EnergonRelics/src/main/java/com/thebrokenrail/energonrelics/block/entity/DefensiveLaserBlockEntity.java

package com.thebrokenrail.energonrelics.block.entity;

import com.thebrokenrail.energonrelics.config.HardcodedConfig;
import com.thebrokenrail.energonrelics.EnergonRelics;
import com.thebrokenrail.energonrelics.block.DefensiveLaserBlock;
import com.thebrokenrail.energonrelics.energy.core.EnergyReceiverBlockEntity;
import com.thebrokenrail.energonrelics.energy.core.util.Action;
import net.minecraft.block.BlockState;
import net.minecraft.block.entity.BlockEntityType;
import net.minecraft.entity.Entity;
import net.minecraft.entity.ItemEntity;
import net.minecraft.entity.LivingEntity;
import net.minecraft.entity.player.PlayerEntity;
import net.minecraft.nbt.CompoundTag;
import net.minecraft.particle.ParticleTypes;
import net.minecraft.server.world.ServerWorld;
import net.minecraft.util.hit.HitResult;
import net.minecraft.util.math.BlockPos;
import net.minecraft.util.math.Box;
import net.minecraft.util.math.MathHelper;
import net.minecraft.util.math.Vec3d;
import net.minecraft.world.RayTraceContext;
import net.minecraft.world.World;
import net.minecraft.world.explosion.Explosion;

import java.util.Comparator;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
import java.util.function.Predicate;

public class DefensiveLaserBlockEntity extends EnergyReceiverBlockEntity {
    private static final float ROTATION_INCREMENT = 4;

    public final Rotation rotation = new Rotation(0, 0, "Rotation");

    private static Vec3d getPosVec(BlockPos pos) {
        return new Vec3d(pos.getX() + 0.5d, pos.getY() + 0.5d, pos.getZ() + 0.5d);
    }

    private Vec3d getPosVec() {
        return getPosVec(getPos());
    }

    @Override
    public BlockState getCachedState() {
        if (hasWorld()) {
            return super.getCachedState();
        } else {
            return EnergonRelics.DEFENSIVE_LASER_BLOCK.getDefaultState();
        }
    }

    public class Rotation {
        private float yaw = 0;
        private float pitch = 0;
        private final String key;

        private Rotation(float yaw, float pitch, String key) {
            setRaw(yaw, pitch);
            this.key = key;
        }

        private void fromTag(CompoundTag tag) {
            CompoundTag rotation = tag.getCompound(key);
            setRaw(rotation.getInt("Yaw"), rotation.getInt("Pitch"));
        }

        private void toTag(CompoundTag tag) {
            CompoundTag rotation = new CompoundTag();
            rotation.putFloat("Yaw", yaw);
            rotation.putFloat("Pitch", pitch);
            tag.put(key, rotation);
        }

        private void setRaw(float yaw, float pitch) {
            setYaw(yaw);
            setPitch(pitch);
        }

        private void setYaw(float yaw) {
            this.yaw = yaw % 360;
        }

        private void setPitch(float pitch) {
            this.pitch = pitch % 360;
        }

        public float getYaw() {
            return yaw;
        }

        public float getPitch() {
            return pitch;
        }

        private void change(float diffYaw, float diffPitch) {
            setRaw(yaw + diffYaw, pitch + diffPitch);
            markDirty();
        }

        private Vec3d getRayVector() {
            return DefensiveLaserBlockEntity.getRayVector(yaw, pitch);
        }

        private float getAngleChange(float from, float to) {
            float diff = MathHelper.subtractAngles(from, to);
            return MathHelper.clamp(diff, -ROTATION_INCREMENT, ROTATION_INCREMENT);
        }

        private void target(float targetYaw, float targetPitch) {
            float yawChange = getAngleChange(yaw, targetYaw);
            float pitchChange = getAngleChange(pitch, targetPitch);
            change(yawChange, pitchChange);
        }
    }

    private static Vec3d getRayVector(float yaw, float pitch) {
        float pitchRad = pitch * (float) DEG2RAD;
        float yawRad = yaw * (float) DEG2RAD;
        float cosYaw = MathHelper.cos(yawRad);
        float sinYaw = MathHelper.sin(yawRad);
        float cosPitch = MathHelper.cos(pitchRad);
        float sinPitch = MathHelper.sin(pitchRad);
        return new Vec3d(sinYaw * cosPitch, -sinPitch, cosYaw * cosPitch);
    }

    public DefensiveLaserBlockEntity(BlockEntityType<?> type) {
        super(type);
    }

    public static final double DEG2RAD = Math.PI / 180d;
    private static final double RAD2DEG = 180d / Math.PI;

    private float getTargetPitch(Vec3d targetPos) {
        Vec3d pos = getPosVec();
        double diffX = targetPos.getX() - pos.getX();
        double diffY = targetPos.getY() - pos.getY();
        double diffZ = targetPos.getZ() - pos.getZ();
        double g = MathHelper.sqrt(diffX * diffX + diffZ * diffZ);
        return (float) -(MathHelper.atan2(diffY, g) * RAD2DEG);
    }

    private float getTargetYaw(Vec3d targetPos) {
        Vec3d pos = getPosVec();
        double diffX = targetPos.getX() - pos.getX();
        double diffZ = targetPos.getZ() - pos.getZ();
        return -((float) (MathHelper.atan2(diffZ, diffX) * RAD2DEG) - 90.0F);
    }

    private static final int COUNTDOWN = 28;

    private LivingEntity target;
    private int countdown = 0;

    private boolean firing = false;

