Unicopia/src/main/java/com/minelittlepony/unicopia/ability/EarthPonyStompAbility.java

package com.minelittlepony.unicopia.ability;

import javax.annotation.Nullable;

import com.minelittlepony.unicopia.Race;
import com.minelittlepony.unicopia.ability.data.Hit;
import com.minelittlepony.unicopia.entity.player.Pony;
import com.minelittlepony.unicopia.util.MagicalDamageSource;
import com.minelittlepony.unicopia.util.WorldEvent;
import com.minelittlepony.unicopia.util.shape.Shape;
import com.minelittlepony.unicopia.util.shape.Sphere;

import net.minecraft.block.Block;
import net.minecraft.block.BlockState;
import net.minecraft.block.Blocks;
import net.minecraft.block.ShapeContext;
import net.minecraft.entity.attribute.EntityAttributes;
import net.minecraft.entity.damage.DamageSource;
import net.minecraft.entity.player.PlayerEntity;
import net.minecraft.particle.BlockStateParticleEffect;
import net.minecraft.particle.ParticleTypes;
import net.minecraft.util.math.BlockPos;
import net.minecraft.util.math.Box;
import net.minecraft.util.math.Direction;
import net.minecraft.util.math.Vec3d;
import net.minecraft.world.World;

/**
 * Earth Pony stomping ability
 */
public class EarthPonyStompAbility implements Ability<Hit> {

    private final double rad = 4;

    private final Box areaOfEffect = new Box(
            -rad, -rad, -rad,
             rad,  rad,  rad
     );

    @Override
    public int getWarmupTime(Pony player) {
        return 3;
    }

    @Override
    public int getCooldownTime(Pony player) {
        return 50;
    }

    @Override
    public boolean canUse(Race race) {
        return race.canUseEarth();
    }

    @Override
    public double getCostEstimate(Pony player) {
        return rad;
    }

    @Nullable
    @Override
    public Hit tryActivate(Pony player) {
        if (!player.getMaster().isOnGround() && !player.getMaster().abilities.flying) {
            player.getMaster().addVelocity(0, -6, 0);
            return Hit.INSTANCE;
        }

        return null;
    }

    @Override
    public Hit.Serializer<Hit> getSerializer() {
        return Hit.SERIALIZER;
    }

    @Override
    public void apply(Pony iplayer, Hit data) {
        PlayerEntity player = iplayer.getMaster();

        BlockPos ppos = player.getBlockPos();
        BlockPos pos = getSolidBlockBelow(ppos, player.getEntityWorld());

        player.addVelocity(0, -(ppos.getSquaredDistance(pos)), 0);

        iplayer.getWorld().getOtherEntities(player, areaOfEffect.offset(iplayer.getOriginVector())).forEach(i -> {
            double dist = Math.sqrt(pos.getSquaredDistance(i.getBlockPos()));

            if (dist <= rad + 3) {
                double force = dist / 5;
                i.addVelocity(
                        -(player.getX() - i.getX()) / force,
                        -(player.getY() - i.getY() - 2) / force + (dist < 1 ? dist : 0),
                        -(player.getZ() - i.getZ()) / force);

                DamageSource damage = MagicalDamageSource.create("smash", player);

                double amount = (4 * player.getAttributeInstance(EntityAttributes.GENERIC_ATTACK_DAMAGE).getValue()) / (float)dist;

                if (i instanceof PlayerEntity) {
                    Race race = Pony.of((PlayerEntity)i).getSpecies();
                    if (race.canUseEarth()) {
                        amount /= 3;
                    }

                    if (race.canFly()) {
                        amount *= 4;
                    }
                }

                i.damage(damage, (float)amount);
            }
        });

        BlockPos.iterate(pos.add(-rad, -rad, -rad), pos.add(rad, rad, rad)).forEach(i -> {
            if (i.getSquaredDistance(player.getX(), player.getY(), player.getZ(), true) <= rad*rad) {
                spawnEffect(player.world, i);
            }
        });

        for (int i = 1; i < 202; i+= 2) {
            spawnParticleRing(player, i, 0);
        }

        iplayer.subtractEnergyCost(rad);
    }

    private void spawnEffect(World w, BlockPos pos) {
        BlockState state = w.getBlockState(pos);

        if (!state.isAir() && w.getBlockState(pos.up()).isAir()) {
            WorldEvent.play(WorldEvent.DESTROY_BLOCK, w, pos, state);
        }
    }

    @Override
    public void preApply(Pony player, AbilitySlot slot) {
        player.getMagicalReserves().getExertion().add(40);
    }

    @Override
    public void postApply(Pony player, AbilitySlot slot) {
        int timeDiff = getCooldownTime(player) - player.getAbilities().getStat(slot).getRemainingCooldown();

        if (player.getMaster().getEntityWorld().getTime() % 1 == 0 || timeDiff == 0) {
            spawnParticleRing(player.getMaster(), timeDiff, 1);
        }
    }

    private void spawnParticleRing(PlayerEntity player, int timeDiff, double yVel) {
        int animationTicks = timeDiff / 10;
        if (animationTicks < 6) {
            Shape shape = new Sphere(true, animationTicks, 1, 0, 1);

            double y = 0.5 + (Math.sin(animationTicks) * 1.5);

            yVel *= y * 5;

            for (int i = 0; i < shape.getVolumeOfSpawnableSpace(); i++) {
                Vec3d point = shape.computePoint(player.getEntityWorld().random).add(player.getPos());
                player.world.addParticle(new BlockStateParticleEffect(ParticleTypes.BLOCK, Blocks.DIRT.getDefaultState()),
                        point.x,
                        point.y + y,
                        point.z,
                        0, yVel, 0
                );
            }
        }
    }

    private static BlockPos getSolidBlockBelow(BlockPos pos, World w) {
        while (!World.isHeightInvalid(pos)) {
            pos = pos.down();

            if (Block.isFaceFullSquare(w.getBlockState(pos).getCollisionShape(w, pos, ShapeContext.absent()), Direction.UP)) {
                return pos;
            }
        }

        return pos;
    }
}