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cd99321 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 | import { useCallback, useEffect, useState } from 'react'
/**
* Live FX rates for the Costs panel, used to convert every amount into the user's
* display currency. Fetches api.frankfurter.dev (no key, already CSP-allowlisted
* for the dashboard widget) for the given base and caches per base in memory +
* localStorage for a few hours. rates[X] = units of X per 1 base, so an amount in
* currency C converts to base as `amount / rates[C]`.
*/
const TTL_MS = 6 * 60 * 60 * 1000 // 6h
const mem = new Map<string, { rates: Record<string, number>; ts: number }>()
function readCache(base: string): { rates: Record<string, number>; ts: number } | null {
const m = mem.get(base)
if (m) return m
try {
const raw = localStorage.getItem('trek_fx_' + base)
if (raw) {
const parsed = JSON.parse(raw) as { rates: Record<string, number>; ts: number }
if (parsed?.rates) { mem.set(base, parsed); return parsed }
}
} catch { /* ignore */ }
return null
}
export function useExchangeRates(base: string) {
const upper = (base || 'EUR').toUpperCase()
const [rates, setRates] = useState<Record<string, number> | null>(() => readCache(upper)?.rates ?? null)
useEffect(() => {
const cached = readCache(upper)
if (cached) setRates(cached.rates)
if (cached && Date.now() - cached.ts < TTL_MS) return
let cancelled = false
fetch(`https://api.frankfurter.dev/v2/rates?base=${encodeURIComponent(upper)}`)
.then(r => r.json())
.then((d: Array<{ quote?: string; rate?: number }>) => {
if (cancelled || !Array.isArray(d)) return
// Frankfurter omits the base's own self-rate, so seed it with `base = 1`.
const rates: Record<string, number> = { [upper]: 1 }
for (const r of d) {
if (r && typeof r.quote === 'string' && typeof r.rate === 'number') rates[r.quote] = r.rate
}
const entry = { rates, ts: Date.now() }
mem.set(upper, entry)
try { localStorage.setItem('trek_fx_' + upper, JSON.stringify(entry)) } catch { /* ignore */ }
setRates(rates)
})
.catch(() => { /* offline → keep cached/identity */ })
return () => { cancelled = true }
}, [upper])
const convert = useCallback(
(amount: number, from: string | null | undefined): number => {
const f = (from || upper).toUpperCase()
if (f === upper || !rates) return amount
const r = rates[f]
return r && r > 0 ? amount / r : amount
},
[rates, upper],
)
return { rates, convert }
}
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