// Copyright 2016 Joe Wilm, The Alacritty Project Contributors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
use std::convert::From;
use std::fmt::{self, Display};
use std::ops::Deref;

use gl;
use glutin::{self, ContextBuilder, ControlFlow, CursorState, Event, EventsLoop,
             MouseCursor as GlutinMouseCursor, WindowBuilder};
use glutin::GlContext;

use MouseCursor;

use config::WindowConfig;

/// Window errors
#[derive(Debug)]
pub enum Error {
    /// Error creating the window
    ContextCreation(glutin::CreationError),

    /// Error manipulating the rendering context
    Context(glutin::ContextError),
}

/// Result of fallible operations concerning a Window.
type Result<T> = ::std::result::Result<T, Error>;

/// A window which can be used for displaying the terminal
///
/// Wraps the underlying windowing library to provide a stable API in Alacritty
pub struct Window {
    event_loop: EventsLoop,
    window: glutin::GlWindow,
    cursor_visible: bool,

    /// Whether or not the window is the focused window.
    pub is_focused: bool,
}

/// Threadsafe APIs for the window
pub struct Proxy {
    inner: glutin::EventsLoopProxy,
}

/// Information about where the window is being displayed
///
/// Useful for subsystems like the font rasterized which depend on DPI and scale
/// factor.
pub struct DeviceProperties {
    /// Scale factor for pixels <-> points.
    ///
    /// This will be 1. on standard displays and may have a different value on
    /// hidpi displays.
    pub scale_factor: f32,
}

/// Size of the window
#[derive(Debug, Copy, Clone)]
pub struct Size<T> {
    pub width: T,
    pub height: T,
}

/// Strongly typed Pixels unit
#[derive(Debug, Copy, Clone)]
pub struct Pixels<T>(pub T);

/// Strongly typed Points unit
///
/// Points are like pixels but adjusted for DPI.
#[derive(Debug, Copy, Clone)]
pub struct Points<T>(pub T);

pub trait ToPoints {
    fn to_points(&self, scale: f32) -> Size<Points<u32>>;
}

impl ToPoints for Size<Points<u32>> {
    #[inline]
    fn to_points(&self, _scale: f32) -> Size<Points<u32>> {
        *self
    }
}

impl ToPoints for Size<Pixels<u32>> {
    fn to_points(&self, scale: f32) -> Size<Points<u32>> {
        let width_pts = (*self.width as f32 / scale) as u32;
        let height_pts = (*self.height as f32 / scale) as u32;

        Size {
            width: Points(width_pts),
            height: Points(height_pts)
        }
    }
}

impl<T: Display> Display for Size<T> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{} × {}", self.width, self.height)
    }
}

macro_rules! deref_newtype {
    ($($src:ty),+) => {
        $(
        impl<T> Deref for $src {
            type Target = T;

            #[inline]
            fn deref(&self) -> &Self::Target {
                &self.0
            }
        }
        )+
    }
}

deref_newtype! { Points<T>, Pixels<T> }


impl<T: Display> Display for Pixels<T> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}px", self.0)
    }
}

impl<T: Display> Display for Points<T> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}pts", self.0)
    }
}

impl ::std::error::Error for Error {
    fn cause(&self) -> Option<&::std::error::Error> {
        match *self {
            Error::ContextCreation(ref err) => Some(err),
            Error::Context(ref err) => Some(err),
        }
    }

    fn description(&self) -> &str {
        match *self {
            Error::ContextCreation(ref _err) => "Error creating gl context",
            Error::Context(ref _err) => "Error operating on render context",
        }
    }
}

impl Display for Error {
    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
        match *self {
            Error::ContextCreation(ref err) => {
                write!(f, "Error creating GL context; {}", err)
            },
            Error::Context(ref err) => {
                write!(f, "Error operating on render context; {}", err)
            },
        }
    }
}

impl From<glutin::CreationError> for Error {
    fn from(val: glutin::CreationError) -> Error {
        Error::ContextCreation(val)
    }
}

impl From<glutin::ContextError> for Error {
    fn from(val: glutin::ContextError) -> Error {
        Error::Context(val)
    }
}

impl Window {
    /// Create a new window
    ///
    /// This creates a window and fully initializes a window.
    pub fn new(
        title: &str,
        window_config: &WindowConfig,
    ) -> Result<Window> {
        let event_loop = EventsLoop::new();

