package electrosphere.client.foliagemanager;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Random;
import java.util.Set;

import org.joml.Matrix4f;
import org.joml.Quaternionf;
import org.joml.Vector3d;
import org.joml.Vector3f;

import electrosphere.engine.Globals;
import electrosphere.entity.Entity;
import electrosphere.entity.EntityCreationUtils;
import electrosphere.entity.EntityDataStrings;
import electrosphere.entity.EntityTags;
import electrosphere.entity.EntityUtils;
import electrosphere.entity.types.camera.CameraEntityUtils;
import electrosphere.renderer.actor.instance.InstancedActor;
import electrosphere.renderer.buffer.ShaderAttribute;
import electrosphere.renderer.buffer.HomogenousUniformBuffer.HomogenousBufferTypes;

/**
 * Manages foliage (grass, small plants, etc) that should be shown, typically instanced
 */
public class ClientFoliageManager {

    //threshold for a grass blade to relocate to a new position
    static final float GRASS_RELOCATION_THRESHOLD = 5f;

    //amount of grass entities to manage
    static final int grassCapacity = 10000;

    //Random for finding new positions for foliage
    Random placementRandomizer = new Random();
    
    //The list of grass entities currently in use
    Set<Entity> grassEntities = new HashSet<Entity>();

    //Used to prevent concurrent usage of grassEntities set
    boolean ready = false;





    //The map of all attributes for instanced foliage
    static final Map<ShaderAttribute,HomogenousBufferTypes> attributes = new HashMap<ShaderAttribute,HomogenousBufferTypes>();

    //model matrix shader attribute
    static ShaderAttribute modelMatrixAttribute;
    
    //set attributes
    static {
        int[] attributeIndices = new int[]{
            5,6,7,8
        };
        modelMatrixAttribute = new ShaderAttribute(attributeIndices);
        attributes.put(modelMatrixAttribute,HomogenousBufferTypes.MAT4F);
    }

    //shader paths
    static final String vertexPath = "shaders/foliage/foliage.vs";
    static final String fragmentPath = "shaders/foliage/foliage.fs";












    /**
     * Starts up the foliage manager
     */
    public void start(){
        //queue grass model
        Globals.assetManager.addModelPathToQueue("models/grass1.fbx");

        Vector3d centerPosition = new Vector3d(0,0,0);
        //create grass entities
        Entity grassEntity = EntityCreationUtils.createClientSpatialEntity();
        makeEntityInstancedFoliage(grassEntity, "models/grass1.fbx", grassCapacity);
        EntityUtils.getPosition(grassEntity).set(getNewPosition(centerPosition));
        EntityUtils.getRotation(grassEntity).set(getNewRotation());
        EntityUtils.getScale(grassEntity).set(new Vector3d(2.0, 2.0, 2.0));
        grassEntities.add(grassEntity);
        for(int i = 0; i < grassCapacity - 1; i++){
            grassEntity = EntityCreationUtils.createClientSpatialEntity();
            makeEntityInstancedFoliage(grassEntity, "models/grass1.fbx", grassCapacity);
            EntityUtils.getPosition(grassEntity).set(getNewPosition(centerPosition));
            EntityUtils.getRotation(grassEntity).set(getNewRotation());
            EntityUtils.getScale(grassEntity).set(new Vector3d(2.0, 2.0, 2.0));
            grassEntities.add(grassEntity);
        }
        ready = true;
    }

    /**
     * Updates all grass entities
     */
    public void update(){
        if(ready){
            Matrix4f modelMatrix = new Matrix4f();
            Vector3f cameraCenter = CameraEntityUtils.getCameraCenter(Globals.playerCamera);
            for(Entity grassEntity : grassEntities){
                Vector3d grassPosition = EntityUtils.getPosition(grassEntity);
                Quaternionf grassRotation = EntityUtils.getRotation(grassEntity);
                Vector3d playerPosition = EntityUtils.getPosition(Globals.playerEntity);
                InstancedActor instancedActor = InstancedActor.getInstancedActor(grassEntity);
                //update position
                if(playerPosition.distance(grassPosition) > GRASS_RELOCATION_THRESHOLD){
                    grassPosition.set(getNewPosition(playerPosition));
                    grassRotation.set(getNewRotation());
                }
                //update uniforms
                // instancedActor.setUniform("position", grassPosition);
                // instancedActor.setUniform("rotation", new Vector4d(
                //     grassRotation.x,
                //     grassRotation.y,
                //     grassRotation.z,
                //     grassRotation.w));
                // instancedActor.setUniform("scale", new Vector3d(EntityUtils.getScale(grassEntity)));

                modelMatrix = modelMatrix.identity();
                Vector3f cameraModifiedPosition = new Vector3f((float)grassPosition.x,(float)grassPosition.y,(float)grassPosition.z).sub(cameraCenter);
                modelMatrix.translate(cameraModifiedPosition);
                modelMatrix.rotate(grassRotation);
                modelMatrix.scale(EntityUtils.getScale(grassEntity));

                instancedActor.setAttribute(modelMatrixAttribute, modelMatrix);

                //draw
                instancedActor.draw(Globals.renderingEngine.getRenderPipelineState());
            }
        }
    }

    /**
     * Gets a good position to put a new blade of grass
     * @param centerPosition The player's position
     * @return The new position for the blade of grass
     */
    protected Vector3d getNewPosition(Vector3d centerPosition){
        double angle = placementRandomizer.nextDouble() * Math.PI * 2;
        double radius = placementRandomizer.nextDouble() * GRASS_RELOCATION_THRESHOLD;
        return new Vector3d(
            centerPosition.x + Math.cos(angle) * radius,
            centerPosition.y,
            centerPosition.z + Math.sin(angle) * radius
        );
    }

    /**
     * Gets a new rotation for a blade of grass
     * @return The rotation
     */
    protected Quaternionf getNewRotation(){
        return new Quaternionf().rotationX(-(float)Math.PI / 2.0f).rotateLocalY((float)Math.PI * placementRandomizer.nextFloat());
    }









    /**
     * Makes an already created entity a drawable, instanced entity (client only) by backing it with an InstancedActor
     * @param entity The entity
     * @param modelPath The model path for the model to back the instanced actor
     */
    public static void makeEntityInstancedFoliage(Entity entity, String modelPath, int capacity){
        entity.putData(EntityDataStrings.INSTANCED_ACTOR, Globals.clientInstanceManager.createInstancedActor(modelPath, vertexPath, fragmentPath, attributes, capacity));
        entity.putData(EntityDataStrings.DATA_STRING_POSITION, new Vector3d(0,0,0));
        entity.putData(EntityDataStrings.DATA_STRING_ROTATION, new Quaternionf().identity());
        entity.putData(EntityDataStrings.DATA_STRING_SCALE, new Vector3f(1,1,1));
        entity.putData(EntityDataStrings.DRAW_SOLID_PASS, true);
        Globals.clientScene.registerEntity(entity);
        Globals.clientScene.registerEntityToTag(entity, EntityTags.DRAW_INSTANCED);
    }




}