#![deny(missing_docs)]

//! The official Piston window wrapper for the Piston game engine
//!
//! **Notice! If this is your first time visiting Piston, [start here](https://github.com/PistonDevelopers/piston).**
//!
//! 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);
//!         });
//!     }
//! }
//! ```
//!
//! The `draw_2d` function calls the closure on render events.
//! There is no need to filter events manually, and there is no overhead.
//!
//! ### 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_device_gl;
extern crate gfx_graphics;
extern crate graphics;
extern crate shader_version;
pub extern crate texture;

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::{ Texture, TextureContext, TextureSettings, Filter, Flip };

use gfx_graphics::{ Gfx2d, GfxGraphics };
use std::time::Duration;
use std::error::Error;

/// Actual factory used by Gfx backend.
pub type GfxFactory = gfx_device_gl::Factory;
/// 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<'static,
    gfx_device_gl::Factory,
    gfx_device_gl::Resources,
    gfx_device_gl::CommandBuffer>;
/// 2D graphics.
pub type G2d<'a> = GfxGraphics<'a,
    gfx_device_gl::Resources,
    gfx_device_gl::CommandBuffer>;
/// Texture type compatible with `G2d`.
pub type G2dTexture = Texture<gfx_device_gl::Resources>;
/// Texture context.
pub type G2dTextureContext = TextureContext<
    gfx_device_gl::Factory,
    gfx_device_gl::Resources,
    gfx_device_gl::CommandBuffer>;

/// Contains everything required for controlling window, graphics, event loop.
#[cfg(not(feature="glutin"))]
pub struct PistonWindow<W: Window> {
    /// 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: Events,
    /// The factory that was created along with the device.
    pub factory: gfx_device_gl::Factory,
}

#[cfg(feature="glutin")]
extern crate glutin_window;
#[cfg(feature="glutin")]
use glutin_window::GlutinWindow;
/// Contains everything required for controlling window, graphics, event loop.
#[cfg(feature="glutin")]
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: Events,
    /// 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
{
    fn build_from_window_settings(settings: &WindowSettings) -> Result<PistonWindow<W>, Box<Error>> {
        // Turn on sRGB.
        let settings = settings.clone().srgb(true);

        // Use OpenGL 3.2 by default, because this is what window backends
        // usually do.
        let api = settings.get_maybe_graphics_api().unwrap_or(Api::opengl(3, 2));
        let samples = settings.get_samples();

        let opengl = OpenGL::from_api(api)
            .expect("Could not detect OpenGL version from graphics API");

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

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

    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
{
    /// Creates a new piston window.
    pub fn new(opengl: OpenGL, samples: u8, mut window: W) -> Self
        where W: OpenGLWindow
    {
        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::texture::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 = Events::new(EventSettings::new());
        PistonWindow {
            window: window,
            encoder: encoder,
            device: device,
            output_color: output_color,
            output_stencil: output_stencil,
            g2d: g2d,
            events: events,
            factory: factory,
        }
    }

    /// Creates context used to create and update textures.
    pub fn create_texture_context(&mut self) -> G2dTextureContext {
        TextureContext {
            factory: self.factory.clone(),
            encoder: self.factory.create_command_buffer().into()
        }
    }

    /// Loads font from a path.
    pub fn load_font<P: AsRef<std::path::Path>>(&mut self, path: P) -> Result<Glyphs, std::io::Error> {
        Glyphs::new(path, TextureContext {
            factory: self.factory.clone(),
            encoder: self.factory.create_command_buffer().into()
        }, TextureSettings::new())
    }

    /// Renders 2D graphics.
    ///
    /// Calls the closure on render events.
    /// There is no need to filter events manually, and there is no overhead.
    pub fn draw_2d<E, F, U>(&mut self, e: &E, f: F) -> Option<U> where
        W: OpenGLWindow,
        E: GenericEvent,
        F: FnOnce(Context, &mut G2d, &mut gfx_device_gl::Device) -> U
    {
        if let Some(args) = e.render_args() {
            self.window.make_current();
            let device = &mut self.device;
            let res = self.g2d.draw(
                &mut self.encoder,
                &self.output_color,
                &self.output_stencil,
                args.viewport(),
                |c, g| f(c, g, device)
            );
            self.encoder.flush(device);
            Some(res)
        } else {
            None
        }
    }

    /// Renders 3D graphics.
    ///
    /// Calls the closure on render events.
    /// There is no need to filter events manually, and there is no overhead.
    pub fn draw_3d<E, F, U>(&mut self, e: &E, f: F) -> Option<U> where
        W: OpenGLWindow,
        E: GenericEvent,
        F: FnOnce(&mut Self) -> U
    {
        if let Some(_) = e.render_args() {
            self.window.make_current();
            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> {
        if let Some(e) = self.events.next(&mut self.window) {
            self.event(&e);
            Some(e)
        } else {
            None
        }
    }

    /// Let window handle new event.
    /// Cleans up after rendering and resizes frame buffers.
    pub fn event<E: GenericEvent>(&mut self, event: &E) {
        use gfx::Device;
        use gfx::memory::Typed;

        if let Some(_) = event.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;
        }
    }
}

impl<W> Window for PistonWindow<W>
    where W: Window
{
    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 wait_event(&mut self) -> (Input, Option<TimeStamp>) {
        Window::wait_event(&mut self.window)
    }
    fn wait_event_timeout(&mut self, timeout: Duration) -> Option<(Input, Option<TimeStamp>)> {
        Window::wait_event_timeout(&mut self.window, timeout)
    }
    fn poll_event(&mut self) -> Option<(Input, Option<TimeStamp>)> {
        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_automatic_close(&self) -> bool { self.window.get_automatic_close() }
    fn set_automatic_close(&mut self, value: bool) {
        self.window.set_automatic_close(value);
    }
    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)
    }
    fn show(&mut self) { self.window.show() }
    fn hide(&mut self) { self.window.hide() }
    fn get_position(&self) -> Option<Position> {
        self.window.get_position()
    }
    fn set_position<P: Into<Position>>(&mut self, pos: P) {
        self.window.set_position(pos)
    }
    fn set_size<S: Into<Size>>(&mut self, size: S) {
        self.window.set_size(size)
    }
}

impl<W> EventLoop for PistonWindow<W>
    where W: Window
{
    fn get_event_settings(&self) -> EventSettings {
        self.events.get_event_settings()
    }

    fn set_event_settings(&mut self, settings: EventSettings) {
        self.events.set_event_settings(settings);
    }
}