use {Event, BuilderAttribs, MouseCursor};
use CreationError;
use CreationError::OsError;
use libc;
use std::{mem, ptr};
use std::cell::Cell;
use std::sync::atomic::AtomicBool;
use std::collections::VecDeque;
use super::ffi;
use std::sync::{Arc, Mutex, Once, ONCE_INIT};

use Api;
use CursorState;
use GlRequest;
use PixelFormat;

pub use self::monitor::{MonitorID, get_available_monitors, get_primary_monitor};

mod events;
mod monitor;

static THREAD_INIT: Once = ONCE_INIT;

// XOpenIM doesn't seem to be thread-safe
lazy_static! {      // TODO: use a static mutex when that's possible, and put me back in my function
    static ref GLOBAL_XOPENIM_LOCK: Mutex<()> = Mutex::new(());
}

fn x_error_callback(_: *mut ffi::Display, event: *mut ffi::XErrorEvent) -> libc::c_int {
    unsafe {
        println!("[glutin] x error code={} major={} minor={}!", (*event).error_code, (*event).request_code, (*event).minor_code);
    }
    0
}

fn ensure_thread_init() {
    THREAD_INIT.call_once(|| {
        unsafe {
            ffi::XInitThreads();
            ffi::XSetErrorHandler(x_error_callback);
        }
    });
}

fn with_c_str<F, T>(s: &str, f: F) -> T where F: FnOnce(*const libc::c_char) -> T {
    use std::ffi::CString;
    let c_str = CString::new(s.as_bytes().to_vec()).unwrap();
    f(c_str.as_ptr())
}

struct XWindow {
    display: *mut ffi::Display,
    window: ffi::Window,
    context: ffi::GLXContext,
    is_fullscreen: bool,
    screen_id: libc::c_int,
    xf86_desk_mode: *mut ffi::XF86VidModeModeInfo,
    ic: ffi::XIC,
    im: ffi::XIM,
}

unsafe impl Send for XWindow {}
unsafe impl Sync for XWindow {}

unsafe impl Send for Window {}
unsafe impl Sync for Window {}

impl Drop for XWindow {
    fn drop(&mut self) {
        unsafe {
            // we don't call MakeCurrent(0, 0) because we are not sure that the context
            // is still the current one
            ffi::glx::DestroyContext(self.display, self.context);

            if self.is_fullscreen {
                ffi::XF86VidModeSwitchToMode(self.display, self.screen_id, self.xf86_desk_mode);
                ffi::XF86VidModeSetViewPort(self.display, self.screen_id, 0, 0);
            }

            ffi::XDestroyIC(self.ic);
            ffi::XCloseIM(self.im);
            ffi::XDestroyWindow(self.display, self.window);
            ffi::XCloseDisplay(self.display);
        }
    }
}

#[derive(Clone)]
pub struct WindowProxy {
    x: Arc<XWindow>,
}

impl WindowProxy {
    pub fn wakeup_event_loop(&self) {
        let mut xev = ffi::XClientMessageEvent {
            type_: ffi::ClientMessage,
            window: self.x.window,
            format: 32,
            message_type: 0,
            serial: 0,
            send_event: 0,
            display: self.x.display,
            l: [0, 0, 0, 0, 0],
        };

        unsafe {
            ffi::XSendEvent(self.x.display, self.x.window, 0, 0, mem::transmute(&mut xev));
            ffi::XFlush(self.x.display);
        }
    }
}

pub struct PollEventsIterator<'a> {
    window: &'a Window,
}

impl<'a> Iterator for PollEventsIterator<'a> {
    type Item = Event;

    fn next(&mut self) -> Option<Event> {
        if let Some(ev) = self.window.pending_events.lock().unwrap().pop_front() {
            return Some(ev);
        }

        loop {
            let mut xev = unsafe { mem::uninitialized() };
            let res = unsafe { ffi::XCheckMaskEvent(self.window.x.display, -1, &mut xev) };
    
            if res == 0 {
                let res = unsafe { ffi::XCheckTypedEvent(self.window.x.display, ffi::ClientMessage, &mut xev) };
    
                if res == 0 {
                    return None;
                }
            }
    
            match xev.type_ {
                ffi::KeymapNotify => {
                    unsafe { ffi::XRefreshKeyboardMapping(&xev) }
                },
    
                ffi::ClientMessage => {
                    use events::Event::{Closed, Awakened};
                    use std::sync::atomic::Ordering::Relaxed;
    
