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// The following was originally taken and adapated from exa source
// repo: https://github.com/ogham/exa
// commit: b9eb364823d0d4f9085eb220233c704a13d0f611
// license: MIT - Copyright (c) 2014 Benjamin Sago

//! System calls for getting the terminal size.
//!
//! Getting the terminal size is performed using an ioctl command that takes
//! the file handle to the terminal -- which in this case, is stdout -- and
//! populates a structure containing the values.
//!
//! The size is needed when the user wants the output formatted into columns:
//! the default grid view, or the hybrid grid-details view.

#[cfg(not(target_os = "windows"))]
extern crate libc;
#[cfg(target_os = "windows")]
extern crate kernel32;
#[cfg(target_os = "windows")]
extern crate winapi;

#[cfg(target_os = "windows")]
use kernel32::{GetConsoleScreenBufferInfo, GetStdHandle};
#[cfg(target_os = "windows")]
use winapi::{CONSOLE_SCREEN_BUFFER_INFO, COORD, SMALL_RECT, STD_OUTPUT_HANDLE};

#[cfg(not(target_os = "windows"))]
use std::mem::zeroed;
#[cfg(not(target_os = "windows"))]
use libc::{STDOUT_FILENO, c_int, c_ulong, winsize};

// Unfortunately the actual command is not standardised...
#[cfg(any(target_os = "linux", target_os = "android"))]
static TIOCGWINSZ: c_ulong = 0x5413;

#[cfg(any(target_os = "macos",
          target_os = "ios",
          target_os = "bitrig",
          target_os = "dragonfly",
          target_os = "freebsd",
          target_os = "netbsd",
          target_os = "openbsd"))]
static TIOCGWINSZ: c_ulong = 0x40087468;

#[cfg(target_os = "solaris")]
static TIOCGWINSZ: c_ulong = 0x5468;

extern "C" {
#[cfg(not(target_os = "windows"))]
    pub fn ioctl(fd: c_int, request: c_ulong, ...) -> c_int;
}

/// Runs the ioctl command. Returns (0, 0) if output is not to a terminal, or
/// there is an error. (0, 0) is an invalid size to have anyway, which is why
/// it can be used as a nil value.
#[cfg(not(target_os = "windows"))]
unsafe fn get_dimensions() -> winsize {
    let mut window: winsize = zeroed();
    let result = ioctl(STDOUT_FILENO, TIOCGWINSZ, &mut window);

    if result == -1 {
        zeroed()
    } else {
        window
    }
}

/// Query the current processes's output, returning its width and height as a
/// number of characters. Returns `None` if the output isn't to a terminal.
#[cfg(not(target_os = "windows"))]
pub fn dimensions() -> Option<(usize, usize)> {
    let w = unsafe { get_dimensions() };

    if w.ws_col == 0 || w.ws_row == 0 {
        None
    } else {
        Some((w.ws_col as usize, w.ws_row as usize))
    }
}

#[cfg(target_os = "windows")]
pub fn dimensions() -> Option<(usize, usize)> {
        let null_coord = COORD{
            X: 0,
            Y: 0,
        };
        let null_smallrect = SMALL_RECT{
            Left: 0,
            Top: 0,
            Right: 0,
            Bottom: 0,
        };

        let stdout_h = unsafe { GetStdHandle(STD_OUTPUT_HANDLE) };
        let mut console_data = CONSOLE_SCREEN_BUFFER_INFO{
            dwSize: null_coord,
            dwCursorPosition: null_coord,
            wAttributes: 0,
            srWindow: null_smallrect,
            dwMaximumWindowSize: null_coord,
        };

        if unsafe { GetConsoleScreenBufferInfo(stdout_h, &mut console_data) } != 0 {
            Some(((console_data.srWindow.Right - console_data.srWindow.Left) as usize, (console_data.srWindow.Bottom - console_data.srWindow.Top) as usize))
        } else {
            None
        }
}