        Window::platform_window_init();
        let window = WindowBuilder::new()
            .with_title(title)
            .with_visibility(false)
            .with_transparency(true)
            .with_decorations(window_config.decorations());
        let context = ContextBuilder::new()
            .with_vsync(true);
        let window = ::glutin::GlWindow::new(window, context, &event_loop)?;
        window.show();

        // Text cursor
        window.set_cursor(GlutinMouseCursor::Text);

        // Set OpenGL symbol loader
        gl::load_with(|symbol| window.get_proc_address(symbol) as *const _);

        // Make the context current so OpenGL operations can run
        unsafe {
            window.make_current()?;
        }

        let window = Window {
            event_loop: event_loop,
            window: window,
            cursor_visible: true,
            is_focused: true,
        };

        window.run_os_extensions();

        Ok(window)
    }

    /// Get some properties about the device
    ///
    /// Some window properties are provided since subsystems like font
    /// rasterization depend on DPI and scale factor.
    pub fn device_properties(&self) -> DeviceProperties {
        DeviceProperties {
            scale_factor: self.window.hidpi_factor(),
        }
    }

    pub fn inner_size_pixels(&self) -> Option<Size<Pixels<u32>>> {
        self.window
            .get_inner_size()
            .map(|(w, h)| Size { width: Pixels(w), height: Pixels(h) })
    }

    #[inline]
    pub fn hidpi_factor(&self) -> f32 {
        self.window.hidpi_factor()
    }

    #[inline]
    pub fn create_window_proxy(&self) -> Proxy {
        Proxy {
            inner: self.event_loop.create_proxy(),
        }
    }

    #[inline]
    pub fn swap_buffers(&self) -> Result<()> {
        self.window
            .swap_buffers()
            .map_err(From::from)
    }

    /// Poll for any available events
    #[inline]
    pub fn poll_events<F>(&mut self, func: F)
        where F: FnMut(Event)
    {
        self.event_loop.poll_events(func);
    }

    #[inline]
    pub fn resize(&self, width: u32, height: u32) {
        self.window.resize(width, height);
    }

    /// Block waiting for events
    #[inline]
    pub fn wait_events<F>(&mut self, func: F)
        where F: FnMut(Event) -> ControlFlow
    {
        self.event_loop.run_forever(func);
    }

    /// Set the window title
    #[inline]
    pub fn set_title(&self, title: &str) {
        self.window.set_title(title);
    }

    #[inline]
    pub fn set_mouse_cursor(&self, cursor: MouseCursor) {
        self.window.set_cursor(match cursor {
            MouseCursor::Arrow => GlutinMouseCursor::Arrow,
            MouseCursor::Text => GlutinMouseCursor::Text,
        });
    }

    /// Set cursor visible
    pub fn set_cursor_visible(&mut self, visible: bool) {
        if visible != self.cursor_visible {
            self.cursor_visible = visible;
            if let Err(err) = self.window.set_cursor_state(if visible {
                CursorState::Normal
            } else {
                CursorState::Hide
            }) {
                warn!("Failed to set cursor visibility: {}", err);
            }
        }
    }

    #[cfg(any(target_os = "linux", target_os = "freebsd", target_os = "dragonfly", target_os = "openbsd"))]
    pub fn platform_window_init() {
        /// Set up env to make XIM work correctly
        use x11_dl::xlib;
        use libc::{setlocale, LC_CTYPE};
        let xlib = xlib::Xlib::open().expect("get xlib");
        unsafe {
            // Use empty c string to fallback to LC_CTYPE in environment variables
            setlocale(LC_CTYPE, b"\0".as_ptr() as *const _);
            // Use empty c string for implementation dependent behavior,
            // which might be the XMODIFIERS set in env
            (xlib.XSetLocaleModifiers)(b"\0".as_ptr() as *const _);
        }
    }

    /// TODO: change this directive when adding functions for other platforms
    #[cfg(not(any(target_os = "linux", target_os = "freebsd", target_os = "dragonfly", target_os = "openbsd")))]
    pub fn platform_window_init() {
    }

