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drizzli/src/routes/weather/14-day/[location]/+page.svelte
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2026-07-25 14:21:46 +02:00

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Svelte

<script lang="ts">
import { onMount } from 'svelte';
import { get } from 'svelte/store';
import { storedEnsembleModel, storedLocation, storedUnits } from '$lib/stores/settings';
import { ChartContainer, ChartToolbar } from '$lib/components/charts';
import { Label } from '$lib/components/ui/label';
import { Switch } from '$lib/components/ui/switch';
import { CHART_COLORS, CanvasChart, type ChartSeries, isColumnUnit } from '$lib/charts';
import {
type DaylightBand,
type EnsembleForecastResult,
fetchEnsembleForecast
} from '$lib/services/weather';
import { defaultParameters, ensembleModelGroups } from '../../options';
import ModelSelector from '../../week/[location]/ModelSelector.svelte';
import type { PageData } from './$types';
const CHART_GROUP = '14-day-ensemble';
// ─── Display State (does NOT trigger data re-fetch) ─────────────────────────
let showLegend = $state(true);
// ─── Data Fetch State ───────────────────────────────────────────────────────
let chartComponents: CanvasChart[] = $state([]);
let mounted = $state(false);
let loading = $state(true);
let loadError = $state<string | null>(null);
let requestVersion = 0;
let { data }: { data: PageData } = $props();
// the URL is the source of truth: location comes from the load function,
// which is also correct on hydrated prerendered pages. The persisted store
// only mirrors it so the header and bare /weather/* redirects follow along.
let location = $derived(data.location);
$effect(() => {
storedLocation.set(data.location);
});
let params = $state({
...defaultParameters,
hourly: ['temperature_2m', 'precipitation', 'wind_speed_10m', 'cloud_cover', 'pressure_msl'],
models: ['ncep_gefs_seamless']
});
// units live in a persisted store; mirror them into params so a change
// re-runs the fetch effect (which reads params.*_unit)
$effect(() => {
params.temperature_unit = $storedUnits.temperature_unit;
params.wind_speed_unit = $storedUnits.wind_speed_unit;
params.precipitation_unit = $storedUnits.precipitation_unit;
});
// ─── Cached API Response ────────────────────────────────────────────────────
interface FetchedData {
ensembleResult: EnsembleForecastResult;
timestamps: number[];
timezone: string;
daylightBands: DaylightBand[];
}
let fetchedData: FetchedData | null = $state(null);
// ─── Lifecycle ──────────────────────────────────────────────────────────────
onMount(() => {
// preselect the persisted ensemble model (client-only, keeps SSR stable)
params.models = [get(storedEnsembleModel)];
mounted = true;
});
// components persist across refetches; entries are null while unmounted
let liveCharts = $derived(chartComponents.filter((chart) => chart != null));
// ─── Data Fetching (only when params.hourly or params.models change) ───────
$effect(() => {
const hourlyVars = params.hourly;
const modelList = params.models;
if (!mounted || !hourlyVars?.length || !modelList?.length) return;
const loc = location;
// versioned so a slow stale response can never overwrite a newer one
const version = ++requestVersion;
loading = true;
loadError = null;
fetchEnsembleForecast({
latitude: loc.latitude!,
longitude: loc.longitude!,
hourlyVariables: hourlyVars,
models: modelList,
forecast_days: 14,
temperature_unit: params.temperature_unit as 'celsius' | 'fahrenheit',
wind_speed_unit: params.wind_speed_unit as 'kmh' | 'ms' | 'mph' | 'kn',
precipitation_unit: params.precipitation_unit as 'mm' | 'inch',
timezone: loc.timezone
})
.then((result: EnsembleForecastResult) => {
if (version !== requestVersion) return;
fetchedData = {
ensembleResult: result,
timestamps: result.timestamps,
timezone: result.timezone,
daylightBands: result.daylightBands
};
loading = false;
})
.catch((err: unknown) => {
if (version !== requestVersion) return;
loadError = err instanceof Error ? err.message : String(err);
loading = false;
});
});
// ─── Chart Building (runs when fetchedData or the variable list changes) ────
// Ensemble members stop at the model's horizon; past it the service collapses
// every value to 0 (min = max = mean = 0). Trim the axis to the last hour that
// actually has data so the charts cut off instead of flat-lining to zero.
