//! Host-independent controls. Levels in dB, times in milliseconds, amounts in percent.
use serde::{Deserialize, Serialize};

/// Bands: the fundamental, low harmonics, mid harmonics and the top.
pub const BANDS: usize = 4;
pub const GAIN_MIN: f32 = -24.;
pub const GAIN_MAX: f32 = 24.;
/// Highest harmonic a band edge can be set to.
pub const TOP_MAX: u32 = 48;

#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq, Default)]
pub enum Source {
    /// Pitch and note starts are detected from the incoming bass.
    #[default]
    Audio,
    /// Notes come from MIDI note input.
    Midi,
}

#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq)]
#[serde(deny_unknown_fields)]
pub struct Settings {
    pub source: Source,
    /// Highest harmonic in the bottom band. 1 keeps the fundamental on its own.
    pub low: u32,
    /// Highest harmonic in the second band.
    pub mid: u32,
    /// Highest harmonic in the third band; everything above is the top band.
    pub high: u32,
    /// Share of the compressed signal, per band, against the dry band.
    pub depth: f32,
    /// Scales every attack and release time.
    pub time: f32,
    /// Amount of upward compression: quiet bands are lifted.
    pub upward: f32,
    /// Amount of downward compression: loud bands are pushed down.
    pub downward: f32,
    /// Gain on the level the compressors see, not on the audio: moves the band levels against
    /// the thresholds. More drive means more squash; at Depth 0 it changes nothing.
    pub drive: f32,
    /// Gain of each band after its compressor, bottom band first.
    pub gains: [f32; BANDS],
    /// Retune time when the pitch slides or bends.
    pub smooth: f32,
    /// Detection threshold in dBFS for note starts (Audio source).
    pub gate: f32,
    /// Round detected pitch to the nearest semitone. Off by default: the level window is one
    /// period of the pitch in use, and a detuned note then gets a window that does not fit.
    pub snap: bool,
    pub output: f32,
    pub bypass: bool,
}
impl Default for Settings {
    fn default() -> Self {
        Self {
            source: Source::Audio,
            low: 1,
            mid: 4,
            high: 16,
            depth: 50.,
            time: 100.,
            upward: 100.,
            downward: 100.,
            drive: 0.,
            gains: [0.; BANDS],
            smooth: 10.,
            gate: -42.,
            snap: false,
            output: 0.,
            bypass: false,
        }
    }
}
impl Settings {
    pub fn validate(&self) -> Result<(), &'static str> {
        let finite = [
            self.depth,
            self.time,
            self.upward,
            self.downward,
            self.drive,
            self.smooth,
            self.gate,
            self.output,
        ]
        .iter()
        .chain(self.gains.iter())
        .all(|v| v.is_finite());
        if !finite {
            return Err("non-finite setting");
        }
        let ok = (1..=8).contains(&self.low)
            && (2..=16).contains(&self.mid)
            && (3..=TOP_MAX).contains(&self.high)
            && self.gains.iter().all(|g| (GAIN_MIN..=GAIN_MAX).contains(g))
            && (0.0..=100.).contains(&self.depth)
            && (10.0..=1000.).contains(&self.time)
            && (0.0..=100.).contains(&self.upward)
            && (0.0..=100.).contains(&self.downward)
            && (-24.0..=24.).contains(&self.drive)
            && (0.0..=100.).contains(&self.smooth)
            && (-60.0..=-20.).contains(&self.gate)
            && (-24.0..=24.).contains(&self.output);
        if ok {
            Ok(())
        } else {
            Err("setting out of range")
        }
    }
    /// Highest harmonic of the bottom three bands, in rising order. Host automation can set
    /// the edges in any order, so a lower edge pushes the next one up instead of failing.
    pub fn tops(&self) -> [u32; BANDS - 1] {
        let low = self.low.clamp(1, 8);
        let mid = self.mid.max(low + 1);
        let high = self.high.max(mid + 1);
        [low, mid, high]
    }
    /// Text for the harmonics of `band`, like "1", "2–4" or "17+".
    pub fn band_label(&self, band: usize) -> String {
        let t = self.tops();
        let first = if band == 0 { 1 } else { t[band - 1] + 1 };
        match band {
            3 => format!("{first}+"),
            _ if first == t[band] => format!("{first}"),
            _ => format!("{first}–{}", t[band]),
        }
    }
}