class Vector {
    constructor(array) {
        this.values = array.slice(0);
    }

    mathOperation(vector, f) {
        if (!vector || !(vector instanceof Vector) || this.values.length !== vector.values.length) {
            throw "invalid operation";
        }

        let result = [];
        for (let i = 0; i < this.values.length; i++) {
            result.push(f(this.values[i], vector.values[i]));
        }

        return new Vector(result);
    }

    add(vector) {
        return this.mathOperation(vector, (t, o) => t + o);
    }

    subtract(vector) {
        return this.mathOperation(vector, (t, o) => t - o);
    }

    dot(vector) {
        return this.mathOperation(vector, (t, o) => t * o)
            .values.reduce((t, e) => t + e, 0);
    }

    norm() {
        return Math.sqrt(this.dot(this));
    }

    toString() {
        return `(${this.values.join(',')})`;
    }

    equals(other) {
        if (!other || !(other instanceof Vector) || this.values.length !== other.values.length) {
            return false;
        } else if (other === this) {
            return true;
        } else {
            for (let i = 0; i < this.values.length; i++) {
                if (this.values[i] !== other.values[i]) {
                    return false;
                }
            }
            return true;
        }
    }
}