extern crate native;

use self::native::NativeTaskBuilder;
use std::task::TaskBuilder;
use std::sync::atomics::AtomicBool;
use std::ptr;
use super::{event, ffi};
use super::{MonitorID, Window};
use {Event, Hints};

/// Stores the current window and its events dispatcher.
/// 
/// We only have one window per thread. We still store the HWND in case where we
///  receive an event for another window.
local_data_key!(WINDOW: (ffi::HWND, Sender<Event>))

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

    // initializing variables to be sent to the task
    let title = title.utf16_units().collect::<Vec<u16>>().append_one(0);    // title to utf16
    //let hints = hints.clone();
    let (tx, rx) = channel();

    // GetMessage must be called in the same thread as CreateWindow,
    //  so we create a new thread dedicated to this window.
    // This is the only safe method. Using `nosend` wouldn't work for non-native runtime.
    TaskBuilder::new().native().spawn(proc() {
        // 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;
            tx.send(Err(format!("RegisterClassEx function failed: {}",
                os::error_string(os::errno() as uint))));
            return;
        }

        // building a RECT object with coordinates
        let mut rect = ffi::RECT {
            left: 0, right: dimensions.map(|(w, _)| w as ffi::LONG).unwrap_or(1024),
            top: 0, bottom: dimensions.map(|(_, h)| h as ffi::LONG).unwrap_or(768),
        };

        // switching to fullscreen if necessary
        // this means adjusting the window's position so that it overlaps the right monitor,
        //  and change the monitor's resolution if necessary
        if monitor.is_some() {
            let monitor = monitor.as_ref().unwrap();

            // adjusting the rect
            {
                let pos = monitor.get_position();
                rect.left += pos.val0() as ffi::LONG;
                rect.right += pos.val0() as ffi::LONG;
                rect.top += pos.val1() as ffi::LONG;
                rect.bottom += pos.val1() as ffi::LONG;
            }

            // changing device settings
            let mut screen_settings: ffi::DEVMODE = unsafe { mem::zeroed() };
            screen_settings.dmSize = mem::size_of::<ffi::DEVMODE>() as ffi::WORD;
            screen_settings.dmPelsWidth = 1024;
            screen_settings.dmPelsHeight = 768;
            screen_settings.dmBitsPerPel = 32;
            screen_settings.dmFields = ffi::DM_BITSPERPEL | ffi::DM_PELSWIDTH | ffi::DM_PELSHEIGHT;

            let result = unsafe { ffi::ChangeDisplaySettingsExW(monitor.get_system_name().as_ptr(),
                &mut screen_settings, ptr::mut_null(), ffi::CDS_FULLSCREEN, ptr::mut_null()) };
            if result != ffi::DISP_CHANGE_SUCCESSFUL {
                tx.send(Err(format!("ChangeDisplaySettings failed: {}", result)));
                return;
            }
        }

        // computing the style and extended style of the window
        let (ex_style, style) = if monitor.is_some() {
            (ffi::WS_EX_APPWINDOW, ffi::WS_POPUP | ffi::WS_CLIPSIBLINGS | ffi::WS_CLIPCHILDREN)
        } else {
            (ffi::WS_EX_APPWINDOW | ffi::WS_EX_WINDOWEDGE,
                ffi::WS_OVERLAPPEDWINDOW | ffi::WS_CLIPSIBLINGS | ffi::WS_CLIPCHILDREN)
        };

        // adjusting the window coordinates using the style
        unsafe { ffi::AdjustWindowRectEx(&mut rect, style, 0, ex_style) };

        // creating the window
        let handle = unsafe {
            let handle = ffi::CreateWindowExW(ex_style, class_name.as_ptr(),
                title.as_ptr() as ffi::LPCWSTR,
                style | ffi::WS_VISIBLE | ffi::WS_CLIPSIBLINGS | ffi::WS_CLIPCHILDREN,
                if monitor.is_some() { 0 } else { ffi::CW_USEDEFAULT},
                if monitor.is_some() { 0 } else { ffi::CW_USEDEFAULT},
                rect.right - rect.left, rect.bottom - rect.top,
                ptr::mut_null(), ptr::mut_null(), ffi::GetModuleHandleW(ptr::null()),
                ptr::mut_null());

