#[cfg(all(feature = "music", not(feature = "32k")))]
use sdl2::audio::AudioCallback;

#[cfg(all(feature = "music", not(feature = "32k")))]
use crate::vendored::micromod::MmC2r;

#[cfg(all(feature = "music", not(feature = "32k")))]
pub struct Music {
  pub pcm: Vec<i16>,
  pub offset: usize,
}

#[cfg(all(feature = "music", not(feature = "32k")))]
impl AudioCallback for Music {
  type Channel = f32;

  fn callback(&mut self, out_f: &mut [f32]) {
    let len = out_f.len();
    let slice = &self.pcm[self.offset..(self.offset + len).min(self.pcm.len() - 1)];
    let len = slice.len();
    pcm_to_f32pcm(&slice, out_f, len);
    self.offset += len;
    if self.offset > self.pcm.len() {
      self.offset = 0;
    }
  }
}

#[cfg(all(feature = "music", not(feature = "32k")))]
pub fn mmc2r_to_pcm(state: &mut MmC2r) -> Vec<i16> {
  let mut destination = Vec::<i16>::new();
  loop {
    let mut out = [0; 4096];
    if !state.get_audio(&mut out, 2048) {
      break;
    }
    for sample in out {
      destination.push(sample);
    }
  }
  // #[cfg(not(feature = "stereo"))]
  // let destination = {
  //   let stereo = destination;
  //   let mut mono = Vec::<i16>::new();
  //   let mut is_first_stereo_pair = true;
  //   let mut stereo_pair_val = 0 as i16;
  //   for sample in stereo {
  //     if is_first_stereo_pair {
  //       stereo_pair_val = sample;
  //     } else {
  //       mono.push(((sample as i32 + stereo_pair_val as i32) / 2) as i16);
  //     }
  //     is_first_stereo_pair = !is_first_stereo_pair;
  //   }
  //   mono
  // };
  destination
}

#[cfg(all(feature = "music", not(feature = "32k")))]
pub fn pcm_to_f32pcm(input: &[i16], output: &mut [f32], len: usize) {
  for i in 0..len {
    output[i] = f32::from(input[i]) / f32::from(0x7FFF as i16);
  }
}