import type RandomGenerator from './RandomGenerator'

/**
 * A symbolic representation of an angle.  It may be
 * manipulated in either degrees or radians.
 */
export default class Angle {

    // the angle in radians
    private _angle: number

    /**
     * Generates a random angle in the range [0, 2π).
     */
    static random(rng: RandomGenerator) {
        return new Angle(rng.uniformFloat(0, 2 * Math.PI), 'rad')
    }

    constructor(value: number, unit: 'deg'|'rad') {
        this.set(value, unit)
    }

    /**
     * Sets the angle to a given value.  The value will be wrapped to the range [0, 2π).
     */
    set(value: number, unit: 'deg'|'rad') {
        switch (unit) {
        case 'deg':
            this._angle = (value * Math.PI / 180) % (2 * Math.PI)
            break
        case 'rad':
            this._angle = value % (2 * Math.PI)
            break
        default:
            throw new Error('Invalid unit')
        }
    }


    /**
     * Returns the angle in radians
     */
    asRadians() {
        return this._angle
    }

    /**
     * Returns the angle in degrees
     */
    asDegrees() {
        return this._angle * 180 / Math.PI
    }

    /**
     * Increments the angle by a given value.  The angle will be wrapped to the range [0, 2π).
     */
    increment(value: number, unit: 'deg'|'rad') {
        switch (unit) {
        case 'deg':
            this._angle = (this._angle + value * Math.PI / 180) % (2 * Math.PI)
            break
        case 'rad':
            this._angle = (this._angle + value) % (2 * Math.PI)
            break
        default:
            throw new Error('Invalid unit')
        }
    }
}