package steam

import (
	"errors"
	"fmt"
	"io"
	"time"
)

// how often are we going to be updating our status information?
const updateEveryNBytes = 10 * 1024 * 1024 // 10mb

// extractUpdate takes care of updating the job as it goes along at updateEveryNBytes
// it will be reported back to the Job's status.
func (l *Library) extractUpdate(j *Job, g *Game, rdr io.ReadCloser) (*Game, error) {
	rdr, wrtr := io.Pipe()

	go func() {
		var err error
		g, err = l.extractPrimitive(j, g, rdr)
		if err != nil {
			j.addError(fmt.Errorf("Installer: extracting %s", err))
		}
		// resp.Body.Close()
		rdr.Close()
	}()

	var total int64
	var err error

	for {
		var n int64
		n, err = io.CopyN(wrtr, rdr, updateEveryNBytes)
		if err == io.EOF {
			break
		} else if err != nil {
			j.addError(fmt.Errorf(
				"Error encountered read error: %w", err))
			break
		}

		total += n
		j.setTransferred(total)

		// rate in bytes/sec
		rate := total / int64(time.Since(*j.StartTime()).Seconds())

		estSize := j.GetSize()

		if estSize == nil {
			j.addError(errors.New("Expected an estimated size, got nil"))
			continue
		}

		remaining := *estSize - total

		j.setETA(time.Duration((remaining / rate) / 1000 / 1000 / 1000))
	}

	if err == io.EOF {
		return g, nil
	}

	return g, err

}