// Copyright (c) 2017, Dennis Hamester <dennis.hamester@startmail.com>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
// FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.

//! This is a small interoperability library for [dacite] and [winit], which allows the creation of
//! Vulkan surfaces in an easy and platform-independent manner.
//!
//! The main entry point to this crate is the `WindowExt` trait, through which Vulkan surfaces can
//! be created for winit `Window`s.
//!
//! This crate deals only with Vulkan surfaces. `Window` and `EventsLoop` must be created and
//! managed manually.
//!
//! ```rust,no_run
//! extern crate dacite;
//! extern crate dacite_winit;
//! extern crate winit;
//!
//! // Import the `WindowExt` trait:
//! use dacite_winit::WindowExt;
//!
//! // Create an `EventsLoop` and a `Window`:
//! let events_loop = winit::EventsLoop::new();
//! let window = winit::Window::new(&events_loop).unwrap();
//!
//! // Determine required extensions before a Vulkan instance is created:
//! let required_extensions = match window.get_required_extensions() {
//!     Ok(required_extensions) => required_extensions,
//!     Err(error) => {
//!         // This error can mean either, that the windowing system is not supported, or that
//!         // a Vulkan error occurred.
//!
//!         // Other functions from the `WindowExt` trait can also return errors, which should be
//!         // handled appropriately.
//!     }
//! };
//!
//! // Create a Vulkan instance and enable at least the extensions required for the window:
//! let create_info = dacite::core::InstanceCreateInfo {
//!     // ...
//!     enabled_extensions: required_extensions.to_extensions(),
//!     // ...
//! };
//!
//! let instance = dacite::core::Instance::create(&create_info, None).unwrap();
//!
//! // While searching for a suitable physical device, use
//! // WindowExt::is_presentation_supported() to determine if the physical device has a queue
//! // family, that can present to the window.
//! let physical_device = // ...
//!
//! // And finally, create a `Surface` from the window:
//! let surface = window.create_surface(&instance,
//!                                     dacite_winit::SurfaceCreateFlags::empty(),
//!                                     None).unwrap();
//! ```
//!
//! [dacite]: https://gitlab.com/dennis-hamester/dacite/tree/master/dacite
//! [winit]: https://github.com/tomaka/winit

#[macro_use]
extern crate bitflags;

extern crate dacite;
extern crate winit;

use dacite::core;
use dacite::khr_surface;
use dacite::khr_wayland_surface;
use dacite::khr_win32_surface;
use dacite::khr_xlib_surface;
use dacite::wayland_wrapper;
use dacite::win32_wrapper;
use dacite::xlib_wrapper;
use std::error;
use std::fmt;
use winit::Window;

/// Extension trait for Vulkan surface creation.
pub trait WindowExt {
    /// Test whether presentation is supported on a physical device.
    ///
    /// This function first determines the correct Vulkan WSI extension for this window and then calls one of the
    /// `get_*_presentation_support_*` family of functions on the `PhysicalDevice`.
    fn is_presentation_supported(&self, physical_device: &core::PhysicalDevice, queue_family_indices: u32) -> Result<bool, Error>;

    /// Determine required Vulkan instance extensions.
    ///
    /// This will always include [`VK_KHR_surface`]. One of the platform-dependent WSI extensions,
    /// that corresponds to this window, will also be added.
    ///
    /// Please note, that the device extension [`VK_KHR_swapchain`] is also required for
    /// presentation.
    ///
    /// [`VK_KHR_surface`]: https://www.khronos.org/registry/vulkan/specs/1.0-extensions/html/vkspec.html#VK_KHR_surface
    /// [`VK_KHR_swapchain`]: https://www.khronos.org/registry/vulkan/specs/1.0-extensions/html/vkspec.html#VK_KHR_swapchain
    fn get_required_extensions(&self) -> Result<core::InstanceExtensionsProperties, Error>;

    /// Create a surface for this window.
    ///
    /// `Instance` must have been created with required extensions, as determined by
    /// `get_required_extensions()`. The `flags` parameter is currently just a place holder. You
    /// should specify `SurfaceCreateFlags::empty()` here.
    fn create_surface(&self, instance: &core::Instance, flags: SurfaceCreateFlags, allocator: Option<Box<core::Allocator>>) -> Result<khr_surface::SurfaceKhr, Error>;
}

impl WindowExt for Window {
    fn is_presentation_supported(&self, physical_device: &core::PhysicalDevice, queue_family_indices: u32) -> Result<bool, Error> {
        let backend = get_backend(self)?;

        match backend {
            Backend::Xlib { .. } => Ok(true), // FIXME: This needs a VisualID, which winit does not expose
            Backend::Wayland { display, .. } => Ok(physical_device.get_wayland_presentation_support_khr(queue_family_indices, display)),
            Backend::Win32 { .. } => Ok(physical_device.get_win32_presentation_support_khr(queue_family_indices)),
        }
    }

    fn get_required_extensions(&self) -> Result<core::InstanceExtensionsProperties, Error> {
        let backend = get_backend(self)?;

        let mut extensions = core::InstanceExtensionsProperties::new();
        extensions.add_khr_surface(25);

        match backend {
            Backend::Xlib { .. } => extensions.add_khr_xlib_surface(6),
            Backend::Wayland { .. } => extensions.add_khr_wayland_surface(5),
            Backend::Win32 { .. } => extensions.add_khr_win32_surface(5),
        };

