ActionHealth/src/main/java/com/zeshanaslam/actionhealth/utils/TargetHelper.java

package com.zeshanaslam.actionhealth.utils;

import com.zeshanaslam.actionhealth.Main;
import org.bukkit.Location;
import org.bukkit.block.Block;
import org.bukkit.entity.Entity;
import org.bukkit.entity.LivingEntity;
import org.bukkit.util.BlockIterator;
import org.bukkit.util.Vector;

import java.util.ArrayList;
import java.util.List;

/**
 * <p>Helper class for getting targets using various methods</p>
 */
public class TargetHelper {

    private Main main;

    public TargetHelper(Main main) {
        this.main = main;
    }

    /**
     * <p>Number of pixels that end up displaying about 1 degree of vision in the client window</p>
     * <p>Not really useful since you can't get the client's window size, but I added it in case
     * it becomes useful sometime</p>
     */
    private final int PIXELS_PER_DEGREE = 35;

    /**
     * <p>Gets all entities the player is looking at within the range</p>
     * <p>Has a little bit of tolerance to make targeting easier</p>
     *
     * @param source living entity to get the targets of
     * @param range  maximum range to check
     * @return all entities in the player's vision line
     */
    public List<LivingEntity> getLivingTargets(LivingEntity source, double range) {
        return getLivingTargets(source, range, main.configStore.lookTolerance);
    }

    /**
     * <p>Gets all entities the player is looking at within the range using
     * the given tolerance.</p>
     *
     * @param source    living entity to get the targets of
     * @param range     maximum range to check
     * @param tolerance tolerance of the line calculation
     * @return all entities in the player's vision line
     */
    public List<LivingEntity> getLivingTargets(LivingEntity source, double range, double tolerance) {
        if (source == null) {
            return new ArrayList<>();
        }

        List<Entity> list = source.getNearbyEntities(range, range, range);
        List<LivingEntity> targets = new ArrayList<LivingEntity>();

        Vector facing = source.getLocation().getDirection();
        double fLengthSq = facing.lengthSquared();

        for (Entity entity : list) {
            if (!isInFront(source, entity) || !(entity instanceof LivingEntity)) continue;

            Vector relative = entity.getLocation().subtract(source.getLocation()).toVector();
            double dot = relative.dot(facing);
            double rLengthSq = relative.lengthSquared();
            double cosSquared = (dot * dot) / (rLengthSq * fLengthSq);
            double sinSquared = 1 - cosSquared;
            double dSquared = rLengthSq * sinSquared;

            // If close enough to vision line, return the entity
            if (dSquared < tolerance) targets.add((LivingEntity) entity);
        }

        return targets;
    }

    /**
     * <p>Gets the entity the player is looking at</p>
     * <p>Has a little bit of tolerance to make targeting easier</p>
     *
     * @param source living entity to get the target of
     * @param range  maximum range to check
     * @return entity player is looing at or null if not found
     */
    public LivingEntity getLivingTarget(LivingEntity source, double range) {
        return getLivingTarget(source, range, main.configStore.lookTolerance);
    }

    /**
     * <p>Gets the entity the player is looking at</p>
     * <p>Has a little bit of tolerance to make targeting easier</p>
     *
     * @param source    living entity to get the target of
     * @param range     maximum range to check
     * @param tolerance tolerance of the line calculation
     * @return entity player is looking at or null if not found
     */
    public LivingEntity getLivingTarget(LivingEntity source, double range, double tolerance) {
        List<LivingEntity> targets = getLivingTargets(source, range, tolerance);
        if (targets.size() == 0) return null;
        LivingEntity target = targets.get(0);
        double minDistance = target.getLocation().distanceSquared(source.getLocation());
        for (LivingEntity entity : targets) {
            double distance = entity.getLocation().distanceSquared(source.getLocation());
            if (distance < minDistance) {
                minDistance = distance;
                target = entity;
            }
        }
        return target;
    }

    /**
     * Gets the targets in a cone
     *
     * @param source entity to get the targets for
     * @param arc    arc angle of the cone
     * @param range  range of the cone
     * @return list of targets
     */
    public List<LivingEntity> getConeTargets(LivingEntity source, double arc, double range) {
        List<LivingEntity> targets = new ArrayList<LivingEntity>();
        List<Entity> list = source.getNearbyEntities(range, range, range);
        if (arc <= 0) return targets;

        // Initialize values
        Vector dir = source.getLocation().getDirection();
        dir.setY(0);
        double cos = Math.cos(arc * Math.PI / 180);
        double cosSq = cos * cos;

        // Get the targets in the cone
        for (Entity entity : list) {
            if (entity instanceof LivingEntity) {

                // Greater than 360 degrees is all targets
                if (arc >= 360) {
                    targets.add((LivingEntity) entity);
                }

                // Otherwise, select targets based on dot product
                else {
                    Vector relative = entity.getLocation().subtract(source.getLocation()).toVector();
                    relative.setY(0);
                    double dot = relative.dot(dir);
                    double value = dot * dot / relative.lengthSquared();
                    if (arc < 180 && dot > 0 && value >= cosSq) targets.add((LivingEntity) entity);
                    else if (arc >= 180 && (dot > 0 || dot <= cosSq)) targets.add((LivingEntity) entity);
                }
            }
        }

        return targets;
    }

    /**
     * Checks if the entity is in front of the entity
     *
     * @param entity entity to check for
     * @param target target to check against
     * @return true if the target is in front of the entity
     */
    public boolean isInFront(Entity entity, Entity target) {
        if (entity.getWorld() != target.getWorld())
            return false;

