use crate::*;

/// Temporal resolutions: sample rate, tempo, MIDI pulses per quaver (beat)
#[derive(Debug, Clone)]
pub struct Timebase {
    /// Audio samples per second
    pub sr:  SampleRate,
    /// MIDI beats per minute
    pub bpm: BeatsPerMinute,
    /// MIDI ticks per beat
    pub ppq: PulsesPerQuaver,
}

impl Timebase {
    /// Specify sample rate, BPM and PPQ
    pub fn new (
        s: impl Into<SampleRate>,
        b: impl Into<BeatsPerMinute>,
        p: impl Into<PulsesPerQuaver>
    ) -> Self {
        Self { sr: s.into(), bpm: b.into(), ppq: p.into() }
    }
    /// Iterate over ticks between start and end.
    #[inline] pub fn pulses_between_samples (&self, start: usize, end: usize) -> TicksIterator {
        TicksIterator { spp: self.samples_per_pulse(), sample: start, start, end }
    }
    /// Return the duration fo a beat in microseconds
    #[inline] pub fn usec_per_beat (&self) -> f64 { 60_000_000f64 / self.bpm.get() }
    /// Return the number of beats in a second
    #[inline] pub fn beat_per_second (&self) -> f64 { self.bpm.get() / 60f64 }
    /// Return the number of microseconds corresponding to a note of the given duration
    #[inline] pub fn note_to_usec (&self, (num, den): (f64, f64)) -> f64 {
        4.0 * self.usec_per_beat() * num / den
    }
    /// Return duration of a pulse in microseconds (BPM-dependent)
    #[inline] pub fn pulse_per_usec (&self) -> f64 { self.ppq.get() / self.usec_per_beat() }
    /// Return duration of a pulse in microseconds (BPM-dependent)
    #[inline] pub fn usec_per_pulse (&self) -> f64 { self.usec_per_beat() / self.ppq.get() }
    /// Return number of pulses to which a number of microseconds corresponds (BPM-dependent)
    #[inline] pub fn usecs_to_pulse (&self, usec: f64) -> f64 { usec * self.pulse_per_usec() }
    /// Convert a number of pulses to a sample number (SR- and BPM-dependent)
    #[inline] pub fn pulses_to_usec (&self, pulse: f64) -> f64 { pulse / self.usec_per_pulse() }
    /// Return number of pulses in a second (BPM-dependent)
    #[inline] pub fn pulses_per_second (&self) -> f64 { self.beat_per_second() * self.ppq.get() }
    /// Return fraction of a pulse to which a sample corresponds (SR- and BPM-dependent)
    #[inline] pub fn pulses_per_sample (&self) -> f64 {
        self.usec_per_pulse() / self.sr.usec_per_sample()
    }
    /// Return number of samples in a pulse (SR- and BPM-dependent)
    #[inline] pub fn samples_per_pulse (&self) -> f64 {
        self.sr.get() / self.pulses_per_second()
    }
    /// Convert a number of pulses to a sample number (SR- and BPM-dependent)
    #[inline] pub fn pulses_to_sample (&self, p: f64) -> f64 {
        self.pulses_per_sample() * p
    }
    /// Convert a number of samples to a pulse number (SR- and BPM-dependent)
    #[inline] pub fn samples_to_pulse (&self, s: f64) -> f64 {
        s / self.pulses_per_sample()
    }
    /// Return the number of samples corresponding to a note of the given duration
    #[inline] pub fn note_to_samples (&self, note: (f64, f64)) -> f64 {
        self.usec_to_sample(self.note_to_usec(note))
    }
    /// Return the number of samples corresponding to the given number of microseconds
    #[inline] pub fn usec_to_sample (&self, usec: f64) -> f64 {
        usec * self.sr.get() / 1000f64
    }
    /// Return the quantized position of a moment in time given a step
    #[inline] pub fn quantize (&self, step: (f64, f64), time: f64) -> (f64, f64) {
        let step = self.note_to_usec(step);
        (time / step, time % step)
    }
    /// Quantize a collection of events
    #[inline] pub fn quantize_into <E: Iterator<Item=(f64, f64)> + Sized, T> (
        &self, step: (f64, f64), events: E
    ) -> Vec<(f64, f64)> {
        events.map(|(time, event)|(self.quantize(step, time).0, event)).collect()
    }
    /// Format a number of pulses into Beat.Bar.Pulse starting from 0
    #[inline] pub fn format_beats_0 (&self, pulse: f64) -> Arc<str> {
        let pulse = pulse as usize;
        let ppq   = self.ppq.get() as usize;
        let (beats, pulses) = if ppq > 0 { (pulse / ppq, pulse % ppq) } else { (0, 0) };
        format!("{}.{}.{pulses:02}", beats / 4, beats % 4).into()
    }
    /// Format a number of pulses into Beat.Bar starting from 0
    #[inline] pub fn format_beats_0_short (&self, pulse: f64) -> Arc<str> {
        let pulse = pulse as usize;
        let ppq   = self.ppq.get() as usize;
        let beats = if ppq > 0 { pulse / ppq } else { 0 };
        format!("{}.{}", beats / 4, beats % 4).into()
    }
    /// Format a number of pulses into Beat.Bar.Pulse starting from 1
    #[inline] pub fn format_beats_1 (&self, pulse: f64) -> Arc<str> {
        let mut string = String::with_capacity(16);
        self.format_beats_1_to(&mut string, pulse).expect("failed to format {pulse} into beat");
        string.into()
    }
    /// Format a number of pulses into Beat.Bar.Pulse starting from 1
    #[inline] pub fn format_beats_1_to (&self, w: &mut impl std::fmt::Write, pulse: f64) -> Result<(), std::fmt::Error> {
        let pulse = pulse as usize;
        let ppq   = self.ppq.get() as usize;
        let (beats, pulses) = if ppq > 0 { (pulse / ppq, pulse % ppq) } else { (0, 0) };
        write!(w, "{}.{}.{pulses:02}", beats / 4 + 1, beats % 4 + 1)
    }
    /// Format a number of pulses into Beat.Bar.Pulse starting from 1
    #[inline] pub fn format_beats_1_short (&self, pulse: f64) -> Arc<str> {
        let pulse = pulse as usize;
        let ppq   = self.ppq.get() as usize;
        let beats = if ppq > 0 { pulse / ppq } else { 0 };
        format!("{}.{}", beats / 4 + 1, beats % 4 + 1).into()
    }
}

impl Default for Timebase {
    fn default () -> Self { Self::new(48000f64, 150f64, DEFAULT_PPQ) }
}