package timeid

import (
	"math"
	"time"
)

/* (1) Generates the current time id
*
* @wsize<float64>				Window Size in seconds
*
* @return id<uint32>				Current time id
* @return parity<uint32>			Current time parity
*
---------------------------------------------------------*/
func Generate(wsize float64) (uint32, uint32) {

	/* (1) If wsize is 0 (div by zero possible error) */
	if wsize == 0 {
		return 0, 0
	}

	/* (2) Get current timestamp */
	timestamp := float64(time.Now().Unix())

	/* (3) Calculate the time id */
	var id = uint32(timestamp / wsize)

	/* (4) Calculate parity */
	var parity = id % 2

	return id, parity
}

/* (2) Try to guess a previous time id from its parity
*
* @wsize<float64>				Window Size in seconds
* @parity<uint32>					Received parity
*
* @return id<uint32>				The guessed time id
*
---------------------------------------------------------*/
func Guess(wsize float64, parity uint32) uint32 {

	/* (1) Get current time id */
	var idNow, parityNow = Generate(wsize)

	/* (2) Update ID with tidNow parity difference */
	return idNow - uint32(math.Abs(float64(parityNow)-float64(parity)))

}