FuelBoard Contributor
fccd0c07ef
- Relay envelope now carries source (api|csv), stations_count, and data_updated (freshest price_last_updated the GOV.UK server reports, independent of relay sync time). - App decodes the new envelope metadata (RelayMeta), persists it after each full fetch, and shows it in Settings → About → Data source: Connection (API/CSV), Stations count, Data updated (local-formatted). - Older relays without the fields decode cleanly (nil meta → em-dash). - 2 new tests for meta decode + absent-meta tolerance; 37/37 pass.
283 lines
13 KiB
Swift
283 lines
13 KiB
Swift
// FuelPriceProvider.swift — data-source seam for FuelBoard.
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//
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// The official UK Fuel Finder API (api.fuelfinder.service.gov.uk) is the live
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// source for station-level prices, but it requires GOV.UK One Login + OAuth 2.0
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// client credentials. For the scaffold we ship SampleFuelProvider (realistic
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// stations around a location, works offline), plus the FuelFinderProvider
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// skeleton with the exact integration steps documented inline so wiring the
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// live API later is a drop-in: change `activeProvider` to `.fuelFinder`.
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import Foundation
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// MARK: - Provider protocol
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protocol FuelPriceProviding {
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/// Fetch stations with prices. `location` may be nil (sort by price only).
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/// `radiusKM` nil = full dataset (device filters); set = focused server-side
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/// radius (alert path). Throws on failure so callers can fall back.
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func fetchStations(near lat: Double?, lng: Double?, fuel: FuelType, radiusKM: Double?) async throws -> [FuelStation]
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}
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enum FuelPriceProvider {
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/// Default: the keyless relay (full-UK Fuel Finder data). Falls back to
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/// the England-wide sample set when the relay is unreachable.
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static let active: FuelPriceProviding = RelayFuelProvider()
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/// Decodes a relay payload into stations, applying the defensive price
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/// band. Internal so the unit-test target can exercise the guard.
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static func decodeStations(from data: Data) throws -> [FuelStation] {
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let payload = try JSONDecoder().decode(RelayResponse.self, from: data)
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return payload.stations.map { relay in
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FuelStation(
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id: relay.id ?? relay.name ?? UUID().uuidString,
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name: (relay.name ?? "Unknown").sanitizedStationTitle,
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brand: relay.brand ?? "",
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address: relay.address ?? "",
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postcode: relay.postcode ?? "",
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lat: relay.lat ?? 0,
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lng: relay.lng ?? 0,
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prices: relay.allPrices,
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priceUpdated: nil
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)
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}
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}
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/// Decodes the relay envelope metadata (source, dataset update time) — the
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/// About section shows these so the user can see which data source is
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/// live and how fresh the GOV.UK data itself is. The fields are additive
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/// on the relay, so older relays simply return nil values.
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static func decodeRelayMeta(from data: Data) -> RelayMeta? {
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guard let payload = try? JSONDecoder().decode(RelayResponse.self, from: data) else {
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return nil
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}
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return RelayMeta(
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source: payload.source,
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stationCount: payload.stationsCount,
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dataUpdated: payload.dataUpdated
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)
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}
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}
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// MARK: - Relay provider (default)
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/// Talks to the FuelBoard Relay (keyless proxy). The relay serves the FULL-UK
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/// Fuel Finder dataset — every station in England, Wales, Scotland, NI — and
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/// filters/sorts server-side. No credentials in the app.
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struct RelayFuelProvider: FuelPriceProviding {
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var baseURL = URL(string: "http://192.168.1.131:8789")!
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/// Envelope metadata from the most recent successful relay fetch —
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/// consumed by Settings → About (source api/csv, station count, GOV.UK
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/// dataset update time). Written by fetchStations, read by the view.
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static var latestMeta: RelayMeta?
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func fetchStations(near lat: Double?, lng: Double?, fuel: FuelType, radiusKM: Double?) async throws -> [FuelStation] {
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var components = URLComponents(url: baseURL.appendingPathComponent("api/v1/stations"), resolvingAgainstBaseURL: false)!
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var query: [URLQueryItem] = [URLQueryItem(name: "fuel", value: fuel.rawValue)]
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if let lat, let lng {
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query.append(URLQueryItem(name: "lat", value: String(lat)))
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query.append(URLQueryItem(name: "lng", value: String(lng)))
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}
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if let radiusKM {
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// Focused fetch (alert path) — small response, server-side radius.