    private Predicate<LivingEntity> getTargetPredicate(boolean useCurrentRotation) {
        return entity -> {
            if (entity.isAlive() && (!(entity instanceof PlayerEntity) || !((PlayerEntity) entity).isCreative()) && !entity.isInvisible() && entity.getPos().distanceTo(getPosVec()) <= HardcodedConfig.DEFENSIVE_LASER_RANGE) {
                Vec3d entityPos = entity.getPos();
                Vec3d start;
                if (useCurrentRotation) {
                    start = rotation.getRayVector().add(getPosVec());
                } else {
                    start = getRayVector(getTargetYaw(entityPos), getTargetPitch(entityPos)).add(getPosVec());
                }
                HitResult result = entity.getEntityWorld().rayTrace(new RayTraceContext(start, entityPos, RayTraceContext.ShapeType.COLLIDER, RayTraceContext.FluidHandling.ANY, getDummyEntity()));
                return result.getType() == HitResult.Type.MISS;
            } else {
                return false;
            }
        };
    }

    private List<LivingEntity> getEntities(Predicate<LivingEntity> predicate) {
        return Objects.requireNonNull(getWorld()).getEntitiesByClass(LivingEntity.class, new Box(getPos()).expand(HardcodedConfig.DEFENSIVE_LASER_RANGE), predicate);
    }

    private Entity getDummyEntity() {
        Vec3d posVec = getPosVec();
        return new ItemEntity(getWorld(), posVec.getX(), posVec.getY(), posVec.getZ());
    }

    private void fire(World world, BlockPos pos) {
        List<LivingEntity> entities = getEntities(entity -> true);
        Vec3d posVec = getPosVec(pos);
        Vec3d collision = null;
        for (LivingEntity entity : entities) {
            Optional<Vec3d> optional = entity.getBoundingBox().rayTrace(posVec, posVec.add(rotation.getRayVector().multiply(HardcodedConfig.DEFENSIVE_LASER_RANGE)));
            if (optional.isPresent()) {
                Vec3d vec = optional.get();
                if (collision == null || vec.distanceTo(posVec) < collision.distanceTo(posVec)) {
                    collision = optional.get();
                }
            }
        }

        Vec3d rotationVec = rotation.getRayVector();
        Vec3d start = rotationVec.add(posVec);
        Vec3d end = rotationVec.multiply(HardcodedConfig.DEFENSIVE_LASER_RANGE).add(posVec);
        HitResult result = world.rayTrace(new RayTraceContext(start, end, RayTraceContext.ShapeType.COLLIDER, RayTraceContext.FluidHandling.ANY, getDummyEntity()));
        if (result.getType() != HitResult.Type.MISS && (collision == null || result.getPos().distanceTo(posVec) < collision.distanceTo(posVec))) {
            collision = result.getPos();
        }

        double distance;
        if (collision != null) {
            world.createExplosion(null, collision.getX(), collision.getY(), collision.getZ(), 2f, Explosion.DestructionType.NONE);

            distance = posVec.distanceTo(collision);
        } else {
            distance = HardcodedConfig.DEFENSIVE_LASER_RANGE;
        }

        double multiplier = 4d;
        distance = distance * multiplier;
        for (int i = 0; i < distance; i++) {
            Vec3d vec = rotationVec.multiply(i / multiplier).add(posVec);
            ((ServerWorld) world).spawnParticles(ParticleTypes.END_ROD, vec.getX(), vec.getY(), vec.getZ(), 1, 0, 0, 0, 0.4f);
        }
    }

    @Override
    protected void tickEnergy() {
        assert getWorld() != null;
        addAction(Action.createBlockStatePropertyAction(HardcodedConfig.DEFENSIVE_LASER_IDLE_ENERGY_REQUIRED, DefensiveLaserBlock.POWERED, true, false));
        if (getCachedState().get(DefensiveLaserBlock.POWERED)) {
            if (countdown > 0) {
                countdown--;
            }
            if (countdown == 1) {
                addAction(new Action(HardcodedConfig.DEFENSIVE_LASER_FIRE_ENERGY_REQUIRED, (world, pos, state) -> {
                    firing = false;
                    fire(world, pos);
                }, (world, pos, state) -> firing = false));
                target = null;
                firing = true;
            } else if (countdown < 1 && !firing) {
                if (target == null) {
                    List<LivingEntity> entities = getEntities(getTargetPredicate(false));
                    if (entities.size() > 0) {
                        Vec3d posVec = getPosVec();
                        entities.sort(Comparator.comparingDouble(entity -> entity.getPos().distanceTo(posVec)));
                        target = entities.get(0);
                    }
                } else {
                    if (getTargetPredicate(false).test(target)) {
                        Optional<Vec3d> optional = target.getBoundingBox().rayTrace(getPosVec(), getPosVec().add(rotation.getRayVector().multiply(HardcodedConfig.DEFENSIVE_LASER_RANGE)));
                        if (optional.isPresent() && getTargetPredicate(true).test(target)) {
                            countdown = COUNTDOWN;
                        } else {
                            Vec3d targetPos = target.getPos();
                            float targetYaw = getTargetYaw(targetPos);
                            float targetPitch = getTargetPitch(targetPos);
                            rotation.target(targetYaw, targetPitch);
                        }
                    } else {
                        target = null;
                    }
                }
            }
        }
    }

    @Override
    public CompoundTag toTag(CompoundTag tag) {
        super.toTag(tag);
        rotation.toTag(tag);
        tag.putInt("Countdown", countdown);
        return tag;
    }

    @Override
    public void fromTag(BlockState state, CompoundTag tag) {
        super.fromTag(state, tag);
        rotation.fromTag(tag);
        countdown = tag.getInt("Countdown");
        firing = false;
    }
}