use crate::*;
use ::std::sync::{Arc, RwLock, atomic::{AtomicUsize, Ordering::*}};
use ::atomic_float::AtomicF64;
use ::tengri::{draw::*, term::*};

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

/// 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>>>,
}

/// 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);

/// 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> {}

pub const DEFAULT_PPQ: f64 = 96.0;

/// FIXME: remove this and use PPQ from timebase everywhere:
pub const PPQ: usize = 96;

/// (pulses, name), assuming 96 PPQ
pub const NOTE_DURATIONS: [(usize, &str);26] = [
    (1,    "1/384"), (2,    "1/192"),
    (3,    "1/128"), (4,    "1/96"),
    (6,    "1/64"),  (8,    "1/48"),
    (12,   "1/32"),  (16,   "1/24"),
    (24,   "1/16"),  (32,   "1/12"),
    (48,   "1/8"),   (64,   "1/6"),
    (96,   "1/4"),   (128,  "1/3"),
    (192,  "1/2"),   (256,  "2/3"),
    (384,  "1/1"),   (512,  "4/3"),
    (576,  "3/2"),   (768,  "2/1"),
    (1152, "3/1"),   (1536, "4/1"),
    (2304, "6/1"),   (3072, "8/1"),
    (3456, "9/1"),   (6144, "16/1"),
];

pub const NOTE_NAMES: [&str; 128] = [
    "C0",  "C#0",  "D0",  "D#0",  "E0",  "F0",  "F#0",  "G0", "G#0", "A0", "A#0", "B0",
    "C1",  "C#1",  "D1",  "D#1",  "E1",  "F1",  "F#1",  "G1", "G#1", "A1", "A#1", "B1",
    "C2",  "C#2",  "D2",  "D#2",  "E2",  "F2",  "F#2",  "G2", "G#2", "A2", "A#2", "B2",
    "C3",  "C#3",  "D3",  "D#3",  "E3",  "F3",  "F#3",  "G3", "G#3", "A3", "A#3", "B3",
    "C4",  "C#4",  "D4",  "D#4",  "E4",  "F4",  "F#4",  "G4", "G#4", "A4", "A#4", "B4",
    "C5",  "C#5",  "D5",  "D#5",  "E5",  "F5",  "F#5",  "G5", "G#5", "A5", "A#5", "B5",
    "C6",  "C#6",  "D6",  "D#6",  "E6",  "F6",  "F#6",  "G6", "G#6", "A6", "A#6", "B6",
    "C7",  "C#7",  "D7",  "D#7",  "E7",  "F7",  "F#7",  "G7", "G#7", "A7", "A#7", "B7",
    "C8",  "C#8",  "D8",  "D#8",  "E8",  "F8",  "F#8",  "G8", "G#8", "A8", "A#8", "B8",
    "C9",  "C#9",  "D9",  "D#9",  "E9",  "F9",  "F#9",  "G9", "G#9", "A9", "A#9", "B9",
    "C10", "C#10", "D10", "D#10", "E10", "F10", "F#10", "G10",
];

def_command!(ClockCommand: |clock: Clock| {
    SeekUsec   { usec:   f64 } => {
        clock.playhead.update_from_usec(*usec); Ok(None) },
    SeekSample { sample: f64 } => {
        clock.playhead.update_from_sample(*sample); Ok(None) },
    SeekPulse  { pulse:  f64 } => {
        clock.playhead.update_from_pulse(*pulse); Ok(None) },
    SetBpm     { bpm:    f64 } => Ok(Some(
        Self::SetBpm { bpm: clock.timebase().bpm.set(*bpm) })),
    SetQuant   { quant:  f64 } => Ok(Some(
        Self::SetQuant { quant: clock.quant.set(*quant) })),
    SetSync    { sync:   f64 } => Ok(Some(
        Self::SetSync { sync: clock.sync.set(*sync) })),

    Play  { position: Option<u32> } => {
        clock.play_from(*position)?; Ok(None) /* TODO Some(Pause(previousPosition)) */ },
    Pause { position: Option<u32> } => {
        clock.pause_at(*position)?; Ok(None) },

    TogglePlayback { position: u32 } => Ok(if clock.is_rolling() {
        clock.pause_at(Some(*position))?; None
    } else {
        clock.play_from(Some(*position))?; None
    }),
});

impl LaunchSync {
    pub fn next (&self) -> f64 {
        note_duration_next(self.get() as usize) as f64
    }
    pub fn prev (&self) -> f64 {
        note_duration_prev(self.get() as usize) as f64
    }
}

impl Quantize {
    pub fn next (&self) -> f64 {
        note_duration_next(self.get() as usize) as f64
    }
    pub fn prev (&self) -> f64 {
        note_duration_prev(self.get() as usize) as f64
    }
}

