'use client';
import { BarChart, type BarChartProps, type BarChartSeries, type BarSeries } from '@snapshot-ui/charts';
import {
Card,
CardHeader,
CardNote,
CardTitle,
DataTable,
FilterBar,
FilterChip,
PageHeader,
PickerOption,
RouterProvider,
SegmentedControl,
SegmentedControlItem,
StatTile,
Switch,
type DataTableColumn,
type Key,
} from '@snapshot-ui/react';
import { usePathname, useRouter, useSearchParams } from 'next/navigation';
import { Suspense, useId, useState, type ReactElement } from 'react';
import {
dollars,
money,
MONTH_FIGURES,
MONTH_KEYS,
MONTH_MIX,
MONTH_MIX_TOTALS,
MONTH_NET_TICKS,
MONTH_TICKS,
MONTHS,
RANKED,
} from './insights-data';
type Grouping = 'month' | 'category' | 'merchant' | 'account';
/** What the month view draws: income beside spending, one of them, net cash flow, or the category mix. */
type Show = 'both' | 'spending' | 'income' | 'net' | 'mix';
/** The page's view, all of it in the URL: `?by=category&compare=1`. The defaults write no parameter. */
interface View {
by: Grouping;
show: Show;
compare: boolean;
}
const GROUPINGS: Grouping[] = ['month', 'category', 'merchant', 'account'];
const SHOWS: Show[] = ['both', 'spending', 'income', 'net', 'mix'];
function viewOf(params: URLSearchParams): View {
const by = GROUPINGS.find((each) => each === params.get('by')) ?? 'month';
const show = SHOWS.find((each) => each === params.get('show')) ?? 'both';
return { by, show, compare: params.get('compare') === '1' };
}
/** The query for a view, with no bare `?` and nothing for a default. */
function queryOf({ by, show, compare }: View): string {
const params = new URLSearchParams();
if (by !== 'month') params.set('by', by);
if (by === 'month' && show !== 'both') params.set('show', show);
if (compare) params.set('compare', '1');
return params.toString();
}
/**
* A grouped bar holds two series at most, so the comparison draws one series beside its previous period: it is
* off while the month view shows income and spending together, or the stacked mix.
*/
const canCompare = ({ by, show }: View): boolean => by !== 'month' || !(show === 'both' || show === 'mix');
/** A row of the table under the chart: a band's name, its figures and the key of its transactions link. */
interface Row {
key: string;
name: string;
figures: string[];
}
/** What a view draws: the card's words, the chart's props and the table's rows. */
interface Drawn {
title: string;
note: string;
chart: BarChartSeries &
Pick<BarChartProps, 'categories' | 'orientation' | 'bands' | 'valueTicks' | 'totals'>;
/** The link's parameter, such as `category=rent`. */
linkBy: string;
columns: string[];
rows: Row[];
}
const MONTH_TITLES: Record<Show, string> = {
both: 'Income and spending',
spending: 'Spending by month',
income: 'Income by month',
net: 'Net cash flow',
mix: 'Spending by category, by month',
};
/** The month view: twelve months standing up, the newest last, and Tab lands on the newest. */
function monthView(show: Show, compare: boolean): Drawn {
const { income, spending, net } = MONTH_FIGURES;
const rows = MONTHS.map((name, index) => ({
key: MONTH_KEYS[index] ?? name,
name,
figures: [spending, income, net].map(({ year }) => dollars(year[index] ?? 0)),
}));
const shared = { categories: MONTHS, bands: 'time', orientation: 'vertical' } as const;
const table = { linkBy: 'month', columns: ['Month', 'Spending', 'Income', 'Net'], rows };
const title = MONTH_TITLES[show];
if (show === 'both' || show === 'mix') {
return {
...table,
title,
note: 'The last twelve months',
chart:
show === 'both'
? {
...shared,
valueTicks: MONTH_TICKS,
// Money that arrived in gain beside money that went out in ink: never a color for spending.
