41 lines
1.3 KiB
TypeScript
41 lines
1.3 KiB
TypeScript
/**
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* format.ts — shared metric value formatting helpers for the Energy view.
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*
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* Rules (from M5 polish requirements):
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* - device_class === "energy" → 3 decimal places (kWh values need precision)
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* - everything else → 2 decimal places
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* - null / undefined / NaN → placeholder "—"
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* - missing metric metadata → default 2 decimal places
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*/
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import type { MetricInfo } from './hooks'
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/** Placeholder shown when a value is unavailable. */
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export const VALUE_PLACEHOLDER = '—'
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/**
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* Format a numeric metric value for display.
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*
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* @param value The raw value from the API payload (any type; non-numeric → "—").
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* @param metric Optional metric metadata from /metrics. When absent, falls back
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* to 2 decimal places.
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* @returns A formatted string ready for display (e.g. "230.25" or "—").
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*/
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export function formatMetricValue(
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value: unknown,
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metric?: MetricInfo | null,
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): string {
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// Guard: null / undefined
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if (value === null || value === undefined) return VALUE_PLACEHOLDER
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const n = Number(value)
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// Guard: NaN or non-finite
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if (!Number.isFinite(n)) return VALUE_PLACEHOLDER
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// Determine decimal places from device_class.
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const decimals = metric?.device_class === 'energy' ? 3 : 2
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return n.toFixed(decimals)
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}
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