/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

#![deny(unsafe_code)]

use std::cell::RefCell;
use std::ffi::c_void;
use std::rc::Rc;

use euclid::default::Size2D;
use gleam::gl;
use log::{debug, warn};
use servo_media::player::context::{GlContext, NativeDisplay};
use surfman::chains::{PreserveBuffer, SwapChain};
#[cfg(all(target_os = "linux", not(target_env = "ohos")))]
use surfman::platform::generic::multi::connection::NativeConnection as LinuxNativeConnection;
#[cfg(all(target_os = "linux", not(target_env = "ohos")))]
use surfman::platform::generic::multi::context::NativeContext as LinuxNativeContext;
pub use surfman::Error;
use surfman::{
    Adapter, Connection, Context, ContextAttributeFlags, ContextAttributes, Device, GLApi,
    NativeContext, NativeDevice, NativeWidget, Surface, SurfaceAccess, SurfaceInfo, SurfaceTexture,
    SurfaceType,
};

/// Describes the OpenGL version that is requested when a context is created.
pub enum GLVersion {
    GL(u8, u8),
    GLES(u8, u8),
}

/// The `RenderingContext` trait defines a set of methods for managing
/// an OpenGL or GLES rendering context.
/// Implementors of this trait are responsible for handling the creation,
/// management, and destruction of the rendering context and its associated
/// resources.
pub trait RenderingContext {
    /// Resizes the rendering surface to the given size.
    fn resize(&self, size: Size2D<i32>);
    /// Presents the rendered frame to the screen.
    fn present(&self);
    /// Makes the context the current OpenGL context for this thread.
    /// After calling this function, it is valid to use OpenGL rendering
    /// commands.
    fn make_current(&self) -> Result<(), Error>;
    /// Returns the OpenGL framebuffer object needed to render to the surface.
    fn framebuffer_object(&self) -> u32;
    /// Returns the OpenGL or GLES API.
    fn gl_api(&self) -> Rc<dyn gleam::gl::Gl>;
    /// Describes the OpenGL version that is requested when a context is created.
    fn gl_version(&self) -> GLVersion;
    /// Returns the GL Context used by servo media player. Default to `GlContext::Unknown`.
    fn gl_context(&self) -> GlContext {
        GlContext::Unknown
    }
    /// Returns the GL Display used by servo media player. Default to `NativeDisplay::Unknown`.
    fn gl_display(&self) -> NativeDisplay {
        NativeDisplay::Unknown
    }
    /// Creates a texture from a given surface and returns the surface texture,
    /// the OpenGL texture object, and the size of the surface. Default to `None`.
    fn create_texture(&self, _surface: Surface) -> Option<(SurfaceTexture, u32, Size2D<i32>)> {
        None
    }
    /// Destroys the texture and returns the surface. Default to `None`.
    fn destroy_texture(&self, _surface_texture: SurfaceTexture) -> Option<Surface> {
        None
    }

    /// The connection to the display server for WebGL. Default to `None`.
    fn connection(&self) -> Option<Connection> {
        None
    }
}

/// A rendering context that uses the Surfman library to create and manage
/// the OpenGL context and surface. This struct provides the default implementation
/// of the `RenderingContext` trait, handling the creation, management, and destruction
/// of the rendering context and its associated resources.
///
/// The `SurfmanRenderingContext` struct encapsulates the necessary data and methods
/// to interact with the Surfman library, including creating surfaces, binding surfaces,
/// resizing surfaces, presenting rendered frames, and managing the OpenGL context state.
#[derive(Clone)]
pub struct SurfmanRenderingContext(Rc<RenderingContextData>);

struct RenderingContextData {
    device: RefCell<Device>,
    context: RefCell<Context>,
    // We either render to a swap buffer or to a native widget
    swap_chain: Option<SwapChain<Device>>,
}

impl Drop for RenderingContextData {
    fn drop(&mut self) {
        let device = &mut self.device.borrow_mut();
        let context = &mut self.context.borrow_mut();
        if let Some(ref swap_chain) = self.swap_chain {
            let _ = swap_chain.destroy(device, context);
        }
        let _ = device.destroy_context(context);
    }
}

