import { getDecimalPlaces } from '$shared/lib/utils';

/**
 * Rounds a value to match the precision of a given step
 *
 * Fixes floating-point precision errors that occur with decimal arithmetic.
 * For example, repeatedly adding 0.05 can produce 1.3499999999999999
 * instead of 1.35 due to IEEE 754 floating-point representation.
 *
 * Uses toFixed() instead of Math.round() for correct decimal rounding.
 *
 * @param value - The value to round
 * @param step - The step size to match precision of (default: 1)
 * @returns The rounded value
 *
 * @example
 * ```ts
 * roundToStepPrecision(1.3499999999999999, 0.05); // 1.35
 * roundToStepPrecision(1.2345, 0.01); // 1.23
 * roundToStepPrecision(1.2345, 0.1); // 1.2
 * roundToStepPrecision(1.5, 1); // 2
 * ```
 */
export function roundToStepPrecision(value: number, step: number = 1): number {
    if (step <= 0) {
        return value;
    }
    const decimals = getDecimalPlaces(step);
    return parseFloat(value.toFixed(decimals));
}