series: [
{ label: 'Income', color: 'gain', values: income.year.map(money) },
{ label: 'Spending', color: 'ink', values: spending.year.map(money) },
],
}
: {
...shared,
valueTicks: MONTH_TICKS,
layout: 'stacked',
series: MONTH_MIX,
totals: MONTH_MIX_TOTALS,
},
};
}
const figures = MONTH_FIGURES[show];
const label = show === 'net' ? 'Net' : show === 'income' ? 'Income' : 'Spending';
const current: BarSeries = {
label,
color: show === 'income' ? 'gain' : 'ink',
values: figures.year.map(money),
};
// The previous period takes the current series' color, striped: the same thing, a year before.
const previous: BarSeries = { label: 'A year before', look: 'hatched', values: figures.before.map(money) };
return {
...table,
title,
note: compare ? 'The last twelve months, against the twelve before' : 'The last twelve months',
chart: {
...shared,
valueTicks: show === 'net' ? MONTH_NET_TICKS : MONTH_TICKS,
series: compare ? [current, previous] : [current],
},
};
}
/**
* A ranked view: rows lying down, amounts at their end, refunds below zero and "Other" last. Each bar links to
* its transactions for the period it shows, October's or, compared, September's: the page's drill-down.
*/
function rankedView(by: Exclude<Grouping, 'month'>, compare: boolean): Drawn {
const rows = RANKED[by];
const october: BarSeries = {
label: 'October',
values: rows.map(({ key, october: value }) => ({ ...money(value), href: `#transactions?${by}=${key}` })),
};
const september: BarSeries = {
label: 'September',
look: 'hatched',
values: rows.map(({ key, september: value }) => ({
...money(value),
href: `#transactions?${by}=${key}&period=2026-09`,
})),
};
const name = by.charAt(0).toUpperCase() + by.slice(1);
return {
title: `Spending by ${by}`,
note: compare ? 'October, against September' : 'October',
chart: {
categories: rows.map((each) => each.name),
// A ranked list reads by its amounts at the end, so it draws no gridlines.
orientation: 'horizontal',
series: compare ? [october, september] : [october],
},
linkBy: by,
columns: compare ? [name, 'October', 'September'] : [name, 'October'],
rows: rows.map((each) => ({
key: each.key,
name: each.name,
figures: (compare ? [each.october, each.september] : [each.october]).map(dollars),
})),
};
}
/**
* The table's columns: the band's name as the row header, then its figures, aligned at the end. On a phone each
* row is an item with its first figure at the end; the chart above it carries the rest.
*/
const columnsOf = (names: string[]): DataTableColumn<Row>[] =>
names.map((header, index) =>
index === 0
? { id: 'name', header, cell: (row) => row.name, isRowHeader: true }
: {
id: header,
header,
cell: (row) => row.figures[index - 1],
align: 'end',
listSlot: index === 1 ? 'end' : 'hidden',
},
);
interface InsightsProps {
view: View;
onView?: (view: View) => void;
/** The router's navigate, the RouterProvider's own, for the chart's links: the charts cannot read the provider. */
navigate?: (href: string) => void;
}
/** The page above the report: header, tiles, filters, the chart card and the table under it. */
function Insights({ view, onView, navigate }: InsightsProps): ReactElement {
const titleId = useId();
const noteId = useId();
// The period is your query's; the fixtures hold October against September, so the chip only keeps its choice.
const [period, setPeriod] = useState<Key | null>('2026-10');
const comparing = view.compare && canCompare(view);
const drawn = view.by === 'month' ? monthView(view.show, comparing) : rankedView(view.by, comparing);
const change = (patch: Partial<View>): void => {
onView?.({ ...view, ...patch });
};
return (
<div className="stack" style={{ width: '100%', minWidth: 0 }}>
{/* An example on a docs page, which has its own h1; the app's own header keeps the default, 1. */}
<PageHeader
headingLevel={2}
title="Insights"
description="Where October's money went, account by account."
