/** @module random */
import { RandomInteger } from './RandomInteger';

/**
 * Random generator for Date time values.
 * 
 * ### Example ###
 * 
 *     let value1 = RandomDateTime.nextDate(new Date(2010,0,1));    // Possible result: 2008-01-03
 *     let value2 = RandomDateTime.nextDateTime(new Date(2017,0.1));// Possible result: 2007-03-11 11:20:32
 *     let value3 = RandomDateTime.updateDateTime(new Date(2010,1,2));// Possible result: 2010-02-05 11:33:23
 */
export class RandomDateTime {

    /**
     * Generates a random Date in the range ['minYear', 'maxYear'].
     * This method generate dates without time (or time set to 00:00:00)
     * 
     * @param min   (optional) minimum range value
     * @param max   max range value
     * @returns     a random Date value.
     */
    public static nextDate(min: Date, max: Date = null): Date {
        if (max == null) {
            max = min;
            min = new Date(max.getFullYear() - 10, 1, 1);
        }

        let diff = max.getTime() - min.getTime();
        if (diff <= 0) return min;

        let time = min.getTime() + RandomInteger.nextInteger(0, diff);
        let date = new Date(time);
        
        return new Date(date.getFullYear(), date.getMonth(), date.getDay());
    }

    /**
     * Generates a random Date and time in the range ['minYear', 'maxYear'].
     * This method generate dates without time (or time set to 00:00:00)
     * 
     * @param min   (optional) minimum range value
     * @param max   max range value
     * @returns     a random Date and time value.
     */
    public static nextDateTime(min: Date, max: Date = null): Date {
        if (max == null) {
            max = min;
            min = new Date(2000, 0, 1);
        }

        let diff = max.getTime() - min.getTime();
        if (diff <= 0) return min;

        let time = min.getTime() + RandomInteger.nextInteger(0, diff);
        return new Date(time);
    }

    /**
     * Updates (drifts) a Date value within specified range defined
     * 
     * @param value     a Date value to drift.
     * @param range     (optional) a range in milliseconds. Default: 10 days
     */
    public static updateDateTime(value: Date, range: number = null): Date {
        range = range != 0 && range != null ? range : 10 * 24 * 3600000;
        if (range < 0) return value;

        let time = value.valueOf() + RandomInteger.nextInteger(-range, range);
        return new Date(time);
    }

}