commit 64849054e9bb5d96a9ab57023ce4bea2d9198f97 parent e3c1f4a45e29c0aeec2984b2d1de3237e0b8e5fc Author: William Casarin <jb55@jb55.com> Date: Fri, 25 Mar 2022 17:07:04 -0700 exchange rates Signed-off-by: William Casarin <jb55@jb55.com> Diffstat:
| A | lightninglink/Rates.swift | | | 76 | ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
1 file changed, 76 insertions(+), 0 deletions(-)
diff --git a/lightninglink/Rates.swift b/lightninglink/Rates.swift @@ -0,0 +1,76 @@ +// +// Rates.swift +// lightninglink +// +// Created by William Casarin on 2022-03-24. +// + +import Foundation + +enum Currency: CustomStringConvertible { + case USD + case CAD + + var description: String { + switch self { + case .USD: return "USD" + case .CAD: return "CAD" + } + } +} + +enum StringNum: Decodable { + case string(String) + case number(Double) + + init (from decoder: Decoder) throws { + let value = try decoder.singleValueContainer() + if let str = try? value.decode(String.self) { + self = .string(str) + } + + self = .number(try value.decode(Double.self)) + } +} + +struct ExchangeRate { + let currency: Currency + let rate: Double +} + +func get_exchange_rate(for_cur: Currency, cb: @escaping (ExchangeRate?) -> ()) { + let url = URL(string: "https://api-pub.bitfinex.com/v2/tickers?=symbols=tBTC\(for_cur)")! + let task = URLSession.shared.dataTask(with: url) { (mdata, response, error) in + guard let data = mdata else { + cb(nil) + return + } + + guard let rate = decode_bitfinex_exchange_rate(data) else { + cb(nil) + return + } + + cb(ExchangeRate(currency: for_cur, rate: rate)) + } + + task.resume() +} + +func decode_bitfinex_exchange_rate(_ data: Data) -> Double? { + guard let container: Array<Array<StringNum>> = decode_data(data) else { + return nil + } + + guard container.count >= 1 && container[0].count >= 2 else { + return nil + } + + switch container[0][1] { + case .string: + return nil + case .number(let xr): + return xr + } +} +