProps<typeof CalendarMonthSelect>["months"];
+		monthFormat: ComponentProps<typeof CalendarMonthSelect>["monthFormat"];
+		years: ComponentProps<typeof CalendarYearSelect>["years"];
+		yearFormat: ComponentProps<typeof CalendarYearSelect>["yearFormat"];
+		month: DateValue;
+		placeholder: DateValue | undefined;
+		locale: string;
+		monthIndex: number;
+	} = $props();
+
+	function formatYear(date: DateValue) {
+		const dateObj = date.toDate(getLocalTimeZone());
+		if (typeof yearFormat === "function") return yearFormat(dateObj.getFullYear());
+		return new DateFormatter(locale, { year: yearFormat }).format(dateObj);
+	}
+
+	function formatMonth(date: DateValue) {
+		const dateObj = date.toDate(getLocalTimeZone());
+		if (typeof monthFormat === "function") return monthFormat(dateObj.getMonth() + 1);
+		return new DateFormatter(locale, { month: monthFormat }).format(dateObj);
+	}
+</script>
+
+{#snippet MonthSelect()}
+	<CalendarMonthSelect
+		{months}
+		{monthFormat}
+		value={month.month}
+		onchange={(e) => {
+			if (!placeholder) return;
+			const v = Number.parseInt(e.currentTarget.value);
+			const newPlaceholder = placeholder.set({ month: v });
+			placeholder = newPlaceholder.subtract({ months: monthIndex });
+		}}
+	/>
+{/snippet}
+
+{#snippet YearSelect()}
+	<CalendarYearSelect {years} {yearFormat} value={month.year} />
+{/snippet}
+
+{#if captionLayout === "dropdown"}
+	{@render MonthSelect()}
+	{@render YearSelect()}
+{:else if captionLayout === "dropdown-months"}
+	{@render MonthSelect()}
+	{#if placeholder}
+		{formatYear(placeholder)}
+	{/if}
+{:else if captionLayout === "dropdown-years"}
+	{#if placeholder}
+		{formatMonth(placeholder)}
+	{/if}
+	{@render YearSelect()}
+{:else}
+	{formatMonth(month)} {formatYear(month)}
+{/if}