nim-ffi/examples/timer/ios/Sources/MyTimer/MyTimer.swift

// Generated by nim-ffi Swift codegen. Do not edit by hand.
//
// Idiomatic Swift wrapper over the library's native (zero-serialization) C ABI.
// Each call is dispatched on the library's background FFI thread; we block on a
// DispatchSemaphore until the result callback fires. A struct return is read out
// of the typed C-POD inside the callback — valid only for the callback's
// lifetime — and copied into a native Swift value.
import CMyTimer
import Foundation

public enum TimerError: Error, CustomStringConvertible {
    case failed(String)
    public var description: String {
        switch self { case let .failed(m): return m }
    }
}

public struct EchoResponse: Equatable {
    public let echoed: String
    public let timerName: String
}

public final class MyTimerNode {
    private let ctx: UnsafeMutableRawPointer

    public init(name: String) throws {
        let box = Box()
        let ud = Unmanaged.passUnretained(box).toOpaque()
        var c_config = CMyTimer.TimerConfig()
        let c_config_name = strdup(name)
        defer { free(c_config_name) }
        c_config.name = UnsafePointer(c_config_name)
        guard let c = my_timer_create(c_config, ackCallback, ud) else {
            throw TimerError.failed("create returned null")
        }
        box.sem.wait()
        guard box.ret == 0 else { throw TimerError.failed(box.text) }
        ctx = c
    }

    public func echo(_ message: String, delayMs: Int = 0) throws -> EchoResponse {
        let box = MyTimerEchoBox()
        let ud = Unmanaged.passUnretained(box).toOpaque()
        var c_req = CMyTimer.EchoRequest()
        let c_req_message = strdup(message)
        defer { free(c_req_message) }
        c_req.message = UnsafePointer(c_req_message)
        c_req.delayMs = Int64(delayMs)
        guard my_timer_echo(ctx, my_timer_echoCallback, ud, c_req) == 0 else {
            throw TimerError.failed("echo dispatch failed")
        }
        box.sem.wait()
        guard box.ret == 0 else { throw TimerError.failed(box.text) }
        return EchoResponse(echoed: box.echoed, timerName: box.timerName)
    }

    public func version() throws -> String {
        let box = Box()
        let ud = Unmanaged.passUnretained(box).toOpaque()
        guard my_timer_version(ctx, stringCallback, ud) == 0 else {
            throw TimerError.failed("version dispatch failed")
        }
        box.sem.wait()
        guard box.ret == 0 else { throw TimerError.failed(box.text) }
        return box.text
    }

    deinit { my_timer_destroy(ctx) }

}

// MARK: - shared callback plumbing
final class Box {
    var ret: Int32 = -1
    var text = ""
    let sem = DispatchSemaphore(value: 0)
}

func rawText(_ msg: UnsafePointer<CChar>?, _ len: Int) -> String {
    guard let m = msg, len > 0 else { return "" }
    let bytes = UnsafeRawPointer(m).assumingMemoryBound(to: UInt8.self)
    return String(decoding: UnsafeBufferPointer(start: bytes, count: len), as: UTF8.self)
}

func ackCallback(_ ret: Int32, _ msg: UnsafePointer<CChar>?,
                 _ len: Int, _ ud: UnsafeMutableRawPointer?) {
    let box = Unmanaged<Box>.fromOpaque(ud!).takeUnretainedValue()
    box.ret = ret
    if ret != 0 { box.text = rawText(msg, len) }
    box.sem.signal()
}

func stringCallback(_ ret: Int32, _ msg: UnsafePointer<CChar>?,
                    _ len: Int, _ ud: UnsafeMutableRawPointer?) {
    let box = Unmanaged<Box>.fromOpaque(ud!).takeUnretainedValue()
    box.ret = ret
    box.text = rawText(msg, len)
    box.sem.signal()
}


final class MyTimerEchoBox {
    var ret: Int32 = -1
    var text = ""
    var echoed = ""
    var timerName = ""
    let sem = DispatchSemaphore(value: 0)
}
private func my_timer_echoCallback(_ ret: Int32, _ msg: UnsafePointer<CChar>?,
                          _ len: Int, _ ud: UnsafeMutableRawPointer?) {
    let box = Unmanaged<MyTimerEchoBox>.fromOpaque(ud!).takeUnretainedValue()
    box.ret = ret
    if ret == 0, let m = msg {
        let resp = UnsafeRawPointer(m).assumingMemoryBound(to: CMyTimer.EchoResponse.self)
        box.echoed = resp.pointee.echoed.map { String(cString: $0) } ?? ""
        box.timerName = resp.pointee.timerName.map { String(cString: $0) } ?? ""
    } else {
        box.text = rawText(msg, len)
    }
    box.sem.signal()
}