                    let client_msg: &ffi::XClientMessageEvent = unsafe { mem::transmute(&xev) };
    
                    if client_msg.l[0] == self.window.wm_delete_window as libc::c_long {
                        self.window.is_closed.store(true, Relaxed);
                        return Some(Closed);
                    } else {
                        return Some(Awakened);
                    }
                },
    
                ffi::ConfigureNotify => {
                    use events::Event::Resized;
                    let cfg_event: &ffi::XConfigureEvent = unsafe { mem::transmute(&xev) };
                    let (current_width, current_height) = self.window.current_size.get();
                    if current_width != cfg_event.width || current_height != cfg_event.height {
                        self.window.current_size.set((cfg_event.width, cfg_event.height));
                        return Some(Resized(cfg_event.width as u32, cfg_event.height as u32));
                    }
                },
    
                ffi::MotionNotify => {
                    use events::Event::MouseMoved;
                    let event: &ffi::XMotionEvent = unsafe { mem::transmute(&xev) };
                    return Some(MouseMoved((event.x as i32, event.y as i32)));
                },
    
                ffi::KeyPress | ffi::KeyRelease => {
                    use events::Event::{KeyboardInput, ReceivedCharacter};
                    use events::ElementState::{Pressed, Released};
                    let event: &mut ffi::XKeyEvent = unsafe { mem::transmute(&xev) };
    
                    if event.type_ == ffi::KeyPress {
                        let raw_ev: *mut ffi::XKeyEvent = event;
                        unsafe { ffi::XFilterEvent(mem::transmute(raw_ev), self.window.x.window) };
                    }
    
                    let state = if xev.type_ == ffi::KeyPress { Pressed } else { Released };
    
                    let written = unsafe {
                        use std::str;
    
                        let mut buffer: [u8; 16] = [mem::uninitialized(); 16];
                        let raw_ev: *mut ffi::XKeyEvent = event;
                        let count = ffi::Xutf8LookupString(self.window.x.ic, mem::transmute(raw_ev),
                            mem::transmute(buffer.as_mut_ptr()),
                            buffer.len() as libc::c_int, ptr::null_mut(), ptr::null_mut());
    
                        str::from_utf8(&buffer[..count as usize]).unwrap_or("").to_string()
                    };
    
                    {
                        let mut pending = self.window.pending_events.lock().unwrap();
                        for chr in written.chars() {
                            pending.push_back(ReceivedCharacter(chr));
                        }
                    }
    
                    let keysym = unsafe {
                        ffi::XKeycodeToKeysym(self.window.x.display, event.keycode as ffi::KeyCode, 0)
                    };
    
                    let vkey =  events::keycode_to_element(keysym as libc::c_uint);
    
                    return Some(KeyboardInput(state, event.keycode as u8, vkey));
                },
    
                ffi::ButtonPress | ffi::ButtonRelease => {
                    use events::Event::{MouseInput, MouseWheel};
                    use events::ElementState::{Pressed, Released};
                    use events::MouseButton::{Left, Right, Middle};
    
                    let event: &ffi::XButtonEvent = unsafe { mem::transmute(&xev) };
    
                    let state = if xev.type_ == ffi::ButtonPress { Pressed } else { Released };
    
                    let button = match event.button {
                        ffi::Button1 => Some(Left),
                        ffi::Button2 => Some(Middle),
                        ffi::Button3 => Some(Right),
                        ffi::Button4 => {
                            self.window.pending_events.lock().unwrap().push_back(MouseWheel(1));
                            None
                        }
                        ffi::Button5 => {
                            self.window.pending_events.lock().unwrap().push_back(MouseWheel(-1));
                            None
                        }
                        _ => None
                    };
    
                    match button {
                        Some(button) =>
                            return Some(MouseInput(state, button)),
                        None => ()
                    };
                },
    
                _ => ()
            };
        }
    }
}

pub struct WaitEventsIterator<'a> {
    window: &'a Window,
}

impl<'a> Iterator for WaitEventsIterator<'a> {
    type Item = Event;

    fn next(&mut self) -> Option<Event> {
        use std::mem;

        while !self.window.is_closed() {
            if let Some(ev) = self.window.pending_events.lock().unwrap().pop_front() {
                return Some(ev);
            }

