#![allow(clippy::too_many_arguments)]

use std::{cell::RefCell, rc::Rc};

use slog::Logger;
use smithay::{
    backend::{
        egl::display::EGLBufferReader,
        renderer::{Renderer, Texture, Transform},
        SwapBuffersError,
    },
    reexports::{
        calloop::LoopHandle,
        wayland_server::protocol::{wl_buffer, wl_surface},
    },
    utils::Rectangle,
    wayland::{
        compositor::{roles::Role, SubsurfaceRole, TraversalAction},
        data_device::DnDIconRole,
        seat::CursorImageRole,
    },
};

use crate::shell::{MyCompositorToken, MyWindowMap, SurfaceData};

struct BufferTextures<T> {
    buffer: Option<wl_buffer::WlBuffer>,
    texture: T,
}

impl<T> Drop for BufferTextures<T> {
    fn drop(&mut self) {
        if let Some(buffer) = self.buffer.take() {
            buffer.release();
        }
    }
}

pub fn draw_cursor<R, E, T>(
    renderer: &mut R,
    surface: &wl_surface::WlSurface,
    egl_buffer_reader: Option<&EGLBufferReader>,
    (x, y): (i32, i32),
    token: MyCompositorToken,
    log: &Logger,
) -> Result<(), SwapBuffersError>
where
    R: Renderer<Error = E, TextureId = T>,
    E: std::error::Error + Into<SwapBuffersError>,
    T: Texture + 'static,
{
    let (dx, dy) = match token.with_role_data::<CursorImageRole, _, _>(surface, |data| data.hotspot) {
        Ok(h) => h,
        Err(_) => {
            warn!(
                log,
                "Trying to display as a cursor a surface that does not have the CursorImage role."
            );
            (0, 0)
        }
    };
    draw_surface_tree(renderer, surface, egl_buffer_reader, (x - dx, y - dy), token, log)
}

fn draw_surface_tree<R, E, T>(
    renderer: &mut R,
    root: &wl_surface::WlSurface,
    egl_buffer_reader: Option<&EGLBufferReader>,
    location: (i32, i32),
    compositor_token: MyCompositorToken,
    log: &Logger,
) -> Result<(), SwapBuffersError>
where
    R: Renderer<Error = E, TextureId = T>,
    E: std::error::Error + Into<SwapBuffersError>,
    T: Texture + 'static,
{
    let mut result = Ok(());

    compositor_token.with_surface_tree_upward(
        root,
        (),
        |_surface, attributes, _, _| {
            // Pull a new buffer if available
            if let Some(data) = attributes.user_data.get::<RefCell<SurfaceData>>() {
                let mut data = data.borrow_mut();
                if data.texture.is_none() {
                    if let Some(buffer) = data.current_state.buffer.take() {
                        match renderer.import_buffer(&buffer, Some(&attributes), egl_buffer_reader) {
                            Ok(m) => {
                                let buffer = if smithay::wayland::shm::with_buffer_contents(&buffer, |_,_| ()).is_ok() {
                                    buffer.release();
                                    None
                                } else {
                                    Some(buffer)
                                };
                                data.texture = Some(Box::new(BufferTextures { buffer, texture: m })
                                    as Box<dyn std::any::Any + 'static>)
                            }
                            // there was an error reading the buffer, release it, we
                            // already logged the error
                            Err(err) => {
                                warn!(log, "Error loading buffer: {:?}", err);
                                buffer.release();
                            }
                        };
                    }
                }
                // Now, should we be drawn ?
                if data.texture.is_some() {
                    TraversalAction::DoChildren(())
                } else {
                    // we are not displayed, so our children are neither
                    TraversalAction::SkipChildren
                }
            } else {
                // we are not displayed, so our children are neither
                TraversalAction::SkipChildren
            }
        },
        |_, _, _, _| {},
        |_, _, _, _| true,
    );

