#![feature(libc)]
extern crate libc;

#[link(name = "m")]
extern {
    fn cos(d: f64) -> f64;
}

#[repr(C)]
struct png_image {
    opaque: *mut libc::c_void,
    version: libc::uint32_t,
    width: libc::uint32_t,
    height: libc::uint32_t,
    format: libc::uint32_t,
    flags: libc::uint32_t,
    colormap_entries: libc::uint32_t,
    warning_or_error:  libc::uint32_t,
    message: [u8; 64],
}

impl png_image {
    fn new() -> png_image {
        let mut img: png_image = unsafe { std::mem::zeroed() };
        img.version = 1;
        return img
    }
}

impl std::fmt::Display for png_image {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        fn get_message(msg: [u8; 64]) -> String {
            let mut vec = Vec::new();
            for i in 0..64 {
                vec.push(msg[i]);
            }
            String::from_utf8(vec).unwrap()
        }

        write!(f, "{}x{} {} {} {} {} {} {}", self.width, self.height, self.version,
               self.format, self.flags, self.colormap_entries, self.warning_or_error,
               get_message(self.message))
    }
}

#[link(name = "png")]
extern {
    fn png_image_begin_read_from_file(img: *mut png_image, file_name: *const u8) -> libc::c_int;
}

fn main() {
    let x = unsafe { cos(3.1415) };
    println!("cos(3.1415) = {}", x);

    unsafe {
        let mut img = png_image::new();
        println!("{}", img);
        let res = png_image_begin_read_from_file(&mut img, "mei.png\0".as_ptr());
        println!("read_from_file: {}", res);
        println!("{}", img);
    }
}