//! Implementation of the multi-gpu [`GraphicsApi`] using
//! user provided GBM devices and OpenGL ES for rendering.

use tracing::warn;
#[cfg(all(feature = "wayland_frontend", feature = "use_system_lib"))]
use wayland_server::protocol::wl_buffer;

use crate::backend::{
    allocator::{
        dmabuf::{AnyError, Dmabuf, DmabufAllocator},
        gbm::{GbmAllocator, GbmBufferFlags, GbmDevice},
        Allocator,
    },
    drm::{CreateDrmNodeError, DrmNode},
    egl::{context::ContextPriority, EGLContext, EGLDisplay, Error as EGLError},
    renderer::{
        gles::{GlesError, GlesRenderer},
        multigpu::{ApiDevice, Error as MultiError, GraphicsApi},
        Renderer, RendererSuper,
    },
    SwapBuffersError,
};
#[cfg(all(feature = "wayland_frontend", feature = "use_system_lib"))]
use crate::{
    backend::{
        allocator::Buffer as BufferTrait,
        egl::display::EGLBufferReader,
        renderer::{
            multigpu::{Error as MultigpuError, MultiRenderer, MultiTexture},
            Bind, ExportMem, ImportDma, ImportEgl, ImportMem,
        },
    },
    utils::{Buffer as BufferCoords, Rectangle},
};
#[cfg(all(feature = "wayland_frontend", feature = "use_system_lib"))]
use std::borrow::BorrowMut;
use std::{
    collections::HashMap,
    fmt,
    os::unix::prelude::AsFd,
    sync::atomic::{AtomicBool, Ordering},
};

/// Errors raised by the [`GbmGlesBackend`]
#[derive(Debug, thiserror::Error)]
pub enum Error {
    /// EGL api error
    #[error(transparent)]
    Egl(#[from] EGLError),
    /// OpenGL error
    #[error(transparent)]
    Gl(#[from] GlesError),
    /// Error creating a drm node
    #[error(transparent)]
    DrmNode(#[from] CreateDrmNodeError),
}

impl From<Error> for SwapBuffersError {
    #[inline]
    fn from(err: Error) -> SwapBuffersError {
        match err {
            x @ Error::DrmNode(_) | x @ Error::Egl(_) => SwapBuffersError::ContextLost(Box::new(x)),
            Error::Gl(x) => x.into(),
        }
    }
}

type Factory = Box<dyn Fn(&EGLDisplay) -> Result<GlesRenderer, Error>>;

/// A [`GraphicsApi`] utilizing user-provided GBM Devices and OpenGL ES for rendering.
pub struct GbmGlesBackend<R, A: AsFd + 'static> {
    devices: HashMap<DrmNode, (EGLDisplay, GbmAllocator<A>)>,
    factory: Option<Factory>,
    context_priority: Option<ContextPriority>,
    allocator_flags: GbmBufferFlags,
    needs_enumeration: AtomicBool,
    _renderer: std::marker::PhantomData<R>,
}

impl<R, A: AsFd + fmt::Debug + 'static> fmt::Debug for GbmGlesBackend<R, A> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("GbmGlesBackend")
            .field("devices", &self.devices)
            .finish()
    }
}

impl<R, A: AsFd + 'static> Default for GbmGlesBackend<R, A> {
    #[inline]
    fn default() -> Self {
        GbmGlesBackend {
            devices: HashMap::new(),
            factory: None,
            context_priority: None,
            allocator_flags: GbmBufferFlags::RENDERING,
            needs_enumeration: AtomicBool::new(true),
            _renderer: std::marker::PhantomData,
        }
    }
}

impl<R, A: AsFd + Clone + Send + 'static> GbmGlesBackend<R, A> {
    /// Initialize a new [`GbmGlesBackend`] with a factory for instantiating [`GlesRenderer`]s
    pub fn with_factory<F>(factory: F) -> Self
    where
        F: Fn(&EGLDisplay) -> Result<GlesRenderer, Error> + 'static,
    {
        Self {
            factory: Some(Box::new(factory)),
            ..Default::default()
        }
    }

    /// Initialize a new [`GbmGlesBackend`] with a [`ContextPriority`] for instantiating [`GlesRenderer`]s
    ///
    /// Note: This is mutually exclusive with [`GbmGlesBackend::with_factory`](GbmGlesBackend::with_factory),
    /// but you can create an [`EGLContext`] with a specific [`ContextPriority`] within your factory.
    /// See [`EGLContext::new_with_priority`] for more information.
    pub fn with_context_priority(priority: ContextPriority) -> Self {
        Self {
            context_priority: Some(priority),
            ..Default::default()
        }
    }