            // this will block until an event arrives, but doesn't remove
            // it from the queue
            let mut xev = unsafe { mem::uninitialized() };
            unsafe { ffi::XPeekEvent(self.window.x.display, &mut xev) };

            // calling poll_events()
            if let Some(ev) = self.window.poll_events().next() {
                return Some(ev);
            }
        }

        None
    }
}

pub struct Window {
    x: Arc<XWindow>,
    is_closed: AtomicBool,
    wm_delete_window: ffi::Atom,
    current_size: Cell<(libc::c_int, libc::c_int)>,
    pixel_format: PixelFormat,
    /// Events that have been retreived with XLib but not dispatched with iterators yet
    pending_events: Mutex<VecDeque<Event>>,
    cursor_state: Mutex<CursorState>,
}

impl Window {
    pub fn new(builder: BuilderAttribs) -> Result<Window, CreationError> {
        ensure_thread_init();
        let dimensions = builder.dimensions.unwrap_or((800, 600));

        // calling XOpenDisplay
        let display = unsafe {
            let display = ffi::XOpenDisplay(ptr::null());
            if display.is_null() {
                return Err(OsError(format!("XOpenDisplay failed")));
            }
            display
        };

        let screen_id = match builder.monitor {
            Some(MonitorID(monitor)) => monitor as i32,
            None => unsafe { ffi::XDefaultScreen(display) },
        };

        // getting the FBConfig
        let fb_config = unsafe {
            let mut visual_attributes = vec![
                ffi::GLX_X_RENDERABLE,  1,
                ffi::GLX_DRAWABLE_TYPE, ffi::GLX_WINDOW_BIT,
                ffi::GLX_RENDER_TYPE,   ffi::GLX_RGBA_BIT,
                ffi::GLX_X_VISUAL_TYPE, ffi::GLX_TRUE_COLOR,
                ffi::GLX_RED_SIZE,      8,
                ffi::GLX_GREEN_SIZE,    8,
                ffi::GLX_BLUE_SIZE,     8,
                ffi::GLX_ALPHA_SIZE,    8,
                ffi::GLX_DEPTH_SIZE,    24,
                ffi::GLX_STENCIL_SIZE,  8,
                ffi::GLX_DOUBLEBUFFER,  1,
            ];

            if let Some(val) = builder.multisampling {
                visual_attributes.push(ffi::glx::SAMPLE_BUFFERS as libc::c_int);
                visual_attributes.push(1);
                visual_attributes.push(ffi::glx::SAMPLES as libc::c_int);
                visual_attributes.push(val as libc::c_int);
            }

            if let Some(val) = builder.srgb {
                visual_attributes.push(ffi::glx_extra::FRAMEBUFFER_SRGB_CAPABLE_ARB as libc::c_int);
                visual_attributes.push(if val {1} else {0});
            }

            visual_attributes.push(0);

            let mut num_fb: libc::c_int = mem::uninitialized();

            let fb = ffi::glx::ChooseFBConfig(display, ffi::XDefaultScreen(display),
                visual_attributes.as_ptr(), &mut num_fb);
            if fb.is_null() {
                return Err(OsError(format!("glx::ChooseFBConfig failed")));
            }
            let preferred_fb = *fb;     // TODO: choose more wisely
            ffi::XFree(fb as *const libc::c_void);
            preferred_fb
        };

        let mut best_mode = -1;
        let modes = unsafe {
            let mut mode_num: libc::c_int = mem::uninitialized();
            let mut modes: *mut *mut ffi::XF86VidModeModeInfo = mem::uninitialized();
            if ffi::XF86VidModeGetAllModeLines(display, screen_id, &mut mode_num, &mut modes) == 0 {
                return Err(OsError(format!("Could not query the video modes")));
            }

            for i in 0..mode_num {
                let mode: ffi::XF86VidModeModeInfo = ptr::read(*modes.offset(i as isize) as *const _);
                if mode.hdisplay == dimensions.0 as u16 && mode.vdisplay == dimensions.1 as u16 {
                    best_mode = i;
                }
            };
            if best_mode == -1 && builder.monitor.is_some() {
                return Err(OsError(format!("Could not find a suitable graphics mode")));
            }

            modes
        };

        let xf86_desk_mode = unsafe {
            *modes.offset(0)
        };

