Code/net/minecraft/world/entity/ai/goal/MoveToBlockGoal.java

package net.minecraft.world.entity.ai.goal;

import java.util.EnumSet;
import net.minecraft.core.BlockPos;
import net.minecraft.world.entity.PathfinderMob;
import net.minecraft.world.level.LevelReader;

public abstract class MoveToBlockGoal extends Goal {
    private static final int GIVE_UP_TICKS = 1200;
    private static final int STAY_TICKS = 1200;
    private static final int INTERVAL_TICKS = 200;
    protected final PathfinderMob mob;
    public final double speedModifier;
    protected int nextStartTick;
    protected int tryTicks;
    private int maxStayTicks;
    protected BlockPos blockPos = BlockPos.ZERO;
    private boolean reachedTarget;
    private final int searchRange;
    private final int verticalSearchRange;
    protected int verticalSearchStart;

    public MoveToBlockGoal(PathfinderMob p_25609_, double p_25610_, int p_25611_) {
        this(p_25609_, p_25610_, p_25611_, 1);
    }

    public MoveToBlockGoal(PathfinderMob p_25613_, double p_25614_, int p_25615_, int p_25616_) {
        this.mob = p_25613_;
        this.speedModifier = p_25614_;
        this.searchRange = p_25615_;
        this.verticalSearchStart = 0;
        this.verticalSearchRange = p_25616_;
        this.setFlags(EnumSet.of(Goal.Flag.MOVE, Goal.Flag.JUMP));
    }

    @Override
    public boolean canUse() {
        if (this.nextStartTick > 0) {
            this.nextStartTick--;
            return false;
        } else {
            this.nextStartTick = this.nextStartTick(this.mob);
            return this.findNearestBlock();
        }
    }

    protected int nextStartTick(PathfinderMob p_25618_) {
        return reducedTickDelay(200 + p_25618_.getRandom().nextInt(200));
    }

    @Override
    public boolean canContinueToUse() {
        return this.tryTicks >= -this.maxStayTicks && this.tryTicks <= 1200 && this.isValidTarget(this.mob.level(), this.blockPos);
    }

    @Override
    public void start() {
        this.moveMobToBlock();
        this.tryTicks = 0;
        this.maxStayTicks = this.mob.getRandom().nextInt(this.mob.getRandom().nextInt(1200) + 1200) + 1200;
    }

    protected void moveMobToBlock() {
        this.mob.getNavigation().moveTo(this.blockPos.getX() + 0.5, this.blockPos.getY() + 1, this.blockPos.getZ() + 0.5, this.speedModifier);
    }

    public double acceptedDistance() {
        return 1.0;
    }

    protected BlockPos getMoveToTarget() {
        return this.blockPos.above();
    }

    @Override
    public boolean requiresUpdateEveryTick() {
        return true;
    }

    @Override
    public void tick() {
        BlockPos blockpos = this.getMoveToTarget();
        if (!blockpos.closerToCenterThan(this.mob.position(), this.acceptedDistance())) {
            this.reachedTarget = false;
            this.tryTicks++;
            if (this.shouldRecalculatePath()) {
                this.mob.getNavigation().moveTo(blockpos.getX() + 0.5, blockpos.getY(), blockpos.getZ() + 0.5, this.speedModifier);
            }
        } else {
            this.reachedTarget = true;
            this.tryTicks--;
        }
    }

    public boolean shouldRecalculatePath() {
        return this.tryTicks % 40 == 0;
    }

    protected boolean isReachedTarget() {
        return this.reachedTarget;
    }

    protected boolean findNearestBlock() {
        int i = this.searchRange;
        int j = this.verticalSearchRange;
        BlockPos blockpos = this.mob.blockPosition();
        BlockPos.MutableBlockPos blockpos$mutableblockpos = new BlockPos.MutableBlockPos();

        for (int k = this.verticalSearchStart; k <= j; k = k > 0 ? -k : 1 - k) {
            for (int l = 0; l < i; l++) {
                for (int i1 = 0; i1 <= l; i1 = i1 > 0 ? -i1 : 1 - i1) {
                    for (int j1 = i1 < l && i1 > -l ? l : 0; j1 <= l; j1 = j1 > 0 ? -j1 : 1 - j1) {
                        blockpos$mutableblockpos.setWithOffset(blockpos, i1, k - 1, j1);
                        if (this.mob.isWithinRestriction(blockpos$mutableblockpos) && this.isValidTarget(this.mob.level(), blockpos$mutableblockpos)) {
                            this.blockPos = blockpos$mutableblockpos;
                            return true;
                        }
                    }
                }
            }
        }

        return false;
    }

    protected abstract boolean isValidTarget(LevelReader p_25619_, BlockPos p_25620_);
}