    /// Sets the default flags to use for allocating buffers via the [`GbmAllocator`]
    /// provided by these backends devices.
    ///
    /// Only affects nodes added via [`add_node`][Self::add_node] *after* calling this method.
    pub fn set_allocator_flags(&mut self, flags: GbmBufferFlags) {
        self.allocator_flags = flags;
    }

    /// Add a new GBM device for a given node to the api
    pub fn add_node(&mut self, node: DrmNode, gbm: GbmDevice<A>) -> Result<(), EGLError> {
        if self.devices.contains_key(&node) {
            return Ok(());
        }

        let allocator = GbmAllocator::new(gbm.clone(), self.allocator_flags);
        self.devices
            .insert(node, (unsafe { EGLDisplay::new(gbm)? }, allocator));
        self.needs_enumeration.store(true, Ordering::SeqCst);
        Ok(())
    }

    /// Remove a given node from the api
    pub fn remove_node(&mut self, node: &DrmNode) {
        if self.devices.remove(node).is_some() {
            self.needs_enumeration.store(true, Ordering::SeqCst);
        }
    }
}

impl<R: From<GlesRenderer> + Renderer<Error = GlesError>, A: AsFd + Clone + 'static> GraphicsApi
    for GbmGlesBackend<R, A>
{
    type Device = GbmGlesDevice<R>;
    type Error = Error;

    fn enumerate(&self, list: &mut Vec<Self::Device>) -> Result<(), Self::Error> {
        self.needs_enumeration.store(false, Ordering::SeqCst);

        // remove old stuff
        list.retain(|renderer| {
            self.devices
                .keys()
                .any(|node| renderer.node.dev_id() == node.dev_id())
        });

        // add new stuff
        let new_renderers = self
            .devices
            .iter()
            .filter(|(node, _)| {
                !list
                    .iter()
                    .any(|renderer| renderer.node.dev_id() == node.dev_id())
            })
            .map(|(node, (display, gbm))| {
                let renderer = if let Some(factory) = self.factory.as_ref() {
                    factory(display)?.into()
                } else {
                    let context =
                        EGLContext::new_with_priority(display, self.context_priority.unwrap_or_default())
                            .map_err(Error::Egl)?;
                    unsafe { GlesRenderer::new(context).map_err(Error::Gl)? }.into()
                };

                Ok(GbmGlesDevice {
                    node: *node,
                    _display: display.clone(),
                    renderer,
                    allocator: Box::new(DmabufAllocator(gbm.clone())),
                })
            })
            .flat_map(|x: Result<GbmGlesDevice<R>, Error>| match x {
                Ok(x) => Some(x),
                Err(x) => {
                    warn!("Skipping GbmDevice: {}", x);
                    None
                }
            })
            .collect::<Vec<GbmGlesDevice<R>>>();
        list.extend(new_renderers);

        // but don't replace already initialized renderers

        Ok(())
    }

    fn needs_enumeration(&self) -> bool {
        self.needs_enumeration.load(Ordering::Acquire)
    }

    fn identifier() -> &'static str {
        "gbm_gles"
    }
}

// TODO: Replace with specialization impl in multigpu/mod once possible
impl<T: GraphicsApi, R: From<GlesRenderer> + Renderer<Error = GlesError>, A: AsFd + Clone + 'static>
    std::convert::From<GlesError> for MultiError<GbmGlesBackend<R, A>, T>
where
    T::Error: 'static,
    <<T::Device as ApiDevice>::Renderer as RendererSuper>::Error: 'static,
{
    #[inline]
    fn from(err: GlesError) -> MultiError<GbmGlesBackend<R, A>, T> {
        MultiError::Render(err)
    }
}

/// [`ApiDevice`] of the [`GbmGlesBackend`]
pub struct GbmGlesDevice<R> {
    node: DrmNode,
    renderer: R,
    allocator: Box<dyn Allocator<Buffer = Dmabuf, Error = AnyError>>,
    _display: EGLDisplay,
}

impl<R: Renderer> fmt::Debug for GbmGlesDevice<R> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("GbmGlesDevice")
            .field("node", &self.node)
            .field("renderer", &self.renderer)
            .finish_non_exhaustive()
    }
}

impl<R: Renderer> ApiDevice for GbmGlesDevice<R> {
    type Renderer = R;

    fn renderer(&self) -> &Self::Renderer {
        &self.renderer
    }
    fn renderer_mut(&mut self) -> &mut Self::Renderer {
        &mut self.renderer
    }
    fn allocator(&mut self) -> &mut dyn Allocator<Buffer = Dmabuf, Error = AnyError> {
        self.allocator.as_mut()
    }
    fn node(&self) -> &DrmNode {
        &self.node
    }
}

