pub trait HasClock: AsRef<Clock> + AsMut<Clock> {
    fn clock     (&self)     -> &Clock     { self.as_ref() }
    fn clock_mut (&mut self) -> &mut Clock { self.as_mut() }
}


/// Temporal resolutions: sample rate, tempo, MIDI pulses per quaver (beat)
///
/// ```
/// let _ = tek::Timebase::default();
/// ```
#[derive(Debug, Clone)] pub struct Timebase {
    /// Audio samples per second
    pub sr:  SampleRate,
    /// MIDI beats per minute
    pub bpm: Bpm,
    /// MIDI ticks per beat
    pub ppq: Ppq,
}

/// Iterator that emits subsequent ticks within a range.
///
/// ```
/// let iter = tek::Ticker::default();
/// ```
#[derive(Debug, Default)] pub struct Ticker {
    pub spp:    f64,
    pub sample: usize,
    pub start:  usize,
    pub end:    usize,
}

/// A point in time in all time scales (microsecond, sample, MIDI pulse)
///
/// ```
/// let _ = tek::Moment::default();
/// ```
#[derive(Debug, Default, Clone)] pub struct Moment {
    pub timebase: Arc<Timebase>,
    /// Current time in microseconds
    pub usec:   Microsecond,
    /// Current time in audio samples
    pub sample: SampleCount,
    /// Current time in MIDI pulses
    pub pulse:  Pulse,
}

///
/// ```
/// let _ = tek::Moment2::default();
/// ```
#[derive(Debug, Clone, Default)] pub enum Moment2 {
    #[default] None,
    Zero,
    Usec(Microsecond),
    Sample(SampleCount),
    Pulse(Pulse),
}

/// MIDI resolution in PPQ (pulses per quarter note)
///
/// ```
///
/// ```
#[derive(Debug, Default)] pub struct Ppq (pub(crate) AtomicF64);

/// Timestamp in MIDI pulses
///
/// ```
///
/// ```
#[derive(Debug, Default)] pub struct Pulse (pub(crate) AtomicF64);

/// Tempo in beats per minute
///
/// ```
///
/// ```
#[derive(Debug, Default)] pub struct Bpm (pub(crate) AtomicF64);

/// Quantization setting for launching clips
///
/// ```
///
/// ```
#[derive(Debug, Default)] pub struct LaunchSync (pub(crate) AtomicF64);

/// Quantization setting for notes
///
/// ```
///
/// ```
#[derive(Debug, Default)] pub struct Quantize (pub(crate) AtomicF64);

/// Timestamp in audio samples
///
/// ```
///
/// ```
#[derive(Debug, Default)] pub struct SampleCount (pub(crate) AtomicF64);

/// Audio sample rate in Hz (samples per second)
///
/// ```
///
/// ```
#[derive(Debug, Default)] pub struct SampleRate (pub(crate) AtomicF64);

/// Timestamp in microseconds
///
/// ```
///
/// ```
#[derive(Debug, Default)] pub struct Microsecond (pub(crate) AtomicF64);

/// The source of time.
///
/// ```
/// let clock = tek::Clock::default();
/// ```
#[derive(Clone, Default)] pub struct Clock {
    /// JACK transport handle.
    pub transport: Arc<Option<Transport>>,
    /// Global temporal resolution (shared by [Moment] fields)
    pub timebase:  Arc<Timebase>,
    /// Current global sample and usec (monotonic from JACK clock)
    pub global:    Arc<Moment>,
    /// Global sample and usec at which playback started
    pub started:   Arc<RwLock<Option<Moment>>>,
    /// Playback offset (when playing not from start)
    pub offset:    Arc<Moment>,
    /// Current playhead position
    pub playhead:  Arc<Moment>,
    /// Note quantization factor
    pub quant:     Arc<Quantize>,
    /// Launch quantization factor
    pub sync:      Arc<LaunchSync>,
    /// Size of buffer in samples
    pub chunk:     Arc<AtomicUsize>,
    // Cache of formatted strings
    pub view_cache: Arc<RwLock<ClockView>>,
    /// For syncing the clock to an external source
    #[cfg(feature = "port")] pub midi_in:   Arc<RwLock<Option<MidiInput>>>,
    /// For syncing other devices to this clock
    #[cfg(feature = "port")] pub midi_out:  Arc<RwLock<Option<MidiOutput>>>,
    /// For emitting a metronome
    #[cfg(feature = "port")] pub click_out: Arc<RwLock<Option<AudioOutput>>>,
}

/// A unit of time, represented as an atomic 64-bit float.
///
/// According to https://stackoverflow.com/a/873367, as per IEEE754,
/// every integer between 1 and 2^53 can be represented exactly.
/// This should mean that, even at 192kHz sampling rate, over 1 year of audio
/// can be clocked in microseconds with f64 without losing precision.
pub trait TimeUnit: InteriorMutable<f64> {}

/// Contains memoized renders of clock values.
///
/// Performance optimization.
#[derive(Debug)] pub struct ClockView {
    pub sr:   Memo<Option<(bool, f64)>, String>,
    pub buf:  Memo<Option<f64>, String>,
    pub lat:  Memo<Option<f64>, String>,
    pub bpm:  Memo<Option<f64>, String>,
    pub beat: Memo<Option<f64>, String>,
    pub time: Memo<Option<f64>, String>,
}