use crate::*;
pub trait HasClock: Send + Sync {
    fn clock (&self) -> &Clock;
    fn clock_mut (&mut self) -> &mut Clock;
}
#[macro_export] macro_rules! has_clock {
    (|$self:ident:$Struct:ident$(<$($L:lifetime),*$($T:ident$(:$U:path)?),*>)?|$cb:expr) => {
        impl $(<$($L),*$($T $(: $U)?),*>)? HasClock for $Struct $(<$($L),*$($T),*>)? {
            fn clock (&$self) -> &Clock { &$cb }
            fn clock_mut (&mut $self) -> &mut Clock { &mut $cb }
        }
    }
}
#[derive(Clone, Debug, PartialEq)]
pub enum ClockCommand {
    Play(Option<u32>),
    Pause(Option<u32>),
    SeekUsec(f64),
    SeekSample(f64),
    SeekPulse(f64),
    SetBpm(f64),
    SetQuant(f64),
    SetSync(f64),
}
provide_num!(u32: |self: Clock| {});
provide!(f64: |self: Clock| {});
atom_command!(ClockCommand: |state: Clock| {
    ("play"        [] Self::Play(None))
    ("play"        [t: u32] Self::Play(t))
    ("pause"       [] Self::Pause(None))
    ("pause"       [t: u32] Self::Pause(t))
    ("toggle"      [] if state.is_rolling() { Self::Pause(None) } else { Self::Play(None) })
    ("toggle"      [t: u32] if state.is_rolling() { Self::Pause(t) } else { Self::Play(t) })
    ("seek/usec"   [t: f64] Self::SeekUsec(t.expect("no usec")))
    ("seek/pulse"  [t: f64] Self::SeekPulse(t.expect("no pulse")))
    ("seek/sample" [t: f64] Self::SeekSample(t.expect("no sample")))
    ("set/bpm"     [t: f64] Self::SetBpm(t.expect("no bpm")))
    ("set/sync"    [t: f64] Self::SetSync(t.expect("no sync")))
    ("set/quant"   [t: f64] Self::SetQuant(t.expect("no quant")))
});
impl<T: HasClock> Command<T> for ClockCommand {
    fn execute (self, state: &mut T) -> Perhaps<Self> {
        self.execute(state.clock_mut())
    }
}
impl Command<Clock> for ClockCommand {
    fn execute (self, state: &mut Clock) -> Perhaps<Self> {
        use ClockCommand::*;
        match self {
            Play(start)        => state.play_from(start)?,
            Pause(pause)       => state.pause_at(pause)?,
            SeekUsec(usec)     => state.playhead.update_from_usec(usec),
            SeekSample(sample) => state.playhead.update_from_sample(sample),
            SeekPulse(pulse)   => state.playhead.update_from_pulse(pulse),
            SetBpm(bpm)        => return Ok(Some(SetBpm(state.timebase().bpm.set(bpm)))),
            SetQuant(quant)    => return Ok(Some(SetQuant(state.quant.set(quant)))),
            SetSync(sync)      => return Ok(Some(SetSync(state.sync.set(sync)))),
        };
        Ok(None)
    }
}

