Convert SatsPrice to a Skip multiplatform app

Sources/SatsPrice/Network/CoinGeckoPriceFetcher.swift

@@ -0,0 +1,48 @@
+// This is free software: you can redistribute and/or modify it
+// under the terms of the GNU General Public License 3.0
+// as published by the Free Software Foundation https://fsf.org
+//
+//  CoinGeckoPriceFetcher.swift
+//  SatsPrice
+//
+//  Created by Terry Yiu on 2/19/24.
+//
+
+import Foundation
+
+private struct CoinGeckoPriceResponse: Codable {
+    let bitcoin: CoinGeckoPrice
+}
+
+private struct CoinGeckoPrice: Codable {
+#if !SKIP
+    let usd: Decimal
+#else
+    let usd: String
+#endif
+}
+
+class CoinGeckoPriceFetcher : PriceFetcher {
+    private static let urlString = "https://api.coingecko.com/api/v3/simple/price?ids=bitcoin&vs_currencies=usd&precision=18"
+
+    func btcToUsd() async throws -> Decimal? {
+        do {
+            guard let urlComponents = URLComponents(string: CoinGeckoPriceFetcher.urlString), let url = urlComponents.url else {
+                return nil
+            }
+
+            let (data, _) = try await URLSession.shared.data(from: url, delegate: nil)
+
+            let priceResponse = try JSONDecoder().decode(CoinGeckoPriceResponse.self, from: data)
+            let price = priceResponse.bitcoin
+
+#if !SKIP
+            return price.usd
+#else
+            return Decimal(price.usd)
+#endif
+        } catch {
+            return nil
+        }
+    }
+}