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) ));

}