use nix::sys::uio::*;
use nix::unistd::*;
use rand::{thread_rng, Rng};
use std::{cmp, iter};

#[test]
fn test_writev() {
    let mut to_write = Vec::with_capacity(16 * 128);
    for _ in 0..16 {
        let s: String = thread_rng().gen_ascii_chars().take(128).collect();
        let b = s.as_bytes();
        to_write.extend(b.iter().map(|x| x.clone()));
    }
    // Allocate and fill iovecs
    let mut iovecs = Vec::new();
    let mut consumed = 0;
    while consumed < to_write.len() {
        let left = to_write.len() - consumed;
        let slice_len = if left < 64 { left } else { thread_rng().gen_range(64, cmp::min(256, left)) };
        let b = &to_write[consumed..consumed+slice_len];
        iovecs.push(IoVec::from_slice(b));
        consumed += slice_len;
    }
    let pipe_res = pipe();
    assert!(pipe_res.is_ok());
    let (reader, writer) = pipe_res.ok().unwrap();
    // FileDesc will close its filedesc (reader).
    let mut read_buf: Vec<u8> = iter::repeat(0u8).take(128 * 16).collect();
    // Blocking io, should write all data.
    let write_res = writev(writer, &iovecs);
    // Successful write
    assert!(write_res.is_ok());
    let written = write_res.ok().unwrap();
    // Check whether we written all data
    assert_eq!(to_write.len(), written);
    let read_res = read(reader, read_buf.as_mut_slice());
    // Successful read
    assert!(read_res.is_ok());
    let read = read_res.ok().unwrap() as usize;
    // Check we have read as much as we written
    assert_eq!(read, written);
    // Check equality of written and read data
    assert_eq!(&to_write, &read_buf);
    let close_res = close(writer);
    assert!(close_res.is_ok());
    let close_res = close(reader);
    assert!(close_res.is_ok());
}

#[test]
fn test_readv() {
    let s:String = thread_rng().gen_ascii_chars().take(128).collect();
    let to_write = s.as_bytes().to_vec();
    let mut storage = Vec::new();
    let mut allocated = 0;
    while allocated < to_write.len() {
        let left = to_write.len() - allocated;
        let vec_len = if left < 64 { left } else { thread_rng().gen_range(64, cmp::min(256, left)) };
        let v: Vec<u8> = iter::repeat(0u8).take(vec_len).collect();
        storage.push(v);
        allocated += vec_len;
    }
    let mut iovecs = Vec::with_capacity(storage.len());
    for v in storage.iter_mut() {
        iovecs.push(IoVec::from_mut_slice(v.as_mut_slice()));
    }
    let pipe_res = pipe();
    assert!(pipe_res.is_ok());
    let (reader, writer) = pipe_res.ok().unwrap();
    // Blocking io, should write all data.
    let write_res = write(writer, &to_write);
    // Successful write
    assert!(write_res.is_ok());
    let read_res = readv(reader, iovecs.as_mut_slice());
    assert!(read_res.is_ok());
    let read = read_res.ok().unwrap();
    // Check whether we've read all data
    assert_eq!(to_write.len(), read);
    // Cccumulate data from iovecs
    let mut read_buf = Vec::with_capacity(to_write.len());
    for iovec in iovecs.iter() {
        read_buf.extend(iovec.as_slice().iter().map(|x| x.clone()));
    }
    // Check whether iovecs contain all written data
    assert_eq!(read_buf.len(), to_write.len());
    // Check equality of written and read data
    assert_eq!(&read_buf, &to_write);
    let close_res = close(reader);
    assert!(close_res.is_ok());
    let close_res = close(writer);
    assert!(close_res.is_ok());
}