        // getting the visual infos
        let mut visual_infos: ffi::glx::types::XVisualInfo = unsafe {
            let vi = ffi::glx::GetVisualFromFBConfig(display, fb_config);
            if vi.is_null() {
                return Err(OsError(format!("glx::ChooseVisual failed")));
            }
            let vi_copy = ptr::read(vi as *const _);
            ffi::XFree(vi as *const libc::c_void);
            vi_copy
        };

        // querying the chosen pixel format
        let pixel_format = {
            let get_attrib = |attrib: libc::c_int| -> i32 {
                let mut value = 0;
                unsafe { ffi::glx::GetFBConfigAttrib(display, fb_config, attrib, &mut value); }
                value
            };

            PixelFormat {
                hardware_accelerated: true,
                red_bits: get_attrib(ffi::GLX_RED_SIZE) as u8,
                green_bits: get_attrib(ffi::GLX_GREEN_SIZE) as u8,
                blue_bits: get_attrib(ffi::GLX_BLUE_SIZE) as u8,
                alpha_bits: get_attrib(ffi::GLX_ALPHA_SIZE) as u8,
                depth_bits: get_attrib(ffi::GLX_DEPTH_SIZE) as u8,
                stencil_bits: get_attrib(ffi::GLX_STENCIL_SIZE) as u8,
                stereoscopy: get_attrib(ffi::GLX_STEREO) != 0,
                double_buffer: get_attrib(ffi::GLX_DOUBLEBUFFER) != 0,
                multisampling: if get_attrib(ffi::glx::SAMPLE_BUFFERS as libc::c_int) != 0 {
                    Some(get_attrib(ffi::glx::SAMPLES as libc::c_int) as u16)
                }else { None },
                srgb: get_attrib(ffi::glx_extra::FRAMEBUFFER_SRGB_CAPABLE_ARB as libc::c_int) != 0,
            }
        };

        // getting the root window
        let root = unsafe { ffi::XDefaultRootWindow(display) };

        // creating the color map
        let cmap = unsafe {
            let cmap = ffi::XCreateColormap(display, root,
                visual_infos.visual, ffi::AllocNone);
            // TODO: error checking?
            cmap
        };

        // creating
        let mut set_win_attr = {
            let mut swa: ffi::XSetWindowAttributes = unsafe { mem::zeroed() };
            swa.colormap = cmap;
            swa.event_mask = ffi::ExposureMask | ffi::StructureNotifyMask |
                ffi::VisibilityChangeMask | ffi::KeyPressMask | ffi::PointerMotionMask |
                ffi::KeyReleaseMask | ffi::ButtonPressMask |
                ffi::ButtonReleaseMask | ffi::KeymapStateMask;
            swa.border_pixel = 0;
            swa.override_redirect = 0;
            swa
        };

        let mut window_attributes = ffi::CWBorderPixel | ffi::CWColormap | ffi:: CWEventMask;
        if builder.monitor.is_some() {
            window_attributes |= ffi::CWOverrideRedirect;
            unsafe {
                ffi::XF86VidModeSwitchToMode(display, screen_id, *modes.offset(best_mode as isize));
                ffi::XF86VidModeSetViewPort(display, screen_id, 0, 0);
                set_win_attr.override_redirect = 1;
            }
        }

        // finally creating the window
        let window = unsafe {
            let win = ffi::XCreateWindow(display, root, 0, 0, dimensions.0 as libc::c_uint,
                dimensions.1 as libc::c_uint, 0, visual_infos.depth, ffi::InputOutput,
                visual_infos.visual, window_attributes,
                &mut set_win_attr);
            win
        };

        // set visibility
        if builder.visible {
            unsafe {
                ffi::XMapRaised(display, window);
                ffi::XFlush(display);
            }
        }

        // creating window, step 2
        let wm_delete_window = unsafe {
            let mut wm_delete_window = with_c_str("WM_DELETE_WINDOW", |delete_window| 
                ffi::XInternAtom(display, delete_window, 0)
            );
            ffi::XSetWMProtocols(display, window, &mut wm_delete_window, 1);
            with_c_str(&*builder.title, |title| {;
                ffi::XStoreName(display, window, title);
            });
            ffi::XFlush(display);

            wm_delete_window
        };

        // creating IM
        let im = unsafe {
            let _lock = GLOBAL_XOPENIM_LOCK.lock().unwrap();

            let im = ffi::XOpenIM(display, ptr::null(), ptr::null_mut(), ptr::null_mut());
            if im.is_null() {
                return Err(OsError(format!("XOpenIM failed")));
            }
            im
        };

