midix_synth 0.0.4

use std::io::Read;

use crate::prelude::*;

pub(crate) struct ZoneInfo {
    pub(crate) generator_index: i32,
    pub(crate) modulator_index: i32,
    pub(crate) generator_count: i32,
    pub(crate) modulator_count: i32,
}

impl ZoneInfo {
    fn new<R: Read + ?Sized>(reader: &mut R) -> Result<Self, SoundFontError> {
        let generator_index = BinaryReader::read_u16(reader)? as i32;
        let modulator_index = BinaryReader::read_u16(reader)? as i32;

        Ok(Self {
            generator_index,
            modulator_index,
            generator_count: 0,
            modulator_count: 0,
        })
    }

    pub(crate) fn read_from_chunk<R: Read + ?Sized>(
        reader: &mut R,
        size: usize,
    ) -> Result<Vec<ZoneInfo>, SoundFontError> {
        if size % 4 != 0 {
            return Err(SoundFontError::InvalidZoneList);
        }

        let count = size / 4;

        let mut zones: Vec<ZoneInfo> = Vec::new();
        for _i in 0..count {
            zones.push(ZoneInfo::new(reader)?);
        }

        for i in 0..(count - 1) {
            zones[i].generator_count = zones[i + 1].generator_index - zones[i].generator_index;
            zones[i].modulator_count = zones[i + 1].modulator_index - zones[i].modulator_index;
        }

        Ok(zones)
    }
}