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session.go
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session.go
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package getparty
import (
"encoding/json"
"fmt"
"io"
"log"
"os"
"strings"
"github.com/vbauerster/mpb/v4"
"github.com/vbauerster/mpb/v4/decor"
)
const (
acceptRangesType = "bytes"
)
// Session represents download session state
type Session struct {
Location string
SuggestedFileName string
ContentMD5 string
AcceptRanges string
StatusCode int
ContentLength int64
ContentType string
HeaderMap map[string]string
Parts []*Part
}
func (s Session) isAcceptRanges() bool {
return strings.EqualFold(s.AcceptRanges, acceptRangesType)
}
func (s Session) calcParts(parts int64) []*Part {
var partSize int64
if s.ContentLength <= 0 {
parts = 1
} else {
partSize = s.ContentLength / parts
}
ps := make([]*Part, parts)
ps[0] = &Part{
FileName: s.SuggestedFileName,
}
stop := s.ContentLength
start := stop
for i := parts - 1; i > 0; i-- {
stop = start - 1
start = stop - partSize
ps[i] = &Part{
FileName: fmt.Sprintf("%s.part%d", s.SuggestedFileName, i),
Start: start,
Stop: stop,
}
}
stop = start - 1
if stop < parts*8 {
return ps[:1]
}
ps[0].Stop = stop
return ps
}
func (s Session) concatenateParts(dlogger *log.Logger, progress *mpb.Progress) (err error) {
if len(s.Parts) <= 1 {
return nil
}
fpart0, err := os.OpenFile(s.Parts[0].FileName, os.O_APPEND|os.O_WRONLY, 0644)
if err != nil {
return err
}
bar := progress.AddBar(int64(len(s.Parts)-1), mpb.BarStyle("|=>-|"),
mpb.BarPriority(len(s.Parts)),
mpb.PrependDecorators(
decor.Name("concatenating:", decor.WCSyncWidth),
decor.Name(" ["),
decor.NewPercentage("%d", decor.WCSyncSpace),
),
mpb.AppendDecorators(
decor.OnComplete(decor.AverageETA(decor.ET_STYLE_MMSS, decor.WCSyncWidth), "ok!"),
decor.Name(" ]"),
),
)
defer func() {
if err != nil {
bar.Abort(false)
}
}()
dlogger.Printf("concatenating: %s", fpart0.Name())
for i := 1; i < len(s.Parts); i++ {
fparti, err := os.Open(s.Parts[i].FileName)
if err != nil {
return err
}
dlogger.Printf("concatenating: %s", fparti.Name())
if _, err := io.Copy(fpart0, fparti); err != nil {
return err
}
for _, err := range [...]error{fparti.Close(), os.Remove(fparti.Name())} {
if err != nil {
dlogger.Printf("concatenateParts: %q %v", fparti.Name(), err)
}
}
bar.Increment()
}
return fpart0.Close()
}
func (s *Session) saveState(fileName string) error {
dst, err := os.Create(fileName)
if err != nil {
return err
}
err = json.NewEncoder(dst).Encode(s)
if e := dst.Close(); err == nil {
err = e
}
return err
}
func (s *Session) loadState(fileName string) error {
src, err := os.Open(fileName)
if err != nil {
return err
}
err = json.NewDecoder(src).Decode(s)
if e := src.Close(); err == nil {
err = e
}
return err
}
func (s *Session) actualPartsOnly() {
parts := s.Parts[:0]
for _, p := range s.Parts {
if p.Skip {
continue
}
parts = append(parts, p)
}
s.Parts = parts
}
func (s Session) totalWritten() int64 {
var total int64
for _, p := range s.Parts {
total += p.Written
}
return total
}
func (s Session) writeSummary(w io.Writer) {
humanSize := decor.SizeB1024(s.ContentLength)
format := fmt.Sprintf("Length: %%s [%s]\n", s.ContentType)
lengthSummary := "unknown"
if s.ContentLength >= 0 {
lengthSummary = fmt.Sprintf("%d (% .2f)", s.ContentLength, humanSize)
if totalWritten := s.totalWritten(); totalWritten > 0 {
remaining := s.ContentLength - totalWritten
lengthSummary += fmt.Sprintf(", %d (% .2f) remaining", remaining, decor.SizeB1024(remaining))
}
}
fmt.Fprintf(w, format, lengthSummary)
if s.ContentMD5 != "" {
fmt.Fprintf(w, "MD5: %s\n", s.ContentMD5)
}
if !s.isAcceptRanges() {
fmt.Fprintln(w, "HTTP server doesn't seem to support byte ranges. Cannot resume.")
}
fmt.Fprintf(w, "Saving to: %q\n\n", s.SuggestedFileName)
}
func (s Session) removeFiles() (err error) {
for _, part := range s.Parts {
if e := os.Remove(part.FileName); err == nil && !os.IsNotExist(e) {
err = e
}
}
return err
}