        // creating input context
        let ic = unsafe {
            let ic = with_c_str("inputStyle", |input_style|
                with_c_str("clientWindow", |client_window|
                    ffi::XCreateIC(
                        im, input_style,
                        ffi::XIMPreeditNothing | ffi::XIMStatusNothing, client_window,
                        window, ptr::null()
                    )
                )
            );
            if ic.is_null() {
                return Err(OsError(format!("XCreateIC failed")));
            }
            ffi::XSetICFocus(ic);
            ic
        };

        // Attempt to make keyboard input repeat detectable
        unsafe {
            let mut supported_ptr = false;
            ffi::XkbSetDetectableAutoRepeat(display, true, &mut supported_ptr);
            if !supported_ptr {
                return Err(OsError(format!("XkbSetDetectableAutoRepeat failed")));
            }
        }


        // creating GL context
        let (context, extra_functions) = unsafe {
            let mut attributes = Vec::new();

            match builder.gl_version {
                GlRequest::Latest => {},
                GlRequest::Specific(Api::OpenGl, (major, minor)) => {
                    attributes.push(ffi::GLX_CONTEXT_MAJOR_VERSION);
                    attributes.push(major as libc::c_int);
                    attributes.push(ffi::GLX_CONTEXT_MINOR_VERSION);
                    attributes.push(minor as libc::c_int);
                },
                GlRequest::Specific(_, _) => panic!("Only OpenGL is supported"),
                GlRequest::GlThenGles { opengl_version: (major, minor), .. } => {
                    attributes.push(ffi::GLX_CONTEXT_MAJOR_VERSION);
                    attributes.push(major as libc::c_int);
                    attributes.push(ffi::GLX_CONTEXT_MINOR_VERSION);
                    attributes.push(minor as libc::c_int);
                },
            }

            if builder.gl_debug {
                attributes.push(ffi::glx_extra::CONTEXT_FLAGS_ARB as libc::c_int);
                attributes.push(ffi::glx_extra::CONTEXT_DEBUG_BIT_ARB as libc::c_int);
            }

            attributes.push(0);

            // loading the extra GLX functions
            let extra_functions = ffi::glx_extra::Glx::load_with(|addr| {
                with_c_str(addr, |s| {
                    use libc;
                    ffi::glx::GetProcAddress(s as *const u8) as *const libc::c_void
                })
            });

            let share = if let Some(win) = builder.sharing {
                win.x.context
            } else {
                ptr::null()
            };

            let mut context = if extra_functions.CreateContextAttribsARB.is_loaded() {
                extra_functions.CreateContextAttribsARB(display as *mut ffi::glx_extra::types::Display,
                    fb_config, share, 1, attributes.as_ptr())
            } else {
                ptr::null()
            };

            if context.is_null() {
                context = ffi::glx::CreateContext(display, &mut visual_infos, share, 1)
            }

            if context.is_null() {
                return Err(OsError(format!("GL context creation failed")));
            }

            (context, extra_functions)
        };

        // vsync
        if builder.vsync {
            unsafe { ffi::glx::MakeCurrent(display, window, context) };

            if extra_functions.SwapIntervalEXT.is_loaded() {
                // this should be the most common extension
                unsafe {
                    extra_functions.SwapIntervalEXT(display as *mut _, window, 1);
                }

                // checking that it worked
                if builder.strict {
                    let mut swap = unsafe { mem::uninitialized() };
                    unsafe {
                        ffi::glx::QueryDrawable(display, window,
                                                ffi::glx_extra::SWAP_INTERVAL_EXT as i32,
                                                &mut swap);
                    }

                    if swap != 1 {
                        return Err(OsError(format!("Couldn't setup vsync: expected \
                                                    interval `1` but got `{}`", swap)));
                    }
                }

            // GLX_MESA_swap_control is not official
            /*} else if extra_functions.SwapIntervalMESA.is_loaded() {
                unsafe {
                    extra_functions.SwapIntervalMESA(1);
                }*/

            } else if extra_functions.SwapIntervalSGI.is_loaded() {
                unsafe {
                    extra_functions.SwapIntervalSGI(1);
                }

