mlua-pulse 0.1.0

//! Track and master effects exposed to Lua and converted into `tunes` effects.

use crate::error::{PulseError, PulseResult};
use std::collections::BTreeMap;
use tunes::composition::TrackBuilder;
use tunes::synthesis::effects::{Chorus, Compressor, Delay, Limiter, Phaser, Reverb, EQ};
use tunes::synthesis::filter::{Filter, FilterSlope, FilterType};
use tunes::track::{Mixer, Track};

/// Metadata describing one Lua-visible effect.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct EffectInfo {
    /// Canonical effect name.
    pub name: &'static str,
    /// Broad effect family.
    pub category: &'static str,
    /// Allowed placement scopes, such as `track` or `master`.
    pub scopes: &'static [&'static str],
    /// Supported parameter names.
    pub parameters: &'static [&'static str],
    /// Supported preset names.
    pub presets: &'static [&'static str],
}

/// One parsed effect option value.
#[derive(Debug, Clone, PartialEq)]
pub enum EffectOption {
    /// Floating point option value.
    Number(f32),
    /// Text option value, commonly used for filter kinds.
    Text(String),
    /// Integer option value, commonly used for filter slopes and phaser stages.
    Integer(i64),
}

/// Parsed options for building an effect.
#[derive(Debug, Clone, Default, PartialEq)]
pub enum EffectOptions {
    /// Use the effect's default settings.
    #[default]
    Default,
    /// Use a named preset.
    Preset(String),
    /// Use named parameter values.
    Params(BTreeMap<String, EffectOption>),
}

const TRACK_AND_MASTER: &[&str] = &["track", "master"];
const TRACK_ONLY: &[&str] = &["track"];

const EFFECT_INFOS: &[EffectInfo] = &[
    EffectInfo {
        name: "delay",
        category: "time",
        scopes: TRACK_AND_MASTER,
        parameters: &["time", "feedback", "mix"],
        presets: &[
            "eighth_note",
            "quarter_note",
            "dotted_eighth",
            "half_note",
            "slapback",
            "ping_pong",
            "doubling",
            "ambient",
        ],
    },
    EffectInfo {
        name: "reverb",
        category: "space",
        scopes: TRACK_AND_MASTER,
        parameters: &["room_size", "damping", "mix"],
        presets: &[
            "room",
            "hall",
            "plate",
            "chamber",
            "cathedral",
            "ambient",
            "subtle",
            "spring",
        ],
    },
    EffectInfo {
        name: "filter",
        category: "filter",
        scopes: TRACK_ONLY,
        parameters: &["type", "cutoff", "resonance", "slope"],
        presets: &[],
    },
    EffectInfo {
        name: "compressor",
        category: "dynamics",
        scopes: TRACK_AND_MASTER,
        parameters: &["threshold", "ratio", "attack", "release", "makeup_gain"],
        presets: &["gentle", "drum_bus", "bass", "master", "aggressive"],
    },
    EffectInfo {
        name: "limiter",
        category: "dynamics",
        scopes: TRACK_AND_MASTER,
        parameters: &["threshold", "release"],
        presets: &[
            "transparent",
            "standard",
            "brick_wall",
            "mastering",
            "safety",
        ],
    },
    EffectInfo {
        name: "chorus",
        category: "modulation",
        scopes: TRACK_AND_MASTER,
        parameters: &["rate", "depth", "mix"],
        presets: &["subtle", "classic", "wide", "vibrato", "thick"],
    },
    EffectInfo {
        name: "phaser",
        category: "modulation",
        scopes: TRACK_AND_MASTER,
        parameters: &["rate", "depth", "feedback", "stages", "mix"],
        presets: &["slow", "classic", "fast", "subtle", "deep"],
    },
    EffectInfo {
        name: "eq",
        category: "filter",
        scopes: TRACK_AND_MASTER,
        parameters: &["low_gain", "mid_gain", "high_gain", "low_freq", "high_freq"],
        presets: &["flat", "bass_boost", "bright", "warm", "phone"],
    },
];

/// Delay effect parameters.
#[derive(Debug, Clone, PartialEq)]
pub struct PulseDelay {
    /// Delay time in seconds.
    pub time: f32,
    /// Feedback amount in `0..=0.99`.
    pub feedback: f32,
    /// Wet/dry mix in `0..=1`.
    pub mix: f32,
}

/// Reverb effect parameters.
#[derive(Debug, Clone, PartialEq)]
pub struct PulseReverb {
    /// Room size in `0..=1`.
    pub room_size: f32,
    /// High-frequency damping in `0..=1`.
    pub damping: f32,
    /// Wet/dry mix in `0..=1`.
    pub mix: f32,
}

/// Filter effect parameters.
#[derive(Debug, Clone, PartialEq)]
pub struct PulseFilter {
    /// Filter algorithm.
    pub kind: PulseFilterKind,
    /// Cutoff frequency in Hertz.
    pub cutoff: f32,
    /// Resonance amount in `0..=0.99`.
    pub resonance: f32,
    /// Filter slope.
    pub slope: PulseFilterSlope,
}

