#![deny(missing_docs)]

//! The official Piston window wrapper for the Piston game engine
//!
//! The purpose of this library is to provide an easy-to-use,
//! simple-to-get-started and convenient-for-applications API for Piston.
//!
//! Sets up:
//!
//! - [Gfx](https://github.com/gfx-rs/gfx) with an OpenGL back-end.
//! - [gfx_graphics](https://github.com/pistondevelopers/gfx_graphics)
//! for 2D rendering.
//! - [glutin_window](https://github.com/pistondevelopers/glutin_window)
//! as default window back-end, but this can be swapped (see below).
//!
//! ### Example
//!
//! ```no_run
//! extern crate piston_window;
//!
//! use piston_window::*;
//!
//! fn main() {
//!     let mut window: PistonWindow =
//!         WindowSettings::new("Hello World!", [512; 2])
//!             .build().unwrap();
//!     while let Some(e) = window.next() {
//!         window.draw_2d(&e, |c, g| {
//!             clear([0.5, 0.5, 0.5, 1.0], g);
//!             rectangle([1.0, 0.0, 0.0, 1.0], // red
//!                       [0.0, 0.0, 100.0, 100.0], // rectangle
//!                       c.transform, g);
//!         });
//!     }
//! }
//! ```
//!
//! ### Swap to another window back-end
//!
//! Change the generic parameter to the window back-end you want to use.
//!
//! ```ignore
//! extern crate piston_window;
//! extern crate sdl2_window;
//!
//! use piston_window::*;
//! use sdl2_window::Sdl2Window;
//!
//! # fn main() {
//!
//! let window: PistonWindow<Sdl2Window> =
//!     WindowSettings::new("title", [512; 2])
//!         .build().unwrap();
//!
//! # }
//! ```
//!
//! ### sRGB
//!
//! The impl of `BuildFromWindowSettings` in this library turns on
//! `WindowSettings::srgb`, because it is required by gfx_graphics.
//!
//! Most images such as those found on the internet uses sRGB,
//! that has a non-linear gamma corrected space.
//! When rendering 3D, make sure textures and colors are in linear gamma space.
//! Alternative is to use `Srgb8` and `Srgba8` formats for textures.
//!
//! For more information about sRGB, see
//! https://github.com/PistonDevelopers/piston/issues/1014
//!
//! ### Library dependencies
//!
//! This library is meant to be used in applications only.
//! It is not meant to be depended on by generic libraries.
//! Instead, libraries should depend on the lower abstractions,
//! such as the [Piston core](https://github.com/pistondevelopers/piston).

extern crate piston;
extern crate gfx;
extern crate gfx_core;
extern crate gfx_device_gl;
extern crate gfx_graphics;
extern crate graphics;
extern crate shader_version;
extern crate glutin_window;

use glutin_window::GlutinWindow;
pub use shader_version::OpenGL;
pub use graphics::*;
pub use piston::window::*;
pub use piston::input::*;
pub use piston::event_loop::*;
pub use gfx_graphics::{ GlyphError, Texture, TextureSettings, Flip };

use gfx_graphics::{ Gfx2d, GfxGraphics };

/// Actual gfx::Stream implementation carried by the window.
pub type GfxEncoder = gfx::Encoder<gfx_device_gl::Resources,
    gfx_device_gl::CommandBuffer>;
/// Glyph cache.
pub type Glyphs = gfx_graphics::GlyphCache<gfx_device_gl::Resources,
    gfx_device_gl::Factory>;
/// 2D graphics.
pub type G2d<'a> = GfxGraphics<'a,
    gfx_device_gl::Resources,
    gfx_device_gl::CommandBuffer>;
/// Texture type compatible with `G2d`.
pub type G2dTexture<'a> = Texture<gfx_device_gl::Resources>;

/// Contains everything required for controlling window, graphics, event loop.
pub struct PistonWindow<W: Window = GlutinWindow> {
    /// The window.
    pub window: W,
    /// GFX encoder.
    pub encoder: GfxEncoder,
    /// GFX device.
    pub device: gfx_device_gl::Device,
    /// Output frame buffer.
    pub output_color: gfx::handle::RenderTargetView<
        gfx_device_gl::Resources, gfx::format::Srgba8>,
    /// Output stencil buffer.
    pub output_stencil: gfx::handle::DepthStencilView<
        gfx_device_gl::Resources, gfx::format::DepthStencil>,
    /// Gfx2d.
    pub g2d: Gfx2d<gfx_device_gl::Resources>,
    /// Event loop state.
    pub events: WindowEvents,
    /// The factory that was created along with the device.
    pub factory: gfx_device_gl::Factory,
}

impl<W> BuildFromWindowSettings for PistonWindow<W>
    where W: Window + OpenGLWindow + BuildFromWindowSettings,
          W::Event: GenericEvent
{
    fn build_from_window_settings(mut settings: WindowSettings)
    -> Result<PistonWindow<W>, String> {
        // Turn on sRGB.
        settings = settings.srgb(true);

        // Use OpenGL 3.2 by default, because this is what window backends
        // usually do.
        let opengl = settings.get_maybe_opengl().unwrap_or(OpenGL::V3_2);
        let samples = settings.get_samples();