            } else if builder.strict {
                return Err(OsError(format!("Couldn't find any available vsync extension")));
            }

            unsafe { ffi::glx::MakeCurrent(display, 0, ptr::null()) };
        }

        // creating the window object
        let window = Window {
            x: Arc::new(XWindow {
                display: display,
                window: window,
                im: im,
                ic: ic,
                context: context,
                screen_id: screen_id,
                is_fullscreen: builder.monitor.is_some(),
                xf86_desk_mode: xf86_desk_mode,
            }),
            is_closed: AtomicBool::new(false),
            wm_delete_window: wm_delete_window,
            current_size: Cell::new((0, 0)),
            pixel_format: pixel_format,
            pending_events: Mutex::new(VecDeque::new()),
            cursor_state: Mutex::new(CursorState::Normal),
        };

        // returning
        Ok(window)
    }

    pub fn is_closed(&self) -> bool {
        use std::sync::atomic::Ordering::Relaxed;
        self.is_closed.load(Relaxed)
    }

    pub fn set_title(&self, title: &str) {
        with_c_str(title, |title| unsafe {
            ffi::XStoreName(self.x.display, self.x.window, title);
            ffi::XFlush(self.x.display);
        })
    }

    pub fn show(&self) {
        unsafe {
            ffi::XMapRaised(self.x.display, self.x.window);
            ffi::XFlush(self.x.display);
        }
    }

    pub fn hide(&self) {
        unsafe {
            ffi::XUnmapWindow(self.x.display, self.x.window);
            ffi::XFlush(self.x.display);
        }
    }

    fn get_geometry(&self) -> Option<(i32, i32, u32, u32, u32)> {
        unsafe {
            use std::mem;

            let mut root: ffi::Window = mem::uninitialized();
            let mut x: libc::c_int = mem::uninitialized();
            let mut y: libc::c_int = mem::uninitialized();
            let mut width: libc::c_uint = mem::uninitialized();
            let mut height: libc::c_uint = mem::uninitialized();
            let mut border: libc::c_uint = mem::uninitialized();
            let mut depth: libc::c_uint = mem::uninitialized();

            if ffi::XGetGeometry(self.x.display, self.x.window,
                &mut root, &mut x, &mut y, &mut width, &mut height,
                &mut border, &mut depth) == 0
            {
                return None;
            }

            Some((x as i32, y as i32, width as u32, height as u32, border as u32))
        }
    }

    pub fn get_position(&self) -> Option<(i32, i32)> {
        self.get_geometry().map(|(x, y, _, _, _)| (x, y))
    }

    pub fn set_position(&self, x: i32, y: i32) {
        unsafe { ffi::XMoveWindow(self.x.display, self.x.window, x as libc::c_int, y as libc::c_int) }
    }

    pub fn get_inner_size(&self) -> Option<(u32, u32)> {
        self.get_geometry().map(|(_, _, w, h, _)| (w, h))
    }

    pub fn get_outer_size(&self) -> Option<(u32, u32)> {
        self.get_geometry().map(|(_, _, w, h, b)| (w + b, h + b))       // TODO: is this really outside?
    }

    pub fn set_inner_size(&self, _x: u32, _y: u32) {
        unimplemented!()
    }

    pub fn create_window_proxy(&self) -> WindowProxy {
        WindowProxy {
            x: self.x.clone()
        }
    }

    pub fn poll_events(&self) -> PollEventsIterator {
        PollEventsIterator {
            window: self
        }
    }

    pub fn wait_events(&self) -> WaitEventsIterator {
        WaitEventsIterator {
            window: self
        }
    }

    pub unsafe fn make_current(&self) {
        let res = ffi::glx::MakeCurrent(self.x.display, self.x.window, self.x.context);
        if res == 0 {
            panic!("glx::MakeCurrent failed");
        }
    }

    pub fn is_current(&self) -> bool {
        unsafe { ffi::glx::GetCurrentContext() == self.x.context }
    }

    pub fn get_proc_address(&self, addr: &str) -> *const () {
        use std::mem;

        unsafe {
            with_c_str(addr, |s| {
                ffi::glx::GetProcAddress(mem::transmute(s)) as *const ()
            })
        }
    }

    pub fn swap_buffers(&self) {
        unsafe { ffi::glx::SwapBuffers(self.x.display, self.x.window) }
    }

    pub fn platform_display(&self) -> *mut libc::c_void {
        self.x.display as *mut libc::c_void
    }

    pub fn platform_window(&self) -> *mut libc::c_void {
        unimplemented!()
    }

