function! SpaceVim#api#iconv#codecs#utf16#import() abort

  return s:utf16
endfunction

let s:base = SpaceVim#api#iconv#codecs#base#import()

let s:utf16 = {}

let s:utf16.Codec = {}
call extend(s:utf16.Codec, s:base.Codec)
let s:utf16.Codec.encoding = "UTF-16"
let s:utf16.Codec.istate = 0
let s:utf16.Codec.ostate = 0

function! s:utf16.Codec.mbtowc(input, start)
  if a:start + 1 >= len(a:input)
    return self.error('UnicodeDecodeError', 'incomplete', a:input, a:start, len(a:input) - 1)
  endif
  let wc = (self.istate
        \ ? a:input[a:start + 0] + (a:input[a:start + 1] * 0x100)
        \ : (a:input[a:start + 0] * 0x100) + a:input[a:start + 1])
  if wc == 0xfeff
    return [[], a:start + 2]
  elseif wc == 0xfffe
    let self.istate = !self.istate
    return [[], a:start + 2]
  elseif wc >= 0xd800 && wc < 0xdc00
    if a:start + 3 >= len(a:input)
      return self.error('UnicodeDecodeError', 'incomplete', a:input, a:start, len(a:input) - 1)
    endif
    let wc2 = (self.istate
          \ ? a:input[a:start + 2] + (a:input[a:start + 3] * 0x100)
          \ : (a:input[a:start + 2] * 0x100) + a:input[a:start + 3])
    if !(wc2 >= 0xdc00 && wc2 < 0xe000)
      return self.error('UnicodeDecodeError', 'invalid', a:input, a:start, a:start + 3)
    endif
    let pwc = 0x10000 + ((wc - 0xd800) * 0x400) + (wc2 - 0xdc00)
    return [[pwc], a:start + 4]
  elseif wc >= 0xdc00 && wc < 0xe000
    return self.error('UnicodeDecodeError', 'invalid', a:input, a:start, a:start + 1)
  else
    return [[wc], a:start + 2]
  endif
endfunction

function! s:utf16.Codec.wctomb(input, start)
  let res = []
  let wc = a:input[a:start]
  if wc != 0xfffe && !(wc >= 0xd800 && wc < 0xe000)
    if !self.ostate
      call add(res, 0xFE)
      call add(res, 0xFF)
    endif
    if wc < 0x10000
      call add(res, wc / 0x100)
      call add(res, wc % 0x100)
      let self.ostate = 1
      return [res, a:start + 1]
    elseif wc < 0x110000
      let wc1 = 0xd800 + ((wc - 0x10000) / 0x400)
      let wc2 = 0xdc00 + ((wc - 0x10000) % 0x400)
      call add(res, wc1 / 0x100)
      call add(res, wc1 % 0x100)
      call add(res, wc2 / 0x100)
      call add(res, wc2 % 0x100)
      let self.ostate = 1
      return [res, a:start + 1]
    endif
  endif
  return self.error('UnicodeEncodeError', 'invalid', a:input, a:start, a:start)
endfunction