package dam.test;

import static org.lwjgl.opengl.GL11.*;
import static org.lwjgl.opengl.GL12.*;
import static org.lwjgl.opengl.GL13.*;
import static org.lwjgl.opengl.GL20.*;
import static org.lwjgl.opengl.GL30.*;

import java.awt.image.BufferedImage;
import java.awt.image.PixelGrabber;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.ShortBuffer;
import java.util.ArrayList;
import java.util.Random;

import javax.imageio.ImageIO;

import org.lwjgl.BufferUtils;
import org.lwjgl.LWJGLException;
import org.lwjgl.input.Keyboard;
import org.lwjgl.input.Mouse;
import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.DisplayMode;
import org.lwjgl.opengl.PixelFormat;

public class TileRenderingTest {

   //Screen size
    private static final int WIDTH = 800, HEIGHT = 600;
    
    //Map size in tiles
    private static final int MAP_WIDTH = 2048, MAP_HEIGHT = 2048;
    
    //Tileset settings (might want to load these from a file, but this will do for now)
    private static final int TILE_WIDTH = 16, TILE_HEIGHT = 16, TILES_PER_ROW = 30, TOTAL_TILES = 16*30;
    
    //Movement speed of arrow keys
    private static final double MOVE_SPEED = 0.5;
    
    //Shader program, LOD uniform location and tileset texture
    private int program;
    private int lodLocation, scaleLocation;
    private int tilesetTexture;
    
    private TileRenderer renderer;
    private double targetScale = 2, currentScale = 2;
    private double x = MAP_WIDTH / 2.0, y = MAP_HEIGHT / 2.0;
    private ArrayList<Integer> keys;
    
    public TileRenderingTest(){
       try{
          Display.setDisplayMode(new DisplayMode(WIDTH, HEIGHT));
          //Display.setDisplayModeAndFullscreen(Display.getDesktopDisplayMode());
          Display.create(new PixelFormat(24, 0, 0, 0, 0));
       } catch(LWJGLException ex){
          ex.printStackTrace();
       }
       
       glOrtho(0, WIDTH, HEIGHT, 0, -1, 1);
       glEnable(GL_TEXTURE_2D);
       
       //Load the shader
        program = glCreateProgram();
        glAttachShader(program, loadShader(GL_VERTEX_SHADER, loadFileSource(new File("shaders/tile/tile.vert"))));
        glAttachShader(program, loadShader(GL_FRAGMENT_SHADER, loadFileSource(new File("shaders/tile/tile2.frag"))));
        glLinkProgram(program);
        String log = glGetProgramInfoLog(program, 65536);
        if(log.length() != 0){
            System.out.println("Program link log:\n" + log);
        }
        
        //Submit uniforms
        glUseProgram(program);
        glUniform2f(glGetUniformLocation(program, "mapSize"), MAP_WIDTH, MAP_HEIGHT);
        glUniform1i(glGetUniformLocation(program, "tileTexture"), 0);
        glUniform1i(glGetUniformLocation(program, "tilesetTexture"), 1);

        lodLocation = glGetUniformLocation(program, "lod");
        scaleLocation = glGetUniformLocation(program, "scale");
        
        //Load tileset texture
        tilesetTexture = glGenTextures();
        glBindTexture(GL_TEXTURE_2D_ARRAY, tilesetTexture);
        
        //Use whatever filtering you want! Mipmaps work!
        
        //Mipmaps:
        glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
        glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        
        //Blocky mipmaps
        //glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_LINEAR);
        //glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        
        //Clamp coordinates to edge
        glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
        
        //Allocate a TILE_WIDTH x TILE_HEIGHT 2D texture array with TOTAL_TILES layers. 
        glTexImage3D(GL_TEXTURE_2D_ARRAY, 0, GL_RGB8, TILE_WIDTH, TILE_HEIGHT, TOTAL_TILES, 0, GL_RGB, GL_UNSIGNED_BYTE, (ByteBuffer)null);
        