/// Compressor effect parameters.
#[derive(Debug, Clone, PartialEq)]
pub struct PulseCompressor {
    /// Compression threshold in the normalized `tunes` amplitude domain.
    pub threshold: f32,
    /// Compression ratio.
    pub ratio: f32,
    /// Attack time in seconds.
    pub attack: f32,
    /// Release time in seconds.
    pub release: f32,
    /// Makeup gain multiplier.
    pub makeup_gain: f32,
}

/// Limiter effect parameters.
#[derive(Debug, Clone, PartialEq)]
pub struct PulseLimiter {
    /// Limiter threshold in dB-style `tunes` units.
    pub threshold: f32,
    /// Release time in seconds.
    pub release: f32,
}

/// Chorus effect parameters.
#[derive(Debug, Clone, PartialEq)]
pub struct PulseChorus {
    /// Modulation rate in Hertz.
    pub rate: f32,
    /// Modulation depth.
    pub depth: f32,
    /// Wet/dry mix in `0..=1`.
    pub mix: f32,
}

/// Phaser effect parameters.
#[derive(Debug, Clone, PartialEq)]
pub struct PulsePhaser {
    /// Modulation rate in Hertz.
    pub rate: f32,
    /// Modulation depth in `0..=1`.
    pub depth: f32,
    /// Feedback amount in `0..=0.95`.
    pub feedback: f32,
    /// Number of phaser stages.
    pub stages: usize,
    /// Wet/dry mix in `0..=1`.
    pub mix: f32,
}

/// Three-band EQ parameters.
#[derive(Debug, Clone, PartialEq)]
pub struct PulseEq {
    /// Low band gain multiplier.
    pub low_gain: f32,
    /// Mid band gain multiplier.
    pub mid_gain: f32,
    /// High band gain multiplier.
    pub high_gain: f32,
    /// Low/mid crossover frequency in Hertz.
    pub low_freq: f32,
    /// Mid/high crossover frequency in Hertz.
    pub high_freq: f32,
}

/// Filter algorithm exposed by `PulseFilter`.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum PulseFilterKind {
    /// Low-pass filter.
    LowPass,
    /// High-pass filter.
    HighPass,
    /// Band-pass filter.
    BandPass,
    /// Notch filter.
    Notch,
    /// All-pass filter.
    AllPass,
    /// Moog-style ladder filter.
    Moog,
}

/// Filter slope exposed by `PulseFilter`.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum PulseFilterSlope {
    /// 12 dB per octave slope.
    Pole12,
    /// 24 dB per octave slope.
    Pole24,
}

/// One effect instance ready to apply to a track or master bus.
#[derive(Debug, Clone, PartialEq)]
pub enum PulseEffect {
    /// Delay.
    Delay(PulseDelay),
    /// Reverb.
    Reverb(PulseReverb),
    /// Filter. This is track-only.
    Filter(PulseFilter),
    /// Compressor.
    Compressor(PulseCompressor),
    /// Limiter.
    Limiter(PulseLimiter),
    /// Chorus.
    Chorus(PulseChorus),
    /// Phaser.
    Phaser(PulsePhaser),
    /// Three-band EQ.
    Eq(PulseEq),
}

impl Default for PulseDelay {
    fn default() -> Self {
        Self {
            time: 0.25,
            feedback: 0.4,
            mix: 0.35,
        }
    }
}

impl Default for PulseReverb {
    fn default() -> Self {
        Self {
            room_size: 0.5,
            damping: 0.5,
            mix: 0.25,
        }
    }
}

impl Default for PulseFilter {
    fn default() -> Self {
        Self {
            kind: PulseFilterKind::LowPass,
            cutoff: 1200.0,
            resonance: 0.3,
            slope: PulseFilterSlope::Pole12,
        }
    }
}

impl Default for PulseCompressor {
    fn default() -> Self {
        Self {
            threshold: 0.5,
            ratio: 2.0,
            attack: 0.01,
            release: 0.1,
            makeup_gain: 1.0,
        }
    }
}

impl Default for PulseLimiter {
    fn default() -> Self {
        Self {
            threshold: -0.3,
            release: 0.05,
        }
    }
}

impl Default for PulseChorus {
    fn default() -> Self {
        Self {
            rate: 1.5,
            depth: 5.0,
            mix: 0.5,
        }
    }
}

impl Default for PulsePhaser {
    fn default() -> Self {
        Self {
            rate: 0.5,
            depth: 0.8,
            feedback: 0.6,
            stages: 4,
            mix: 0.6,
        }
    }
}

impl Default for PulseEq {
    fn default() -> Self {
        Self {
            low_gain: 1.0,
            mid_gain: 1.0,
            high_gain: 1.0,
            low_freq: 300.0,
            high_freq: 3000.0,
        }
    }
}

/// Returns metadata for all Lua-visible effects.
#[must_use]
pub fn effect_infos() -> &'static [EffectInfo] {
    EFFECT_INFOS
}

/// Returns effect names in stable API order.
#[must_use]
pub fn effect_names() -> Vec<&'static str> {
    EFFECT_INFOS.iter().map(|info| info.name).collect()
}

