package me.hammerle.snuviengine.api;

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.nio.IntBuffer;
import javax.imageio.ImageIO;
import org.lwjgl.BufferUtils;
import static org.lwjgl.opengl.GL11.*;
import static org.lwjgl.opengl.GL12.*;
import static org.lwjgl.opengl.GL30.*;

public class Texture
{
    public class Animation
    {
        private IntBuffer[] data;
        private int[] wi;
        private int[] he;
        private final int offsetX;
        private final int offsetY;
        private int index = 0;
        
        private Animation(int offsetX, int offsetY, String... paths)
        {
            this.offsetX = offsetX;
            this.offsetY = offsetY;
            
            int l = paths.length;
            data = new IntBuffer[l];
            wi = new int[l];
            he = new int[l];
            
            for(int i = 0; i < l; i++)
            {
                BufferedImage image;
                try
                {
                    image = ImageIO.read(new File(paths[i]));
                }
                catch(IOException | IllegalArgumentException ex)
                {
                    throw new TextureException("cannot read texture file '" + paths[i] + "'");
                }

                if(offsetX + image.getWidth() > w || offsetY + image.getHeight() > h)
                {
                    System.out.println(offsetX + " " + image.getWidth() + " " +  w + " " + offsetY + " " + image.getHeight() + " " + h);
                    throw new TextureException("animation image '" + paths[i] + "'is out of range");
                }
                
                wi[i] = image.getWidth();
                he[i] = image.getHeight();
                IntBuffer buffer = BufferUtils.createIntBuffer(wi[i] * he[i]);
                for(int y = 0; y < he[i]; y++)
                {
                    for(int x = 0; x < wi[i]; x++)
                    {
                        int c = image.getRGB(x, y);
                        buffer.put((c << 8) | ((c >> 24) & 0xFF));
                    }
                }
                buffer.flip();
                data[i] = buffer;
            }
        }
        
        public void nextFrame()
        {
            GLHelper.glBindTexture(texture);
            glTexSubImage2D(GL_TEXTURE_2D, 0, offsetX, offsetY, wi[index], he[index], GL_RGBA, GL_UNSIGNED_INT_8_8_8_8, data[index]);
            index = (index + 1) % data.length;
        }
    }
    
    private int texture = -1; 
    private final String path;
    private final int w;
    private final int h;
    private IntBuffer buffer;
    
    public Texture(String path)
    {
        this.path = path;
        
        BufferedImage image;
        try
        {
            image = ImageIO.read(new File(path));
        }
        catch(IOException | IllegalArgumentException ex)
        {
            throw new TextureException("cannot read texture file '" + path + "'");
        }
        
        w = image.getWidth();
        h = image.getHeight();
        buffer = BufferUtils.createIntBuffer(w * h);
        for(int y = 0; y < h; y++)
        {
            for(int x = 0; x < w; x++)
            {
                int c = image.getRGB(x, y);
                buffer.put((c << 8) | ((c >> 24) & 0xFF));
            }
        }
        buffer.flip();
        
        Shader.addTask(() -> loadTexture());
    }
    
    public Animation addAnimation(int offsetX, int offsetY, String... paths)
    {
        return new Animation(offsetX, offsetY, paths);
    }
    
    private void loadTexture()
    {
        if(texture != -1)
        {
            throw new TextureException("a texture is already loaded");
        }
        
        texture = glGenTextures();
        
        GLHelper.glBindTexture(texture);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_INT_8_8_8_8, buffer);
        buffer = null;
        glGenerateMipmap(GL_TEXTURE_2D);
    }    

    public void bindTexture()
    {
        if(texture == -1)
        {
            throw new TextureException("cannot load non loaded texture");
        }
        GLHelper.glBindTexture(texture);
    }
}