impl RenderingContext for SurfmanRenderingContext {
    fn gl_context(&self) -> GlContext {
        #[cfg(all(target_os = "linux", not(target_env = "ohos")))]
        {
            match self.native_context() {
                NativeContext::Default(LinuxNativeContext::Default(native_context)) => {
                    GlContext::Egl(native_context.egl_context as usize)
                },
                NativeContext::Default(LinuxNativeContext::Alternate(native_context)) => {
                    GlContext::Egl(native_context.egl_context as usize)
                },
                NativeContext::Alternate(_) => GlContext::Unknown,
            }
        }
        #[cfg(target_os = "windows")]
        {
            #[cfg(feature = "no-wgl")]
            {
                GlContext::Egl(self.native_context().egl_context as usize)
            }
            #[cfg(not(feature = "no-wgl"))]
            GlContext::Unknown
        }
        #[cfg(not(any(
            target_os = "windows",
            all(target_os = "linux", not(target_env = "ohos"))
        )))]
        {
            GlContext::Unknown
        }
    }
    fn gl_display(&self) -> NativeDisplay {
        #[cfg(all(target_os = "linux", not(target_env = "ohos")))]
        {
            match self.connection().native_connection() {
                surfman::NativeConnection::Default(LinuxNativeConnection::Default(connection)) => {
                    NativeDisplay::Egl(connection.0 as usize)
                },
                surfman::NativeConnection::Default(LinuxNativeConnection::Alternate(
                    connection,
                )) => NativeDisplay::X11(connection.x11_display as usize),
                surfman::NativeConnection::Alternate(_) => NativeDisplay::Unknown,
            }
        }
        #[cfg(target_os = "windows")]
        {
            #[cfg(feature = "no-wgl")]
            {
                NativeDisplay::Egl(self.native_device().egl_display as usize)
            }
            #[cfg(not(feature = "no-wgl"))]
            NativeDisplay::Unknown
        }
        #[cfg(not(any(
            target_os = "windows",
            all(target_os = "linux", not(target_env = "ohos"))
        )))]
        {
            NativeDisplay::Unknown
        }
    }
    fn resize(&self, size: Size2D<i32>) {
        if let Err(err) = self.resize(size) {
            warn!("Failed to resize surface: {:?}", err);
        }
    }
    fn present(&self) {
        if let Err(err) = self.present() {
            warn!("Failed to present surface: {:?}", err);
        }
    }
    fn make_current(&self) -> Result<(), Error> {
        self.make_gl_context_current()
    }
    fn framebuffer_object(&self) -> u32 {
        self.context_surface_info()
            .unwrap_or(None)
            .and_then(|info| info.framebuffer_object)
            .map(|fbo| fbo.0.get())
            .unwrap_or(0)
    }
    #[allow(unsafe_code)]
    fn gl_api(&self) -> Rc<dyn gleam::gl::Gl> {
        let context = self.0.context.borrow();
        let device = self.0.device.borrow();
        match self.connection().gl_api() {
            GLApi::GL => unsafe { gl::GlFns::load_with(|s| device.get_proc_address(&context, s)) },
            GLApi::GLES => unsafe {
                gl::GlesFns::load_with(|s| device.get_proc_address(&context, s))
            },
        }
    }
    fn gl_version(&self) -> GLVersion {
        let device = self.0.device.borrow();
        let context = self.0.context.borrow();
        let descriptor = device.context_descriptor(&context);
        let attributes = device.context_descriptor_attributes(&descriptor);
        let major = attributes.version.major;
        let minor = attributes.version.minor;
        match self.connection().gl_api() {
            GLApi::GL => GLVersion::GL(major, minor),
            GLApi::GLES => GLVersion::GLES(major, minor),
        }
    }

    fn create_texture(&self, surface: Surface) -> Option<(SurfaceTexture, u32, Size2D<i32>)> {
        let device = &self.0.device.borrow();
        let context = &mut self.0.context.borrow_mut();
        let SurfaceInfo {
            id: front_buffer_id,
            size,
            ..
        } = device.surface_info(&surface);
        debug!("... getting texture for surface {:?}", front_buffer_id);
        let surface_texture = device.create_surface_texture(context, surface).unwrap();
        let gl_texture = device
            .surface_texture_object(&surface_texture)
            .map(|tex| tex.0.get())
            .unwrap_or(0);
        Some((surface_texture, gl_texture, size))
    }

