#![cfg(windows)]

extern crate lpwstr;
extern crate winapi;

use std::ffi::OsString;
use std::mem;
use std::ptr;
use lpwstr::FromWide;

use winapi::shared::winerror::ERROR_BUFFER_OVERFLOW;
use winapi::um::errhandlingapi::GetLastError;
use winapi::um::winbase::GetComputerNameW;

fn main() {
    let computer_name;

    unsafe {
        // Find the needed size
        let mut chars_needed = 0;
        assert_eq!(GetComputerNameW(ptr::null_mut(), &mut chars_needed), 0);
        assert_eq!(GetLastError(), ERROR_BUFFER_OVERFLOW);

        // Allocate and get the name
        let mut buffer = vec![mem::uninitialized(); chars_needed as usize];
        assert_ne!(GetComputerNameW(buffer.as_mut_ptr(), &mut chars_needed), 0);
        // chars_needed is now the character count not including the null terminator

        assert_eq!(buffer[buffer.len()-1], 0);
        computer_name = OsString::from_wide_ptr_null(buffer.as_ptr());
        assert_eq!(computer_name.len(), chars_needed as usize);
    }

    println!("{}", computer_name.to_string_lossy());
}