use std::kinds::marker::NoSend;
use std::sync::Mutex;
use std::sync::atomics::AtomicBool;
use std::ptr;
use {Event, Hints};

mod ffi;

pub struct Window {
    window: ffi::HWND,
    hdc: ffi::HDC,
    context: ffi::HGLRC,
    gl_library: ffi::HMODULE,
    events_receiver: Receiver<Event>,
    should_close: AtomicBool,
    nosend: NoSend,
}

/// Stores the list of all the windows.
/// Only available on callback thread.
local_data_key!(pub WINDOWS_LIST: Mutex<Vec<(ffi::HWND, Sender<Event>)>>)

impl Window {
    pub fn new(dimensions: Option<(uint, uint)>, title: &str, _hints: &Hints)
        -> Result<Window, String>
    {
        use std::mem;
        use std::os;

        // initializing WINDOWS_LIST if needed
        // this is safe because WINDOWS_LIST is task-local
        if WINDOWS_LIST.get().is_none() {
            WINDOWS_LIST.replace(Some(Mutex::new(Vec::new())));
        }

        // registering the window class
        let class_name: Vec<u16> = "Window Class".utf16_units().collect::<Vec<u16>>()
            .append_one(0);
        
        let class = ffi::WNDCLASSEX {
            cbSize: mem::size_of::<ffi::WNDCLASSEX>() as ffi::UINT,
            style: ffi::CS_HREDRAW | ffi::CS_VREDRAW,
            lpfnWndProc: callback,
            cbClsExtra: 0,
            cbWndExtra: 0,
            hInstance: unsafe { ffi::GetModuleHandleW(ptr::null()) },
            hIcon: ptr::mut_null(),
            hCursor: ptr::mut_null(),
            hbrBackground: ptr::mut_null(),
            lpszMenuName: ptr::null(),
            lpszClassName: class_name.as_ptr(),
            hIconSm: ptr::mut_null(),
        };

        if unsafe { ffi::RegisterClassExW(&class) } == 0 {
            use std::os;
            return Err(format!("RegisterClassEx function failed: {}",
                os::error_string(os::errno() as uint)))
        }

        // creating the window
        let handle = unsafe {
            use libc;

            let handle = ffi::CreateWindowExW(0, class_name.as_ptr(),
                title.utf16_units().collect::<Vec<u16>>().append_one(0).as_ptr() as ffi::LPCWSTR,
                ffi::WS_OVERLAPPEDWINDOW | ffi::WS_VISIBLE,
                dimensions.map(|(x, _)| x as libc::c_int).unwrap_or(ffi::CW_USEDEFAULT),
                dimensions.map(|(_, y)| y as libc::c_int).unwrap_or(ffi::CW_USEDEFAULT),
                ffi::CW_USEDEFAULT, ffi::CW_USEDEFAULT,
                ptr::mut_null(), ptr::mut_null(), ffi::GetModuleHandleW(ptr::null()),
                ptr::mut_null());

            if handle.is_null() {
                use std::os;
                return Err(format!("CreateWindowEx function failed: {}",
                    os::error_string(os::errno() as uint)))
            }

            handle
        };

        // adding it to WINDOWS_LIST
        let events_receiver = {
            let (tx, rx) = channel();
            let list = WINDOWS_LIST.get().unwrap();
            let mut list = list.lock();
            list.push((handle, tx));
            rx
        };

        // Getting the HDC of the window
        let hdc = {
            let hdc = unsafe { ffi::GetDC(handle) };
            if hdc.is_null() {
                return Err(format!("GetDC function failed: {}",
                    os::error_string(os::errno() as uint)))
            }
            hdc
        };

        // getting the pixel format that we will use
        // TODO: use something cleaner which uses hints
        let pixel_format = {
            let mut output: ffi::PIXELFORMATDESCRIPTOR = unsafe { mem::uninitialized() };

            if unsafe { ffi::DescribePixelFormat(hdc, 1,
                mem::size_of::<ffi::PIXELFORMATDESCRIPTOR>() as ffi::UINT, &mut output) } == 0
            {
                return Err(format!("DescribePixelFormat function failed: {}",
                    os::error_string(os::errno() as uint)))
            }

            output
        };

        // calling SetPixelFormat
        unsafe {
            if ffi::SetPixelFormat(hdc, 1, &pixel_format) == 0 {
                return Err(format!("SetPixelFormat function failed: {}",
                    os::error_string(os::errno() as uint)))
            }
        }

        // creating the context
        let context = {
            let ctxt = unsafe { ffi::wglCreateContext(hdc) };
            if ctxt.is_null() {
                return Err(format!("wglCreateContext function failed: {}",
                    os::error_string(os::errno() as uint)))
            }
            ctxt
        };

        // loading opengl32
        let gl_library = {
            let name = "opengl32.dll".utf16_units().collect::<Vec<u16>>().append_one(0).as_ptr();
            let lib = unsafe { ffi::LoadLibraryW(name) };
            if lib.is_null() {
                return Err(format!("LoadLibrary function failed: {}",
                    os::error_string(os::errno() as uint)))
            }
            lib
        };

        // building the struct
        Ok(Window{
            window: handle,
            hdc: hdc,
            context: context,
            gl_library: gl_library,
            events_receiver: events_receiver,
            should_close: AtomicBool::new(false),
            nosend: NoSend,
        })
    }

    pub fn should_close(&self) -> bool {
        use std::sync::atomics::Relaxed;
        self.should_close.load(Relaxed)
    }