        BufferedImage image = null;
        try{
           image = ImageIO.read(new File("files/tiles/tileset.png")); 
        }catch(IOException ex){
           ex.printStackTrace();
        }
        
       int[] pixels = new int[TILE_WIDTH * TILE_HEIGHT];
       ByteBuffer buffer = BufferUtils.createByteBuffer(pixels.length * 3);
       
        int x = 0, y = 0;
        for(int i = 0; i < TOTAL_TILES; i++){
           //Split the big tileset into one tile per image
           BufferedImage subImage = image.getSubimage(x*TILE_WIDTH, y*TILE_HEIGHT, TILE_WIDTH, TILE_HEIGHT);
            PixelGrabber pg = new PixelGrabber(subImage, 0, 0, TILE_WIDTH, TILE_HEIGHT, pixels, 0, TILE_WIDTH);
            try {
                pg.grabPixels();
            } catch (InterruptedException ex) {
                System.err.println("Interrupted while loading texture. Epic error.");
            }
            for(int j = 0; j < pixels.length; j++){
               int pixel = pixels[j];
                buffer.put((byte) ((pixel >> 16) & 0xFF));     // Red component
                buffer.put((byte) ((pixel >> 8) & 0xFF));      // Green component
                buffer.put((byte) (pixel & 0xFF));
            }
            buffer.flip();
            //Load a single tile (a layer of the texture array).
            glTexSubImage3D(GL_TEXTURE_2D_ARRAY, 0, 0, 0, i, TILE_WIDTH, TILE_HEIGHT, 1, GL_RGB, GL_UNSIGNED_BYTE, buffer);
           
           if(++x == TILES_PER_ROW){
              x = 0;
              y++;
           }
        }
        
        //Generate mipmaps.
        glGenerateMipmap(GL_TEXTURE_2D_ARRAY);
        
        //Create tile renderer and set each tile to a random tile 
        renderer = new TileRenderer(program, lodLocation, scaleLocation, tilesetTexture, MAP_WIDTH, MAP_HEIGHT);
        
        Random r = new Random(8235928375l);
        ShortBuffer b = BufferUtils.createShortBuffer(MAP_WIDTH * MAP_HEIGHT * 3);
        for(y = 0; y < MAP_HEIGHT; y++){
           for(x = 0; x < MAP_WIDTH; x++){
              int tile = (int)(r.nextInt(TOTAL_TILES));
              b.put((short) tile)
              .put((short) x)
              .put((short) y);
           }
        }
        b.flip();
        renderer.bindTileTexture();
        glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, MAP_WIDTH, MAP_HEIGHT, GL_RGB, GL_UNSIGNED_SHORT, b);
        
        //Currently pressed keys
        keys = new ArrayList<Integer>();
    }
    
    //Loads shader source from a file.
    private static String loadFileSource(File file){
        if(!file.exists()){
            System.out.println("Unable to open file " + file.getAbsolutePath() + "!!!");
            return null;
        }

        StringBuilder source = new StringBuilder();
        String line;
        try {
            BufferedReader reader = new BufferedReader(new FileReader(file));
            while ((line = reader.readLine()) != null) {
                source.append(line).append('\n');
            }
        } catch (Exception e) {
            System.out.println("Failed to read shader source!");
            e.printStackTrace();
            return null;
        }
        return source.toString();
    }
    
    //Creates a shader of the specified type with the specified source code
    private int loadShader(int type, String source){
       int id = glCreateShader(type);
        glShaderSource(id, source);
        glCompileShader(id);

        String errorLog = glGetShaderInfoLog(id, 65536);
        if(errorLog.length() != 0){
            System.out.println("Shader compile log: \n" + errorLog);
        }
        return id;
    }
    
    
    public void gameloop(){
       while(!Display.isCloseRequested()){
          
          //Test program input handling
          while(Mouse.next()){
             if(Mouse.getEventDWheel() > 0){
                targetScale *= 1.1;
             }
             if(Mouse.getEventDWheel() < 0){
                targetScale /= 1.1;
             }
          }
          
          while(Keyboard.next()){
             int button = Keyboard.getEventKey();
             if(Keyboard.getEventKeyState()){
                if(!keys.contains(button)){
                   keys.add(button);
                }
             }else{
                keys.remove((Integer)button);
             }
          }
          
          if(keys.contains(Keyboard.KEY_LEFT)){
             x -= MOVE_SPEED/currentScale;
          }
          
          if(keys.contains(Keyboard.KEY_RIGHT)){
             x += MOVE_SPEED/currentScale;
          }
          
          if(keys.contains(Keyboard.KEY_UP)){
             y -= MOVE_SPEED/currentScale;
          }
          
          if(keys.contains(Keyboard.KEY_DOWN)){
             y += MOVE_SPEED/currentScale;
          }
          
