package statistics

import (
	"fmt"
	"os"
	"time"
)

// An observer, to track reduction performance.
type Tracker struct {
	start time.Time
	steps uint64
}

// Create a new reduction performance tracker.
func Track() *Tracker {
	return &Tracker{}
}

func (t *Tracker) Start() {
	t.start = time.Now()
	t.steps = 0
}

func (t *Tracker) Step() {
	t.steps++
}

func (t *Tracker) End() {
	results := Results{
		StepsTaken:  t.steps,
		TimeElapsed: uint64(time.Since(t.start).Milliseconds()),
	}

	fmt.Fprint(os.Stderr, results.String())
}