/>
{/* The summary: each figure's change against September is drawn while the page compares. */}
<div className="tile-row">
<StatTile
label="Spent"
value={dollars(4220)}
caption="October"
change={comparing ? { direction: 'up', label: 'Up $415 vs September' } : undefined}
/>
<StatTile
label="Income"
value={dollars(5200)}
caption="October"
change={comparing ? { direction: 'flat', label: 'Same as September' } : undefined}
/>
<StatTile
label="Net"
value={dollars(980)}
caption="October"
change={comparing ? { direction: 'down', label: 'Down $415 vs September' } : undefined}
/>
</div>
<FilterBar>
<FilterChip label="Period" selectionMode="single" value={period} onChange={setPeriod}>
<PickerOption id="2026-10">October 2026</PickerOption>
<PickerOption id="2026-09">September 2026</PickerOption>
<PickerOption id="2026-q3">July to September 2026</PickerOption>
</FilterChip>
</FilterBar>
<Card as="section" aria-labelledby={titleId}>
<CardHeader>
<CardTitle id={titleId} level={3}>
{drawn.title}
</CardTitle>
<CardNote id={noteId}>{drawn.note}</CardNote>
{/* The two controls on one line, from the start, wrapping where the card is narrow. */}
<div style={{ display: 'flex', flexWrap: 'wrap', gap: 'var(--spacing-part)' }}>
<SegmentedControl
aria-label="Group by"
size="sm"
value={view.by}
onChange={(by) => {
change({ by: by as Grouping });
}}
>
<SegmentedControlItem value="month">Month</SegmentedControlItem>
<SegmentedControlItem value="category">Category</SegmentedControlItem>
<SegmentedControlItem value="merchant">Merchant</SegmentedControlItem>
<SegmentedControlItem value="account">Account</SegmentedControlItem>
</SegmentedControl>
{view.by === 'month' ? (
<SegmentedControl
aria-label="Show"
size="sm"
value={view.show}
onChange={(show) => {
change({ show: show as Show });
}}
>
<SegmentedControlItem value="both">Both</SegmentedControlItem>
<SegmentedControlItem value="spending">Spending</SegmentedControlItem>
<SegmentedControlItem value="income">Income</SegmentedControlItem>
<SegmentedControlItem value="net">Net</SegmentedControlItem>
<SegmentedControlItem value="mix">Mix</SegmentedControlItem>
</SegmentedControl>
) : null}
</div>
<Switch
isSelected={comparing}
isDisabled={!canCompare(view)}
description={canCompare(view) ? undefined : 'Choose Spending, Income or Net to compare.'}
onChange={(compare) => {
change({ compare });
}}
>
Compare to previous period
</Switch>
</CardHeader>
{/* One chart for every grouping: new props, never a new chart, so a focused bar hands focus on. */}
<BarChart {...drawn.chart} aria-labelledby={`${titleId} ${noteId}`} navigate={navigate} />
</Card>
<DataTable
aria-label={`Transactions by ${view.by}`}
items={drawn.rows}
columns={columnsOf(drawn.columns)}
getKey={(row) => row.key}
getRowHref={(row) => `#transactions?${drawn.linkBy}=${row.key}`}
/>
</div>
);
}
/** The view the URL names, kept in state so a control answers at once while the URL catches up. */
function InsightsFromUrl({ navigate }: Pick<InsightsProps, 'navigate'>): ReactElement {
const router = useRouter();
const pathname = usePathname();
const searchParams = useSearchParams();
const key = searchParams.toString();
const [view, setView] = useState(() => viewOf(new URLSearchParams(key)));
const [seen, setSeen] = useState(key);
// The URL changed under the page, by Back or Forward: draw its view.
if (key !== seen) {
setSeen(key);
setView(viewOf(new URLSearchParams(key)));
}
return (
<Insights
view={view}
navigate={navigate}
onView={(next) => {
const query = queryOf(next);
setView(next);
setSeen(query);
router.replace(query ? `${pathname}?${query}` : pathname, { scroll: false });
}}
/>
);
}
/** The first view: months, income beside spending, as the static page's server renders it. */
const FIRST = viewOf(new URLSearchParams());
/**
* The Insights page's client part: everything but the month's report, which a server component renders beside
* it. The grouping and the comparison live in the URL, so a link or a reload keeps them.
*/
export default function InsightsRecipe(): ReactElement {
const router = useRouter();
const navigate = (href: string): void => {
router.push(href, { scroll: false });
};
return (
// An app wraps its whole tree once; the example wraps only itself. The chart takes the same navigate.
<RouterProvider navigate={navigate}>
<Suspense fallback={<Insights view={FIRST} navigate={navigate} />}>
<InsightsFromUrl navigate={navigate} />
</Suspense>
</RouterProvider>
);
}