import { Euler } from './Euler';
import { Vector3 } from './Vector3';
import { Matrix4 } from './Matrix4';

/**
 * Implementation of a quaternion. This is used for rotating things without incurring in the dreaded gimbal lock issue, amongst other advantages.
 *
 * @example
 * const quaternion = new THREE.Quaternion();
 * quaternion.setFromAxisAngle( new THREE.Vector3( 0, 1, 0 ), Math.PI / 2 );
 * const vector = new THREE.Vector3( 1, 0, 0 );
 * vector.applyQuaternion( quaternion );
 */
export class Quaternion {
    /**
     * @param x x coordinate
     * @param y y coordinate
     * @param z z coordinate
     * @param w w coordinate
     */
    constructor(x?: number, y?: number, z?: number, w?: number);

    /**
     * @default 0
     */
    x: number;

    /**
     * @default 0
     */
    y: number;

    /**
     * @default 0
     */
    z: number;

    /**
     * @default 1
     */
    w: number;
    readonly isQuaternion: true;

    /**
     * Sets values of this quaternion.
     */
    set(x: number, y: number, z: number, w: number): Quaternion;

    /**
     * Clones this quaternion.
     */
    clone(): this;

    /**
     * Copies values of q to this quaternion.
     */
    copy(q: Quaternion): this;

    /**
     * Sets this quaternion from rotation specified by Euler angles.
     */
    setFromEuler(euler: Euler, update?: boolean): Quaternion;

    /**
     * Sets this quaternion from rotation specified by axis and angle.
     * Adapted from http://www.euclideanspace.com/maths/geometry/rotations/conversions/angleToQuaternion/index.htm.
     * Axis have to be normalized, angle is in radians.
     */
    setFromAxisAngle(axis: Vector3, angle: number): Quaternion;

    /**
     * Sets this quaternion from rotation component of m. Adapted from http://www.euclideanspace.com/maths/geometry/rotations/conversions/matrixToQuaternion/index.htm.
     */
    setFromRotationMatrix(m: Matrix4): Quaternion;
    setFromUnitVectors(vFrom: Vector3, vTo: Vector3): Quaternion;
    angleTo(q: Quaternion): number;
    rotateTowards(q: Quaternion, step: number): Quaternion;

    identity(): Quaternion;

    /**
     * Inverts this quaternion.
     */
    invert(): Quaternion;

    conjugate(): Quaternion;
    dot(v: Quaternion): number;
    lengthSq(): number;

    /**
     * Computes length of this quaternion.
     */
    length(): number;

    /**
     * Normalizes this quaternion.
     */
    normalize(): Quaternion;

    /**
     * Multiplies this quaternion by b.
     */
    multiply(q: Quaternion): Quaternion;
    premultiply(q: Quaternion): Quaternion;

    /**
     * Sets this quaternion to a x b
     * Adapted from http://www.euclideanspace.com/maths/algebra/realNormedAlgebra/quaternions/code/index.htm.
     */
    multiplyQuaternions(a: Quaternion, b: Quaternion): Quaternion;

    slerp(qb: Quaternion, t: number): Quaternion;
    slerpQuaternions(qa: Quaternion, qb: Quaternion, t: number): Quaternion;
    equals(v: Quaternion): boolean;

    /**
     * Sets this quaternion's x, y, z and w value from the provided array or array-like.
     * @param array the source array or array-like.
     * @param offset (optional) offset into the array. Default is 0.
     */
    fromArray(array: number[] | ArrayLike<number>, offset?: number): this;

    /**
     * Returns an array [x, y, z, w], or copies x, y, z and w into the provided array.
     * @param array (optional) array to store the quaternion to. If this is not provided, a new array will be created.
     * @param offset (optional) optional offset into the array.
     * @return The created or provided array.
     */
    toArray(array?: number[], offset?: number): number[];

    /**
     * Copies x, y, z and w into the provided array-like.
     * @param array array-like to store the quaternion to.
     * @param offset (optional) optional offset into the array.
     * @return The provided array-like.
     */
    toArray(array: ArrayLike<number>, offset?: number): ArrayLike<number>;

    _onChange(callback: () => void): Quaternion;
    _onChangeCallback: () => void;

    static slerpFlat(
        dst: number[],
        dstOffset: number,
        src0: number[],
        srcOffset: number,
        src1: number[],
        stcOffset1: number,
        t: number,
    ): Quaternion;

    static multiplyQuaternionsFlat(
        dst: number[],
        dstOffset: number,
        src0: number[],
        srcOffset: number,
        src1: number[],
        stcOffset1: number,
    ): number[];

    /**
     * @deprecated Use qm.slerpQuaternions( qa, qb, t ) instead..
     */
    static slerp(qa: Quaternion, qb: Quaternion, qm: Quaternion, t: number): number;

    /**
     * @deprecated Use {@link Vector#applyQuaternion vector.applyQuaternion( quaternion )} instead.
     */
    multiplyVector3(v: any): any;

    /**
     * @deprecated Use {@link Quaternion#invert .invert()} instead.
     */
    inverse(): Quaternion;
}