    /// See the docs in the crate root file.
    pub fn get_api(&self) -> ::Api {
        ::Api::OpenGl
    }

    pub fn get_pixel_format(&self) -> PixelFormat {
        self.pixel_format.clone()
    }

    pub fn set_window_resize_callback(&mut self, _: Option<fn(u32, u32)>) {
    }

    pub fn set_cursor(&self, cursor: MouseCursor) {
        unsafe {
            use std::ffi::CString;
            let cursor_name = match cursor {
                MouseCursor::Alias => "link",
                MouseCursor::Arrow => "arrow",
                MouseCursor::Cell => "plus",
                MouseCursor::Copy => "copy",
                MouseCursor::Crosshair => "crosshair",
                MouseCursor::Default => "left_ptr",
                MouseCursor::Grabbing => "grabbing",
                MouseCursor::Hand | MouseCursor::Grab => "hand",
                MouseCursor::Help => "question_arrow",
                MouseCursor::Move => "move",
                MouseCursor::NoDrop => "circle",
                MouseCursor::NotAllowed => "crossed_circle",
                MouseCursor::Progress => "left_ptr_watch",

                /// Resize cursors
                MouseCursor::EResize => "right_side",
                MouseCursor::NResize => "top_side",
                MouseCursor::NeResize => "top_right_corner",
                MouseCursor::NwResize => "top_left_corner",
                MouseCursor::SResize => "bottom_side",
                MouseCursor::SeResize => "bottom_right_corner",
                MouseCursor::SwResize => "bottom_left_corner",
                MouseCursor::WResize => "left_side",
                MouseCursor::EwResize | MouseCursor::ColResize => "h_double_arrow",
                MouseCursor::NsResize | MouseCursor::RowResize => "v_double_arrow",
                MouseCursor::NwseResize => "bd_double_arrow",
                MouseCursor::NeswResize => "fd_double_arrow",

                MouseCursor::Text | MouseCursor::VerticalText => "xterm",
                MouseCursor::Wait => "watch",
                
                /// TODO: Find matching X11 cursors
                MouseCursor::ContextMenu | MouseCursor::NoneCursor |
                MouseCursor::AllScroll | MouseCursor::ZoomIn |
                MouseCursor::ZoomOut => "left_ptr",
            };
            let c_string = CString::new(cursor_name.as_bytes().to_vec()).unwrap();
            let xcursor = ffi::XcursorLibraryLoadCursor(self.x.display, c_string.as_ptr());
            ffi::XDefineCursor (self.x.display, self.x.window, xcursor);
            ffi::XFlush(self.x.display);
        }
    }

    pub fn set_cursor_state(&self, state: CursorState) -> Result<(), String> {
        let mut cursor_state = self.cursor_state.lock().unwrap();

        match (state, *cursor_state) {
            (CursorState::Normal, CursorState::Grab) => {
                unsafe {
                    ffi::XUngrabPointer(self.x.display, ffi::CurrentTime);
                    *cursor_state = CursorState::Normal;
                    Ok(())
                }
            },

            (CursorState::Grab, CursorState::Normal) => {
                unsafe {
                    *cursor_state = CursorState::Grab;

                    match ffi::XGrabPointer(
                        self.x.display, self.x.window, false,
                        ffi::ButtonPressMask | ffi::ButtonReleaseMask | ffi::EnterWindowMask |
                        ffi::LeaveWindowMask | ffi::PointerMotionMask | ffi::PointerMotionHintMask |
                        ffi::Button1MotionMask | ffi::Button2MotionMask | ffi::Button3MotionMask |
                        ffi::Button4MotionMask | ffi::Button5MotionMask | ffi::ButtonMotionMask |
                        ffi::KeymapStateMask,
                        ffi::GrabModeAsync, ffi::GrabModeAsync,
                        self.x.window, 0, ffi::CurrentTime
                    ) {
                        ffi::GrabSuccess => Ok(()),
                        ffi::AlreadyGrabbed | ffi::GrabInvalidTime |
                        ffi::GrabNotViewable | ffi::GrabFrozen
                            => Err("cursor could not be grabbed".to_string()),
                        _ => unreachable!(),
                    }
                }
            },

            _ => unimplemented!(),
        }
    }

    pub fn hidpi_factor(&self) -> f32 {
        1.0
    }

    pub fn set_cursor_position(&self, x: i32, y: i32) -> Result<(), ()> {
        unsafe {
            ffi::XWarpPointer(self.x.display, 0, self.x.window, 0, 0, 0, 0, x, y);
        }

        Ok(())
    }
}