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Permit the configuration of customs HEAD URLs #1

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Permit the configuration of customs HEAD URLs #1

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53 changes: 22 additions & 31 deletions downloader.go
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,8 @@ import (
)

type Config struct {
Url string
URL string
HeadURL string
Concurrency int

// output filename
Expand All @@ -35,7 +36,7 @@ func getFilenameAndExt(fileName string) (string, string) {
return strings.TrimSuffix(fileName, ext), ext
}

type downloader struct {
type Downloader struct {
// true if the download has been paused
Paused bool
config *Config
Expand All @@ -47,19 +48,19 @@ type downloader struct {
bar *progressbar.ProgressBar
}

func (d *downloader) Pause() {
func (d *Downloader) Pause() {
d.Paused = true
d.cancel()
}

func (d *downloader) Resume() {
func (d *Downloader) Resume() {
d.config.Resume = true
d.Paused = false
d.Download()
}

// Returns the progress bar's state
func (d *downloader) ProgressState() progressbar.State {
func (d *Downloader) ProgressState() progressbar.State {
if d.bar != nil {
return d.bar.State()
}
Expand All @@ -70,7 +71,7 @@ func (d *downloader) ProgressState() progressbar.State {
// Add a number to the filename if file already exist
// For instance, if filename `hello.pdf` already exist
// it returns hello(1).pdf
func (d *downloader) renameFilenameIfNecessary() {
func (d *Downloader) renameFilenameIfNecessary() {
if d.config.Resume {
return // in resume mode, no need to rename
}
Expand All @@ -90,52 +91,42 @@ func (d *downloader) renameFilenameIfNecessary() {
}
}

func New(url string) (*downloader, error) {
if url == "" {
func NewFromConfig(config *Config) (*Downloader, error) {
if config.URL == "" {
return nil, errors.New("Url is empty")
}

config := &Config{
Url: url,
Concurrency: 1,
}

return NewFromConfig(config)
}

func NewFromConfig(config *Config) (*downloader, error) {
if config.Url == "" {
return nil, errors.New("Url is empty")
if config.HeadURL == "" {
config.HeadURL = config.URL
}
if config.Concurrency < 1 {
config.Concurrency = 1
log.Print("Concurrency level: 1")
}
if config.OutFilename == "" {
config.OutFilename = detectFilename(config.Url)
config.OutFilename = detectFilename(config.URL)
}
if config.CopyBufferSize == 0 {
config.CopyBufferSize = 1024
}

d := &downloader{config: config}
d := &Downloader{config: config}

// rename file if such file already exist
d.renameFilenameIfNecessary()
log.Printf("Output file: %s", filepath.Base(config.OutFilename))
return d, nil
}

func (d *downloader) getPartFilename(partNum int) string {
func (d *Downloader) getPartFilename(partNum int) string {
return d.config.OutFilename + ".part" + strconv.Itoa(partNum)
}

func (d *downloader) Download() {
func (d *Downloader) Download() {
ctx, cancel := context.WithCancel(context.Background())
d.context = ctx
d.cancel = cancel

res, err := http.Head(d.config.Url)
res, err := http.Head(d.config.HeadURL)
if err != nil {
log.Fatal(err)
}
Expand All @@ -152,13 +143,13 @@ func (d *downloader) Download() {
}

// Server does not support partial download for this file
func (d *downloader) simpleDownload() {
func (d *Downloader) simpleDownload() {
if d.config.Resume {
log.Fatal("Cannot resume. Must be downloaded again")
}

// make a request
res, err := http.Get(d.config.Url)
res, err := http.Get(d.config.URL)
if err != nil {
log.Fatal(err)
}
Expand All @@ -182,7 +173,7 @@ func (d *downloader) simpleDownload() {
}

// download concurrently
func (d *downloader) multiDownload(contentSize int) {
func (d *Downloader) multiDownload(contentSize int) {
partSize := contentSize / d.config.Concurrency

startRange := 0
Expand Down Expand Up @@ -223,7 +214,7 @@ func (d *downloader) multiDownload(contentSize int) {
}
}

func (d *downloader) merge() {
func (d *Downloader) merge() {
destination, err := os.OpenFile(d.config.OutFilename, os.O_CREATE|os.O_WRONLY, 0666)
if err != nil {
log.Fatal(err)
Expand All @@ -242,15 +233,15 @@ func (d *downloader) merge() {
}
}

func (d *downloader) downloadPartial(rangeStart, rangeStop int, partialNum int, wg *sync.WaitGroup) {
func (d *Downloader) downloadPartial(rangeStart, rangeStop int, partialNum int, wg *sync.WaitGroup) {
defer wg.Done()
if rangeStart >= rangeStop {
// nothing to download
return
}

// create a request
req, err := http.NewRequest("GET", d.config.Url, nil)
req, err := http.NewRequest("GET", d.config.URL, nil)
if err != nil {
log.Fatal(err)
}
Expand Down