/// Looks up one effect's metadata by name.
///
/// # Errors
///
/// Returns `PulseError::InvalidEffect` when `name` is unknown.
pub fn effect_info(name: &str) -> PulseResult<&'static EffectInfo> {
    let normalized = normalize_name(name);
    EFFECT_INFOS
        .iter()
        .find(|info| normalize_name(info.name) == normalized)
        .ok_or_else(|| PulseError::InvalidEffect {
            name: name.to_string(),
        })
}

/// Builds an effect from a name and parsed options.
///
/// # Errors
///
/// Returns an error when the name, preset, option name, or option value is invalid.
pub fn effect_from_options(name: &str, options: EffectOptions) -> PulseResult<PulseEffect> {
    match normalize_name(name).as_str() {
        "delay" => build_delay(options).map(PulseEffect::Delay),
        "reverb" => build_reverb(options).map(PulseEffect::Reverb),
        "filter" => build_filter(options).map(PulseEffect::Filter),
        "compressor" => build_compressor(options).map(PulseEffect::Compressor),
        "limiter" => build_limiter(options).map(PulseEffect::Limiter),
        "chorus" => build_chorus(options).map(PulseEffect::Chorus),
        "phaser" => build_phaser(options).map(PulseEffect::Phaser),
        "eq" => build_eq(options).map(PulseEffect::Eq),
        _ => Err(PulseError::InvalidEffect {
            name: name.to_string(),
        }),
    }
}

fn normalize_name(value: &str) -> String {
    value
        .trim()
        .to_ascii_lowercase()
        .replace(['_', '-', ' '], "")
}

fn option_key_error(effect: &str, option: &str) -> PulseError {
    PulseError::InvalidEffectOption {
        effect: effect.to_string(),
        option: option.to_string(),
        value: "unsupported".to_string(),
    }
}

fn option_value_error(effect: &str, option: &str, value: impl ToString) -> PulseError {
    PulseError::InvalidEffectOption {
        effect: effect.to_string(),
        option: option.to_string(),
        value: value.to_string(),
    }
}

fn invalid_preset(effect: &str, preset: &str) -> PulseError {
    PulseError::InvalidEffectPreset {
        effect: effect.to_string(),
        preset: preset.to_string(),
    }
}

fn number_option(effect: &str, option: &str, value: &EffectOption) -> PulseResult<f32> {
    match value {
        EffectOption::Number(value) if value.is_finite() => Ok(*value),
        EffectOption::Integer(value) => Ok(*value as f32),
        EffectOption::Number(value) => Err(option_value_error(effect, option, value)),
        EffectOption::Text(value) => Err(option_value_error(effect, option, value)),
    }
}

fn integer_option(effect: &str, option: &str, value: &EffectOption) -> PulseResult<i64> {
    match value {
        EffectOption::Integer(value) => Ok(*value),
        EffectOption::Number(value) if value.is_finite() && value.fract() == 0.0 => {
            Ok(*value as i64)
        }
        EffectOption::Number(value) => Err(option_value_error(effect, option, value)),
        EffectOption::Text(value) => Err(option_value_error(effect, option, value)),
    }
}

fn text_option(effect: &str, option: &str, value: &EffectOption) -> PulseResult<String> {
    match value {
        EffectOption::Text(value) => Ok(value.clone()),
        EffectOption::Number(value) => Err(option_value_error(effect, option, value)),
        EffectOption::Integer(value) => Err(option_value_error(effect, option, value)),
    }
}

fn bounded_number(
    effect: &str,
    option: &str,
    value: &EffectOption,
    min: f32,
    max: f32,
) -> PulseResult<f32> {
    let value = number_option(effect, option, value)?;
    if (min..=max).contains(&value) {
        Ok(value)
    } else {
        Err(option_value_error(effect, option, value))
    }
}

fn unsupported_option(effect: &str, key: &str) -> PulseResult<()> {
    Err(option_key_error(effect, key))
}

fn build_delay(options: EffectOptions) -> PulseResult<PulseDelay> {
    match options {
        EffectOptions::Default => Ok(PulseDelay::default()),
        EffectOptions::Preset(preset) => match normalize_name(&preset).as_str() {
            "eighthnote" => Ok(PulseDelay {
                time: 0.125,
                feedback: 0.35,
                mix: 0.3,
            }),
            "quarternote" => Ok(PulseDelay {
                time: 0.25,
                feedback: 0.4,
                mix: 0.35,
            }),
            "dottedeighth" => Ok(PulseDelay {
                time: 0.1875,
                feedback: 0.35,
                mix: 0.3,
            }),
            "halfnote" => Ok(PulseDelay {
                time: 0.5,
                feedback: 0.45,
                mix: 0.4,
            }),
            "slapback" => Ok(PulseDelay {
                time: 0.08,
                feedback: 0.0,
                mix: 0.3,
            }),
            "pingpong" => Ok(PulseDelay {
                time: 0.375,
                feedback: 0.5,
                mix: 0.4,
            }),
            "doubling" => Ok(PulseDelay {
                time: 0.03,
                feedback: 0.0,
                mix: 0.2,
            }),
            "ambient" => Ok(PulseDelay {
                time: 1.0,
                feedback: 0.6,
                mix: 0.5,
            }),
            _ => Err(invalid_preset("delay", &preset)),
        },
        EffectOptions::Params(params) => {
            let mut effect = PulseDelay::default();
            for (key, value) in params {
                match key.as_str() {
                    "time" => effect.time = bounded_number("delay", "time", &value, 0.001, 10.0)?,
                    "feedback" => {
                        effect.feedback = bounded_number("delay", "feedback", &value, 0.0, 0.99)?;
                    }
                    "mix" => effect.mix = bounded_number("delay", "mix", &value, 0.0, 1.0)?,
                    _ => unsupported_option("delay", &key)?,
                }
            }
            Ok(effect)
        }
    }
}

