import CoreAudio
import Foundation

// Reads or sets the physical sample format of one output device's first stream, by device name, and reports the
// host's default and system output devices. It never changes a default device.

func property<Value>(_ object: AudioObjectID, _ selector: AudioObjectPropertySelector, scope: AudioObjectPropertyScope = kAudioObjectPropertyScopeGlobal, initial: Value) -> Value {
    var address = AudioObjectPropertyAddress(mSelector: selector, mScope: scope, mElement: kAudioObjectPropertyElementMain)
    var value = initial
    var size = UInt32(MemoryLayout<Value>.size)
    AudioObjectGetPropertyData(object, &address, 0, nil, &size, &value)
    return value
}

func array<Element>(_ object: AudioObjectID, _ selector: AudioObjectPropertySelector, scope: AudioObjectPropertyScope, of _: Element.Type, zero: Element) -> [Element] {
    var address = AudioObjectPropertyAddress(mSelector: selector, mScope: scope, mElement: kAudioObjectPropertyElementMain)
    var size: UInt32 = 0
    AudioObjectGetPropertyDataSize(object, &address, 0, nil, &size)
    var values = [Element](repeating: zero, count: Int(size) / MemoryLayout<Element>.size)
    AudioObjectGetPropertyData(object, &address, 0, nil, &size, &values)
    return values
}

func name(_ device: AudioObjectID) -> String {
    let value: Unmanaged<CFString>? = property(device, kAudioObjectPropertyName, initial: nil)
    return value?.takeRetainedValue() as String? ?? "?"
}

func describe(_ format: AudioStreamBasicDescription) -> String {
    "\(Int(format.mSampleRate)) Hz \(format.mChannelsPerFrame) ch \(format.mBitsPerChannel) bit"
}

let system = AudioObjectID(kAudioObjectSystemObject)
let defaultOutput: AudioObjectID = property(system, kAudioHardwarePropertyDefaultOutputDevice, initial: 0)
let systemOutput: AudioObjectID = property(system, kAudioHardwarePropertyDefaultSystemOutputDevice, initial: 0)
print("default output=\(name(defaultOutput)) system output=\(name(systemOutput))")

let arguments = Array(CommandLine.arguments.dropFirst())
let devices = array(system, kAudioHardwarePropertyDevices, scope: kAudioObjectPropertyScopeGlobal, of: AudioObjectID.self, zero: 0)
guard let device = devices.first(where: { name($0) == arguments[0] }) else {
    print("no device named \(arguments[0])")
    exit(1)
}
let streams = array(device, kAudioDevicePropertyStreams, scope: kAudioObjectPropertyScopeOutput, of: AudioObjectID.self, zero: 0)
guard let stream = streams.first else {
    print("no output stream")
    exit(1)
}
let current: AudioStreamBasicDescription = property(stream, kAudioStreamPropertyPhysicalFormat, initial: AudioStreamBasicDescription())
print("physical format=\(describe(current))")
if arguments.count > 1, let bits = UInt32(arguments[1]) {
    let available = array(stream, kAudioStreamPropertyAvailablePhysicalFormats, scope: kAudioObjectPropertyScopeGlobal, of: AudioStreamRangedDescription.self, zero: AudioStreamRangedDescription())
    guard var chosen = available.map(\.mFormat).first(where: { $0.mBitsPerChannel == bits && $0.mSampleRate == 48000 }) else {
        print("no \(bits)-bit format among \(available.map { describe($0.mFormat) })")
        exit(1)
    }
    var address = AudioObjectPropertyAddress(mSelector: kAudioStreamPropertyPhysicalFormat, mScope: kAudioObjectPropertyScopeGlobal, mElement: kAudioObjectPropertyElementMain)
    let status = AudioObjectSetPropertyData(stream, &address, 0, nil, UInt32(MemoryLayout<AudioStreamBasicDescription>.size), &chosen)
    usleep(300_000)
    let applied: AudioStreamBasicDescription = property(stream, kAudioStreamPropertyPhysicalFormat, initial: AudioStreamBasicDescription())
    print("set \(bits) bit: status \(status), physical format now=\(describe(applied))")
}