        Ok(PistonWindow::new(opengl, samples, try!(settings.build())))
    }
}

fn create_main_targets(dim: gfx::tex::Dimensions) ->
(gfx::handle::RenderTargetView<
    gfx_device_gl::Resources, gfx::format::Srgba8>,
 gfx::handle::DepthStencilView<
    gfx_device_gl::Resources, gfx::format::DepthStencil>) {
    use gfx_core::factory::Typed;
    use gfx::format::{DepthStencil, Format, Formatted, Srgba8};

    let color_format: Format = <Srgba8 as Formatted>::get_format();
    let depth_format: Format = <DepthStencil as Formatted>::get_format();
    let (output_color, output_stencil) =
        gfx_device_gl::create_main_targets_raw(dim,
                                               color_format.0,
                                               depth_format.0);
    let output_color = Typed::new(output_color);
    let output_stencil = Typed::new(output_stencil);
    (output_color, output_stencil)
}

impl<W> PistonWindow<W>
    where W: Window, W::Event: GenericEvent
{
    /// Creates a new piston window.
    pub fn new(opengl: OpenGL, samples: u8, mut window: W) -> Self
        where W: OpenGLWindow
    {
        use piston::window::{ OpenGLWindow, Window };
        use gfx_core::factory::Typed;

        let (device, mut factory) =
            gfx_device_gl::create(|s|
                window.get_proc_address(s) as *const _);

        let (output_color, output_stencil) = {
            let aa = samples as gfx::tex::NumSamples;
            let draw_size = window.draw_size();
            let dim = (draw_size.width as u16, draw_size.height as u16,
                       1, aa.into());
            create_main_targets(dim)
        };

        let g2d = Gfx2d::new(opengl, &mut factory);
        let encoder = factory.create_command_buffer().into();
        let events = window.events();
        PistonWindow {
            window: window,
            encoder: encoder,
            device: device,
            output_color: output_color,
            output_stencil: output_stencil,
            g2d: g2d,
            events: events,
            factory: factory,
        }
    }

    /// Renders 2D graphics.
    pub fn draw_2d<E, F, U>(&mut self, e: &E, f: F) -> Option<U> where
        E: GenericEvent,
        F: FnOnce(Context, &mut G2d) -> U
    {
        use piston::input::RenderEvent;

        if let Some(args) = e.render_args() {
            let res = self.g2d.draw(
                &mut self.encoder,
                &self.output_color,
                &self.output_stencil,
                args.viewport(),
                f
            );
            self.encoder.flush(&mut self.device);
            Some(res)
        } else {
            None
        }
    }

    /// Renders 3D graphics.
    pub fn draw_3d<E, F, U>(&mut self, e: &E, f: F) -> Option<U> where
        E: GenericEvent,
        F: FnOnce(&mut Self) -> U
    {
        use piston::input::RenderEvent;

        if let Some(_) = e.render_args() {
            let res = f(self);
            self.encoder.flush(&mut self.device);
            Some(res)
        } else {
            None
        }
    }

    /// Returns next event.
    /// Cleans up after rendering and resizes frame buffers.
    pub fn next(&mut self) -> Option<Event<<W as Window>::Event>> {
        use piston::input::*;
        use gfx_core::factory::Typed;
        use gfx::Device;

        if let Some(e) = self.events.next(&mut self.window) {
            if let Some(_) = e.after_render_args() {
                // After swapping buffers.
                self.device.cleanup();
            }

            // Check whether window has resized and update the output.
            let dim = self.output_color.raw().get_dimensions();
            let (w, h) = (dim.0, dim.1);
            let draw_size = self.window.draw_size();
            if w != draw_size.width as u16 || h != draw_size.height as u16 {
                let dim = (draw_size.width as u16,
                           draw_size.height as u16,
                           dim.2, dim.3);
                let (output_color, output_stencil) = create_main_targets(dim);
                self.output_color = output_color;
                self.output_stencil = output_stencil;
            }
            Some(e)
        } else {
            None
        }
    }
}

impl<W> Window for PistonWindow<W>
    where W: Window
{
    type Event = <W as Window>::Event;

    fn should_close(&self) -> bool { self.window.should_close() }
    fn set_should_close(&mut self, value: bool) {
        self.window.set_should_close(value)
    }
    fn size(&self) -> Size { self.window.size() }
    fn draw_size(&self) -> Size { self.window.draw_size() }
    fn swap_buffers(&mut self) { self.window.swap_buffers() }
    fn poll_event(&mut self) -> Option<Self::Event> {
        Window::poll_event(&mut self.window)
    }
}

impl<W> AdvancedWindow for PistonWindow<W>
    where W: AdvancedWindow
{
    fn get_title(&self) -> String { self.window.get_title() }
    fn set_title(&mut self, title: String) {
        self.window.set_title(title)
    }
    fn get_exit_on_esc(&self) -> bool { self.window.get_exit_on_esc() }
    fn set_exit_on_esc(&mut self, value: bool) {
        self.window.set_exit_on_esc(value)
    }
    fn set_capture_cursor(&mut self, value: bool) {
        self.window.set_capture_cursor(value)
    }
}

impl<W> EventLoop for PistonWindow<W>
    where W: Window
{
    fn set_ups(&mut self, frames: u64) {
        self.events.set_ups(frames);
    }

    fn set_max_fps(&mut self, frames: u64) {
        self.events.set_max_fps(frames);
    }

    fn set_swap_buffers(&mut self, enable: bool) {
        self.events.set_swap_buffers(enable);
    }

    fn set_bench_mode(&mut self, enable: bool) {
        self.events.set_bench_mode(enable);
    }
}