// Copyright 2004 Adam Megacz, see the COPYING file for licensing [LGPL]
// Author: Brian Alliet

package org.xwt.plat;
import org.xwt.*;
import org.xwt.js.*;
import org.xwt.util.*;

abstract class OpenGL {
    static final boolean pretendToBeACrappyVideoCard = false;
    boolean rectangularTextures;
    boolean hasRectangularTextures() { return rectangularTextures; }
    int maxTexSize;
    int maxRectTexSize;
    float glVersion;
    String version;
    String renderer;
    String vendor;
    
    private native void natInit();
    
    private static float parseVersion(String s) {
        int end = s.indexOf(' ');
        if(end < 0) end = s.length();
        try {
            return Float.parseFloat(s.substring(0,end));
        } catch(NumberFormatException e) {
            return 1.1f; // just a guess
        }
    }
    
    // This MUST be called after OpenGL is instansiated (and activateSharedContext is functioning)
    public void init() throws NotSupportedException {
        natInit();
        glVersion = parseVersion(version);
        if(glVersion < 1.1) throw new NotSupportedException("OpenGL 1.1 or greater is required. (you have: " + version +" - " + glVersion + ")");
        if(pretendToBeACrappyVideoCard) {
            maxTexSize = 512;
            maxRectTexSize = 0;
            rectangularTextures = false;
        }
        Log.diag(this,"Renderer: " + renderer);
        Log.diag(this,"Version: " + version);
        Log.diag(this,"Vendor: " + vendor);
        Log.diag(this,"Rectangular textures: " + (rectangularTextures ? "supported" : "unsupported"));
        Log.diag(this,"Max texture size: " + maxTexSize);
        Log.diag(this,"Max rectangular texture size: " + maxRectTexSize);
    }
    
    protected abstract void activateSharedContext();

    public static class NotSupportedException extends Exception {
        public NotSupportedException(String s) { super(s); }
    }

    public static abstract class GLPixelBuffer extends PixelBuffer {
        protected int width;
        protected int height;
        public int getWidth() { return width; }
        public int getHeight() { return height; }
        
        private boolean glScissorEnabled = false;
        
        public GLPixelBuffer(int width, int height) {
            this.width = width;
            this.height = height;
        }
        
        // This should activate the drawing context and prepare the double buffer for drawing
        protected abstract void activateContext();
        
        protected static native void drawableInit(int w, int h);
        
        private static native void setColor(int color);
        
        public native void setClip(int x, int y, int x2, int y2);
        public native void resetClip();
        public native void fillTrapezoid(int x1, int x2, int y1, int x3, int x4, int y2, int color);
            
        public void drawString(String font, String text, int x, int y, int color) {
            //System.out.println("drawString(): " + text);
        }

        public void drawGlyph(org.xwt.Font.Glyph source, int dx, int dy, int cx1, int cy1, int cx2, int cy2, int rgb) {
            drawPicture_(((org.xwt.Platform.DefaultGlyph)source).getPicture(), dx, dy, cx1, cy1, cx2, cy2, rgb);
        }
        public void drawPicture(Picture source, int dx, int dy, int cx1, int cy1, int cx2, int cy2) {
            drawPicture_(source, dx, dy, cx1, cy1, cx2, cy2, 0xffffffff);
        }

        private void drawPicture_(Picture source, int dx, int dy, int cx1, int cy1, int cx2, int cy2, int color) {
            activateContext();
            setColor(color);
            GLPicture p = getInnerPicture(source, gl);
            p.draw(dx,dy,cx1,cy1,cx2,cy2);
        }
    }

    // FIXME ugly
    public static OpenGL gl = null;
    public OpenGL() { gl = this; }
    
    public final static int roundToPowerOf2(int n) {
        if(((n-1)&n)==0) return n;
        for(int x=2;x!=0;x<<=1) if(n < x) return x;
        return 0;
    }
    
    private static GLPicture getInnerPicture(Picture p, OpenGL gl) {
        OpenGLPicture oglp = (OpenGLPicture)p;
        if (!oglp.isLoaded || oglp.realPicture != null) return oglp.realPicture;
        if (gl.rectangularTextures && p.width <= gl.maxRectTexSize && p.height <= gl.maxRectTexSize) 
            oglp.realPicture = new RectGLPicture(p.data,p.width,p.height,oglp.alphaOnly,gl);
        else if (p.width <= gl.maxTexSize && p.height <= gl.maxTexSize)
            oglp.realPicture = new SquareGLPicture(p.data,p.width,p.height,oglp.alphaOnly,gl);
        else
            oglp.realPicture = new MosaicGLPicture(p.data,p.width,p.height,oglp.alphaOnly,gl);
        p.data = null;
        return oglp.realPicture;
    }
    
    public Picture _createPicture(JS r, boolean alphaOnly) { return new OpenGLPicture(r, false); }

    public static class OpenGLPicture extends Picture {
        public OpenGLPicture(JS r, boolean a) { super(r); alphaOnly = a; }
        boolean alphaOnly;
        GLPicture realPicture = null;
    }

    public Font.Glyph _createGlyph(org.xwt.Font f, char c) { return new org.xwt.Platform.DefaultGlyph(f, c); }
    
    private native void natDeleteTexture(int tex);
    public void deleteTexture(final int tex) {
        // CHECKME: Is this safe to do from finalize()?
        // natDeleteTexture MUST be run from the message queue thread
        Scheduler.add(new Scheduler.Task() { public void perform() { natDeleteTexture(tex); }});
    }
    
