/*******************************************************************************
 * Copyright 2011 See AUTHORS file.
 *
 * 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.
 ******************************************************************************/

package com.badlogic.gdx;

import com.badlogic.gdx.graphics.Cursor;
import com.badlogic.gdx.graphics.Cursor.SystemCursor;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.GL30;
import com.badlogic.gdx.graphics.Mesh;
import com.badlogic.gdx.graphics.Pixmap;
import com.badlogic.gdx.graphics.g2d.Batch;
import com.badlogic.gdx.graphics.g2d.BitmapFont;
import com.badlogic.gdx.graphics.glutils.FrameBuffer;
import com.badlogic.gdx.graphics.glutils.GLVersion;
import com.badlogic.gdx.graphics.glutils.IndexBufferObject;
import com.badlogic.gdx.graphics.glutils.ShaderProgram;
import com.badlogic.gdx.graphics.glutils.VertexArray;
import com.badlogic.gdx.graphics.glutils.VertexBufferObject;

/** This interface encapsulates communication with the graphics processor. Depending on the available hardware and the current
 * {@link Application} configuration, access to {@link GL20} and {@link GL30} are provided here.
 * <p>
 * If supported by the backend, this interface lets you query the available display modes (graphics resolution and color depth)
 * and change it.
 * <p>
 * This interface can be used to switch between continuous and non-continuous rendering (see
 * {@link #setContinuousRendering(boolean)}), and to explicitly {@link #requestRendering()}.
 * <p>
 * There are many more utility classes that are not directly generated by the {@link Graphics} interfaces. See {@link VertexArray}
 * , {@link VertexBufferObject}, {@link IndexBufferObject}, {@link Mesh}, {@link ShaderProgram} and {@link FrameBuffer},
 * {@link BitmapFont}, {@link Batch} and so on. All these classes are managed, meaning they don't need to be reloaded on a context
 * loss. Explore the com.badlogic.gdx.graphics package for more classes that might come in handy.
 * @author mzechner */
public interface Graphics {
	/** Enumeration describing different types of {@link Graphics} implementations.
	 *
	 * @author mzechner */
	public enum GraphicsType {
		AndroidGL, LWJGL, WebGL, iOSGL, JGLFW, Mock, LWJGL3
	}

	/** Describe a fullscreen display mode
	 *
	 * @author mzechner */
	public class DisplayMode {
		/** the width in physical pixels **/
		public final int width;
		/** the height in physical pixles **/
		public final int height;
		/** the refresh rate in Hertz **/
		public final int refreshRate;
		/** the number of bits per pixel, may exclude alpha **/
		public final int bitsPerPixel;

		protected DisplayMode (int width, int height, int refreshRate, int bitsPerPixel) {
			this.width = width;
			this.height = height;
			this.refreshRate = refreshRate;
			this.bitsPerPixel = bitsPerPixel;
		}

		public String toString () {
			return width + "x" + height + ", bpp: " + bitsPerPixel + ", hz: " + refreshRate;
		}
	}

	/** Describes a monitor
	 *
	 * @author badlogic
	 */
	public class Monitor {
		public final int virtualX;
		public final int virtualY;
		public final String name;

		protected Monitor (int virtualX, int virtualY, String name) {
			this.virtualX = virtualX;
			this.virtualY = virtualY;
			this.name = name;
		}
	}

	/** Class describing the bits per pixel, depth buffer precision, stencil precision and number of MSAA samples. */
	public static class BufferFormat {
		/* number of bits per color channel */
		public final int r, g, b, a;
		/* number of bits for depth and stencil buffer */
		public final int depth, stencil;
		/** number of samples for multi-sample anti-aliasing (MSAA) **/
		public final int samples;
		/** whether coverage sampling anti-aliasing is used. in that case you have to clear the coverage buffer as well! */
		public final boolean coverageSampling;

		public BufferFormat (int r, int g, int b, int a, int depth, int stencil, int samples, boolean coverageSampling) {
			this.r = r;
			this.g = g;
			this.b = b;
			this.a = a;
			this.depth = depth;
			this.stencil = stencil;
			this.samples = samples;
			this.coverageSampling = coverageSampling;
		}

		public String toString () {
			return "r: " + r + ", g: " + g + ", b: " + b + ", a: " + a + ", depth: " + depth + ", stencil: " + stencil
				+ ", num samples: " + samples + ", coverage sampling: " + coverageSampling;
		}
	}

