//! Sound representation.

use crate::durandal::err::*;
use std::io;

pub fn write_wav(out: &mut impl io::Write, snd: &impl Sound) -> ResultS<()>
{
   let rate     = u32::from(snd.rate());
   let bps      = rate * 2;
   let dat_size = snd.len() as u32 * 2;
   let hdr_size = 36 + dat_size;

   out.write_all(b"RIFF")?;
   out.write_all(&u32::to_le_bytes(hdr_size))?;
   out.write_all(b"WAVE")?;
   out.write_all(b"fmt ")?;
   out.write_all(&u32::to_le_bytes(16))?;
   out.write_all(&u16::to_le_bytes(1))?; // PCM
   out.write_all(&u16::to_le_bytes(1))?; // mono
   out.write_all(&u32::to_le_bytes(rate))?;
   out.write_all(&u32::to_le_bytes(bps))?;
   out.write_all(&u16::to_le_bytes(2))?; // block alignment
   out.write_all(&u16::to_le_bytes(16))?; // bits per sample
   out.write_all(b"data")?;
   out.write_all(&u32::to_le_bytes(dat_size))?;

   for p in 0..snd.len() {
      let sample = snd.index(p);
      out.write_all(&sample.to_le_bytes())?;
   }

   Ok(())
}

pub trait Sound
{
   fn rate(&self) -> u16;
   fn len(&self) -> usize;
   fn index(&self, p: usize) -> i16;
   fn lp_beg(&self) -> usize;
   fn lp_end(&self) -> usize;

   fn is_empty(&self) -> bool {self.len() == 0}

   fn get(&self, p: usize) -> Option<i16>
   {
      if p < self.len() {
         Some(self.index(p))
      } else {
         None
      }
   }
}

impl Sound16
{
   /// Creates a new `Sound16`.
   pub fn new(rate: u16, lp_beg: usize, lp_end: usize, len: usize) -> Self
   {
      Self{rate, lp_beg, lp_end, data: Vec::with_capacity(len)}
   }

   /// Creates a new `Sound16` from an unsigned 8-bit stream.
   pub fn new_from_8(rate: u16, lp_beg: usize, lp_end: usize, b: &[u8])
                     -> Self
   {
      let mut snd = Self::new(rate, lp_beg, lp_end, b.len());

      for &sample in b {
         snd.data.push(Self::sample_from_8(sample));
      }

      snd
   }

   /// Creates a new `Sound16` from a signed 16-bit stream.
   pub fn new_from_16(rate: u16, lp_beg: usize, lp_end: usize, b: &[u8])
                      -> Self
   {
      let mut snd = Self::new(rate, lp_beg, lp_end, b.len() / 2);

      for i in (0..b.len()).step_by(2) {
         snd.data.push(i16::from_le_bytes([b[i], b[i + 1]]));
      }

      snd
   }

   /// Creates a signed 16-bit sample from an unsigned 8-bit sample.
   pub fn sample_from_8(sample: u8) -> i16 {(i16::from(sample) - 0x80) << 8}
}

impl Sound for Sound16
{
   fn rate(&self) -> u16 {self.rate}
   fn len(&self) -> usize {self.data.len()}
   fn index(&self, p: usize) -> i16 {self.data[p]}
   fn lp_beg(&self) -> usize {self.lp_beg}
   fn lp_end(&self) -> usize {self.lp_end}
}

pub struct Sound16
{
   rate:     u16,
   lp_beg:   usize,
   lp_end:   usize,
   pub data: Vec<i16>,
}

// EOF