fn build_reverb(options: EffectOptions) -> PulseResult<PulseReverb> {
    match options {
        EffectOptions::Default => Ok(PulseReverb::default()),
        EffectOptions::Preset(preset) => match normalize_name(&preset).as_str() {
            "room" => Ok(PulseReverb {
                room_size: 0.3,
                damping: 0.7,
                mix: 0.2,
            }),
            "hall" => Ok(PulseReverb {
                room_size: 0.8,
                damping: 0.5,
                mix: 0.3,
            }),
            "plate" => Ok(PulseReverb {
                room_size: 0.5,
                damping: 0.3,
                mix: 0.25,
            }),
            "chamber" => Ok(PulseReverb {
                room_size: 0.6,
                damping: 0.6,
                mix: 0.25,
            }),
            "cathedral" => Ok(PulseReverb {
                room_size: 0.95,
                damping: 0.4,
                mix: 0.4,
            }),
            "ambient" => Ok(PulseReverb {
                room_size: 0.9,
                damping: 0.4,
                mix: 0.5,
            }),
            "subtle" => Ok(PulseReverb {
                room_size: 0.4,
                damping: 0.6,
                mix: 0.15,
            }),
            "spring" => Ok(PulseReverb {
                room_size: 0.4,
                damping: 0.8,
                mix: 0.3,
            }),
            _ => Err(invalid_preset("reverb", &preset)),
        },
        EffectOptions::Params(params) => {
            let mut effect = PulseReverb::default();
            for (key, value) in params {
                match key.as_str() {
                    "room_size" => {
                        effect.room_size = bounded_number("reverb", "room_size", &value, 0.0, 1.0)?;
                    }
                    "damping" => {
                        effect.damping = bounded_number("reverb", "damping", &value, 0.0, 1.0)?;
                    }
                    "mix" => effect.mix = bounded_number("reverb", "mix", &value, 0.0, 1.0)?,
                    _ => unsupported_option("reverb", &key)?,
                }
            }
            Ok(effect)
        }
    }
}

fn build_filter(options: EffectOptions) -> PulseResult<PulseFilter> {
    match options {
        EffectOptions::Default => Ok(PulseFilter::default()),
        EffectOptions::Preset(preset) => Err(invalid_preset("filter", &preset)),
        EffectOptions::Params(params) => {
            let mut effect = PulseFilter::default();
            for (key, value) in params {
                match key.as_str() {
                    "type" => {
                        let kind = text_option("filter", "type", &value)?;
                        effect.kind = match normalize_name(&kind).as_str() {
                            "lowpass" => PulseFilterKind::LowPass,
                            "highpass" => PulseFilterKind::HighPass,
                            "bandpass" => PulseFilterKind::BandPass,
                            "notch" => PulseFilterKind::Notch,
                            "allpass" => PulseFilterKind::AllPass,
                            "moog" => PulseFilterKind::Moog,
                            _ => return Err(option_value_error("filter", "type", kind)),
                        };
                    }
                    "cutoff" => {
                        effect.cutoff = bounded_number("filter", "cutoff", &value, 20.0, 20000.0)?;
                    }
                    "resonance" => {
                        effect.resonance =
                            bounded_number("filter", "resonance", &value, 0.0, 0.99)?;
                    }
                    "slope" => {
                        let slope = integer_option("filter", "slope", &value)?;
                        effect.slope = match slope {
                            12 => PulseFilterSlope::Pole12,
                            24 => PulseFilterSlope::Pole24,
                            _ => return Err(option_value_error("filter", "slope", slope)),
                        };
                    }
                    _ => unsupported_option("filter", &key)?,
                }
            }
            Ok(effect)
        }
    }
}

