export class Block {
    /**
     * @param {string} id
     * @param {[number, number, number]} pos
     * @param {Object} state
     * @param {Array<World>} world
     */
    constructor(id, pos, state, world = []) {
        this.id = id;
        this.pos = pos;
        this.state = state;
        this.worlds = world;
    }

    delete() {
        for (let world of this.worlds) {
            world.blocks
        }
    }
}

export class World {
    constructor() {
        this.blocks = new Map();
        this.listeners = new Set();
    }

    /**
     * Subscribe to modify events.
     * @param {function()} callback. Called when this world is modified.
     * @returns {function()} Unsubscribe function.
     */
    subscribe(callback) {
        this.listeners.add(callback);
        return () => this.listeners.delete(callback);
    }

    /**
     * Notify all listeners of a modification.
     */
    notify() {
        for (const listener of this.listeners) listener();
    }

    /**
     * Set a block and state at a position.
     * @param {string} id
     * @param {number} x
     * @param {number} y
     * @param {number} z
     * @param {Object} state
     */
    set(id, x, y, z, state = {}) {
        const key = `${x},${y},${z}`;
        this.blocks.set(key, new Block(id, [x, y, z], state));
        this.notify();
    }

    /**
     * Remove a block at a position.
     * @param {number} x
     * @param {number} y
     * @param {number} z
     */
    del(x, y, z) {
        if (this.blocks.delete(`${x},${y},${z}`)) {
            this.notify();
        }
    }

    /**
     * Get a block at a position.
     * @param {number} x
     * @param {number} y
     * @param {number} z
     * @returns {any}
     */
    get(x, y, z) {
        return this.blocks.get(`${x},${y},${z}`);
    }
}