/// Implement an arithmetic operation for a unit of time
#[macro_export] macro_rules! impl_op {
    ($T:ident, $Op:ident, $method:ident, |$a:ident,$b:ident|{$impl:expr}) => {
        impl $Op<Self> for $T {
            type Output = Self; #[inline] fn $method (self, other: Self) -> Self::Output {
                let $a = self.get(); let $b = other.get(); Self($impl.into())
            }
        }
        impl $Op<usize> for $T {
            type Output = Self; #[inline] fn $method (self, other: usize) -> Self::Output {
                let $a = self.get(); let $b = other as f64; Self($impl.into())
            }
        }
        impl $Op<f64> for $T {
            type Output = Self; #[inline] fn $method (self, other: f64) -> Self::Output {
                let $a = self.get(); let $b = other; Self($impl.into())
            }
        }
    }
}

/// Define and implement a unit of time
#[macro_export] macro_rules! impl_time_unit {
    ($T:ident) => {
        impl Gettable<f64> for $T {
            fn get (&self) -> f64 { self.0.load(Relaxed) }
        }
        impl InteriorMutable<f64> for $T {
            fn set (&self, value: f64) -> f64 {
                let old = self.get();
                self.0.store(value, Relaxed);
                old
            }
        }
        impl TimeUnit for $T {}
        impl_op!($T, Add, add, |a, b|{a + b});
        impl_op!($T, Sub, sub, |a, b|{a - b});
        impl_op!($T, Mul, mul, |a, b|{a * b});
        impl_op!($T, Div, div, |a, b|{a / b});
        impl_op!($T, Rem, rem, |a, b|{a % b});
        impl From<f64>   for $T    { fn from (value: f64)   -> Self { Self(value.into()) } }
        impl From<usize> for $T    { fn from (value: usize) -> Self { Self((value as f64).into()) } }
        impl From<$T>    for f64   { fn from (value: $T)    -> Self { value.get() } }
        impl From<$T>    for usize { fn from (value: $T)    -> Self { value.get() as usize } }
        impl From<&$T>   for f64   { fn from (value: &$T)   -> Self { value.get() } }
        impl From<&$T>   for usize { fn from (value: &$T)   -> Self { value.get() as usize } }
        impl Clone for $T { fn clone (&self) -> Self { Self(self.get().into()) } }
    }
}

impl std::fmt::Debug for Clock {
    fn fmt (&self, f: &mut 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<'static>, 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(MidiInput::new(jack,   &"M/clock", &[])?))),
            midi_out:  Arc::new(RwLock::new(Some(MidiOutput::new(jack,  &"clock/M", &[])?))),
            click_out: Arc::new(RwLock::new(Some(AudioOutput::new(jack, &"click",   &[])?))),
            ..Default::default()
        };
        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) -> &Bpm {
        &self.timebase.bpm
    }
    /// Current MIDI resolution
    pub fn ppq (&self) -> &Ppq {
        &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
        }
    }

    pub fn next_launch_instant (&self) -> Moment {
        Moment::from_pulse(self.timebase(), self.next_launch_pulse() as f64)
    }

    /// Get index of first sample to populate.
    ///
    /// Greater than 0 means that the first pulse of the clip
    /// falls somewhere in the middle of the chunk.
    pub fn get_sample_offset (&self, scope: &ProcessScope, started: &Moment) -> usize{
        (scope.last_frame_time() as usize).saturating_sub(
            started.sample.get() as usize +
            self.started.read().unwrap().as_ref().unwrap().sample.get() as usize
        )
    }

    // Get iterator that emits sample paired with pulse.
    //
    // * Sample: index into output buffer at which to write MIDI event
    // * Pulse: index into clip from which to take the MIDI event
    //
    // Emitted for each sample of the output buffer that corresponds to a MIDI pulse.
    pub fn get_pulses (&self, scope: &ProcessScope, offset: usize) -> Ticker {
        self.timebase().pulses_between_samples(offset, offset + scope.n_frames() as usize)
    }
}

impl Clock {
    fn _todo_provide_u32 (&self) -> u32 {
        todo!()
    }
    fn _todo_provide_opt_u32 (&self) -> Option<u32> {
        todo!()
    }
    fn _todo_provide_f64 (&self) -> f64 {
        todo!()
    }
}

impl<T: HasClock> Act<T> for ClockCommand {
    fn act (&self, state: &mut T) -> Perhaps<Self> {
        self.act(state.clock_mut()) // awesome
    }
}

#[cfg(feature = "clock")] impl_has!(Clock: |self: Track|self.sequencer.clock);
impl_default!(Timebase: Self::new(48000f64, 150f64, DEFAULT_PPQ));
impl_time_unit!(SampleCount);
impl_time_unit!(SampleRate);
impl_time_unit!(Microsecond);
impl_time_unit!(Quantize);
impl_time_unit!(Ppq);
impl_time_unit!(Pulse);
impl_time_unit!(Bpm);
impl_time_unit!(LaunchSync);

mod moment; pub use self::moment::*;
mod ticker; pub use self::ticker::*;
mod timebase; pub use self::timebase::*;
mod clock_view; pub use self::clock_view::*;