    /// Calls SetWindowText on the HWND.
    pub fn set_title(&self, text: &str) {
        unsafe {
            ffi::SetWindowTextW(self.window,
                text.utf16_units().collect::<Vec<u16>>().append_one(0).as_ptr() as ffi::LPCWSTR);
        }
    }

    pub fn get_position(&self) -> (uint, uint) {
        unimplemented!()
    }

    pub fn set_position(&self, x: uint, y: uint) {
        use libc;

        unsafe {
            ffi::SetWindowPos(self.window, ptr::mut_null(), x as libc::c_int, y as libc::c_int,
                0, 0, ffi::SWP_NOZORDER | ffi::SWP_NOSIZE);
            ffi::UpdateWindow(self.window);
        }
    }

    pub fn get_size(&self) -> (uint, uint) {
        unimplemented!()
    }

    pub fn set_size(&self, x: uint, y: uint) {
        use libc;

        unsafe {
            ffi::SetWindowPos(self.window, ptr::mut_null(), 0, 0, x as libc::c_int,
                y as libc::c_int, ffi::SWP_NOZORDER | ffi::SWP_NOREPOSITION);
            ffi::UpdateWindow(self.window);
        }
    }

    // TODO: return iterator
    pub fn poll_events(&self) -> Vec<Event> {
        unimplemented!()
    }

    // TODO: return iterator
    pub fn wait_events(&self) -> Vec<Event> {
        use std::mem;

        {
            let mut msg = unsafe { mem::uninitialized() };

            if unsafe { ffi::GetMessageW(&mut msg, ptr::mut_null(), 0, 0) } == 0 {
                use std::sync::atomics::Relaxed;
                use Closed;

                self.should_close.store(true, Relaxed);
                return vec![Closed]
            }

            unsafe { ffi::TranslateMessage(&msg) };
            unsafe { ffi::DispatchMessageW(&msg) };
        }

        let mut events = Vec::new();
        loop {
            match self.events_receiver.try_recv() {
                Ok(ev) => events.push(ev),
                Err(_) => break
            }
        }
        events
    }

    pub fn make_current(&self) {
        unsafe { ffi::wglMakeCurrent(self.hdc, self.context) }
    }

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

        unsafe {
            addr.with_c_str(|s| {
                let p = ffi::wglGetProcAddress(s) as *const ();
                if !p.is_null() { return p; }
                ffi::GetProcAddress(self.gl_library, s) as *const ()
            })
        }
    }

    pub fn swap_buffers(&self) {
        unsafe {
            ffi::SwapBuffers(self.hdc);
        }
    }
}

#[unsafe_destructor]
impl Drop for Window {
    fn drop(&mut self) {
        unsafe { ffi::DestroyWindow(self.window); }
    }
}

fn send_event(window: ffi::HWND, event: Event) {
    let locked = WINDOWS_LIST.get().unwrap();
    let mut locked = locked.lock();
    locked.retain(|&(ref val, ref sender)| {
        if val != &window { return true }

        sender.send_opt(event).is_ok()
    });
}

extern "stdcall" fn callback(window: ffi::HWND, msg: ffi::UINT,
    wparam: ffi::WPARAM, lparam: ffi::LPARAM) -> ffi::LRESULT
{
    match msg {
        ffi::WM_DESTROY => {
            use Closed;
            send_event(window, Closed);
            unsafe { ffi::PostQuitMessage(0); }
            0
        },

        ffi::WM_SIZE => {
            use SizeChanged;
            let w = ffi::LOWORD(lparam as ffi::DWORD) as uint;
            let h = ffi::HIWORD(lparam as ffi::DWORD) as uint;
            send_event(window, SizeChanged(w, h));
            0
        },

        ffi::WM_PAINT => {
            use NeedRefresh;
            send_event(window, NeedRefresh);
            0
        },

        ffi::WM_MOUSEMOVE => {
            use CursorPositionChanged;

            let x = ffi::GET_X_LPARAM(lparam) as uint;
            let y = ffi::GET_Y_LPARAM(lparam) as uint;

            send_event(window, CursorPositionChanged(x, y));

            0
        },

        _ => unsafe {
            ffi::DefWindowProcW(window, msg, wparam, lparam)
        }
    }
}

/*fn hints_to_pixelformat(hints: &Hints) -> ffi::PIXELFORMATDESCRIPTOR {
    use std::mem;

    ffi::PIXELFORMATDESCRIPTOR {
        nSize: size_of::<ffi::PIXELFORMATDESCRIPTOR>(),
        nVersion: 1,
        dwFlags:
            if hints.stereo { PFD_STEREO } else { 0 },
        iPixelType: PFD_TYPE_RGBA,
        cColorBits: hints.red_bits + hints.green_bits + hints.blue_bits,
        cRedBits: 

    pub nSize: WORD,
    pub nVersion: WORD,
    pub dwFlags: DWORD,
    pub iPixelType: BYTE,
    pub cColorBits: BYTE,
    pub cRedBits: BYTE,
    pub cRedShift: BYTE,
    pub cGreenBits: BYTE,
    pub cGreenShift: BYTE,
    pub cBlueBits: BYTE,
    pub cBlueShift: BYTE,
    pub cAlphaBits: BYTE,
    pub cAlphaShift: BYTE,
    pub cAccumBits: BYTE,
    pub cAccumRedBits: BYTE,
    pub cAccumGreenBits: BYTE,
    pub cAccumBlueBits: BYTE,
    pub cAccumAlphaBits: BYTE,
    pub cDepthBits: BYTE,
    pub cStencilBits: BYTE,
    pub cAuxBuffers: BYTE,
    pub iLayerType: BYTE,
    pub bReserved: BYTE,
    pub dwLayerMask: DWORD,
    pub dwVisibleMask: DWORD,
    pub dwDamageMask: DWORD,
    }
}*/