        // Get the necessary vectors
        Vector facing = entity.getLocation().getDirection();
        Vector relative = target.getLocation().subtract(entity.getLocation()).toVector();

        // If the dot product is positive, the target is in front
        return facing.dot(relative) >= main.configStore.lookDot;
    }

    /**
     * Checks if the entity is in front of the entity restricted to the given angle
     *
     * @param entity entity to check for
     * @param target target to check against
     * @param angle  angle to restrict it to (0-360)
     * @return true if the target is in front of the entity
     */
    public boolean isInFront(Entity entity, Entity target, double angle) {
        if (angle <= 0) return false;
        if (angle >= 360) return true;

        // Get the necessary data
        double dotTarget = Math.cos(angle);
        Vector facing = entity.getLocation().getDirection();
        Vector relative = target.getLocation().subtract(entity.getLocation()).toVector().normalize();

        // Compare the target dot product with the actual result
        return facing.dot(relative) >= dotTarget;
    }

    /**
     * Checks if the target is behind the entity
     *
     * @param entity entity to check for
     * @param target target to check against
     * @return true if the target is behind the entity
     */
    public boolean isBehind(Entity entity, Entity target) {
        return !isInFront(entity, target);
    }

    /**
     * Checks if the entity is behind the player restricted to the given angle
     *
     * @param entity entity to check for
     * @param target target to check against
     * @param angle  angle to restrict it to (0-360)
     * @return true if the target is behind the entity
     */
    public boolean isBehind(Entity entity, Entity target, double angle) {
        if (angle <= 0) return false;
        if (angle >= 360) return true;

        // Get the necessary data
        double dotTarget = Math.cos(angle);
        Vector facing = entity.getLocation().getDirection();
        Vector relative = entity.getLocation().subtract(target.getLocation()).toVector().normalize();

        // Compare the target dot product and the actual result
        return facing.dot(relative) >= dotTarget;
    }

    /**
     * Checks whether or not the line between the two points is obstructed
     *
     * @param loc1 first location
     * @param loc2 second location
     * @return the location of obstruction or null if not obstructed
     */
    public boolean isObstructed(Location loc1, Location loc2) {
        if (loc1.getX() == loc2.getX() && loc1.getY() == loc2.getY() && loc1.getZ() == loc2.getZ()) {
            return false;
        }
        Vector slope = loc2.clone().subtract(loc1).toVector();
        int steps = (int) (slope.length() * 4) + 1;
        slope.multiply(1.0 / steps);
        Location temp = loc1.clone();
        for (int i = 0; i < steps; i++) {
            temp.add(slope);
            if (temp.getBlock().getType().isSolid() && !temp.getBlock().getType().toString().contains("FENCE") && !temp.getBlock().getType().toString().contains("GLASS")) {
                return true;
            }
        }
        return false;
    }

    /**
     * Retrieves an open location along the line for teleporting or linear targeting
     *
     * @param loc1        start location of the path
     * @param loc2        end location of the path
     * @param throughWall whether or not going through walls is allowed
     * @return the farthest open location along the path
     */
    public Location getOpenLocation(Location loc1, Location loc2, boolean throughWall) {
        // Special case
        if (loc1.getX() == loc2.getX() && loc1.getY() == loc2.getY() && loc1.getZ() == loc2.getZ()) {
            return loc1;
        }

        // Common data
        Vector slope = loc2.clone().subtract(loc1).toVector();
        int steps = (int) (slope.length() * 4) + 1;
        slope.multiply(1.0 / steps);

        // Going through walls starts at the end and traverses backwards
        if (throughWall) {
            Location temp = loc2.clone();
            while (temp.getBlock().getType().isSolid() && steps > 0) {
                temp.subtract(slope);
                steps--;
            }
            temp.setX(temp.getBlockX() + 0.5);
            temp.setZ(temp.getBlockZ() + 0.5);
            temp.setY(temp.getBlockY() + 1);
            return temp;
        }

        // Not going through walls starts at the beginning and traverses forward
        else {
            Location temp = loc1.clone();
            while (!temp.getBlock().getType().isSolid() && steps > 0) {
                temp.add(slope);
                steps--;
            }
            temp.subtract(slope);
            temp.setX(temp.getBlockX() + 0.5);
            temp.setZ(temp.getBlockZ() + 0.5);
            temp.setY(temp.getBlockY() + 1);
            return temp;
        }
    }

    public Block getTarget(Location from, int distance) {
        BlockIterator itr = new BlockIterator(from, 0, distance);
        while (itr.hasNext()) {
            Block block = itr.next();
            if (!block.getType().isOccluding()) {
                continue;
            }
            return block;
        }
        return null;
    }

    public boolean canSee(LivingEntity from, Location to) {
        return getTarget(from.getEyeLocation(), (int) Math.ceil(from.getLocation().distance(to))) == null;
    }
}