    #[cfg(any(target_os = "linux", target_os = "freebsd", target_os = "dragonfly", target_os = "openbsd"))]
    pub fn set_urgent(&self, is_urgent: bool) {
        use glutin::os::unix::WindowExt;
        use std::os::raw;
        use x11_dl::xlib::{self, XUrgencyHint};

        let xlib_display = self.window.get_xlib_display();
        let xlib_window = self.window.get_xlib_window();

        if let (Some(xlib_window), Some(xlib_display)) = (xlib_window, xlib_display) {
            let xlib = xlib::Xlib::open().expect("get xlib");

            unsafe {
                let mut hints = (xlib.XGetWMHints)(xlib_display as _, xlib_window as _);

                if hints.is_null() {
                    hints = (xlib.XAllocWMHints)();
                }

                if is_urgent {
                    (*hints).flags |= XUrgencyHint;
                } else {
                    (*hints).flags &= !XUrgencyHint;
                 }

                (xlib.XSetWMHints)(xlib_display as _, xlib_window as _, hints);

                (xlib.XFree)(hints as *mut raw::c_void);
            }
        }

    }

    #[cfg(not(any(target_os = "linux", target_os = "freebsd", target_os = "dragonfly", target_os = "openbsd")))]
    pub fn set_urgent(&self, _: bool) {
    }

    #[cfg(any(target_os = "linux", target_os = "freebsd", target_os = "dragonfly", target_os = "openbsd"))]
    pub fn send_xim_spot(&self, x: i16, y: i16) {
        use glutin::os::unix::WindowExt;
        self.window.send_xim_spot(x, y);
    }

    #[cfg(not(any(target_os = "linux", target_os = "freebsd", target_os = "dragonfly", target_os = "openbsd")))]
    pub fn send_xim_spot(&self, _x: i16, _y: i16) {
    }

    #[cfg(not(target_os = "macos"))]
    pub fn get_window_id(&self) -> Option<usize> {
        use glutin::os::unix::WindowExt;

        match self.window.get_xlib_window() {
            Some(xlib_window) => Some(xlib_window as usize),
            None => None
        }
    }

    #[cfg(target_os = "macos")]
    pub fn get_window_id(&self) -> Option<usize> {
        None
    }
}

pub trait OsExtensions {
    fn run_os_extensions(&self) {}
}

#[cfg(not(any(target_os = "linux", target_os = "freebsd", target_os="dragonfly", target_os="openbsd")))]
impl OsExtensions for Window { }

#[cfg(any(target_os = "linux", target_os = "freebsd", target_os="dragonfly", target_os="openbsd"))]
impl OsExtensions for Window {
    fn run_os_extensions(&self) {
        use glutin::os::unix::WindowExt;
        use x11_dl::xlib::{self, XA_CARDINAL, PropModeReplace};
        use std::ffi::{CStr};
        use std::ptr;
        use libc::getpid;

        let xlib_display = self.window.get_xlib_display();
        let xlib_window = self.window.get_xlib_window();

        if let (Some(xlib_window), Some(xlib_display)) = (xlib_window, xlib_display) {
            let xlib = xlib::Xlib::open().expect("get xlib");

            // Set _NET_WM_PID to process pid
            unsafe {
                let _net_wm_pid = CStr::from_ptr(b"_NET_WM_PID\0".as_ptr() as *const _);
                let atom = (xlib.XInternAtom)(xlib_display as *mut _, _net_wm_pid.as_ptr(), 0);
                let pid = getpid();

                (xlib.XChangeProperty)(xlib_display as _, xlib_window as _, atom,
                    XA_CARDINAL, 32, PropModeReplace, &pid as *const i32 as *const u8, 1);

            }
            // Although this call doesn't actually pass any data, it does cause
            // WM_CLIENT_MACHINE to be set. WM_CLIENT_MACHINE MUST be set if _NET_WM_PID is set
            // (which we do above).
            unsafe {
                (xlib.XSetWMProperties)(xlib_display as _, xlib_window as _, ptr::null_mut(),
                    ptr::null_mut(), ptr::null_mut(), 0, ptr::null_mut(), ptr::null_mut(),
                    ptr::null_mut());
            }
        }
    }
}

impl Proxy {
    /// Wakes up the event loop of the window
    ///
    /// This is useful for triggering a draw when the renderer would otherwise
    /// be waiting on user input.
    pub fn wakeup_event_loop(&self) {
        self.inner.wakeup().unwrap();
    }
}

pub trait SetInnerSize<T> {
    fn set_inner_size<S: ToPoints>(&mut self, size: &S);
}

impl SetInnerSize<Pixels<u32>> for Window {
    fn set_inner_size<T: ToPoints>(&mut self, size: &T) {
        let size = size.to_points(self.hidpi_factor());
        self.window.set_inner_size(*size.width as _, *size.height as _);
    }
}