	/** Returns whether OpenGL ES 3.0 is available. If it is you can get an instance of {@link GL30} via {@link #getGL30()} to
	 * access OpenGL ES 3.0 functionality. Note that this functionality will only be available if you instructed the
	 * {@link Application} instance to use OpenGL ES 3.0!
	 *
	 * @return whether OpenGL ES 3.0 is available */
	public boolean isGL30Available ();

	/** @return the {@link GL20} instance */
	public GL20 getGL20 ();

	/** @return the {@link GL30} instance or null if not supported */
	public GL30 getGL30 ();

	/** @return the width of the client area in logical pixels. */
	public int getWidth ();

	/** @return the height of the client area in logical pixels */
	public int getHeight ();

	/** @return the width of the framebuffer in physical pixels */
	public int getBackBufferWidth ();

	/** @return the height of the framebuffer in physical pixels */
	public int getBackBufferHeight ();

	/** Returns the id of the current frame. The general contract of this method is that the id is incremented only when the
	 * application is in the running state right before calling the {@link ApplicationListener#render()} method. Also, the id of
	 * the first frame is 0; the id of subsequent frames is guaranteed to take increasing values for 2<sup>63</sup>-1 rendering
	 * cycles.
	 * @return the id of the current frame */
	public long getFrameId ();

	/** @return the time span between the current frame and the last frame in seconds. Might be smoothed over n frames. */
	public float getDeltaTime ();

	/** @return the time span between the current frame and the last frame in seconds, without smoothing **/
	public float getRawDeltaTime ();

	/** @return the average number of frames per second */
	public int getFramesPerSecond ();

	/** @return the {@link GraphicsType} of this Graphics instance */
	public GraphicsType getType ();

	/** @return the {@link GLVersion} of this Graphics instance */
	public GLVersion getGLVersion ();

	/** @return the pixels per inch on the x-axis */
	public float getPpiX ();

	/** @return the pixels per inch on the y-axis */
	public float getPpiY ();

	/** @return the pixels per centimeter on the x-axis */
	public float getPpcX ();

	/** @return the pixels per centimeter on the y-axis. */
	public float getPpcY ();

	/** This is a scaling factor for the Density Independent Pixel unit, following the same conventions as
	 * android.util.DisplayMetrics#density, where one DIP is one pixel on an approximately 160 dpi screen. Thus on a 160dpi screen
	 * this density value will be 1; on a 120 dpi screen it would be .75; etc.
	 *
	 * @return the logical density of the Display. */
	public float getDensity ();

	/** Whether the given backend supports a display mode change via calling {@link Graphics#setFullscreenMode(DisplayMode)}
	 *
	 * @return whether display mode changes are supported or not. */
	public boolean supportsDisplayModeChange ();

	/** @return the primary monitor **/
	public Monitor getPrimaryMonitor();

	/** @return the monitor the application's window is located on */
	public Monitor getMonitor();

	/** @return the currently connected {@link Monitor}s */
	public Monitor[] getMonitors();

	/** @return the supported fullscreen {@link DisplayMode}(s) of the monitor the window is on */
	public DisplayMode[] getDisplayModes ();

	/** @return the supported fullscreen {@link DisplayMode}s of the given {@link Monitor} */
	public DisplayMode[] getDisplayModes(Monitor monitor);

	/** @return the current {@link DisplayMode} of the monitor the window is on. */
	public DisplayMode getDisplayMode ();

	/** @return the current {@link DisplayMode} of the given {@link Monitor} */
	public DisplayMode getDisplayMode (Monitor monitor);

	/** Sets the window to full-screen mode.
	 *
	 * @param displayMode the display mode.
	 * @return whether the operation succeeded. */
	public boolean setFullscreenMode (DisplayMode displayMode);

	/** Sets the window to windowed mode.
	 *
	 * @param width the width in pixels
	 * @param height the height in pixels
	 * @return whether the operation succeeded*/
	public boolean setWindowedMode (int width, int height);

