Initial commit

SatsPrice/Network/CoinGeckoSpotPriceFetcher.swift

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+//
+//  CoinGeckoSpotPriceFetcher.swift
+//  SatsPrice
+//
+//  Created by Terry Yiu on 2/19/24.
+//
+
+import Foundation
+import BigDecimal
+
+private struct CoinGeckoSpotPriceResponse: Codable {
+    let bitcoin: CoinGeckoSpotPrice
+}
+
+private struct CoinGeckoSpotPrice: Codable {
+    let usd: Decimal
+}
+
+class CoinGeckoSpotPriceFetcher : SpotPriceFetcher {
+    private static let urlString = "https://api.coingecko.com/api/v3/simple/price?ids=bitcoin&vs_currencies=usd&precision=18"
+
+    func btcToUsd() async throws -> BigDecimal? {
+        do {
+            guard let urlComponents = URLComponents(string: CoinGeckoSpotPriceFetcher.urlString), let url = urlComponents.url else {
+                return nil
+            }
+
+            let (data, _) = try await URLSession.shared.data(from: url, delegate: nil)
+
+            let spotPriceResponse = try JSONDecoder().decode(CoinGeckoSpotPriceResponse.self, from: data)
+            let spotPrice = spotPriceResponse.bitcoin
+
+            return BigDecimal(spotPrice.usd)
+        } catch {
+            return nil
+        }
+    }
+}

SatsPrice/Network/CoinbaseSpotPriceFetcher.swift

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+//
+//  CoinbaseSpotPriceFetcher.swift
+//  SatsPrice
+//
+//  Created by Terry Yiu on 2/19/24.
+//
+
+import Foundation
+import BigDecimal
+
+private struct CoinbaseSpotPriceResponse: Codable {
+    let data: CoinbaseSpotPrice
+}
+
+private struct CoinbaseSpotPrice: Codable {
+    let amount: String
+    let base: String
+    let currency: String
+}
+
+class CoinbaseSpotPriceFetcher : SpotPriceFetcher {
+    private static let urlString = "https://api.coinbase.com/v2/prices/BTC-USD/spot"
+    private static let btc = "BTC"
+    private static let usd = "USD"
+
+    func btcToUsd() async throws -> BigDecimal? {
+        do {
+            guard let urlComponents = URLComponents(string: CoinbaseSpotPriceFetcher.urlString), let url = urlComponents.url else {
+                return nil
+            }
+
+            let (data, _) = try await URLSession.shared.data(from: url, delegate: nil)
+
+            let coinbaseSpotPriceResponse = try JSONDecoder().decode(CoinbaseSpotPriceResponse.self, from: data)
+            let coinbaseSpotPrice = coinbaseSpotPriceResponse.data
+
+            guard coinbaseSpotPrice.base == CoinbaseSpotPriceFetcher.btc && coinbaseSpotPrice.currency == CoinbaseSpotPriceFetcher.usd else {
+                return nil
+            }
+
+            return BigDecimal(coinbaseSpotPrice.amount)
+        } catch {
+            return nil
+        }
+    }
+}

SatsPrice/Network/SpotPriceFetcher.swift

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+//
+//  SpotPriceFetcher.swift
+//  SatsPrice
+//
+//  Created by Terry Yiu on 2/19/24.
+//
+
+import Foundation
+import BigDecimal
+
+protocol SpotPriceFetcher {
+    func btcToUsd() async throws -> BigDecimal?
+}

SatsPrice/Network/SpotPriceFetcherDelegator.swift

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+//
+//  SpotPriceFetcherDelegator.swift
+//  SatsPrice
+//
+//  Created by Terry Yiu on 2/20/24.
+//
+
+import Foundation
+import BigDecimal
+
+class SpotPriceFetcherDelegator: SpotPriceFetcher {
+    private let coinbaseSpotPriceFetcher = CoinbaseSpotPriceFetcher()
+    private let coinGeckoSpotPriceFetcher = CoinGeckoSpotPriceFetcher()
+
+    var spotPriceSource: SpotPriceSource = .coinbase
+
+    private var delegate: SpotPriceFetcher {
+        switch spotPriceSource {
+        case .coinbase:
+            coinbaseSpotPriceFetcher
+        case .coingecko:
+            coinGeckoSpotPriceFetcher
+        }
+    }
+
+    func btcToUsd() async throws -> BigDecimal? {
+        return try await delegate.btcToUsd()
+    }
+}