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query.append(URLQueryItem(name: "radius", value: String(radiusKM)))
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query.append(URLQueryItem(name: "limit", value: "500"))
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} else {
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// Full-UK dump: NO radius — the device filters locally
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// (5/10/15-mile radius, fuel, sort). 10,000 covers the dataset.
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query.append(URLQueryItem(name: "limit", value: "10000"))
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}
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components.queryItems = query
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let (data, response) = try await URLSession.shared.data(from: components.url!)
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guard let http = response as? HTTPURLResponse, http.statusCode == 200 else {
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throw FuelProviderError.relayUnavailable
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}
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let stations = try FuelPriceProvider.decodeStations(from: data)
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Self.latestMeta = FuelPriceProvider.decodeRelayMeta(from: data)
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return stations
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}
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}
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private struct RelayResponse: Codable {
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/// Envelope metadata surfaced in Settings → About so the user can see
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/// which relay source is live and how fresh the GOV.UK data is.
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let source: String?
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let stationsCount: Int?
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let dataUpdated: String?
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enum CodingKeys: String, CodingKey {
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case source, stations
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case stationsCount = "stations_count"
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case dataUpdated = "data_updated"
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}
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struct RelayStation: Codable {
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let id: String?
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let name: String?
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let brand: String?
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let address: String?
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let postcode: String?
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let lat: Double?
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let lng: Double?
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let price: Double?
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let prices: [String: Double]?
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/// Map relay grade keys (E5/E10/DIESEL) to FuelType for ALL fuels the
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/// station sells — one fetch populates every fuel tab. Defensive guard:
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/// any grade outside the 50–500 pence/litre band is dropped, so a relay
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/// regression (e.g. the band being removed server-side) can't re-poison
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/// the nationwide cheapest reference with 1.3p / 1589p garbage.
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var allPrices: [FuelType: Double] {
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var result: [FuelType: Double] = [:]
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if let prices {
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for (grade, value) in prices {
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guard (50...500).contains(value) else { continue }
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switch grade.uppercased() {
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case "E10": result[.e10] = value
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case "E5": result[.e5] = value
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case "DIESEL", "B7", "B7S", "B7P", "B10": result[.diesel] = value
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default: break
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}
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}
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}
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// Backwards-compat: relay versions without `prices` still send `price`.
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if result.isEmpty, let price, (50...500).contains(price) {
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result[.e10] = price
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}
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return result
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}
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}
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let stations: [RelayStation]
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}
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/// Envelope metadata from the relay response — which data source is live
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/// (api/csv) and the freshest price-update timestamp the GOV.UK server
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/// itself reports for the dataset. Displayed in Settings → About.
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struct RelayMeta: Codable, Equatable {
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let source: String?
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let stationCount: Int?
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let dataUpdated: String?
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}
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// MARK: - Sample provider (offline fallback only)
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/// Representative stations spread across ENGLAND (one cluster per region) so
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/// the fallback works anywhere in the country — it is NOT tied to one town.
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/// Real England-wide data comes from the relay (full-UK Fuel Finder CSV/API).
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/// Prices in pence/litre.
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struct SampleFuelProvider: FuelPriceProviding {
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func fetchStations(near lat: Double?, lng: Double?, fuel: FuelType, radiusKM: Double?) async throws -> [FuelStation] {
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try await Task.sleep(nanoseconds: 300_000_000) // simulate fetch
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return Self.sampleStations
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}
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static let sampleStations: [FuelStation] = [
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// Yorkshire & the Humber (Halifax area)
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FuelStation(id: "y1", name: "Morrisons Halifax", brand: "Morrisons",
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address: "Haugh Shaw Road", postcode: "HX1 3TU",
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lat: 53.7265, lng: -1.8580,
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prices: [.e10: 137.9, .e5: 144.9, .diesel: 144.9],
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priceUpdated: nil),
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FuelStation(id: "y2", name: "Asda Leeds Crown Point", brand: "Asda",
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address: "Crown Point Road", postcode: "LS10 1ET",
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lat: 53.7800, lng: -1.5300,
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prices: [.e10: 136.9, .e5: 143.9, .diesel: 143.9],