fn build_compressor(options: EffectOptions) -> PulseResult<PulseCompressor> {
    match options {
        EffectOptions::Default => Ok(PulseCompressor::default()),
        EffectOptions::Preset(preset) => match normalize_name(&preset).as_str() {
            "gentle" => Ok(PulseCompressor {
                threshold: 0.5,
                ratio: 2.0,
                attack: 0.01,
                release: 0.1,
                makeup_gain: 1.0,
            }),
            "drumbus" => Ok(PulseCompressor {
                threshold: 0.6,
                ratio: 4.0,
                attack: 0.01,
                release: 0.15,
                makeup_gain: 1.0,
            }),
            "bass" => Ok(PulseCompressor {
                threshold: 0.5,
                ratio: 6.0,
                attack: 0.02,
                release: 0.2,
                makeup_gain: 1.0,
            }),
            "master" => Ok(PulseCompressor {
                threshold: 0.6,
                ratio: 2.5,
                attack: 0.01,
                release: 0.1,
                makeup_gain: 1.0,
            }),
            "aggressive" => Ok(PulseCompressor {
                threshold: 0.3,
                ratio: 8.0,
                attack: 0.005,
                release: 0.08,
                makeup_gain: 1.0,
            }),
            _ => Err(invalid_preset("compressor", &preset)),
        },
        EffectOptions::Params(params) => {
            let mut effect = PulseCompressor::default();
            for (key, value) in params {
                match key.as_str() {
                    "threshold" => {
                        effect.threshold =
                            bounded_number("compressor", "threshold", &value, 0.0, 1.0)?;
                    }
                    "ratio" => {
                        effect.ratio = bounded_number("compressor", "ratio", &value, 1.0, 20.0)?;
                    }
                    "attack" => {
                        effect.attack = bounded_number("compressor", "attack", &value, 0.001, 1.0)?;
                    }
                    "release" => {
                        effect.release =
                            bounded_number("compressor", "release", &value, 0.001, 5.0)?;
                    }
                    "makeup_gain" => {
                        effect.makeup_gain =
                            bounded_number("compressor", "makeup_gain", &value, 0.1, 4.0)?;
                    }
                    _ => unsupported_option("compressor", &key)?,
                }
            }
            Ok(effect)
        }
    }
}

fn build_limiter(options: EffectOptions) -> PulseResult<PulseLimiter> {
    match options {
        EffectOptions::Default => Ok(PulseLimiter::default()),
        EffectOptions::Preset(preset) => match normalize_name(&preset).as_str() {
            "transparent" => Ok(PulseLimiter {
                threshold: -0.5,
                release: 0.1,
            }),
            "standard" => Ok(PulseLimiter {
                threshold: -0.3,
                release: 0.05,
            }),
            "brickwall" => Ok(PulseLimiter {
                threshold: -0.1,
                release: 0.005,
            }),
            "mastering" => Ok(PulseLimiter {
                threshold: -0.2,
                release: 0.08,
            }),
            "safety" => Ok(PulseLimiter {
                threshold: 0.0,
                release: 0.01,
            }),
            _ => Err(invalid_preset("limiter", &preset)),
        },
        EffectOptions::Params(params) => {
            let mut effect = PulseLimiter::default();
            for (key, value) in params {
                match key.as_str() {
                    "threshold" => {
                        effect.threshold =
                            bounded_number("limiter", "threshold", &value, -60.0, 0.0)?;
                    }
                    "release" => {
                        effect.release = bounded_number("limiter", "release", &value, 0.001, 5.0)?;
                    }
                    _ => unsupported_option("limiter", &key)?,
                }
            }
            Ok(effect)
        }
    }
}

fn build_chorus(options: EffectOptions) -> PulseResult<PulseChorus> {
    match options {
        EffectOptions::Default => Ok(PulseChorus::default()),
        EffectOptions::Preset(preset) => match normalize_name(&preset).as_str() {
            "subtle" => Ok(PulseChorus {
                rate: 0.5,
                depth: 3.0,
                mix: 0.3,
            }),
            "classic" => Ok(PulseChorus {
                rate: 1.5,
                depth: 5.0,
                mix: 0.5,
            }),
            "wide" => Ok(PulseChorus {
                rate: 0.8,
                depth: 8.0,
                mix: 0.6,
            }),
            "vibrato" => Ok(PulseChorus {
                rate: 5.0,
                depth: 3.0,
                mix: 1.0,
            }),
            "thick" => Ok(PulseChorus {
                rate: 2.0,
                depth: 7.0,
                mix: 0.7,
            }),
            _ => Err(invalid_preset("chorus", &preset)),
        },
        EffectOptions::Params(params) => {
            let mut effect = PulseChorus::default();
            for (key, value) in params {
                match key.as_str() {
                    "rate" => effect.rate = bounded_number("chorus", "rate", &value, 0.1, 10.0)?,
                    "depth" => {
                        effect.depth = bounded_number("chorus", "depth", &value, 0.5, 50.0)?;
                    }
                    "mix" => effect.mix = bounded_number("chorus", "mix", &value, 0.0, 1.0)?,
                    _ => unsupported_option("chorus", &key)?,
                }
            }
            Ok(effect)
        }
    }
}

