49 lines
1.7 KiB
TypeScript
49 lines
1.7 KiB
TypeScript
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import { EMISSION_FACTORS } from '#shared/emissions'
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import type { Coord } from '#shared/types'
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const TRAIN_AVG_KMH = 90
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/**
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* Distance a vol d oiseau entre deux points geographiques en km.
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* Formule de Haversine, rayon terrestre moyen 6371 km.
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*/
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function haversineKm(a: { lat: number, lon: number }, b: { lat: number, lon: number }): number {
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const toRad = (d: number) => (d * Math.PI) / 180
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const R = 6371
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const dLat = toRad(b.lat - a.lat)
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const dLon = toRad(b.lon - a.lon)
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const s = Math.sin(dLat / 2) ** 2
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+ Math.cos(toRad(a.lat)) * Math.cos(toRad(b.lat)) * Math.sin(dLon / 2) ** 2
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return 2 * R * Math.asin(Math.sqrt(s))
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}
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/**
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* Fabrique une estimation train quand Transitous ne couvre pas le trajet.
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* Distance vol d oiseau x 1.2 pour approximer le detour ferroviaire,
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* vitesse pratique moyenne 90 km/h (compromis TGV/TER), facteur ADEME train
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* generique. C est un ordre de grandeur, pas un horaire.
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*/
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export function estimateTrainTrip(
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from: { lat: number, lon: number },
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to: { lat: number, lon: number },
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) {
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const straightKm = haversineKm(from, to)
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// Facteur 1.2 : les voies ferrees suivent rarement une ligne droite.
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const distanceKm = Math.round(straightKm * 1.2 * 10) / 10
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const durationMin = Math.round((distanceKm / TRAIN_AVG_KMH) * 60)
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const co2Grams = Math.round(distanceKm * EMISSION_FACTORS.train)
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// Geometrie ligne droite [depart, arrivee] pour que la carte affiche
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// quelque chose de coherent avec l estimation textuelle.
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const geometry: Coord[] = [[from.lon, from.lat], [to.lon, to.lat]]
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return {
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mode: 'train' as const,
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distanceKm,
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durationMin,
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co2Grams,
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geometry,
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estimated: true,
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}
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}
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