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package main
import (
"fmt"
"io"
"net/http"
"os"
"path/filepath"
"strings"
)
func Min(x, y int64) int64 {
if x < y {
return x
}
return y
}
func Max(x, y int64) int64 {
if x > y {
return x
}
return y
}
// WriteCounter counts the number of bytes written to it
type WriteCounter struct {
ContentLength int64
BytesWritten uint64
Step int64
}
func NewWriteCounter(contentLength int64) *WriteCounter {
ptr := new(WriteCounter)
ptr.ContentLength = contentLength
ptr.Step = Max(contentLength/20, 1)
return ptr
}
func (wc *WriteCounter) Write(p []byte) (int, error) {
n := len(p)
wc.BytesWritten += uint64(n)
wc.PrintProgress()
return n, nil
}
func (wc *WriteCounter) PrintProgress() {
// clear the line by using a character return to go back to the start of the
// line and remove the remaining characters
fmt.Printf("\r%s", strings.Repeat(" ", 35))
// steps can be at most 20 -> get the minimum of (n_steps) and 20
steps := int(Min(int64(wc.BytesWritten)/wc.Step, 20))
fmt.Printf("\r[%s%s] %d/%d bytes complete", strings.Repeat("#", steps), strings.Repeat(" ", 20-steps), wc.BytesWritten, wc.ContentLength)
}
func downloadFile(path string, url string) error {
// make sure dir exists
os.MkdirAll(filepath.Dir(path), 0755)
// create .part file
output, err := os.Create(path + ".part")
if err != nil {
return err
}
defer output.Close()
// get data
response, err := http.Get(url)
if err != nil {
return err
}
defer response.Body.Close()
// create progress reporter
counter := NewWriteCounter(response.ContentLength)
_, err = io.Copy(output, io.TeeReader(response.Body, counter))
if err != nil {
return err
}
fmt.Printf("\n")
output.Close()
return os.Rename(path+".part", path)
}
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