fn build_phaser(options: EffectOptions) -> PulseResult<PulsePhaser> {
    match options {
        EffectOptions::Default => Ok(PulsePhaser::default()),
        EffectOptions::Preset(preset) => match normalize_name(&preset).as_str() {
            "slow" => Ok(PulsePhaser {
                rate: 0.3,
                depth: 0.7,
                feedback: 0.5,
                stages: 4,
                mix: 0.5,
            }),
            "classic" => Ok(PulsePhaser {
                rate: 0.5,
                depth: 0.8,
                feedback: 0.6,
                stages: 4,
                mix: 0.6,
            }),
            "fast" => Ok(PulsePhaser {
                rate: 2.0,
                depth: 0.9,
                feedback: 0.7,
                stages: 6,
                mix: 0.7,
            }),
            "subtle" => Ok(PulsePhaser {
                rate: 0.4,
                depth: 0.5,
                feedback: 0.3,
                stages: 4,
                mix: 0.4,
            }),
            "deep" => Ok(PulsePhaser {
                rate: 0.6,
                depth: 1.0,
                feedback: 0.8,
                stages: 8,
                mix: 0.8,
            }),
            _ => Err(invalid_preset("phaser", &preset)),
        },
        EffectOptions::Params(params) => {
            let mut effect = PulsePhaser::default();
            for (key, value) in params {
                match key.as_str() {
                    "rate" => effect.rate = bounded_number("phaser", "rate", &value, 0.1, 10.0)?,
                    "depth" => {
                        effect.depth = bounded_number("phaser", "depth", &value, 0.0, 1.0)?;
                    }
                    "feedback" => {
                        effect.feedback = bounded_number("phaser", "feedback", &value, 0.0, 0.95)?;
                    }
                    "mix" => effect.mix = bounded_number("phaser", "mix", &value, 0.0, 1.0)?,
                    "stages" => {
                        let stages = integer_option("phaser", "stages", &value)?;
                        effect.stages = match stages {
                            2 | 4 | 6 | 8 => stages as usize,
                            _ => return Err(option_value_error("phaser", "stages", stages)),
                        };
                    }
                    _ => unsupported_option("phaser", &key)?,
                }
            }
            Ok(effect)
        }
    }
}

fn build_eq(options: EffectOptions) -> PulseResult<PulseEq> {
    match options {
        EffectOptions::Default => Ok(PulseEq::default()),
        EffectOptions::Preset(preset) => match normalize_name(&preset).as_str() {
            "flat" => Ok(PulseEq::default()),
            "bassboost" => Ok(PulseEq {
                low_gain: 1.5,
                mid_gain: 1.0,
                high_gain: 1.0,
                low_freq: 100.0,
                high_freq: 3000.0,
            }),
            "bright" => Ok(PulseEq {
                low_gain: 0.8,
                mid_gain: 1.0,
                high_gain: 1.4,
                low_freq: 300.0,
                high_freq: 5000.0,
            }),
            "warm" => Ok(PulseEq {
                low_gain: 1.3,
                mid_gain: 1.0,
                high_gain: 0.9,
                low_freq: 150.0,
                high_freq: 3000.0,
            }),
            "phone" => Ok(PulseEq {
                low_gain: 0.2,
                mid_gain: 1.4,
                high_gain: 0.2,
                low_freq: 600.0,
                high_freq: 3000.0,
            }),
            _ => Err(invalid_preset("eq", &preset)),
        },
        EffectOptions::Params(params) => {
            let mut effect = PulseEq::default();
            for (key, value) in params {
                match key.as_str() {
                    "low_gain" => {
                        effect.low_gain = bounded_number("eq", "low_gain", &value, 0.0, 4.0)?;
                    }
                    "mid_gain" => {
                        effect.mid_gain = bounded_number("eq", "mid_gain", &value, 0.0, 4.0)?;
                    }
                    "high_gain" => {
                        effect.high_gain = bounded_number("eq", "high_gain", &value, 0.0, 4.0)?;
                    }
                    "low_freq" => {
                        effect.low_freq = bounded_number("eq", "low_freq", &value, 20.0, 20000.0)?;
                    }
                    "high_freq" => {
                        effect.high_freq =
                            bounded_number("eq", "high_freq", &value, 20.0, 20000.0)?;
                    }
                    _ => unsupported_option("eq", &key)?,
                }
            }
            if effect.high_freq <= effect.low_freq {
                return Err(option_value_error("eq", "high_freq", effect.high_freq));
            }
            Ok(effect)
        }
    }
}

impl PulseDelay {
    /// Converts this wrapper to the corresponding `tunes` delay.
    #[must_use]
    pub fn to_tunes(&self) -> Delay {
        Delay::new(self.time, self.feedback, self.mix)
    }
}

impl PulseReverb {
    /// Converts this wrapper to the corresponding `tunes` reverb.
    #[must_use]
    pub fn to_tunes(&self) -> Reverb {
        Reverb::new(self.room_size, self.damping, self.mix)
    }
}

impl PulseFilter {
    /// Converts this wrapper to the corresponding `tunes` filter.
    #[must_use]
    pub fn to_tunes(&self) -> Filter {
        let filter_type = match self.kind {
            PulseFilterKind::LowPass => FilterType::LowPass,
            PulseFilterKind::HighPass => FilterType::HighPass,
            PulseFilterKind::BandPass => FilterType::BandPass,
            PulseFilterKind::Notch => FilterType::Notch,
            PulseFilterKind::AllPass => FilterType::AllPass,
            PulseFilterKind::Moog => FilterType::Moog,
        };
        let slope = match self.slope {
            PulseFilterSlope::Pole12 => FilterSlope::Pole12dB,
            PulseFilterSlope::Pole24 => FilterSlope::Pole24dB,
        };
        Filter::with_slope(filter_type, self.cutoff, self.resonance, slope)
    }
}

