// 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;
#[cfg(not(any(target_os = "macos", windows)))]
use std::ffi::c_void;
use std::fmt::Display;

use glutin::dpi::{LogicalPosition, LogicalSize, PhysicalSize};
#[cfg(target_os = "macos")]
use glutin::os::macos::WindowExt;
#[cfg(not(any(target_os = "macos", windows)))]
use glutin::os::unix::{EventsLoopExt, WindowExt};
#[cfg(not(target_os = "macos"))]
use glutin::Icon;
#[cfg(not(any(target_os = "macos", windows)))]
use glutin::Window as GlutinWindow;
use glutin::{
    self, ContextBuilder, ControlFlow, Event, EventsLoop, MouseCursor, PossiblyCurrent,
    WindowBuilder,
};
#[cfg(not(target_os = "macos"))]
use image::ImageFormat;
#[cfg(not(any(target_os = "macos", windows)))]
use x11_dl::xlib::{Xlib, Display as XDisplay, PropModeReplace, XErrorEvent};

use crate::config::{Config, Decorations, StartupMode, WindowConfig};
use crate::gl;

// It's required to be in this directory due to the `windows.rc` file
#[cfg(not(target_os = "macos"))]
static WINDOW_ICON: &[u8] = include_bytes!("../../extra/windows/alacritty.ico");

/// Default Alacritty name, used for window title and class.
pub const DEFAULT_NAME: &str = "Alacritty";

/// 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,
    windowed_context: glutin::WindowedContext<PossiblyCurrent>,
    mouse_visible: bool,

    /// Keep track of the current mouse cursor to avoid unnecessarily changing it
    current_mouse_cursor: MouseCursor,

    /// 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: f64,
}

impl ::std::error::Error for Error {
    fn cause(&self) -> Option<&dyn (::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)
    }
}

fn create_gl_window(
    mut window: WindowBuilder,
    event_loop: &EventsLoop,
    srgb: bool,
    dimensions: Option<LogicalSize>,
) -> Result<glutin::WindowedContext<PossiblyCurrent>> {
    if let Some(dimensions) = dimensions {
        window = window.with_dimensions(dimensions);
    }

    let windowed_context = ContextBuilder::new()
        .with_srgb(srgb)
        .with_vsync(true)
        .with_hardware_acceleration(None)
        .build_windowed(window, event_loop)?;

    // Make the context current so OpenGL operations can run
    let windowed_context = unsafe { windowed_context.make_current().map_err(|(_, e)| e)? };

    Ok(windowed_context)
}

impl Window {
    /// Create a new window
    ///
    /// This creates a window and fully initializes a window.
    pub fn new(
        event_loop: EventsLoop,
        config: &Config,
        dimensions: Option<LogicalSize>,
    ) -> Result<Window> {
        let title = config.window.title.as_ref().map_or(DEFAULT_NAME, |t| t);

        let window_builder = Window::get_platform_window(title, &config.window);
        let windowed_context =
            create_gl_window(window_builder.clone(), &event_loop, false, dimensions)
                .or_else(|_| create_gl_window(window_builder, &event_loop, true, dimensions))?;
        let window = windowed_context.window();

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

        // Set OpenGL symbol loader. This call MUST be after window.make_current on windows.
        gl::load_with(|symbol| windowed_context.get_proc_address(symbol) as *const _);

        // On X11, embed the window inside another if the parent ID has been set
        #[cfg(not(any(target_os = "macos", windows)))]
        {
            if event_loop.is_x11() {
                if let Some(parent_window_id) = config.window.embed {
                    x_embed_window(window, parent_window_id);
                }
            }
        }

        let window = Window {
            event_loop,
            current_mouse_cursor: MouseCursor::Default,
            windowed_context,
            mouse_visible: true,
            is_focused: false,
        };

        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().get_hidpi_factor() }
    }

    pub fn inner_size_pixels(&self) -> Option<LogicalSize> {
        self.window().get_inner_size()
    }

    pub fn set_inner_size(&mut self, size: LogicalSize) {
        self.window().set_inner_size(size);
    }

    #[inline]
    pub fn hidpi_factor(&self) -> f64 {
        self.window().get_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.windowed_context.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, size: PhysicalSize) {
        self.windowed_context.resize(size);
    }

    /// Show window
    #[inline]
    pub fn show(&self) {
        self.window().show();
    }

    /// 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(&mut self, cursor: MouseCursor) {
        if cursor != self.current_mouse_cursor {
            self.current_mouse_cursor = cursor;
            self.window().set_cursor(cursor);
        }
    }

    /// Set mouse cursor visible
    pub fn set_mouse_visible(&mut self, visible: bool) {
        if visible != self.mouse_visible {
            self.mouse_visible = visible;
            self.window().hide_cursor(!visible);
        }
    }