#[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>,
    /// For syncing the clock to an external source
    pub midi_in:   Arc<RwLock<Option<JackMidiIn>>>,
    /// For syncing other devices to this clock
    pub midi_out:  Arc<RwLock<Option<JackMidiOut>>>,
    /// For emitting a metronome
    pub click_out: Arc<RwLock<Option<JackAudioOut>>>,
}
impl std::fmt::Debug for Clock {
    fn fmt (&self, f: &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error> {
        f.debug_struct("Clock")
            .field("timebase", &self.timebase)
            .field("chunk",    &self.chunk)
            .field("quant",    &self.quant)
            .field("sync",     &self.sync)
            .field("global",   &self.global)
            .field("playhead", &self.playhead)
            .field("started",  &self.started)
            .finish()
    }
}
impl Clock {
    pub fn new (jack: &Jack, bpm: Option<f64>) -> Usually<Self> {
        let (chunk, transport) = jack.with_client(|c|(c.buffer_size(), c.transport()));
        let timebase = Arc::new(Timebase::default());
        let clock = Self {
            quant:     Arc::new(24.into()),
            sync:      Arc::new(384.into()),
            transport: Arc::new(Some(transport)),
            chunk:     Arc::new((chunk as usize).into()),
            global:    Arc::new(Moment::zero(&timebase)),
            playhead:  Arc::new(Moment::zero(&timebase)),
            offset:    Arc::new(Moment::zero(&timebase)),
            started:   RwLock::new(None).into(),
            timebase,
            midi_in:   Arc::new(RwLock::new(Some(JackMidiIn::new(jack, "M/clock", &[])?))),
            midi_out:  Arc::new(RwLock::new(Some(JackMidiOut::new(jack, "clock/M", &[])?))),
            click_out: Arc::new(RwLock::new(Some(JackAudioOut::new(jack, "click", &[])?))),
        };
        if let Some(bpm) = bpm {
            clock.timebase.bpm.set(bpm);
        }
        Ok(clock)
    }
    pub fn timebase (&self) -> &Arc<Timebase> {
        &self.timebase
    }
    /// Current sample rate
    pub fn sr (&self) -> &SampleRate {
        &self.timebase.sr
    }
    /// Current tempo
    pub fn bpm (&self) -> &BeatsPerMinute {
        &self.timebase.bpm
    }
    /// Current MIDI resolution
    pub fn ppq (&self) -> &PulsesPerQuaver {
        &self.timebase.ppq
    }
    /// Next pulse that matches launch sync (for phrase switchover)
    pub fn next_launch_pulse (&self) -> usize {
        let sync  = self.sync.get() as usize;
        let pulse = self.playhead.pulse.get() as usize;
        if pulse % sync == 0 {
            pulse
        } else {
            (pulse / sync + 1) * sync
        }
    }
    /// Start playing, optionally seeking to a given location beforehand
    pub fn play_from (&self, start: Option<u32>) -> Usually<()> {
        if let Some(transport) = self.transport.as_ref() {
            if let Some(start) = start {
                transport.locate(start)?;
            }
            transport.start()?;
        }
        Ok(())
    }
    /// Pause, optionally seeking to a given location afterwards
    pub fn pause_at (&self, pause: Option<u32>) -> Usually<()> {
        if let Some(transport) = self.transport.as_ref() {
            transport.stop()?;
            if let Some(pause) = pause {
                transport.locate(pause)?;
            }
        }
        Ok(())
    }
    /// Is currently paused?
    pub fn is_stopped (&self) -> bool {
        self.started.read().unwrap().is_none()
    }
    /// Is currently playing?
    pub fn is_rolling (&self) -> bool {
        self.started.read().unwrap().is_some()
    }
    /// Update chunk size
    pub fn set_chunk (&self, n_frames: usize) {
        self.chunk.store(n_frames, Relaxed);
    }
    pub fn update_from_scope (&self, scope: &ProcessScope) -> Usually<()> {
        // Store buffer length
        self.set_chunk(scope.n_frames() as usize);

        // Store reported global frame and usec
        let CycleTimes { current_frames, current_usecs, .. } = scope.cycle_times()?;
        self.global.sample.set(current_frames as f64);
        self.global.usec.set(current_usecs as f64);

        let mut started = self.started.write().unwrap();

        // If transport has just started or just stopped,
        // update starting point:
        if let Some(transport) = self.transport.as_ref() {
            match (transport.query_state()?, started.as_ref()) {
                (TransportState::Rolling, None) => {
                    let moment = Moment::zero(&self.timebase);
                    moment.sample.set(current_frames as f64);
                    moment.usec.set(current_usecs as f64);
                    *started = Some(moment);
                },
                (TransportState::Stopped, Some(_)) => {
                    *started = None;
                },
                _ => {}
            };
        }

        self.playhead.update_from_sample(started.as_ref()
            .map(|started|current_frames as f64 - started.sample.get())
            .unwrap_or(0.));

        Ok(())
    }

    pub fn bbt (&self) -> PositionBBT {
        let pulse = self.playhead.pulse.get() as i32;
        let ppq   = self.timebase.ppq.get() as i32;
        let bpm   = self.timebase.bpm.get();
        let bar   = (pulse / ppq) / 4;
        PositionBBT {
            bar:              1 + bar,
            beat:             1 + (pulse / ppq) % 4,
            tick:             (pulse % ppq),
            bar_start_tick:   (bar * 4 * ppq) as f64,
            beat_type:        4.,
            beats_per_bar:    4.,
            beats_per_minute: bpm,
            ticks_per_beat:   ppq as f64
        }
    }
}