    fn destroy_texture(&self, surface_texture: SurfaceTexture) -> Option<Surface> {
        self.destroy_surface_texture(surface_texture).ok()
    }

    fn connection(&self) -> Option<Connection> {
        Some(self.connection())
    }
}

impl SurfmanRenderingContext {
    pub fn create(
        connection: &Connection,
        adapter: &Adapter,
        headless: Option<Size2D<i32>>,
    ) -> Result<Self, Error> {
        let mut device = connection.create_device(adapter)?;
        let flags = ContextAttributeFlags::ALPHA |
            ContextAttributeFlags::DEPTH |
            ContextAttributeFlags::STENCIL;
        let version = match connection.gl_api() {
            GLApi::GLES => surfman::GLVersion { major: 3, minor: 0 },
            GLApi::GL => surfman::GLVersion { major: 3, minor: 2 },
        };
        let context_attributes = ContextAttributes { flags, version };
        let context_descriptor = device.create_context_descriptor(&context_attributes)?;
        let mut context = device.create_context(&context_descriptor, None)?;
        let surface_access = SurfaceAccess::GPUOnly;
        let swap_chain = if let Some(size) = headless {
            let surface_type = SurfaceType::Generic { size };
            let surface = device.create_surface(&context, surface_access, surface_type)?;
            device
                .bind_surface_to_context(&mut context, surface)
                .map_err(|(err, mut surface)| {
                    let _ = device.destroy_surface(&mut context, &mut surface);
                    err
                })?;
            device.make_context_current(&context)?;
            Some(SwapChain::create_attached(
                &mut device,
                &mut context,
                surface_access,
            )?)
        } else {
            None
        };
        let device = RefCell::new(device);
        let context = RefCell::new(context);
        let data = RenderingContextData {
            device,
            context,
            swap_chain,
        };
        Ok(SurfmanRenderingContext(Rc::new(data)))
    }

    pub fn create_surface(
        &self,
        surface_type: SurfaceType<NativeWidget>,
    ) -> Result<Surface, Error> {
        let device = &mut self.0.device.borrow_mut();
        let context = &self.0.context.borrow();
        let surface_access = SurfaceAccess::GPUOnly;
        device.create_surface(context, surface_access, surface_type)
    }

    pub fn bind_surface(&self, surface: Surface) -> Result<(), Error> {
        let device = &self.0.device.borrow();
        let context = &mut self.0.context.borrow_mut();
        device
            .bind_surface_to_context(context, surface)
            .map_err(|(err, mut surface)| {
                let _ = device.destroy_surface(context, &mut surface);
                err
            })?;

        device.make_context_current(context)?;
        Ok(())
    }

    pub fn destroy_surface(&self, mut surface: Surface) -> Result<(), Error> {
        let device = &self.0.device.borrow();
        let context = &mut self.0.context.borrow_mut();
        device.destroy_surface(context, &mut surface)
    }

    pub fn create_surface_texture(&self, surface: Surface) -> Result<SurfaceTexture, Error> {
        let device = &self.0.device.borrow();
        let context = &mut self.0.context.borrow_mut();
        device
            .create_surface_texture(context, surface)
            .map_err(|(error, _)| error)
    }

    pub fn destroy_surface_texture(
        &self,
        surface_texture: SurfaceTexture,
    ) -> Result<Surface, Error> {
        let device = &self.0.device.borrow();
        let context = &mut self.0.context.borrow_mut();
        device
            .destroy_surface_texture(context, surface_texture)
            .map_err(|(error, _)| error)
    }

    pub fn make_gl_context_current(&self) -> Result<(), Error> {
        let device = &self.0.device.borrow();
        let context = &self.0.context.borrow();
        device.make_context_current(context)
    }

    pub fn swap_chain(&self) -> Result<&SwapChain<Device>, Error> {
        self.0.swap_chain.as_ref().ok_or(Error::WidgetAttached)
    }

