import Foundation

class AsyncPipe {
    let pipe: Pipe
    let task: Task<(), Error>
    typealias continuation = UnsafeContinuation<Int, Never>
    
    init() {
        self.pipe = Pipe()
        self.task = Task.detached { [pipe = self.pipe] in
            while (!Task.isCancelled) {
                let data = try pipe.fileHandleForReading.read(upToCount: 8)!
                let raw = data.reduce(0) { $0 << 8 + UInt64($1) }
                let cont = unsafeBitCast(raw, to: continuation.self)
                cont.resume(returning: Int.random(in: 0...4))
            }
        }
    }
    
    func nop() async -> Int {
        return await withUnsafeContinuation() { cont in
            let raw = unsafeBitCast(cont, to: UInt64.self)
            
            withUnsafeBytes(of: raw.bigEndian) { buf in
                try! self.pipe.fileHandleForWriting.write(contentsOf: buf)
            }
        }
    }
    
    deinit {
        self.task.cancel()
    }
}

func pipeBenchmark() async {
    let ring = AsyncPipe()
    var sum = 0
    for _ in 1...100000 {
        sum += await ring.nop()
    }
    print("Done! Random output:", sum)
}

await pipeBenchmark()