    private static abstract class GLPicture {
        protected int width;
        protected int height;
        
        public final int getWidth() { return width; }
        public final int getHeight() { return height; }
                
        public GLPicture(int w, int h) {
            this.width = w;
            this.height = h;
        }
        
        public abstract void draw(int dx, int dy, int cx1, int cy1, int cx2, int cy2);
        protected abstract void finalize();
    }
    
    private static class RectGLPicture extends GLPicture {
        private OpenGL gl;
        public int textureName;
                
        public native void natInit(Object data, boolean alphaOnly);
        
        public RectGLPicture(Object data,int w, int h, boolean alphaOnly, OpenGL gl) {
            super(w,h);
            this.gl = gl;
            natInit(data,alphaOnly);
        }
    
        public native void draw(int dx, int dy, int cx1, int cy1, int cx2, int cy2);  
        protected void finalize() { gl.deleteTexture(textureName); }
    }
    
    private static class SquareGLPicture extends GLPicture {
        private int texHeight;
        private int texWidth;
        private OpenGL gl;
        public int textureName;
                
        public native void natInit(Object data, boolean alphaOnly);
                
        public SquareGLPicture(Object data,int w, int h, boolean alphaOnly, OpenGL gl) {
            super(w,h);
            this.gl = gl;
            if(w > 0x7fffffff || h > 0x7fffffff) throw new Error("insane texture size: " + w + "x" + h);
            texHeight = roundToPowerOf2(h);
            texWidth = roundToPowerOf2(w);
            natInit(data,alphaOnly);
        }
        
        public native void draw(int dx, int dy, int cx1, int cy1, int cx2, int cy2);  
        protected void finalize() { gl.deleteTexture(textureName); }
    }
    
    private static class MosaicGLPicture extends GLPicture {
        private static final int overlap = 8;
        
        int psize;
        GLPicture[][] pics;
        
        private static float wastedSpace(int w,int h,int size) {
            int w2 = size * ((w+size-1)/size);
            int h2 = size * ((h+size-1)/size);
            return 1.0f-(float)(w*h)/(float)(w2*h2);
        }
        
        private static Object subData(Object data, int x, int y, int w, int h, int rowSize) {
            if(data instanceof byte[]) return subData((byte[])data,x,y,w,h,rowSize);
            if(data instanceof int[]) return subData((int[])data,x,y,w,h,rowSize);
            throw new Error("not reached");
        }
        
        private static int[] subData(int[] data, int x, int y, int w, int h, int rowSize) {
            int[] sub = new int[w*h];
            int row = y;
            for(int i=0;i<h;i++,row++)
                for(int j=0;j<w;j++)
                    sub[i*w+j] = data[row*rowSize+j+x];
            return sub;
        }
        
        private static byte[] subData(byte[] data, int x, int y, int w, int h, int rowSize) {
            byte[] sub = new byte[w*h];
            int row = y;
            for(int i=0;i<h;i++,row++)
                for(int j=0;j<w;j++)
                    sub[i*w+j] = data[row*rowSize+j+x];
            return sub;
        }
        
        public MosaicGLPicture(Object data,int w, int h, boolean alphaOnly, OpenGL gl) {
            super(w,h);
            psize = gl.maxTexSize;
            while(wastedSpace(w,h,psize) > 0.40) psize/=2;
            Log.info(this,"Using psize: " + psize + " for " + w + "x" + h + " image (wasted space: " + wastedSpace(w,h,psize));
            
            int rows = (h+psize-1)/psize;
            int cols = (w+psize-1)/psize;
            intintp,tmp2;
            
            pics = new GLPicture[rows][cols];
            for(int i=0;i<rows-1;i++)
                for(int j=0;j<cols-1;j++)
                    pics[i][j] = new SquareGLPicture(subData(data,j*psize,i*psize,psize,psize,w),psize,psize,alphaOnly,gl);
            tmp = (rows-1)*psize;
            for(int i=0;i<cols-1;i++)
                pics[rows-1][i] = new SquareGLPicture(subData(data,i*psize,tmp,psize,h-tmp,w),psize,h-tmp,alphaOnly,gl);
            tmp2 = (cols-1)*psize;
            for(int i=0;i<rows-1;i++)
                pics[i][cols-1] = new SquareGLPicture(subData(data,tmp2,i*psize,w-tmp2,psize,w),w-tmp2,psize,alphaOnly,gl);
            pics[rows-1][cols-1] = new SquareGLPicture(subData(data,tmp2,tmp,w-tmp2,h-tmp,w),w-tmp2,h-tmp,alphaOnly,gl);
        }
        protected void finalize() {  }
        
        private static final int max(int a, int b) { return a > b ? a : b; }
        private static final int min(int a, int b) { return a < b ? a : b; }
        
        public void draw(int dx, int dy, int cx1, int cy1, int cx2, int cy2) {
            int totalWidth = width;
            int totalHeight = height;
            // *{x,y}{1,2} key: d=dest s=src, p=bounds of this picture, i=intersection of s and p, pd = dest of this pic
            for(int i=0;i<pics.length;i++) {
                for(int j=0;j<pics[i].length;j++) {
                    int px1 = j*psize + dx;
                    int py1 = i*psize + dy;
                    pics[i][j].draw(px1, py1, cx1, cy1, cx2, cy2);
                }
            }
        }
    }
}