63 lines
2.6 KiB
Swift
63 lines
2.6 KiB
Swift
import Foundation
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/// Pure, testable logic behind the Siri "cheapest fuel near me" intent.
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/// Foundation-only on purpose: `Shared/` joins both the app and widget
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/// targets, and FuelBoardTests exercises this directly.
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enum SiriCheapestLookup {
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/// The cheapest station selling `fuel` WITHIN `withinMiles` of the given
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/// point, tie-broken by distance. Stations without a price for `fuel`, or
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/// farther than the radius, are skipped entirely. Returns nil when no
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/// station sells the fuel inside the radius.
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///
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/// Radius scoping mirrors the app's Stations tab (search radius
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/// 5/10/15 mi): without it, "cheapest near me" silently answers the
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/// UK-wide minimum — a genuinely cheap station hundreds of miles away
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/// (found with real data: GULF HISTON 100.9p was 132 mi from the phone).
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static func cheapest(
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in stations: [FuelStation],
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fuel: FuelType,
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fromLat lat: Double,
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lng: Double,
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withinMiles: Double
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) -> FuelStation? {
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let radiusKM = withinMiles * 1.60934
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return stations
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.filter { $0.prices[fuel] != nil && $0.distanceKM(to: lat, lng2: lng) <= radiusKM }
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.min { lhs, rhs in
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guard let lp = lhs.prices[fuel], let rp = rhs.prices[fuel] else {
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return false
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}
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if lp != rp { return lp < rp }
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return lhs.distanceKM(to: lat, lng2: lng) < rhs.distanceKM(to: lat, lng2: lng)
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}
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}
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/// A short freshness stamp for the dialog: "as of 6:30 AM".
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/// Prefers the GOV.UK `data_updated` stamp carried by the relay (ISO 8601
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/// with or without fractional seconds); falls back to the local
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/// last-refresh date; returns "" when there is no data at all.
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static func freshnessLabel(updated: String?, lastRefresh: Date?, now: Date = Date()) -> String {
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let date: Date?
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if let updated {
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date = Self.parseISO(updated) ?? lastRefresh
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} else {
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date = lastRefresh
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}
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guard let date else { return "" }
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let formatter = DateFormatter()
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formatter.dateFormat = "h:mm a"
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formatter.locale = Locale(identifier: "en_GB")
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return "as of \(formatter.string(from: date))"
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}
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private static func parseISO(_ string: String) -> Date? {
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let withFraction = ISO8601DateFormatter()
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withFraction.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
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if let date = withFraction.date(from: string) { return date }
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let plain = ISO8601DateFormatter()
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plain.formatOptions = [.withInternetDateTime]
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return plain.date(from: string)
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}
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}
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