//! Binary data conversion utilities.

use crate::durandal::err::*;

pub type Ident = [u8; 4];

pub trait BinUtil
{
   // Checked
   fn c_iden(&self, i: usize) -> ResultS<Ident>;
   fn c_u32b(&self, i: usize) -> ResultS<u32>;
   fn c_u16b(&self, i: usize) -> ResultS<u16>;

   fn c_i32b(&self, i: usize) -> ResultS<i32>
   {
      match self.c_u32b(i) {
         Ok(n) => Ok(n as i32),
         Err(e) => Err(e),
      }
   }
   fn c_i16b(&self, i: usize) -> ResultS<i16>
   {
      match self.c_u16b(i) {
         Ok(n) => Ok(n as i16),
         Err(e) => Err(e),
      }
   }

   // Optional
   fn o_iden(&self, i: usize) -> Option<Ident>
   {
      self.c_iden(i).ok()
   }
   fn o_u32b(&self, i: usize) -> Option<u32>
   {
      self.c_u32b(i).ok()
   }
   fn o_u16b(&self, i: usize) -> Option<u16>
   {
      self.c_u16b(i).ok()
   }
   fn o_i32b(&self, i: usize) -> Option<i32>
   {
      self.c_i32b(i).ok()
   }
   fn o_i16b(&self, i: usize) -> Option<i16>
   {
      self.c_i16b(i).ok()
   }

   // Unchecked
   fn b_iden(&self, i: usize) -> Ident
   {
      self.c_iden(i).unwrap()
   }
   fn b_u32b(&self, i: usize) -> u32
   {
      self.c_u32b(i).unwrap()
   }
   fn b_u16b(&self, i: usize) -> u16
   {
      self.c_u16b(i).unwrap()
   }
   fn b_i32b(&self, i: usize) -> i32
   {
      self.c_i32b(i).unwrap()
   }
   fn b_i16b(&self, i: usize) -> i16
   {
      self.c_i16b(i).unwrap()
   }
}

impl BinUtil for [u8]
{
   fn c_iden(&self, i: usize) -> ResultS<Ident>
   {
      if i + 3 < self.len() {
         Ok([self[i], self[i + 1], self[i + 2], self[i + 3]])
      } else {
         Err(err_msg("not enough data"))
      }
   }

   fn c_u32b(&self, i: usize) -> ResultS<u32>
   {
      if i + 3 < self.len() {
         Ok(u32::from_be_bytes([self[i],
                                self[i + 1],
                                self[i + 2],
                                self[i + 3]]))
      } else {
         Err(err_msg("not enough data"))
      }
   }

   fn c_u16b(&self, i: usize) -> ResultS<u16>
   {
      if i + 1 < self.len() {
         Ok(u16::from_be_bytes([self[i], self[i + 1]]))
      } else {
         Err(err_msg("not enough data"))
      }
   }
}

pub fn d_u32b(n: u32) -> [u8; 4]
{
   n.to_be_bytes()
}
pub fn d_u16b(n: u16) -> [u8; 2]
{
   n.to_be_bytes()
}
pub fn d_i32b(n: i32) -> [u8; 4]
{
   d_u32b(n as u32)
}
pub fn d_i16b(n: i16) -> [u8; 2]
{
   d_u16b(n as u16)
}

// EOF