package uulm.teamname.marvelous.gamelibrary.gamelogic;

import uulm.teamname.marvelous.gamelibrary.IntVector2;
import uulm.teamname.marvelous.gamelibrary.entities.Entity;
import uulm.teamname.marvelous.gamelibrary.entities.EntityID;
import uulm.teamname.marvelous.gamelibrary.entities.EntityType;
import uulm.teamname.marvelous.gamelibrary.entities.Rock;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;

/** Represents a managed list of {@link Entity}s. */
public class EntityManager {
    /** The internal collection of {@link Entity}s */
    private final HashSet<Entity> entities = new HashSet<>();

    /** A set of all currently used {@link Rock} entity ids */
    private final HashSet<Integer> usedRockSlots = new HashSet<>();

    /**
     * Takes over all the entities from a different {@link EntityManager}.
     * @param other The entity list to take the data from
     */
    public void cloneFrom(EntityManager other) {
        entities.clear();
        for(Entity entity: other.entities) {
            entities.add(entity.clone());
        }

        usedRockSlots.clear();
        usedRockSlots.addAll(other.usedRockSlots);
    }

    /**
     * Finds an unused {@link Rock} entity id
     * @return The first free id
     */
    public int findFreeRockSlot() {
        int i = 0;
        while(usedRockSlots.contains(i)) {
            i++;
        }
        return i;
    }

    /**
     * Clears the list of entities.
     */
    public void clear() {
        entities.clear();
        usedRockSlots.clear();
    }

    /**
     * Adds an entity to the list.
     * @param entity The {@link Entity} to add
     */
    public void addEntity(Entity entity) {
        if(entity.id.isSameType(EntityType.Rocks)) {
            usedRockSlots.add(entity.id.id);
        }
        entities.add(entity);
    }

    /**
     * Adds multiple entities to the list.
     * @param entities The entities to add
     */
    public void addEntities(Entity... entities) {
        for(Entity e: entities) {
            this.addEntity(e);
        }
    }

    /**
     * Removes an entity from the list.
     * @param entity The {@link Entity} to remove
     */
    public boolean removeEntity(Entity entity) {
        if(entity.id.isSameType(EntityType.Rocks)) {
            usedRockSlots.remove(entity.id.id);
        }
        return entities.remove(entity);
    }

    /**
     * Finds an entity with an {@link EntityID}.
     * @param id The id to search for
     * @return The found {@link Entity} or null if none found
     */
    public Entity findEntity(EntityID id) {
        for(Entity entity: entities) {
            if(entity.id == id) {
                return entity;
            }
        }
        return null;
    }

    /**
     * Finds all entities with a position.
     * @param pos The position to check on
     * @return The found {@link Entity}s matching the position
     */
    public ArrayList<Entity> findByPosition(IntVector2 pos) {
        ArrayList<Entity> found = new ArrayList<>();
        for(Entity entity: entities) {
            if(entity.getPosition() == pos) {
                found.add(entity);
            }
        }
        return found;
    }

    /**
     * Checks if any entity on a position blocks vision.
     * @param pos The position to check on
     * @return Whether or not anything on the position blocks vision
     */
    public boolean blocksVision(IntVector2 pos) {
        for(Entity entity: entities) {
            if(entity.getPosition() == pos && entity.blocksVision()) {
                return true;
            }
        }
        return false;
    }

    /**
     * Checks if any entity on a position blocks movement.
     * @param pos The position to check on
     * @return Whether or not anything on the position blocks movement
     */
    public boolean blocksMovement(IntVector2 pos) {
        for(Entity entity: entities) {
            if(entity.getPosition() == pos && entity.blocksMovement()) {
                return true;
            }
        }
        return false;
    }

    /**
     * Iterates over all entities inside the list.
     * @return An iterator over every {@link Entity}
     */
    public Iterator<Entity> getEntities() {
        return entities.iterator();
    }

    /**
     * Exports all entities as an array.
     * @return An array containing every {@link Entity}
     */
    public Entity[] export() {
        return (Entity[])entities.toArray();
    }
}