#[cfg(all(feature = "wayland_frontend", feature = "use_system_lib"))]
impl<R, A> ImportEgl for MultiRenderer<'_, '_, GbmGlesBackend<R, A>, GbmGlesBackend<R, A>>
where
    A: AsFd + Clone + 'static,
    R: From<GlesRenderer>
        + BorrowMut<GlesRenderer>
        + Renderer<Error = GlesError>
        + Bind<Dmabuf>
        + ImportDma
        + ImportMem
        + ImportEgl
        + ExportMem
        + 'static,
    R::TextureId: Clone + Send,
{
    fn bind_wl_display(&mut self, display: &wayland_server::DisplayHandle) -> Result<(), EGLError> {
        self.render.renderer_mut().bind_wl_display(display)
    }
    fn unbind_wl_display(&mut self) {
        self.render.renderer_mut().unbind_wl_display()
    }
    fn egl_reader(&self) -> Option<&EGLBufferReader> {
        self.render.renderer().egl_reader()
    }

    #[profiling::function]
    fn import_egl_buffer(
        &mut self,
        buffer: &wl_buffer::WlBuffer,
        surface: Option<&crate::wayland::compositor::SurfaceData>,
        damage: &[Rectangle<i32, BufferCoords>],
    ) -> Result<Self::TextureId, Self::Error> {
        if let Some(dmabuf) = Self::try_import_egl(self.render.renderer_mut(), buffer)
            .ok()
            .or_else(|| {
                self.target
                    .as_mut()
                    .and_then(|renderer| Self::try_import_egl(renderer.device.renderer_mut(), buffer).ok())
            })
            .or_else(|| {
                self.other_renderers
                    .iter_mut()
                    .find_map(|renderer| Self::try_import_egl(renderer.renderer_mut(), buffer).ok())
            })
        {
            let texture = MultiTexture::from_surface(surface, dmabuf.size(), dmabuf.format());
            let texture_ref = texture.0.clone();
            let res = self.import_dmabuf_internal(&dmabuf, texture, Some(damage));
            if res.is_ok() {
                if let Some(surface) = surface {
                    surface.data_map.insert_if_missing_threadsafe(|| texture_ref);
                }
            }
            return res;
        }

        Err(MultigpuError::DeviceMissing)
    }
}

#[cfg(all(feature = "wayland_frontend", feature = "use_system_lib"))]
impl<R, A> MultiRenderer<'_, '_, GbmGlesBackend<R, A>, GbmGlesBackend<R, A>>
where
    A: AsFd + Clone + 'static,
    R: From<GlesRenderer>
        + BorrowMut<GlesRenderer>
        + Renderer<Error = GlesError>
        + ImportDma
        + ImportMem
        + ImportEgl
        + ExportMem
        + 'static,
{
    #[profiling::function]
    fn try_import_egl(
        renderer: &mut R,
        buffer: &wl_buffer::WlBuffer,
    ) -> Result<Dmabuf, MultigpuError<GbmGlesBackend<R, A>, GbmGlesBackend<R, A>>> {
        if !renderer
            .borrow_mut()
            .extensions
            .iter()
            .any(|ext| ext == "GL_OES_EGL_image")
        {
            return Err(MultigpuError::Render(GlesError::GLExtensionNotSupported(&[
                "GL_OES_EGL_image",
            ])));
        }

        if renderer.egl_reader().is_none() {
            return Err(MultigpuError::Render(GlesError::EGLBufferAccessError(
                crate::backend::egl::BufferAccessError::NotManaged(crate::backend::egl::EGLError::BadDisplay),
            )));
        }

        unsafe {
            renderer
                .borrow_mut()
                .egl_context()
                .make_current()
                .map_err(GlesError::from)
                .map_err(MultigpuError::Render)?
        };

        let egl = renderer
            .egl_reader()
            .as_ref()
            .unwrap()
            .egl_buffer_contents(buffer)
            .map_err(GlesError::EGLBufferAccessError)
            .map_err(MultigpuError::Render)?;
        renderer
            .borrow_mut()
            .egl_context()
            .display()
            .create_dmabuf_from_image(egl.image(0).unwrap(), egl.size, egl.y_inverted)
            .map_err(GlesError::BindBufferEGLError)
            .map_err(MultigpuError::Render)
    }
}