        Ok(extensions)
    }

    fn create_surface(&self, instance: &core::Instance, _: SurfaceCreateFlags, allocator: Option<Box<core::Allocator>>) -> Result<khr_surface::SurfaceKhr, Error> {
        let backend = get_backend(self)?;

        match backend {
            Backend::Xlib { display, window } => {
                let create_info = khr_xlib_surface::XlibSurfaceCreateInfoKhr {
                    flags: khr_xlib_surface::XlibSurfaceCreateFlagsKhr::empty(),
                    dpy: display,
                    window: window,
                    chain: None,
                };

                Ok(instance.create_xlib_surface_khr(&create_info, allocator)?)
            }

            Backend::Wayland { display, surface } => {
                let create_info = khr_wayland_surface::WaylandSurfaceCreateInfoKhr {
                    flags: khr_wayland_surface::WaylandSurfaceCreateFlagsKhr::empty(),
                    display: display,
                    surface: surface,
                    chain: None,
                };

                Ok(instance.create_wayland_surface_khr(&create_info, allocator)?)
            }

            Backend::Win32 { hinstance, hwnd } => {
                let create_info = khr_win32_surface::Win32SurfaceCreateInfoKhr {
                    flags: khr_win32_surface::Win32SurfaceCreateFlagsKhr::empty(),
                    hinstance: hinstance,
                    hwnd: hwnd,
                    chain: None,
                };

                Ok(instance.create_win32_surface_khr(&create_info, allocator)?)
            }
        }
    }
}

/// Error type used throughout this crate.
#[derive(Debug)]
pub enum Error {
    /// The windowing system is not supported by either dacite-winit or dacite.
    Unsupported,

    /// A Vulkan error occurred.
    VulkanError(core::Error),
}

impl fmt::Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            Error::Unsupported => write!(f, "Unsupported"),
            Error::VulkanError(e) => write!(f, "VulkanError({})", e),
        }
    }
}

impl error::Error for Error {
    fn description(&self) -> &str {
        match *self {
            Error::Unsupported => "The windowing system is not supported",
            Error::VulkanError(ref e) => e.description(),
        }
    }
}

impl From<core::Error> for Error {
    fn from(e: core::Error) -> Self {
        Error::VulkanError(e)
    }
}

bitflags! {
    /// Flags used for surface creation.
    ///
    /// This is currently a placeholder, with no valid flags. Use `SurfaceCreateFlags::empty()`.
    pub struct SurfaceCreateFlags: u32 {
        /// Dummy flag
        ///
        /// This flag exists just to satisfy the bitflags! macro, which doesn't support empty
        /// flags. Use `SurfaceCreateFlags::empty()` instead.
        const SURFACE_CREATE_DUMMY = 0;
    }
}

#[allow(dead_code)]
enum Backend {
    Xlib {
        display: *mut xlib_wrapper::Display,
        window: xlib_wrapper::Window,
    },

    Wayland {
        display: *mut wayland_wrapper::wl_display,
        surface: *mut wayland_wrapper::wl_surface,
    },

    Win32 {
        hinstance: win32_wrapper::HINSTANCE,
        hwnd: win32_wrapper::HWND,
    },
}

#[allow(unused_variables)]
#[allow(unreachable_code)]
fn get_backend(window: &Window) -> Result<Backend, Error> {
    #[cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd", target_os = "openbsd"))]
    {
        use winit::os::unix::WindowExt;

        if let (Some(display), Some(window)) = (window.get_xlib_display(), window.get_xlib_window()) {
            return Ok(Backend::Xlib {
                display: display as _,
                window: dacite::xlib_wrapper::Window(window as _),
            });
        }

        if let (Some(display), Some(surface)) = (window.get_wayland_display(), window.get_wayland_surface()) {
            return Ok(Backend::Wayland {
                display: display as _,
                surface: surface as _,
            });
        }
    }

    #[cfg(target_os = "windows")]
    {
        use winit::os::windows::WindowExt;

        return Ok(Backend::Win32 {
            hinstance: ::std::ptr::null_mut(), // FIXME: Need HINSTANCE of the correct module
            hwnd: window.get_hwnd() as _,
        });
    }

    Err(Error::Unsupported)
}