use glium::glutin;
use glium::glutin::event::{Event, WindowEvent};
use glium::glutin::event_loop::{ControlFlow, EventLoop};
use glium::glutin::window::WindowBuilder;
use glium::{Display, Surface};
use imgui::{Context, FontConfig, FontGlyphRanges, FontSource, Ui, ViewportFlags};
use imgui_glium_renderer::Renderer;
use imgui_winit_support::{HiDpiMode, WinitPlatform};
use std::collections::HashMap;
use std::path::Path;
use std::time::Instant;

mod clipboard;

pub struct System {
    pub event_loop: EventLoop<()>,
    pub display: glium::Display,
    pub imgui: Context,
    pub platform: WinitPlatform,
    pub renderer: Renderer,
    pub font_size: f32,
}

pub fn init(title: &str) -> System {
    let title = match Path::new(&title).file_name() {
        Some(file_name) => file_name.to_str().unwrap(),
        None => title,
    };
    let event_loop = EventLoop::new();
    let context = glutin::ContextBuilder::new().with_vsync(true);
    let builder = WindowBuilder::new()
        .with_title(title.to_owned())
        .with_inner_size(glutin::dpi::LogicalSize::new(1024f64, 768f64));
    let display =
        Display::new(builder, context, &event_loop).expect("Failed to initialize display");

    let mut imgui = Context::create();
    imgui.set_ini_filename(None);

    if let Some(backend) = clipboard::init() {
        imgui.set_clipboard_backend(backend);
    } else {
        eprintln!("Failed to initialize clipboard");
    }

    let mut platform = WinitPlatform::init(&mut imgui);
    WinitPlatform::init_viewports(&mut imgui, display.gl_window().window(), &event_loop);
    {
        let gl_window = display.gl_window();
        let window = gl_window.window();

        let dpi_mode = if let Ok(factor) = std::env::var("IMGUI_EXAMPLE_FORCE_DPI_FACTOR") {
            // Allow forcing of HiDPI factor for debugging purposes
            match factor.parse::<f64>() {
                Ok(f) => HiDpiMode::Locked(f),
                Err(e) => panic!("Invalid scaling factor: {}", e),
            }
        } else {
            HiDpiMode::Default
        };

        platform.attach_window(imgui.io_mut(), window, dpi_mode);
    }

    // Fixed font size. Note imgui_winit_support uses "logical
    // pixels", which are physical pixels scaled by the devices
    // scaling factor. Meaning, 13.0 pixels should look the same size
    // on two different screens, and thus we do not need to scale this
    // value (as the scaling is handled by winit)
    let font_size = 13.0;

    imgui.fonts().add_font(&[
        FontSource::TtfData {
            data: include_bytes!("../../../resources/Roboto-Regular.ttf"),
            size_pixels: font_size,
            config: Some(FontConfig {
                // As imgui-glium-renderer isn't gamma-correct with
                // it's font rendering, we apply an arbitrary
                // multiplier to make the font a bit "heavier". With
                // default imgui-glow-renderer this is unnecessary.
                rasterizer_multiply: 1.5,
                // Oversampling font helps improve text rendering at
                // expense of larger font atlas texture.
                oversample_h: 4,
                oversample_v: 4,
                ..FontConfig::default()
            }),
        },
        FontSource::TtfData {
            data: include_bytes!("../../../resources/mplus-1p-regular.ttf"),
            size_pixels: font_size,
            config: Some(FontConfig {
                // Oversampling font helps improve text rendering at
                // expense of larger font atlas texture.
                oversample_h: 4,
                oversample_v: 4,
                // Range of glyphs to rasterize
                glyph_ranges: FontGlyphRanges::japanese(),
                ..FontConfig::default()
            }),
        },
    ]);

    let renderer = Renderer::init(&mut imgui, &display).expect("Failed to initialize renderer");

    System {
        event_loop,
        display,
        imgui,
        platform,
        renderer,
        font_size,
    }
}

struct ViewportStorage<'a, T: 'static> {
    event_loop: &'a glium::glutin::event_loop::EventLoopWindowTarget<T>,
    viewports: &'a mut HashMap<imgui::Id, glium::glutin::window::Window>,
}

impl<'a, T> imgui_winit_support::WinitPlatformViewportStorage for ViewportStorage<'a, T> {
    fn create_window(&mut self, id: imgui::Id, flags: imgui::ViewportFlags) {
        let builder = WindowBuilder::new()
            .with_always_on_top(flags.contains(ViewportFlags::TOP_MOST))
            // .with_decorations(!flags.contains(ViewportFlags::NO_DECORATION))
            .with_resizable(true)
            .with_visible(false);

        let window = builder.build(self.event_loop).unwrap();
        self.viewports.insert(id, window);
    }

    fn remove_windows(&mut self, filter: impl Fn(imgui::Id) -> bool) {
        self.viewports.retain(|id, _| !filter(*id));
    }

    fn get_window(
        &mut self,
        id: glium::glutin::window::WindowId,
    ) -> Option<(imgui::Id, &glium::glutin::window::Window)> {
        let res = self
            .viewports
            .iter()
            .find(|(_, wnd)| wnd.id() == id)
            .map(|(id, wnd)| (*id, wnd));
        res
    }

    fn for_each(&mut self, mut func: impl FnMut(imgui::Id, &glium::glutin::window::Window)) {
        for (id, wnd) in self.viewports.iter() {
            func(*id, wnd);
        }
    }
}

impl System {
    pub fn main_loop<F: FnMut(&mut bool, &mut Ui) + 'static>(self, mut run_ui: F) {
        let System {
            event_loop,
            display,
            mut imgui,
            mut platform,
            mut renderer,
            ..
        } = self;
        let mut last_frame = Instant::now();

        let mut viewports = HashMap::new();

        event_loop.run(move |event, window_target, control_flow| match event {
            Event::NewEvents(_) => {
                let now = Instant::now();
                imgui.io_mut().update_delta_time(now - last_frame);
                last_frame = now;
            }
            Event::MainEventsCleared => {
                let gl_window = display.gl_window();
                platform
                    .prepare_frame(imgui.io_mut(), gl_window.window())
                    .expect("Failed to prepare frame");
                gl_window.window().request_redraw();

                let mut storage = ViewportStorage {
                    event_loop: window_target,
                    viewports: &mut viewports,
                };
                platform.update_viewports(&mut imgui, &mut storage);
            }
            Event::RedrawRequested(_) => {
                let ui = imgui.frame();

                let mut run = true;
                run_ui(&mut run, ui);
                if !run {
                    *control_flow = ControlFlow::Exit;
                }

                let gl_window = display.gl_window();
                let mut target = display.draw();
                target.clear_color_srgb(1.0, 1.0, 1.0, 1.0);
                platform.prepare_render(ui, gl_window.window());
                let draw_data = imgui.render();
                renderer
                    .render(&mut target, draw_data)
                    .expect("Rendering failed");
                target.finish().expect("Failed to swap buffers");

                imgui.update_platform_windows();
            }
            Event::WindowEvent {
                event: WindowEvent::CloseRequested,
                window_id,
                ..
            } if window_id == display.gl_window().window().id() => {
                *control_flow = ControlFlow::Exit
            }
            event => {
                let gl_window = display.gl_window();
                platform.handle_event(imgui.io_mut(), gl_window.window(), &event);

                let mut storage = ViewportStorage {
                    event_loop: window_target,
                    viewports: &mut viewports,
                };
                platform.handle_viewport_event(
                    &mut imgui,
                    gl_window.window(),
                    &mut storage,
                    &event,
                );
            }
        })
    }
}