Show each wallet's balance in USD

2026-09-29 21:02:45 +08:00
parent 0b1b253d30
commit 58d862161e
4 changed files with 115 additions and 0 deletions
@@ -0,0 +1,79 @@
+import Foundation
+
+/// USD prices for the two tickers the wallet supports, fetched from a public
+/// price API and cached briefly so a screen does not fetch on every refresh.
+final class PriceService {
+  static let shared = PriceService()
+
+  struct Prices: Codable {
+    var xrp: Double?
+    var xmr: Double?
+    var fetchedAt: Date?
+  }
+
+  private static let cacheLifetime: TimeInterval = 60
+  private var memory: Prices?
+  private var inFlight: Task<Prices, Never>?
+
+  private init() {}
+
+  func prices() async -> Prices {
+    if let memory, let fetchedAt = memory.fetchedAt,
+       Date().timeIntervalSince(fetchedAt) < Self.cacheLifetime {
+      return memory
+    }
+    if let inFlight { return await inFlight.value }
+
+    let task = Task<Prices, Never> { [weak self] in
+      guard let self else { return Prices(fetchedAt: nil) }
+      let prices = await self.fetch()
+      self.memory = prices
+      return prices
+    }
+    inFlight = task
+    let result = await task.value
+    inFlight = nil
+    return result
+  }
+
+  private func fetch() async -> Prices {
+    if let prices = try? await fromCoinGecko() { return prices }
+    return (try? await fromKraken()) ?? Prices(fetchedAt: nil)
+  }
+
+  private func fromCoinGecko() async throws -> Prices {
+    guard let url = URL(string: "https://api.coingecko.com/api/v3/simple/price?ids=monero,ripple&vs_currencies=usd") else {
+      throw XRPError.network("Invalid price endpoint")
+    }
+    let (data, response) = try await URLSession.shared.data(from: url)
+    guard let http = response as? HTTPURLResponse, (200..<300).contains(http.statusCode) else {
+      throw XRPError.network("CoinGecko request failed")
+    }
+    let json = try JSONSerialization.jsonObject(with: data) as? [String: Any] ?? [:]
+    return Prices(
+      xrp: (json["ripple"] as? [String: Any]).flatMap { ($0["usd"] as? NSNumber)?.doubleValue },
+      xmr: (json["monero"] as? [String: Any]).flatMap { ($0["usd"] as? NSNumber)?.doubleValue },
+      fetchedAt: Date())
+  }
+
+  private func fromKraken() async throws -> Prices {
+    guard let url = URL(string: "https://api.kraken.com/0/public/Ticker?pair=XRPUSD,XMRUSD") else {
+      throw XRPError.network("Invalid price endpoint")
+    }
+    let (data, response) = try await URLSession.shared.data(from: url)
+    guard let http = response as? HTTPURLResponse, (200..<300).contains(http.statusCode) else {
+      throw XRPError.network("Kraken request failed")
+    }
+    let json = try JSONSerialization.jsonObject(with: data) as? [String: Any] ?? [:]
+    let result = json["result"] as? [String: Any] ?? [:]
+
+    func lastTrade(_ key: String) -> Double? {
+      (result[key] as? [String: Any])
+        .flatMap { entry in (entry["c"] as? [Any])?.first }
+        .flatMap { ($0 as? String).flatMap(Double.init) }
+    }
+    return Prices(xrp: lastTrade("XXRPZUSD") ?? lastTrade("XRPUSD"),
+                  xmr: lastTrade("XXMRZUSD") ?? lastTrade("XMRUSD"),
+                  fetchedAt: Date())
+  }
+}