impl PulseCompressor {
    /// Converts this wrapper to the corresponding `tunes` compressor.
    #[must_use]
    pub fn to_tunes(&self) -> Compressor {
        Compressor::new(
            self.threshold,
            self.ratio,
            self.attack,
            self.release,
            self.makeup_gain,
        )
    }
}

impl PulseLimiter {
    /// Converts this wrapper to the corresponding `tunes` limiter.
    #[must_use]
    pub fn to_tunes(&self) -> Limiter {
        Limiter::new(self.threshold, self.release)
    }
}

impl PulseChorus {
    /// Converts this wrapper to the corresponding `tunes` chorus.
    #[must_use]
    pub fn to_tunes(&self) -> Chorus {
        Chorus::new(self.rate, self.depth, self.mix)
    }
}

impl PulsePhaser {
    /// Converts this wrapper to the corresponding `tunes` phaser.
    #[must_use]
    pub fn to_tunes(&self) -> Phaser {
        Phaser::new(self.rate, self.depth, self.feedback, self.stages, self.mix)
    }
}

impl PulseEq {
    /// Converts this wrapper to the corresponding `tunes` EQ.
    #[must_use]
    pub fn to_tunes(&self) -> EQ {
        EQ::new(
            self.low_gain,
            self.mid_gain,
            self.high_gain,
            self.low_freq,
            self.high_freq,
        )
    }
}

impl PulseEffect {
    /// Returns the canonical effect name.
    #[must_use]
    pub fn name(&self) -> &'static str {
        match self {
            Self::Delay(_) => "delay",
            Self::Reverb(_) => "reverb",
            Self::Filter(_) => "filter",
            Self::Compressor(_) => "compressor",
            Self::Limiter(_) => "limiter",
            Self::Chorus(_) => "chorus",
            Self::Phaser(_) => "phaser",
            Self::Eq(_) => "eq",
        }
    }

    /// Returns whether this effect can be applied to the master bus.
    #[must_use]
    pub fn allowed_on_master(&self) -> bool {
        !matches!(self, Self::Filter(_))
    }

    /// Applies this effect to a `tunes` track builder.
    #[must_use]
    pub fn apply_to_track_builder<'a>(&self, builder: TrackBuilder<'a>) -> TrackBuilder<'a> {
        match self {
            Self::Delay(value) => builder.delay(value.to_tunes()),
            Self::Reverb(value) => builder.reverb(value.to_tunes()),
            Self::Filter(value) => builder.filter(value.to_tunes()),
            Self::Compressor(value) => builder.compressor(value.to_tunes()),
            Self::Limiter(value) => builder.limiter(value.to_tunes()),
            Self::Chorus(value) => builder.chorus(value.to_tunes()),
            Self::Phaser(value) => builder.phaser(value.to_tunes()),
            Self::Eq(value) => builder.eq(value.to_tunes()),
        }
    }

    /// Applies this effect directly to an existing `tunes` track.
    pub(crate) fn apply_to_track(&self, track: &mut Track) {
        match self {
            Self::Delay(value) => {
                track.effects = track.effects.clone().with_delay(value.to_tunes())
            }
            Self::Reverb(value) => {
                track.effects = track.effects.clone().with_reverb(value.to_tunes());
            }
            Self::Filter(value) => {
                track.filter = value.to_tunes();
            }
            Self::Compressor(value) => {
                track.effects = track.effects.clone().with_compressor(value.to_tunes());
            }
            Self::Limiter(value) => {
                track.effects = track.effects.clone().with_limiter(value.to_tunes());
            }
            Self::Chorus(value) => {
                track.effects = track.effects.clone().with_chorus(value.to_tunes());
            }
            Self::Phaser(value) => {
                track.effects = track.effects.clone().with_phaser(value.to_tunes());
            }
            Self::Eq(value) => {
                track.effects = track.effects.clone().with_eq(value.to_tunes());
            }
        }
    }

    /// Applies this effect to a `tunes` mixer master bus.
    ///
    /// # Errors
    ///
    /// Returns an invalid-scope error when called for a track-only effect.
    pub fn apply_to_master(&self, mixer: &mut Mixer) -> PulseResult<()> {
        match self {
            Self::Delay(value) => mixer.master_delay(value.to_tunes()),
            Self::Reverb(value) => mixer.master_reverb(value.to_tunes()),
            Self::Filter(_) => {
                return Err(PulseError::InvalidEffectScope {
                    effect: "filter".to_string(),
                    scope: "master".to_string(),
                });
            }
            Self::Compressor(value) => mixer.master_compressor(value.to_tunes()),
            Self::Limiter(value) => mixer.master_limiter(value.to_tunes()),
            Self::Chorus(value) => mixer.master_chorus(value.to_tunes()),
            Self::Phaser(value) => mixer.master_phaser(value.to_tunes()),
            Self::Eq(value) => mixer.master_eq(value.to_tunes()),
        }
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::collections::BTreeMap;

    fn params(entries: &[(&str, EffectOption)]) -> EffectOptions {
        let mut values = BTreeMap::new();
        for (key, value) in entries {
            values.insert((*key).to_string(), value.clone());
        }
        EffectOptions::Params(values)
    }

