79 lines
2.9 KiB
Swift
79 lines
2.9 KiB
Swift
import Foundation
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/// USD prices for the two tickers the wallet supports, fetched from a public
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/// price API and cached briefly so a screen does not fetch on every refresh.
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final class PriceService {
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static let shared = PriceService()
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struct Prices: Codable {
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var xrp: Double?
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var xmr: Double?
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var fetchedAt: Date?
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}
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private static let cacheLifetime: TimeInterval = 60
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private var memory: Prices?
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private var inFlight: Task<Prices, Never>?
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private init() {}
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func prices() async -> Prices {
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if let memory, let fetchedAt = memory.fetchedAt,
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Date().timeIntervalSince(fetchedAt) < Self.cacheLifetime {
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return memory
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}
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if let inFlight { return await inFlight.value }
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let task = Task<Prices, Never> { [weak self] in
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guard let self else { return Prices(fetchedAt: nil) }
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let prices = await self.fetch()
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self.memory = prices
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return prices
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}
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inFlight = task
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let result = await task.value
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inFlight = nil
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return result
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}
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private func fetch() async -> Prices {
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if let prices = try? await fromCoinGecko() { return prices }
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return (try? await fromKraken()) ?? Prices(fetchedAt: nil)
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}
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private func fromCoinGecko() async throws -> Prices {
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guard let url = URL(string: "https://api.coingecko.com/api/v3/simple/price?ids=monero,ripple&vs_currencies=usd") else {
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throw XRPError.network("Invalid price endpoint")
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}
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let (data, response) = try await URLSession.shared.data(from: url)
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guard let http = response as? HTTPURLResponse, (200..<300).contains(http.statusCode) else {
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throw XRPError.network("CoinGecko request failed")
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}
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let json = try JSONSerialization.jsonObject(with: data) as? [String: Any] ?? [:]
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return Prices(
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xrp: (json["ripple"] as? [String: Any]).flatMap { ($0["usd"] as? NSNumber)?.doubleValue },
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xmr: (json["monero"] as? [String: Any]).flatMap { ($0["usd"] as? NSNumber)?.doubleValue },
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fetchedAt: Date())
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}
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private func fromKraken() async throws -> Prices {
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guard let url = URL(string: "https://api.kraken.com/0/public/Ticker?pair=XRPUSD,XMRUSD") else {
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throw XRPError.network("Invalid price endpoint")
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}
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let (data, response) = try await URLSession.shared.data(from: url)
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guard let http = response as? HTTPURLResponse, (200..<300).contains(http.statusCode) else {
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throw XRPError.network("Kraken request failed")
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}
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let json = try JSONSerialization.jsonObject(with: data) as? [String: Any] ?? [:]
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let result = json["result"] as? [String: Any] ?? [:]
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func lastTrade(_ key: String) -> Double? {
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(result[key] as? [String: Any])
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.flatMap { entry in (entry["c"] as? [Any])?.first }
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.flatMap { ($0 as? String).flatMap(Double.init) }
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}
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return Prices(xrp: lastTrade("XXRPZUSD") ?? lastTrade("XRPUSD"),
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xmr: lastTrade("XXMRZUSD") ?? lastTrade("XMRUSD"),
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fetchedAt: Date())
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}
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} |