    #[cfg(not(any(target_os = "macos", windows)))]
    pub fn get_platform_window(title: &str, window_config: &WindowConfig) -> WindowBuilder {
        use glutin::os::unix::WindowBuilderExt;

        let decorations = match window_config.decorations {
            Decorations::None => false,
            _ => true,
        };

        let icon = Icon::from_bytes_with_format(WINDOW_ICON, ImageFormat::ICO);

        let class = &window_config.class;

        let mut builder = WindowBuilder::new()
            .with_title(title)
            .with_visibility(false)
            .with_transparency(true)
            .with_decorations(decorations)
            .with_maximized(window_config.startup_mode() == StartupMode::Maximized)
            .with_window_icon(icon.ok())
            // X11
            .with_class(class.instance.clone(), class.general.clone())
            // Wayland
            .with_app_id(class.instance.clone());

        if let Some(ref val) = window_config.gtk_theme_variant {
            builder = builder.with_gtk_theme_variant(val.clone())
        }

        builder
    }

    #[cfg(windows)]
    pub fn get_platform_window(title: &str, window_config: &WindowConfig) -> WindowBuilder {
        let decorations = match window_config.decorations {
            Decorations::None => false,
            _ => true,
        };

        let icon = Icon::from_bytes_with_format(WINDOW_ICON, ImageFormat::ICO);

        WindowBuilder::new()
            .with_title(title)
            .with_visibility(cfg!(windows))
            .with_decorations(decorations)
            .with_transparency(true)
            .with_maximized(window_config.startup_mode() == StartupMode::Maximized)
            .with_window_icon(icon.ok())
    }

    #[cfg(target_os = "macos")]
    pub fn get_platform_window(title: &str, window_config: &WindowConfig) -> WindowBuilder {
        use glutin::os::macos::WindowBuilderExt;

        let window = WindowBuilder::new()
            .with_title(title)
            .with_visibility(false)
            .with_transparency(true)
            .with_maximized(window_config.startup_mode() == StartupMode::Maximized);

        match window_config.decorations {
            Decorations::Full => window,
            Decorations::Transparent => window
                .with_title_hidden(true)
                .with_titlebar_transparent(true)
                .with_fullsize_content_view(true),
            Decorations::Buttonless => window
                .with_title_hidden(true)
                .with_titlebar_buttons_hidden(true)
                .with_titlebar_transparent(true)
                .with_fullsize_content_view(true),
            Decorations::None => window.with_titlebar_hidden(true),
        }
    }

    #[cfg(not(any(target_os = "macos", windows)))]
    pub fn set_urgent(&self, is_urgent: bool) {
        self.window().set_urgent(is_urgent);
    }

    #[cfg(target_os = "macos")]
    pub fn set_urgent(&self, is_urgent: bool) {
        self.window().request_user_attention(is_urgent);
    }

    #[cfg(windows)]
    pub fn set_urgent(&self, _is_urgent: bool) {}

    pub fn set_ime_spot(&self, pos: LogicalPosition) {
        self.window().set_ime_spot(pos);
    }

    pub fn set_position(&self, pos: LogicalPosition) {
        self.window().set_position(pos);
    }

    #[cfg(not(any(target_os = "macos", target_os = "windows")))]
    pub fn get_window_id(&self) -> Option<usize> {
        match self.window().get_xlib_window() {
            Some(xlib_window) => Some(xlib_window as usize),
            None => None,
        }
    }

    #[cfg(not(any(target_os = "macos", target_os = "windows")))]
    pub fn is_x11(&self) -> bool {
        self.event_loop.is_x11()
    }

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

    /// Hide the window
    pub fn hide(&self) {
        self.window().hide();
    }

    /// Fullscreens the window on the current monitor.
    pub fn set_fullscreen(&self, fullscreen: bool) {
        let glutin_window = self.window();
        if fullscreen {
            let current_monitor = glutin_window.get_current_monitor();
            glutin_window.set_fullscreen(Some(current_monitor));
        } else {
            glutin_window.set_fullscreen(None);
        }
    }

    pub fn set_maximized(&self, maximized: bool) {
        self.window().set_maximized(maximized);
    }

    #[cfg(target_os = "macos")]
    pub fn set_simple_fullscreen(&self, fullscreen: bool) {
        self.window().set_simple_fullscreen(fullscreen);
    }

    #[cfg(not(any(target_os = "macos", target_os = "windows")))]
    pub fn get_wayland_display(&self) -> Option<*mut c_void> {
        self.window().get_wayland_display()
    }

    fn window(&self) -> &glutin::Window {
        self.windowed_context.window()
    }
}

#[cfg(not(any(target_os = "macos", windows)))]
fn x_embed_window(window: &GlutinWindow, parent_id: u64) {
    let (xlib_display, xlib_window) = match (window.get_xlib_display(), window.get_xlib_window()) {
        (Some(display), Some(window)) => (display, window),
        _ => return,
    };

    let xlib = Xlib::open().expect("get xlib");

    unsafe {
        let atom = (xlib.XInternAtom)(xlib_display as *mut _, "_XEMBED".as_ptr() as *const _, 0);
        (xlib.XChangeProperty)(
            xlib_display as _,
            xlib_window as _,
            atom,
            atom,
            32,
            PropModeReplace,
            [0, 1].as_ptr(),
            2,
        );

        // Register new error handler
        let old_handler = (xlib.XSetErrorHandler)(Some(xembed_error_handler));

        // Check for the existence of the target before attempting reparenting
        (xlib.XReparentWindow)(xlib_display as _, xlib_window as _, parent_id, 0, 0);

        // Drain errors and restore original error handler
        (xlib.XSync)(xlib_display as _, 0);
        (xlib.XSetErrorHandler)(old_handler);
    }
}

#[cfg(not(any(target_os = "macos", windows)))]
unsafe extern "C" fn xembed_error_handler(_: *mut XDisplay, _: *mut XErrorEvent) -> i32 {
    die!("Could not embed into specified window.");
}

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();
    }
}