let validLength = $derived.by((): number => {
if (!fetchedData) return 0;
const temp = fetchedData.ensembleResult.variables['temperature_2m'];
const n = fetchedData.timestamps.length;
if (!temp) return n;
let last = 0;
for (let i = 0; i < n; i++) {
if (!(temp.max[i] === 0 && temp.min[i] === 0 && temp.average[i] === 0)) last = i + 1;
}
return last || n;
});
// Timestamps from the service are in milliseconds; CanvasChart uses seconds.
let timestampsSec = $derived.by(() =>
fetchedData ? fetchedData.timestamps.slice(0, validLength).map((t) => t / 1000) : []
);
// Surface a note when the chosen model's ensemble stops short of the request.
let fullHours = $derived.by(() => (fetchedData ? fetchedData.timestamps.length : 0));
let validDays = $derived(Math.max(0, Math.round(validLength / 24)));
let isTrimmed = $derived(fetchedData != null && validLength > 0 && validLength < fullHours - 1);
interface ChartDef {
title?: string;
subtitle?: string;
unit: string;
showCredit: boolean;
series: ChartSeries[];
zeroBaseLeft?: boolean;
yMin?: number;
yMax?: number;
}
// Sensible axis behaviour per variable so the y-scale stays readable (e.g.
// pressure never anchored to zero; percentages pinned to 0-100).
function axisForVar(v: string): { zeroBaseLeft: boolean; yMin?: number; yMax?: number } {
if (['pressure_msl', 'surface_pressure', 'temperature_2m', 'dew_point_2m'].includes(v)) {
return { zeroBaseLeft: false };
}
if (['relative_humidity_2m', 'cloud_cover', 'precipitation_probability'].includes(v)) {
return { zeroBaseLeft: true, yMin: 0, yMax: 100 };
}
return { zeroBaseLeft: true };
}
const BAND_COLOR = 'rgba(115, 192, 222, 0.9)';
// Human labels for the plotted ensemble variables (API names → readable title)
const VAR_LABELS: Record<string, string> = {
temperature_2m: 'Temperature',
apparent_temperature: 'Feels like',
precipitation: 'Precipitation',
rain: 'Rain',
snowfall: 'Snowfall',
wind_speed_10m: 'Wind speed',
wind_gusts_10m: 'Wind gusts',
relative_humidity_2m: 'Relative humidity',
cloud_cover: 'Cloud cover',
pressure_msl: 'Pressure (MSL)',
dew_point_2m: 'Dew point'
};
const varLabel = (v: string): string =>
VAR_LABELS[v] ?? v.replace(/_/g, ' ').replace(/\b\w/g, (c) => c.toUpperCase());
let chartDefs = $derived.by((): ChartDef[] => {
if (!fetchedData) return [];
const { ensembleResult } = fetchedData;
const variables = params.hourly || [];
const defs: ChartDef[] = [];
for (let vi = 0; vi < variables.length; vi++) {
const variable = variables[vi];
const varData = ensembleResult.variables[variable];
if (!varData) continue;
const unit = varData.unit;
const isColumn = isColumnUnit(unit);
const memberCount = varData.members.length;
// Trim to the valid horizon so the axis scale ignores the trailing
// zeros the service pads past the model's range.
const vMax = varData.max.slice(0, validLength);
const vMin = varData.min.slice(0, validLength);
const vAvg = varData.average.slice(0, validLength);
// Min/max spread band + mean, instead of every individual member
const series: ChartSeries[] = [
{
name: 'Max',
type: 'line',
color: BAND_COLOR,
data: vMax,
width: 1,
fill: true,
fillOpacity: 0.25,
bandTo: vMin,
format: (v) => `${v.toFixed(1)} ${unit}`
},
{
name: 'Mean',
type: isColumn ? 'bar' : 'line',
color: CHART_COLORS.average,
data: vAvg,
width: 3.5,
dashed: !isColumn,
outline: !isColumn,
format: (v) => `${v.toFixed(1)} ${unit}`
},
{
name: 'Min',
type: 'line',
color: BAND_COLOR,
data: vMin,
width: 1,
format: (v) => `${v.toFixed(1)} ${unit}`
}
];
const isFirst = vi === 0;
const isLast = vi === variables.length - 1;
const axis = axisForVar(variable);
defs.push({
// each chart is labelled so the variable is obvious at a glance
title: `${varLabel(variable)}${isColumn ? '' : ' spread'}`,
subtitle: isFirst
? `min · mean · max across ${memberCount} ensemble members`
