113 lines
5.3 KiB
Swift
113 lines
5.3 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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/// Throws on failure so callers can fall back to cached/sample data.
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func fetchStations(near lat: Double?, lng: Double?, fuel: FuelType) async throws -> [FuelStation]
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}
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enum FuelPriceProvider {
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static let active: FuelPriceProviding = SampleFuelProvider()
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}
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// MARK: - Sample provider (default for the scaffold)
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/// Ships realistic stations around Cambridge (52.2053, 0.1218) so the app and
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/// widget render meaningful data with zero setup. Prices in pence/litre.
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struct SampleFuelProvider: FuelPriceProviding {
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func fetchStations(near lat: Double?, lng: Double?, fuel: FuelType) 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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FuelStation(id: "s1", name: "Shell Cambridge Retail Park", brand: "Shell",
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address: "12 Retail Park Way", postcode: "CB1 3EW",
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lat: 52.1955, lng: 0.1380,
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prices: [.e10: 142.9, .e5: 149.9, .diesel: 148.9],
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priceUpdated: nil),
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FuelStation(id: "s2", name: "Tesco Express Hills Road", brand: "Tesco",
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address: "245 Hills Road", postcode: "CB2 8RP",
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lat: 52.1809, lng: 0.1398,
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prices: [.e10: 138.9, .e5: 146.9, .diesel: 145.9],
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priceUpdated: nil),
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FuelStation(id: "s3", name: "BP Milton Road", brand: "BP",
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address: "161 Milton Road", postcode: "CB4 1XE",
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lat: 52.2160, lng: 0.1410,
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prices: [.e10: 140.9, .diesel: 147.9],
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priceUpdated: nil),
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FuelStation(id: "s4", name: "Morrisons Newmarket Road", brand: "Morrisons",
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address: "Newmarket Road", postcode: "CB5 8AA",
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lat: 52.2164, lng: 0.1599,
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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: "s5", name: "Sainsbury's Coldhams Lane", brand: "Sainsbury's",
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address: "Coldhams Lane", postcode: "CB1 3HY",
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lat: 52.2025, lng: 0.1589,
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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: "s6", name: "Esso Cherry Hinton", brand: "Esso",
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address: "Cherry Hinton Road", postcode: "CB1 9AP",
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lat: 52.1854, lng: 0.1657,
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prices: [.e10: 141.9, .e5: 148.9, .diesel: 147.9],
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priceUpdated: nil),
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FuelStation(id: "s7", name: "Gulf Fen Road", brand: "Gulf",
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address: "Fen Road", postcode: "CB4 1UN",
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lat: 52.2201, lng: 0.1470,
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prices: [.e10: 143.9, .e5: 151.9, .diesel: 149.9],
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priceUpdated: nil),
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FuelStation(id: "s8", name: "Asda Beehive Centre", brand: "Asda",
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address: "Coldhams Lane", postcode: "CB1 3ER",
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lat: 52.1995, lng: 0.1641,
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prices: [.e10: 136.9, .e5: 143.9, .diesel: 143.9],
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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) 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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var errorDescription: String? { "Live Fuel Finder API not wired yet — activate with GOV.UK One Login credentials." }
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}
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