    #[test]
    fn effect_catalog_exposes_v1_effects() {
        let names = effect_names();

        assert_eq!(names.len(), 8);
        assert!(names.contains(&"delay"));
        assert!(names.contains(&"reverb"));
        assert!(names.contains(&"filter"));
        assert!(names.contains(&"compressor"));
        assert!(names.contains(&"limiter"));
        assert!(names.contains(&"chorus"));
        assert!(names.contains(&"phaser"));
        assert!(names.contains(&"eq"));

        let delay = effect_info("delay").expect("delay info should exist");
        assert_eq!(delay.category, "time");
        assert!(delay.scopes.contains(&"track"));
        assert!(delay.scopes.contains(&"master"));
        assert!(delay.parameters.contains(&"time"));
        assert!(delay.presets.contains(&"quarter_note"));

        let filter = effect_info("filter").expect("filter info should exist");
        assert_eq!(filter.scopes, &["track"]);
    }

    #[test]
    fn invalid_effect_name_reports_stable_error() {
        let error = effect_from_options("shimmer", EffectOptions::Default)
            .expect_err("unknown effect should fail");

        assert_eq!(error.to_string(), "invalid effect: shimmer");
    }

    #[test]
    fn delay_validates_params_and_presets() {
        let effect = effect_from_options(
            "delay",
            params(&[
                ("time", EffectOption::Number(0.25)),
                ("feedback", EffectOption::Number(0.35)),
                ("mix", EffectOption::Number(0.3)),
            ]),
        )
        .expect("valid delay should parse");

        let PulseEffect::Delay(delay) = effect else {
            panic!("expected delay");
        };
        assert_eq!(delay.time, 0.25);
        assert_eq!(delay.feedback, 0.35);
        assert_eq!(delay.mix, 0.3);

        let preset = effect_from_options("delay", EffectOptions::Preset("slapback".to_string()))
            .expect("delay preset should parse");
        assert!(matches!(preset, PulseEffect::Delay(_)));

        let invalid =
            effect_from_options("delay", params(&[("feedback", EffectOption::Number(1.2))]))
                .expect_err("feedback outside range should fail");
        assert_eq!(
            invalid.to_string(),
            "invalid effect option delay.feedback: 1.2"
        );
    }

    #[test]
    fn filter_validates_type_cutoff_resonance_and_scope() {
        let effect = effect_from_options(
            "filter",
            params(&[
                ("type", EffectOption::Text("low_pass".to_string())),
                ("cutoff", EffectOption::Number(1800.0)),
                ("resonance", EffectOption::Number(0.4)),
                ("slope", EffectOption::Integer(24)),
            ]),
        )
        .expect("valid filter should parse");

        let PulseEffect::Filter(filter) = effect else {
            panic!("expected filter");
        };
        assert_eq!(filter.kind, PulseFilterKind::LowPass);
        assert_eq!(filter.cutoff, 1800.0);
        assert_eq!(filter.resonance, 0.4);
        assert_eq!(filter.slope, PulseFilterSlope::Pole24);
        assert!(!PulseEffect::Filter(filter).allowed_on_master());

        let invalid = effect_from_options(
            "filter",
            params(&[("type", EffectOption::Text("comb".to_string()))]),
        )
        .expect_err("unknown filter type should fail");
        assert_eq!(
            invalid.to_string(),
            "invalid effect option filter.type: comb"
        );
    }

    #[test]
    fn eq_rejects_invalid_frequency_order() {
        let invalid = effect_from_options(
            "eq",
            params(&[
                ("low_freq", EffectOption::Number(5000.0)),
                ("high_freq", EffectOption::Number(200.0)),
            ]),
        )
        .expect_err("high frequency must be above low frequency");

        assert_eq!(
            invalid.to_string(),
            "invalid effect option eq.high_freq: 200"
        );
    }

    #[test]
    fn all_default_effects_convert_to_tunes_types() {
        let effects = [
            effect_from_options("delay", EffectOptions::Default).unwrap(),
            effect_from_options("reverb", EffectOptions::Default).unwrap(),
            effect_from_options("filter", EffectOptions::Default).unwrap(),
            effect_from_options("compressor", EffectOptions::Default).unwrap(),
            effect_from_options("limiter", EffectOptions::Default).unwrap(),
            effect_from_options("chorus", EffectOptions::Default).unwrap(),
            effect_from_options("phaser", EffectOptions::Default).unwrap(),
            effect_from_options("eq", EffectOptions::Default).unwrap(),
        ];

        for effect in effects {
            match effect {
                PulseEffect::Delay(value) => {
                    let _ = value.to_tunes();
                }
                PulseEffect::Reverb(value) => {
                    let _ = value.to_tunes();
                }
                PulseEffect::Filter(value) => {
                    let _ = value.to_tunes();
                }
                PulseEffect::Compressor(value) => {
                    let _ = value.to_tunes();
                }
                PulseEffect::Limiter(value) => {
                    let _ = value.to_tunes();
                }
                PulseEffect::Chorus(value) => {
                    let _ = value.to_tunes();
                }
                PulseEffect::Phaser(value) => {
                    let _ = value.to_tunes();
                }
                PulseEffect::Eq(value) => {
                    let _ = value.to_tunes();
                }
            }
        }
    }
}