: `min · mean · max (${unit})`,
unit,
showCredit: isLast,
series,
zeroBaseLeft: axis.zeroBaseLeft,
yMin: axis.yMin,
yMax: axis.yMax
});
}
return defs;
});
</script>
<!-- ─── Page hero: location + ensemble model selection ─────────────────────── -->
<div class="relative mb-3 flex flex-wrap items-center justify-between gap-x-6 gap-y-3 md:mb-5">
<div class="flex min-w-0 items-center gap-3">
<img
class="h-10 w-10 shrink-0 rounded-full shadow-sm ring-2 ring-border"
src="/images/country-flags/{(location.country_code || 'united_nations').toLowerCase()}.svg"
alt={location.country ?? ''}
/>
<div class="min-w-0">
<h1 class="truncate text-2xl leading-tight font-bold tracking-tight md:text-3xl">
{location.name}
</h1>
<p class="truncate text-sm text-muted-foreground">
<span class="lg:hidden"
>{#if location.admin1}{location.admin1},
{/if}{location.country ?? ''}<span class="mx-1 opacity-50">·</span></span
>14-day ensemble forecast
</p>
</div>
</div>
<div class="lg:absolute lg:right-0 lg:top-0 flex w-full items-center gap-3 sm:w-auto">
<ModelSelector
selectedModel={params.models?.[0] ?? 'ncep_gefs_seamless'}
groups={ensembleModelGroups}
label="Ensemble model"
onModelChange={(model) => {
params.models = [model];
storedEnsembleModel.set(model);
}}
/>
</div>
</div>
<!-- ─── Chart Area ─────────────────────────────────────────────────────────── -->
{#if isTrimmed}
<div
class="mb-4 flex items-start gap-2 rounded-md border border-amber-300/60 bg-amber-50 px-3.5 py-2.5 text-sm text-amber-800 dark:border-amber-800/50 dark:bg-amber-950/30 dark:text-amber-200"
>
<svg
class="mt-0.5 h-4 w-4 shrink-0"
fill="none"
stroke="currentColor"
viewBox="0 0 24 24"
stroke-width="2"
>
<path
stroke-linecap="round"
stroke-linejoin="round"
d="M12 9v4m0 4h.01M10.3 3.9 1.8 18a2 2 0 0 0 1.7 3h17a2 2 0 0 0 1.7-3L13.7 3.9a2 2 0 0 0-3.4 0z"
/>
</svg>
<span>
This model's ensemble only reaches about <strong>{validDays} days</strong> ahead, the spread is
trimmed to its available range.
</span>
</div>
{/if}
{#if loadError}
<div
class="mb-4 rounded-md border border-destructive/50 bg-destructive/10 px-4 py-3 text-sm text-destructive"
>
Failed to load weather data: {loadError}
</div>
{/if}
{#if fetchedData}
<!-- full-bleed graphs until lg / contained card on lg+; titles stay within
the page margins (padded), the graphs bleed to the edges -->
<div class="-mx-3 border-y border-border/70 bg-card shadow-sm lg:mx-0 lg:rounded-2xl lg:border">
{#each chartDefs as def, i (i)}
<div class="px-0 pt-1.5 pb-1 lg:px-4 lg:pb-3 {i > 0 ? 'border-t border-border/50' : ''}">
<div class="mb-1 px-3 lg:px-0">
<h4 class="text-sm font-bold tracking-tight">{def.title}</h4>
{#if def.subtitle}
<p class="text-xs text-muted-foreground">{def.subtitle}</p>
{/if}
</div>
<ChartContainer {loading} chartCount={1} chartHeight={300} minWidth={520} bleed={false}>
<CanvasChart
bind:this={chartComponents[i]}
timestamps={timestampsSec}
timezone={fetchedData.timezone}
series={def.series}
bands={fetchedData.daylightBands}
unit={def.unit}
showCredit={def.showCredit}
zeroBaseLeft={def.zeroBaseLeft ?? true}
yMin={def.yMin}
yMax={def.yMax}
{showLegend}
height={300}
group={CHART_GROUP}
/>
</ChartContainer>
</div>
{/each}
</div>
{:else}
<!-- reserve the chart area height before data arrives (no layout shift) -->
<ChartContainer loading chartCount={params.hourly?.length || 1} chartHeight={340} bleed={false} />
{/if}
<!-- ─── Toolbar: Controls + Download ───────────────────────────────────────── -->
<div class="mt-6 md:mt-10">
<ChartToolbar charts={liveCharts} fileName="14-day-forecast">
{#snippet controls()}
<div class="flex items-center gap-2">
<Switch id="show_legend" name="Show legend" bind:checked={showLegend} />
<Label for="show_legend" class="cursor-pointer text-base leading-none">Show legend</Label>
</div>
{/snippet}
</ChartToolbar>
</div>