// Copyright 2015 The Gfx-rs Developers.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#[deny(missing_docs)]

extern crate gfx_core as core;
extern crate gfx_device_gl as device_gl;
extern crate glutin;

#[cfg(feature = "headless")]
pub use headless::{init_headless, init_headless_raw};

use core::{format, handle, texture};
use core::memory::Typed;
use device_gl::Resources as R;
use glutin::GlContext;

#[cfg(feature = "headless")]
mod headless;
// this module just covers the holes of `winit`... hopefully, temporary
#[cfg(target_os = "emscripten")]
pub mod emscripten;

/// Initialize with a window builder.
/// Generically parametrized version over the main framebuffer format.
///
/// # Example
///
/// ```no_run
/// extern crate gfx_core;
/// extern crate gfx_device_gl;
/// extern crate gfx_window_glutin;
/// extern crate glutin;
///
/// use gfx_core::format::{DepthStencil, Rgba8};
///
/// fn main() {
///     let events_loop = glutin::EventsLoop::new();
///     let window_builder = glutin::WindowBuilder::new().with_title("Example".to_string());
///     let context = glutin::ContextBuilder::new();
///     let (window, device, factory, rtv, stv) =
///         gfx_window_glutin::init::<Rgba8, DepthStencil>(window_builder, context, &events_loop);
///
///     // your code
/// }
/// ```
pub fn init<Cf, Df>(window: glutin::WindowBuilder,
                    context: glutin::ContextBuilder,
                    events_loop: &glutin::EventsLoop) ->
            (glutin::GlWindow, device_gl::Device, device_gl::Factory,
            handle::RenderTargetView<R, Cf>, handle::DepthStencilView<R, Df>)
where
    Cf: format::RenderFormat,
    Df: format::DepthFormat,
{
    let (window, device, factory, color_view, ds_view) = init_raw(
        window,
        context,
        events_loop,
        Cf::get_format(),
        Df::get_format());
    (window, device, factory, Typed::new(color_view), Typed::new(ds_view))
}

/// Initialize with an existing Glutin window.
/// Generically parametrized version over the main framebuffer format.
///
/// # Example (using Piston to create the window)
///
/// ```rust,ignore
/// extern crate piston;
/// extern crate glutin_window;
/// extern crate gfx_window_glutin;
///
/// // Create window with Piston
/// let settings = piston::window::WindowSettings::new("Example", [800, 600]);
/// let mut glutin_window = glutin_window::GlutinWindow::new(&settings).unwrap();
///
/// // Initialise gfx
/// let (mut device, mut factory, main_color, main_depth) =
///     gfx_window_glutin::init_existing::<ColorFormat, DepthFormat>(&glutin_window.window);
///
/// let mut encoder: gfx::Encoder<_, _> = factory.create_command_buffer().into();
/// ```
pub fn init_existing<Cf, Df>(window: &glutin::GlWindow) ->
            (device_gl::Device, device_gl::Factory,
            handle::RenderTargetView<R, Cf>, handle::DepthStencilView<R, Df>)
where
    Cf: format::RenderFormat,
    Df: format::DepthFormat,
{
    let (device, factory, color_view, ds_view) = init_existing_raw(window, Cf::get_format(), Df::get_format());
    (device, factory, Typed::new(color_view), Typed::new(ds_view))
}

fn get_window_dimensions(window: &glutin::GlWindow) -> texture::Dimensions {
    // https://github.com/tomaka/winit/pull/370
    #[cfg(target_os = "emscripten")]
    let (width, height) = emscripten::get_canvas_size();
    #[cfg(not(target_os = "emscripten"))]
    let (width, height) = {
        let size = window.get_inner_size().unwrap().to_physical(window.get_hidpi_factor());
        (size.width as _, size.height as _)
    };
    let aa = window
        .get_pixel_format().multisampling
        .unwrap_or(0) as texture::NumSamples;

    (width, height, 1, aa.into())
}

/// Initialize with a window builder. Raw version.
pub fn init_raw(window: glutin::WindowBuilder,
                mut context: glutin::ContextBuilder,
                events_loop: &glutin::EventsLoop,
                color_format: format::Format,
                ds_format: format::Format) ->
                (glutin::GlWindow, device_gl::Device, device_gl::Factory,
                handle::RawRenderTargetView<R>, handle::RawDepthStencilView<R>)
{
    let window = {
        let color_total_bits = color_format.0.get_total_bits();
        let alpha_bits = color_format.0.get_alpha_stencil_bits();
        let depth_total_bits = ds_format.0.get_total_bits();
        let stencil_bits = ds_format.0.get_alpha_stencil_bits();

        context = context
            .with_depth_buffer(depth_total_bits - stencil_bits)
            .with_stencil_buffer(stencil_bits)
            .with_pixel_format(color_total_bits - alpha_bits, alpha_bits)
            .with_srgb(color_format.1 == format::ChannelType::Srgb);

        glutin::GlWindow::new(window, context, &events_loop).unwrap()
    };

    let (device, factory, color_view, ds_view) = init_existing_raw(&window, color_format, ds_format);

    (window, device, factory, color_view, ds_view)
}

/// Initialize with an existing Glutin window. Raw version.
pub fn init_existing_raw(
    window: &glutin::GlWindow,
    color_format: format::Format, ds_format: format::Format,
) -> (device_gl::Device, device_gl::Factory,
      handle::RawRenderTargetView<R>, handle::RawDepthStencilView<R>)
{
    unsafe { window.make_current().unwrap() };
    let (device, factory) = device_gl::create(|s|
        window.get_proc_address(s) as *const std::os::raw::c_void);

    // create the main color/depth targets
    let dim = get_window_dimensions(window);
    let (color_view, ds_view) = device_gl::create_main_targets_raw(dim, color_format.0, ds_format.0);

    // done
    (device, factory, color_view, ds_view)
}

/// Update the internal dimensions of the main framebuffer targets. Generic version over the format.
pub fn update_views<Cf, Df>(window: &glutin::GlWindow, color_view: &mut handle::RenderTargetView<R, Cf>,
                    ds_view: &mut handle::DepthStencilView<R, Df>)
where
    Cf: format::RenderFormat,
    Df: format::DepthFormat,
{
    let dim = color_view.get_dimensions();
    assert_eq!(dim, ds_view.get_dimensions());
    if let Some((cv, dv)) = update_views_raw(window, dim, Cf::get_format(), Df::get_format()) {
        *color_view = Typed::new(cv);
        *ds_view = Typed::new(dv);
    }
}

/// Return new main target views if the window resolution has changed from the old dimensions.
pub fn update_views_raw(window: &glutin::GlWindow, old_dimensions: texture::Dimensions,
                        color_format: format::Format, ds_format: format::Format)
                        -> Option<(handle::RawRenderTargetView<R>, handle::RawDepthStencilView<R>)>
{
    let dim = get_window_dimensions(window);
    if dim != old_dimensions {
        Some(device_gl::create_main_targets_raw(dim, color_format.0, ds_format.0))
    }else {
        None
    }
}

/// Create new main target views based on the current size of the window.
/// Best called just after a WindowResize event.
pub fn new_views<Cf, Df>(window: &glutin::GlWindow)
        -> (handle::RenderTargetView<R, Cf>, handle::DepthStencilView<R, Df>) where
    Cf: format::RenderFormat,
    Df: format::DepthFormat,
{
    let dim = get_window_dimensions(window);
    let (color_view_raw, depth_view_raw) =
        device_gl::create_main_targets_raw(dim, Cf::get_format().0, Df::get_format().0);
    (Typed::new(color_view_raw), Typed::new(depth_view_raw))
}