	/** Sets the title of the window. Ignored on Android.
	 *
	 * @param title the title. */
	public void setTitle (String title);

	/** Sets the window decoration as enabled or disabled. On Android, this will enable/disable
	 *  the menu bar.
	 *
	 *  Note that immediate behavior of this method may vary depending on the implementation. It
	 *  may be necessary for the window to be recreated in order for the changes to take effect.
	 *  Consult the documentation for the backend in use for more information.
	 *
	 *  Supported on all GDX desktop backends and on Android (to disable the menu bar).
	 *
	 * @param undecorated true if the window border or status bar should be hidden. false otherwise.
	 */
	public void setUndecorated (boolean undecorated);

	/** Sets whether or not the window should be resizable. Ignored on Android.
	 *
	 *  Note that immediate behavior of this method may vary depending on the implementation. It
	 *  may be necessary for the window to be recreated in order for the changes to take effect.
	 *  Consult the documentation for the backend in use for more information.
	 *
	 *  Supported on all GDX desktop backends.
	 *
	 * @param resizable
	 */
	public void setResizable (boolean resizable);

	/** Enable/Disable vsynching. This is a best-effort attempt which might not work on all platforms.
	 *
	 * @param vsync vsync enabled or not. */
	public void setVSync (boolean vsync);

	/** @return the format of the color, depth and stencil buffer in a {@link BufferFormat} instance */
	public BufferFormat getBufferFormat ();

	/** @param extension the extension name
	 * @return whether the extension is supported */
	public boolean supportsExtension (String extension);

	/** Sets whether to render continuously. In case rendering is performed non-continuously, the following events will trigger a
	 * redraw:
	 *
	 * <ul>
	 * <li>A call to {@link #requestRendering()}</li>
	 * <li>Input events from the touch screen/mouse or keyboard</li>
	 * <li>A {@link Runnable} is posted to the rendering thread via {@link Application#postRunnable(Runnable)}</li>
	 * </ul>
	 *
	 * Life-cycle events will also be reported as usual, see {@link ApplicationListener}. This method can be called from any
	 * thread.
	 *
	 * @param isContinuous whether the rendering should be continuous or not. */
	public void setContinuousRendering (boolean isContinuous);

	/** @return whether rendering is continuous. */
	public boolean isContinuousRendering ();

	/** Requests a new frame to be rendered if the rendering mode is non-continuous. This method can be called from any thread. */
	public void requestRendering ();

	/** Whether the app is fullscreen or not */
	public boolean isFullscreen ();

	/** Create a new cursor represented by the {@link com.badlogic.gdx.graphics.Pixmap}. The Pixmap must be in RGBA8888 format,
	 * width & height must be powers-of-two greater than zero (not necessarily equal), and alpha transparency must be single-bit
	 * (i.e., 0x00 or 0xFF only). This function returns a Cursor object that can be set as the system cursor by calling
	 * {@link #setCursor(Cursor)} .
	 *
	 * @param pixmap the mouse cursor image as a {@link com.badlogic.gdx.graphics.Pixmap}
	 * @param xHotspot the x location of the hotspot pixel within the cursor image (origin top-left corner)
	 * @param yHotspot the y location of the hotspot pixel within the cursor image (origin top-left corner)
	 * @return a cursor object that can be used by calling {@link #setCursor(Cursor)} or null if not supported */
	public Cursor newCursor (Pixmap pixmap, int xHotspot, int yHotspot);

	/** Only viable on the lwjgl-backend and on the gwt-backend. Browsers that support cursor:url() and support the png format (the
	 * pixmap is converted to a data-url of type image/png) should also support custom cursors. Will set the mouse cursor image to
	 * the image represented by the {@link com.badlogic.gdx.graphics.Cursor}. It is recommended to call this function in the main render thread, and maximum one time per frame.
	 *
	 * @param cursor the mouse cursor as a {@link com.badlogic.gdx.graphics.Cursor} */
	public void setCursor (Cursor cursor);

	/**
	 * Sets one of the predefined {@link SystemCursor}s
	 */
	public void setSystemCursor(SystemCursor systemCursor);
}