    pub fn resize(&self, size: Size2D<i32>) -> Result<(), Error> {
        let device = &mut self.0.device.borrow_mut();
        let context = &mut self.0.context.borrow_mut();
        if let Some(swap_chain) = self.0.swap_chain.as_ref() {
            return swap_chain.resize(device, context, size);
        }
        let mut surface = device.unbind_surface_from_context(context)?.unwrap();
        device.resize_surface(context, &mut surface, size)?;
        device
            .bind_surface_to_context(context, surface)
            .map_err(|(err, mut surface)| {
                let _ = device.destroy_surface(context, &mut surface);
                err
            })
    }

    pub fn present(&self) -> Result<(), Error> {
        let device = &mut self.0.device.borrow_mut();
        let context = &mut self.0.context.borrow_mut();
        if let Some(ref swap_chain) = self.0.swap_chain {
            return swap_chain.swap_buffers(device, context, PreserveBuffer::No);
        }
        let mut surface = device.unbind_surface_from_context(context)?.unwrap();
        device.present_surface(context, &mut surface)?;
        device
            .bind_surface_to_context(context, surface)
            .map_err(|(err, mut surface)| {
                let _ = device.destroy_surface(context, &mut surface);
                err
            })
    }

    /// Invoke a closure with the surface associated with the current front buffer.
    /// This can be used to create a surfman::SurfaceTexture to blit elsewhere.
    pub fn with_front_buffer<F: FnOnce(&Device, Surface) -> Surface>(&self, f: F) {
        let device = &mut self.0.device.borrow_mut();
        let context = &mut self.0.context.borrow_mut();
        let surface = device
            .unbind_surface_from_context(context)
            .unwrap()
            .unwrap();
        let surface = f(device, surface);
        device.bind_surface_to_context(context, surface).unwrap();
    }

    pub fn device(&self) -> std::cell::Ref<Device> {
        self.0.device.borrow()
    }

    pub fn connection(&self) -> Connection {
        let device = &self.0.device.borrow();
        device.connection()
    }

    pub fn adapter(&self) -> Adapter {
        let device = &self.0.device.borrow();
        device.adapter()
    }

    pub fn native_context(&self) -> NativeContext {
        let device = &self.0.device.borrow();
        let context = &self.0.context.borrow();
        device.native_context(context)
    }

    pub fn native_device(&self) -> NativeDevice {
        let device = &self.0.device.borrow();
        device.native_device()
    }

    pub fn context_attributes(&self) -> ContextAttributes {
        let device = &self.0.device.borrow();
        let context = &self.0.context.borrow();
        let descriptor = &device.context_descriptor(context);
        device.context_descriptor_attributes(descriptor)
    }

    pub fn context_surface_info(&self) -> Result<Option<SurfaceInfo>, Error> {
        let device = &self.0.device.borrow();
        let context = &self.0.context.borrow();
        device.context_surface_info(context)
    }

    pub fn surface_info(&self, surface: &Surface) -> SurfaceInfo {
        let device = &self.0.device.borrow();
        device.surface_info(surface)
    }

    pub fn surface_texture_object(&self, surface: &SurfaceTexture) -> u32 {
        let device = &self.0.device.borrow();
        device
            .surface_texture_object(surface)
            .map(|t| t.0.get())
            .unwrap_or_default()
    }

    pub fn get_proc_address(&self, name: &str) -> *const c_void {
        let device = &self.0.device.borrow();
        let context = &self.0.context.borrow();
        device.get_proc_address(context, name)
    }

    pub fn unbind_native_surface_from_context(&self) -> Result<(), Error> {
        let device = self.0.device.borrow_mut();
        let mut context = self.0.context.borrow_mut();
        let mut surface = device.unbind_surface_from_context(&mut context)?.unwrap();
        device.destroy_surface(&mut context, &mut surface)?;
        Ok(())
    }

    pub fn bind_native_surface_to_context(&self, native_widget: NativeWidget) -> Result<(), Error> {
        let mut device = self.0.device.borrow_mut();
        let mut context = self.0.context.borrow_mut();
        let surface_access = SurfaceAccess::GPUOnly;
        let surface_type = SurfaceType::Widget { native_widget };
        let surface = device.create_surface(&context, surface_access, surface_type)?;
        device
            .bind_surface_to_context(&mut context, surface)
            .map_err(|(err, mut surface)| {
                let _ = device.destroy_surface(&mut context, &mut surface);
                err
            })?;
        device.make_context_current(&context)?;
        Ok(())
    }
}