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

            handle
        };

        // calling SetForegroundWindow if fullscreen
        if monitor.is_some() {
            unsafe { ffi::SetForegroundWindow(handle) };
        }

        // filling the WINDOW task-local storage
        let events_receiver = {
            let (tx, rx) = channel();
            WINDOW.replace(Some((handle, tx)));
            rx
        };

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

            output
        };

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

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

        // loading the opengl32 module
        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() {
                tx.send(Err(format!("LoadLibrary function failed: {}",
                    os::error_string(os::errno() as uint))));
                return;
            }
            lib
        };

        // building the struct
        tx.send(Ok(Window{
            window: handle,
            hdc: hdc,
            context: context,
            gl_library: gl_library,
            events_receiver: events_receiver,
            is_closed: AtomicBool::new(false),
        }));

        // now that the `Window` struct is initialized, the main `Window::new()` function will
        //  return and this events loop will run in parallel
        loop {
            let mut msg = unsafe { mem::uninitialized() };

            if unsafe { ffi::GetMessageW(&mut msg, ptr::mut_null(), 0, 0) } == 0 {
                break;
            }

            unsafe { ffi::TranslateMessage(&msg) };
            unsafe { ffi::DispatchMessageW(&msg) };     // calls `callback` (see below)
        }
    });

    rx.recv()
}

/// Checks that the window is the good one, and if so send the event to it.
fn send_event(window: ffi::HWND, event: Event) {
    let stored = match WINDOW.get() {
        None => return,
        Some(v) => v
    };

    let &(ref win, ref sender) = stored.deref();

    if win != &window {
        return;
    }

    sender.send_opt(event).ok();  // ignoring if closed
}

/// This is the callback that is called by `DispatchMessage` in the events loop.
/// 
/// Returning 0 tells the Win32 API that the message has been processed.
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;
            unsafe { ffi::PostQuitMessage(0); }
            send_event(window, Closed);
            0
        },

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

        ffi::WM_MOVE => {
            use events::Moved;
            let x = ffi::LOWORD(lparam as ffi::DWORD) as i16 as int;
            let y = ffi::HIWORD(lparam as ffi::DWORD) as i16 as int;
            send_event(window, Moved(x, y));
            0
        },

        ffi::WM_CHAR => {
            use std::mem;
            use events::ReceivedCharacter;
            let chr: char = unsafe { mem::transmute(wparam) };
            send_event(window, ReceivedCharacter(chr));
            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
        },

        ffi::WM_KEYDOWN => {
            use events::Pressed;
            let element = event::vkeycode_to_element(wparam);
            if element.is_some() {
                send_event(window, Pressed(element.unwrap()));
            }
            0
        },

        ffi::WM_KEYUP => {
            use events::Released;
            let element = event::vkeycode_to_element(wparam);
            if element.is_some() {
                send_event(window, Released(element.unwrap()));
            }
            0
        },

        ffi::WM_LBUTTONDOWN => {
            use events::{Pressed, Button0};
            send_event(window, Pressed(Button0));
            0
        },

        ffi::WM_LBUTTONUP => {
            use events::{Released, Button0};
            send_event(window, Released(Button0));
            0
        },

        ffi::WM_RBUTTONDOWN => {
            use events::{Pressed, Button1};
            send_event(window, Pressed(Button1));
            0
        },

        ffi::WM_RBUTTONUP => {
            use events::{Released, Button1};
            send_event(window, Released(Button1));
            0
        },

        ffi::WM_MBUTTONDOWN => {
            use events::{Pressed, Button2};
            send_event(window, Pressed(Button2));
            0
        },

        ffi::WM_MBUTTONUP => {
            use events::{Released, Button2};
            send_event(window, Released(Button2));
            0
        },

        ffi::WM_SETFOCUS => {
            use events::Focused;
            send_event(window, Focused(true));
            0
        },

        ffi::WM_KILLFOCUS => {
            use events::Focused;
            send_event(window, Focused(false));
            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,
    }
}*/