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priceUpdated: nil),
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FuelStation(id: "y3", name: "Tesco Express York", brand: "Tesco",
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address: "Fulford Road", postcode: "YO10 4AB",
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lat: 53.9500, lng: -1.0800,
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prices: [.e10: 138.9, .e5: 146.9, .diesel: 145.9],
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priceUpdated: nil),
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// North West
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FuelStation(id: "nw1", name: "Sainsbury's Manchester", brand: "Sainsbury's",
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address: "Regent Road", postcode: "M5 3QH",
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lat: 53.4700, lng: -2.2800,
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prices: [.e10: 139.9, .e5: 147.9, .diesel: 146.9],
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priceUpdated: nil),
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FuelStation(id: "nw2", name: "Shell Liverpool", brand: "Shell",
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address: "Rice Lane", postcode: "L9 1AD",
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lat: 53.4400, lng: -2.9600,
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prices: [.e10: 142.9, .e5: 149.9, .diesel: 148.9],
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priceUpdated: nil),
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// Midlands
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FuelStation(id: "m1", name: "Morrisons Birmingham", brand: "Morrisons",
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address: "Hagley Road", postcode: "B16 8NA",
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lat: 52.4700, lng: -1.9500,
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prices: [.e10: 137.9, .e5: 144.9, .diesel: 144.9],
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priceUpdated: nil),
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FuelStation(id: "m2", name: "Tesco Express Nottingham", brand: "Tesco",
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address: "Mansfield Road", postcode: "NG5 2DP",
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lat: 52.9900, lng: -1.1500,
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prices: [.e10: 138.9, .e5: 146.9, .diesel: 145.9],
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priceUpdated: nil),
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// South East / London
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FuelStation(id: "se1", name: "Asda Wembley", brand: "Asda",
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address: "Great Central Way", postcode: "HA9 0DB",
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lat: 51.5500, lng: -0.2800,
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prices: [.e10: 136.9, .e5: 143.9, .diesel: 143.9],
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priceUpdated: nil),
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FuelStation(id: "se2", name: "BP Brighton", brand: "BP",
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address: "Lewes Road", postcode: "BN2 3QB",
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lat: 50.8300, lng: -0.1100,
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prices: [.e10: 140.9, .diesel: 147.9],
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priceUpdated: nil),
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// South West
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FuelStation(id: "sw1", name: "Esso Bristol", brand: "Esso",
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address: "Wells Road", postcode: "BS4 2PP",
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lat: 51.4400, lng: -2.5700,
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prices: [.e10: 141.9, .e5: 148.9, .diesel: 147.9],
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priceUpdated: nil),
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// North East
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FuelStation(id: "ne1", name: "Gulf Newcastle", brand: "Gulf",
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address: "Scotswood Road", postcode: "NE4 7AA",
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lat: 54.9700, lng: -1.6400,
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prices: [.e10: 143.9, .e5: 151.9, .diesel: 149.9],
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priceUpdated: nil),
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]
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}
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// MARK: - Fuel Finder API provider (integration point)
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/// Live provider skeleton for the official GOV.UK Fuel Finder API.
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///
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/// To activate:
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/// 1. Sign in at developer.fuel-finder.service.gov.uk with GOV.UK One Login,
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/// register an app, and generate client credentials (client_id + secret).
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/// 2. Implement token fetch: POST to the token endpoint with OAuth 2.0
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/// client_credentials grant → access_token (expires in 1h).
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/// 3. GET prices with `Authorization: Bearer <token>` and decode the
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/// stations JSON into [FuelStation].
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///
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/// Endpoints (per gov.uk docs):
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/// base: https://api.fuelfinder.service.gov.uk
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/// auth: base + /v1/token
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/// prices: base + /v1/prices (full snapshot)
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/// price: base + /v1/prices/GB-12345 (single station)
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///
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/// Then switch `FuelPriceProvider.active` to `FuelFinderProvider(...)`.
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struct FuelFinderProvider: FuelPriceProviding {
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let baseURL = URL(string: "https://api.fuelfinder.service.gov.uk")!
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let clientID: String
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let clientSecret: String
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func fetchStations(near lat: Double?, lng: Double?, fuel: FuelType, radiusKM: Double?) async throws -> [FuelStation] {
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// TODO: OAuth token → GET /v1/prices → map to FuelStation.
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// The live API requires authentication; see notes above.
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throw FuelProviderError.notImplemented
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}
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}
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enum FuelProviderError: LocalizedError {
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case notImplemented
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case relayUnavailable
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var errorDescription: String? {
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switch self {
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case .notImplemented:
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return "Live Fuel Finder API not wired yet — activate with GOV.UK One Login credentials."
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case .relayUnavailable:
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return "FuelBoard Relay unreachable — showing cached/sample data."
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}
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}
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}
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