import java.awt.*;
import java.awt.image.*;
import java.io.*;

/**
 * Handles frame buffer and Targa TGA image files.
 * @author: Phil Gage
 */
class FrameBuffer {
    final int headersize = 18;
    private int[] pix;  //array for Java Image
    private byte buf[]; //TGA data
    private byte header[]= new byte[headersize]; //TGA header
    int width=0, height=0;
    /** Can use 0 for null color since alpha normally 1 bits  */
    private int NULLCOLOR = 0;

    /** Constuctor when image size unknown before loadtga */
    FrameBuffer () {
    }

    /** Constuctor when image size known */
    FrameBuffer (int width, int height) {
        this.width = width;
        this.height = height;
        buf = new byte[3*width*height+headersize];
        pix = new int[width*height];
        for (int i=0; i<width*height; i++)
           pix[i] = NULLCOLOR;
        for (int i=0; i<headersize; i++)
            header[i] = 0;
    }

    /** Set frame buffer pixel (x,y) to null color */
    void erasePixel (int x, int y) {
        pix[width*y+x] = NULLCOLOR;
    }

    /** Return true if frame buffer pixel (x,y) not null color */
    boolean validPixel (int x, int y) {
        return pix[width*y+x] != NULLCOLOR;
    }

    /** Set frame buffer pixel (x,y) to color c */
    void setPixel (int x, int y, Color c) {
        // Clamp color range to 0..1
        if (c.r < 0.0) c.r = 0.0;
        if (c.g < 0.0) c.g = 0.0;
        if (c.b < 0.0) c.b = 0.0;
        if (c.r > 1.0) c.r = 1.0;
        if (c.g > 1.0) c.g = 1.0;
        if (c.b > 1.0) c.b = 1.0;
        // Pack into TGA alpha, red, green, blue format
        pix[width*y+x] =  255<<24 | (int)(255*c.r)<<16 |
                          (int)(255*c.g)<<8 | (int)(255*c.b);
   }

    /** Get frame buffer pixel (x,y) color */
    void getPixel (int x, int y, Color color) {
        // Unpack from TGA alpha, red, green, blue format
        color.r = (double)((pix[width*y+x]>>16) & 255) / 255.0;
        color.g = (double)((pix[width*y+x]>>8) & 255) / 255.0;
        color.b = (double)((pix[width*y+x]>>0) & 255) / 255.0;
    }

    /** Return Image of current buffer for display */
    public Image getImage (Frame f) {
       Image img;
       img = f.createImage(new MemoryImageSource(width,height,pix,0,width));
       return img;
    }

    /** Read frame buffer from TGA image file
        Returns true if file is found and loaded */
    public boolean loadtga (String filename) {
        try {
            FileInputStream in = new FileInputStream (filename);
            in.read (header, 0, headersize);
            // If not initialized, read width, height and alloc
            if (width == 0) {
                // Signed bytes are tricky to convert to ints
                width = header[12] > 0 ? header[12] : (int)header[12] + 256;
                width += 256*(int)header[13];
                height = header[14] > 0 ? header[14] : (int)header[14] + 256;
                height += 256*(int)header[15];
                System.out.println ("Image width=" + width +
                                    " height=" + height);
                // Check size to avoid nasty crash
                if (width < 10 || width > 1280 ||
                    height < 10 || height > 1024) {
                    System.out.println ("Bad Image size");
                    return false;
                }
                buf = new byte[3*width*height];
            }
            in.read (buf, 0, 3*width*height);
            // Must alloc pix for each frame, saved in image
            pix = new int[width*height];
            for (int i=0; i<width*height; i++) {
                pix[i] = 255<<24 |
                         ((int)buf[3*i+2]<<16)&0xff0000 |
                         ((int)buf[3*i+1]<<8)&0xff00 |
                         ((int)buf[3*i+0]<<0)&0xff;
            }
        }
        catch (Exception e) {
//            System.out.println ("loadtga error: " + e);
            return false;
        }
        return true;
    }

    /** Write frame buffer to TGA image file
        Returns true if file is successfully saved */
    public boolean savetga (String filename) {
        header[2] = 2; //imagetype
        header[13] = (byte)(width >> 8);
        header[12] = (byte)(width & 255);
        header[15] = (byte)(height >> 8);
        header[14] = (byte)(height & 255);
        header[16] = 24; //pixelsize
        header[17] = 32; //descriptor
        for (int i=0; i<width*height; i++) {
            buf[3*i+2] = (byte)((pix[i]>>16) & 255);
            buf[3*i+1] = (byte)((pix[i]>>8) & 255);
            buf[3*i+0] = (byte)((pix[i]>>0) & 255);
        }
        try {
            FileOutputStream out = new FileOutputStream (filename);
            out.write (header, 0, headersize);
            out.write (buf, 0, 3*width*height);
        }
        catch (Exception e) {
            System.out.println ("savetga error: " + e);
            return false;
        }
        return true;
    }

    /** Shift image by x,y pixels, could improve speed */
    void shift (int x, int y) {
        int offset = x + y*width;
        int last = width*height-1;
        if (offset > 0)
            for (int i=last; i>=offset; i--)
                pix[i] = pix[i-offset];
        else if (offset < 0)
            for (int i=0; i<=last+offset; i++)
                pix[i] = pix[i-offset];
    }

}