          //Smooth scaling
          currentScale += (targetScale - currentScale) / 100;
          
          //Clear color buffer
          glClear(GL_COLOR_BUFFER_BIT);
          glPushMatrix();
          
          glTranslated(WIDTH/2.0, HEIGHT/2.0, 0);
          glScaled(currentScale, currentScale, 1);
          

          //Comment out these two lines for non-isometric view:
          //glScalef(1, 0.5f, 1);
          //glRotatef(-45, 0, 0, 1);
          
          //glRotatef(f, 0, 0, 1);
          //f += 0.01f;
          
          
          glTranslated(-x, -y, 0);
          
          double size = Math.min(TILE_WIDTH, TILE_HEIGHT) / currentScale;
          float lod = (float)(Math.log(size) / Math.log(2));
          renderer.render(lod, Math.max(1, Math.min(16, (float)currentScale)));
          

          glPopMatrix();
          
          Display.update();
       }
    }
    
    float f = 11;
    
    public static class TileRenderer{
       
       private int shaderProgram;
       private int lodLocation, scaleLocation;
       private int tilesetTexture;
       
       private int width, height;
       private int tileTexture;
       private ShortBuffer buffer;
       
       public TileRenderer(int shaderProgram, int lodLocation, int scaleLocation, int tilesetTexture, int width, int height){
          this.shaderProgram = shaderProgram;
          this.lodLocation = lodLocation;
          this.scaleLocation = scaleLocation;
          this.tilesetTexture = tilesetTexture;
          
          this.width = width;
          this.height = height;
          
          /*Create a texture to hold tile indices for each tile.
          Uses the red and green channels of an RGB texture for a maximum of
          65536 tiles. The maximum texture size is 16384, so that is the 
          real limit as we can't have more texture layers than that
          in the other shader. This can be worked around though by not using
          a texture array.*/
          tileTexture = glGenTextures();
          glBindTexture(GL_TEXTURE_2D, tileTexture);
          
          //NO FILTERING! IMPORTANT!
            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_CLAMP_TO_EDGE);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB16, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, (ByteBuffer)null);
            
            buffer = BufferUtils.createShortBuffer(3);
       }
       
       public void bindTileTexture(){
          glBindTexture(GL_TEXTURE_2D, tileTexture);
       }
       
       //Remember to bind the tile texture before calling setTile(...).
       public void setTile(int x, int y, int tile){
          buffer.put((short) tile)
          .put((short)x)
          .put((short)y)
          .flip();
          glTexSubImage2D(GL_TEXTURE_2D, 0, x, y, 1, 1, GL_RGB, GL_UNSIGNED_SHORT, buffer);
          System.out.println((short) tile);
       }
       
       public void render(float lod, float scale){
          glUseProgram(shaderProgram);

          glUniform1f(lodLocation, lod);
          glUniform1f(scaleLocation, scale);
          
          //Bind tile index texture
          glActiveTexture(GL_TEXTURE0);
          glBindTexture(GL_TEXTURE_2D, tileTexture);
          
          //Bind tileset texture array
          glActiveTexture(GL_TEXTURE1);
          glBindTexture(GL_TEXTURE_2D_ARRAY, tilesetTexture);
          
          glBegin(GL_QUADS);
          {
             glTexCoord2f(0, 0);
             glVertex2f(0, 0);

             glTexCoord2f(width, 0);
             glVertex2f(width, 0);

             glTexCoord2f(width, height);
             glVertex2f(width, height);

             glTexCoord2f(0, height);
             glVertex2f(0, height);
          }
          glEnd();

          glActiveTexture(GL_TEXTURE0);
          glBindTexture(GL_TEXTURE_2D, 0);
       }
    }
    
    public static void main(String[] args){
       new TileRenderingTest().gameloop();
    }
}