import { Point } from "./Point";

export class Vector2
{
    x: number;
    y: number;
    readonly isVector2: boolean = true;
    constructor(x: number = 0, y: number = 0)
    {
        this.x = x;
        this.y = y;
    }
    get width(): number { return this.x; }
    set width(value: number) { this.x = value; }
    get height(): number { return this.y; }
    set height(value: number) { this.y = value; }
    set(x: number, y: number): Vector2
    {
        this.x = x;
        this.y = y;
        return this;
    }
    setScalar(scalar: number): Vector2
    {
        this.x = scalar;
        this.y = scalar;
        return this;
    }
    setX(x: number): Vector2
    {
        this.x = x;
        return this;
    }
    setY(y: number): Vector2
    {
        this.y = y;
        return this;
    }
    setComponent(index: number, value: number): Vector2
    {
        switch (index)
        {
            case 0: this.x = value; break;
            case 1: this.y = value; break;
            default: throw new Error('index is out of range: ' + index);
        }
        return this;
    }
    getComponent(index: number): number
    {
        switch (index)
        {
            case 0: return this.x;
            case 1: return this.y;
            default: throw new Error('index is out of range: ' + index);
        }
    }
    clone(): Vector2
    {
        return new (this.constructor as any)().copy(this);
    }
    copy(v: Vector2): Vector2
    {
        this.x = v.x;
        this.y = v.y;
        return this;
    }
    add(v: Point): Vector2
    {
        this.x += v.x;
        this.y += v.y;
        return this;
    }
    addScalar(s: number): Vector2
    {
        this.x += s;
        this.y += s;
        return this;
    }
    addVectors(a: Vector2, b: Vector2): Vector2
    {
        this.x = a.x + b.x;
        this.y = a.y + b.y;
        return this;
    }
    addScaledVector(v: Vector2, s: number): Vector2
    {
        this.x += v.x * s;
        this.y += v.y * s;
        return this;
    }
    sub(v: Vector2): Vector2
    {
        this.x -= v.x;
        this.y -= v.y;
        return this;
    }
    subScalar(s: number): Vector2
    {
        this.x -= s;
        this.y -= s;
        return this;
    }
    subVectors(a: Vector2, b: Vector2): Vector2
    {
        this.x = a.x - b.x;
        this.y = a.y - b.y;
        return this;
    }
    multiply(v: Vector2): Vector2
    {
        this.x *= v.x;
        this.y *= v.y;
        return this;
    }
    multiplyScalar(scalar: number): Vector2
    {
        if (isFinite(scalar))
        {
            this.x *= scalar;
            this.y *= scalar;
        } else
        {
            this.x = 0;
            this.y = 0;
        }
        return this;
    }
    divide(v: Vector2): Vector2
    {
        this.x /= v.x;
        this.y /= v.y;
        return this;
    }
    divideScalar(scalar: number): Vector2
    {
        return this.multiplyScalar(1 / scalar);
    }
    min(v: Vector2): Vector2
    {
        this.x = Math.min(this.x, v.x);
        this.y = Math.min(this.y, v.y);
        return this;
    }
    max(v: Vector2): Vector2
    {
        this.x = Math.max(this.x, v.x);
        this.y = Math.max(this.y, v.y);
        return this;
    }
    clamp(min: Vector2, max: Vector2): Vector2
    {
        // This function assumes min < max, if this assumption isn't true it will not operate correctly
        this.x = Math.max(min.x, Math.min(max.x, this.x));
        this.y = Math.max(min.y, Math.min(max.y, this.y));
        return this;
    }
    private static clampScalar_min = new Vector2();
    private static clampScalar_max = new Vector2();
    clampScalar(minVal: number, maxVal: number): Vector2
    {
        const min: Vector2 = Vector2.clampScalar_min.set(minVal, minVal);
        const max: Vector2 = Vector2.clampScalar_max.set(maxVal, maxVal);
        return this.clamp(min, max);
    }
    clampLength(min: number, max: number): Vector2
    {
        const length: number = this.length();
        return this.multiplyScalar(Math.max(min, Math.min(max, length)) / length);
    }
    floor(): Vector2
    {
        this.x = Math.floor(this.x);
        this.y = Math.floor(this.y);
        return this;
    }
    ceil(): Vector2
    {
        this.x = Math.ceil(this.x);
        this.y = Math.ceil(this.y);
        return this;
    }
    round(): Vector2
    {
        this.x = Math.round(this.x);
        this.y = Math.round(this.y);
        return this;
    }
    roundToZero(): Vector2
    {
        this.x = (this.x < 0) ? Math.ceil(this.x) : Math.floor(this.x);
        this.y = (this.y < 0) ? Math.ceil(this.y) : Math.floor(this.y);
        return this;
    }
    negate(): Vector2
    {
        this.x = - this.x;
        this.y = - this.y;
        return this;
    }
    dot(v: Vector2): number
    {
        return this.x * v.x + this.y * v.y;
    }
    lengthSq(): number
    {
        return this.x * this.x + this.y * this.y;
    }
    length(): number
    {
        return Math.sqrt(this.x * this.x + this.y * this.y);
    }
    lengthManhattan(): number
    {
        return Math.abs(this.x) + Math.abs(this.y);
    }
    normalize(): Vector2
    {
        return this.divideScalar(this.length());
    }
    angle(): number
    {
        // computes the angle in radians with respect to the positive x-axis
        let angle: number = Math.atan2(this.y, this.x);
        if (angle < 0) angle += 2 * Math.PI;
        return angle;
    }
    distanceTo(v: Vector2): number
    {
        return Math.sqrt(this.distanceToSquared(v));
    }
    distanceToSquared(v: Vector2): number
    {
        const dx: number = this.x - v.x, dy: number = this.y - v.y;
        return dx * dx + dy * dy;
    }
    distanceToManhattan(v: Vector2): number
    {
        return Math.abs(this.x - v.x) + Math.abs(this.y - v.y);
    }
    setLength(length: number): Vector2
    {
        return this.multiplyScalar(length / this.length());
    }
    lerp(v: Vector2, alpha: number): Vector2
    {
        this.x += (v.x - this.x) * alpha;
        this.y += (v.y - this.y) * alpha;
        return this;
    }
    lerpVectors(v1: Vector2, v2: Vector2, alpha: number): Vector2
    {
        return this.subVectors(v2, v1).multiplyScalar(alpha).add(v1);
    }
    equals(v: Vector2): boolean
    {
        return ((v.x === this.x) && (v.y === this.y));
    }
    fromArray(array: Float32Array | number[], offset: number = 0): Vector2
    {
        this.x = array[offset];
        this.y = array[offset + 1];
        return this;
    }
    toArray(array: Float32Array | number[] = [], offset: number = 0): Float32Array | number[]
    {
        array[offset] = this.x;
        array[offset + 1] = this.y;
        return array;
    }
    fromAttribute(attribute: any, index: number, offset: number = 0): Vector2
    {
        index = index * attribute.itemSize + offset;
        this.x = attribute.array[index];
        this.y = attribute.array[index + 1];
        return this;
    }
    rotateAround(center: Vector2, angle: number): Vector2
    {
        const c: number = Math.cos(angle), s: number = Math.sin(angle);
        const x: number = this.x - center.x;
        const y: number = this.y - center.y;
        this.x = x * c - y * s + center.x;
        this.y = x * s + y * c + center.y;
        return this;
    }
}