/**
 * 
 * @param source 
 * @param short_period 
 * @param long_period 
 * @param size 
 * @returns 
 */
export async function ppo(
    source: Array<number>, short_period: number,
    long_period: number, size: number = source.length
) {

    const ppo: Array<number> = []

    // if (short_period < 1) throw new Error("Invalid Options")
    // if (long_period < 2) throw new Error("Invalid Options")
    // if (long_period < short_period) throw new Error("Invalid Options")
    // if (size <= 1) throw new Error("Out of range")

    const short_per = 2 / (short_period + 1)
    const long_per = 2 / (long_period + 1)

    let short_ema = source[0]
    let long_ema = source[0]

    for (let i = 1; i < size; ++i) {
        short_ema = (source[i] - short_ema) * short_per + short_ema
        long_ema = (source[i] - long_ema) * long_per + long_ema
        const out = 100.0 * (short_ema - long_ema) / long_ema

        ppo.push(out)
    }

    return ppo
}