    compositor_token.with_surface_tree_upward(
        root,
        location,
        |_surface, attributes, role, &(mut x, mut y)| {
            // Pull a new buffer if available
            if let Some(data) = attributes.user_data.get::<RefCell<SurfaceData>>() {
                let data = data.borrow();
                // Now, should we be drawn ?
                if data.texture.is_some() {
                    // if yes, also process the children
                    if Role::<SubsurfaceRole>::has(role) {
                        x += data.current_state.sub_location.0;
                        y += data.current_state.sub_location.1;
                    }
                    TraversalAction::DoChildren((x, y))
                } else {
                    // we are not displayed, so our children are neither
                    TraversalAction::SkipChildren
                }
            } else {
                // we are not displayed, so our children are neither
                TraversalAction::SkipChildren
            }
        },
        |_surface, attributes, role, &(mut x, mut y)| {
            if let Some(ref data) = attributes.user_data.get::<RefCell<SurfaceData>>() {
                let mut data = data.borrow_mut();
                let (sub_x, sub_y) = data.current_state.sub_location;
                if let Some(texture) = data
                    .texture
                    .as_mut()
                    .and_then(|x| x.downcast_mut::<BufferTextures<T>>())
                {
                    // we need to re-extract the subsurface offset, as the previous closure
                    // only passes it to our children
                    if Role::<SubsurfaceRole>::has(role) {
                        x += sub_x;
                        y += sub_y;
                    }
                    if let Err(err) = renderer.render_texture_at(
                        &texture.texture,
                        (x, y),
                        Transform::Normal, /* TODO */
                        1.0,
                    ) {
                        result = Err(err.into());
                    }
                }
            }
        },
        |_, _, _, _| true,
    );

    result
}

pub fn draw_windows<R, E, T>(
    renderer: &mut R,
    egl_buffer_reader: Option<&EGLBufferReader>,
    window_map: &MyWindowMap,
    output_rect: Option<Rectangle>,
    compositor_token: MyCompositorToken,
    log: &::slog::Logger,
) -> Result<(), SwapBuffersError>
where
    R: Renderer<Error = E, TextureId = T>,
    E: std::error::Error + Into<SwapBuffersError>,
    T: Texture + 'static,
{
    let mut result = Ok(());

    // redraw the frame, in a simple but inneficient way
    window_map.with_windows_from_bottom_to_top(|toplevel_surface, mut initial_place, bounding_box| {
        // skip windows that do not overlap with a given output
        if let Some(output) = output_rect {
            if !output.overlaps(bounding_box) {
                return;
            }
            initial_place.0 -= output.x;
        }
        if let Some(wl_surface) = toplevel_surface.get_surface() {
            // this surface is a root of a subsurface tree that needs to be drawn
            if let Err(err) = draw_surface_tree(
                renderer,
                &wl_surface,
                egl_buffer_reader,
                initial_place,
                compositor_token,
                log,
            ) {
                result = Err(err);
            }
        }
    });

    result
}

pub fn draw_dnd_icon<R, E, T>(
    renderer: &mut R,
    surface: &wl_surface::WlSurface,
    egl_buffer_reader: Option<&EGLBufferReader>,
    (x, y): (i32, i32),
    token: MyCompositorToken,
    log: &::slog::Logger,
) -> Result<(), SwapBuffersError>
where
    R: Renderer<Error = E, TextureId = T>,
    E: std::error::Error + Into<SwapBuffersError>,
    T: Texture + 'static,
{
    if !token.has_role::<DnDIconRole>(surface) {
        warn!(
            log,
            "Trying to display as a dnd icon a surface that does not have the DndIcon role."
        );
    }
    draw_surface_tree(renderer, surface, egl_buffer_reader, (x, y), token, log)
}

pub fn schedule_initial_render<R: Renderer + 'static, Data: 'static>(
    renderer: Rc<RefCell<R>>,
    evt_handle: &LoopHandle<Data>,
    logger: ::slog::Logger,
) where
    <R as Renderer>::Error: Into<SwapBuffersError>,
{
    let result = {
        let mut renderer = renderer.borrow_mut();
        // Does not matter if we render an empty frame
        renderer
            .begin(1, 1, Transform::Normal)
            .map_err(Into::<SwapBuffersError>::into)
            .and_then(|_| {
                renderer
                    .clear([0.8, 0.8, 0.9, 1.0])
                    .map_err(Into::<SwapBuffersError>::into)
            })
            .and_then(|_| renderer.finish())
    };
    if let Err(err) = result {
        match err {
            SwapBuffersError::AlreadySwapped => {}
            SwapBuffersError::TemporaryFailure(err) => {
                // TODO dont reschedule after 3(?) retries
                warn!(logger, "Failed to submit page_flip: {}", err);
                let handle = evt_handle.clone();
                evt_handle.insert_idle(move |_| schedule_initial_render(renderer, &handle, logger));
            }
            SwapBuffersError::ContextLost(err) => panic!("Rendering loop lost: {}", err),
        }
    }
}