/**
 * The cache hit rate as a progress bar (ui-visual-redesign.md): the share of
 * the window's queries answered from memory, the bar it fills, and under it the
 * three figures that share went with — hits, what went upstream instead, and
 * how long an answer took on average.
 */

import * as stylex from "@stylexjs/stylex";
import { formatCount, formatMicros, formatPercent } from "@/lib/format";
import Card from "@/ui/Card";
import { styles as shared } from "@/ui/styles";
import { colors } from "@/ui/tokens.stylex";

const styles = stylex.create({
	body: {
		display: "flex",
		flexDirection: "column",
		gap: "0.75rem",
	},
	track: {
		height: "0.5rem",
		borderRadius: "999px",
		backgroundColor: colors.chartGreenSurface,
		overflow: "hidden",
	},
	fill: {
		display: "block",
		height: "100%",
		borderRadius: "999px",
		backgroundColor: colors.chartGreen,
	},
	/** Dynamic: the bar's length is the share itself. */
	fillWidth: (percent: number) => ({ width: `${percent}%` }),
	percent: {
		margin: 0,
		fontSize: "2.5rem",
		lineHeight: 1,
		fontWeight: 400,
		letterSpacing: "-0.02em",
		color: colors.chartGreen,
	},
	note: {
		fontSize: "0.875rem",
		lineHeight: "1.25rem",
		color: colors.textMuted,
	},
	split: {
		display: "flex",
		flexWrap: "wrap",
		gap: "1.5rem",
		margin: 0,
		marginTop: "0.5rem",
		paddingTop: "1rem",
		borderTopWidth: 1,
		borderTopStyle: "solid",
		borderTopColor: colors.border,
	},
	/** Label first in the DOM, figure on top visually. */
	splitItem: {
		display: "flex",
		flexDirection: "column-reverse",
		gap: "0.125rem",
	},
	splitValue: {
		margin: 0,
		fontSize: "1.125rem",
		lineHeight: "1.5rem",
		fontWeight: 550,
		color: colors.text,
	},
	splitLabel: {
		fontSize: "0.75rem",
		lineHeight: "1rem",
		color: colors.textMuted,
	},
});

export interface CacheCardData {
	queries: number;
	/** Answers served from cache: the window's `cached` buckets summed. */
	hits: number;
	/** Answers that went to an upstream resolver or a forward zone. */
	forwarded: number;
	avg_response_time_us: number | null;
}

export default function CacheCard({ data }: { data: CacheCardData }) {
	const share = data.queries === 0 ? null : data.hits / data.queries;
	const percent = share === null ? "—" : formatPercent(share);
	return (
		<Card
			title="Cache hit rate"
			description="Answers served straight from memory, without asking an upstream resolver."
		>
			<div {...stylex.props(styles.body)}>
				<div
					role="img"
					aria-label={
						share === null ? "No queries in this period" : `${percent} of queries served from cache`
					}
					{...stylex.props(styles.track)}
				>
					<span {...stylex.props(styles.fill, styles.fillWidth(share === null ? 0 : share * 100))} />
				</div>
				<p {...stylex.props(styles.percent, shared.tabularNums)}>{percent}</p>
				<p {...stylex.props(styles.note)}>of queries answered from cache</p>
				<dl {...stylex.props(styles.split)}>
					<div {...stylex.props(styles.splitItem)}>
						<dt {...stylex.props(styles.splitLabel)}>cache hits</dt>
						<dd {...stylex.props(styles.splitValue, shared.tabularNums)}>{formatCount(data.hits)}</dd>
					</div>
					<div {...stylex.props(styles.splitItem)}>
						<dt {...stylex.props(styles.splitLabel)}>forwarded upstream</dt>
						<dd {...stylex.props(styles.splitValue, shared.tabularNums)}>{formatCount(data.forwarded)}</dd>
					</div>
					<div {...stylex.props(styles.splitItem)}>
						<dt {...stylex.props(styles.splitLabel)}>avg response</dt>
						<dd {...stylex.props(styles.splitValue, shared.tabularNums)}>
							{data.avg_response_time_us === null ? "—" : formatMicros(data.avg_response_time_us)}
						</dd>
					</div>
				</dl>
			</div>
		</Card>
	);
}