Multiple:

- Added LICENSE
- Updated README
- Added progress indicator
- File downloads as .tmp file before being completed

LICENSE

@@ -0,0 +1,19 @@
+Copyright <2021> <Donnie Corbitt>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to 
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do 
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all 
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 
+SOFTWARE.

README.md

@@ -2,15 +2,12 @@
 This is a download manager that I'm making entirely in go.
 
 # Building
-run the following command to run without making an executable:
-
-`go run dmig.go`
-
-or to build an executable...
+`go mod init dmig`
 
 `go build dmig.go`
 
-
 # TODO
 - [x] Ask for url of file to download instead of needing to edit source
-- [ ] Add progress bar/percentage
+- [x] Add progress bar/percentage
+- [ ] Have automatic file naming
+- [ ] Assume the url is https by default

dmig.go

@@ -16,8 +16,35 @@ import (
 	"io"
 	"net/http"
 	"os"
+	"strings"
+
+	"github.com/dustin/go-humanize"
 )
 
+// WriteCounter counts the number of bytes written to it. It implements to the
+// io.Writer interface and we pass this into io.TeeReader() which will report
+// progress on each write cycle.
+type WriteCounter struct {
+	Total uint64
+}
+
+func (wc *WriteCounter) Write(p []byte) (int, error) {
+	n := len(p)
+	wc.Total += 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 and
+	// remove the remaining characters by filling it with spaces
+	fmt.Printf("\r%s", strings.Repeat(" ", 35))
+
+	// Return again and print current status of download
+	// Humanize package used so the amount is in a human readable way (ex: 100MB)
+	fmt.Printf("\rDownloading... %s complete", humanize.Bytes(wc.Total))
+}
+
 func main() {
 	// Asks the user what the url to the file is.
 	// Input will be below the following text.
@@ -37,13 +64,21 @@ func main() {
 	if err != nil {
 		panic(err)
 	}
-	fmt.Println("Downloaded: " + fileUrl)
+	fmt.Println("Downloaded: " + fileName)
 }
 
 // DownloadedFile will download a url to a local file. It's efficient because it
 // write as it downloads and not load the whole file into memory
 func DownloadFile(filepath string, url string) error {
 	
+	// Create the file, but give it a tmp file extension, this means we won't 
+	// overwrite a file unless it's downloaded, the .tmp will be removed when 
+	// download completes.
+	out, err := os.Create(filepath + ".tmp")
+	if err != nil {
+		return err
+	}
+
 	// Get the data
 	resp, err := http.Get(url)
 	if err != nil {
@@ -51,14 +86,21 @@ func DownloadFile(filepath string, url string) error {
 	}
 	defer resp.Body.Close()
 
-	// Create the file
-	out, err := os.Create(filepath)
-	if err != nil {
+	// Create progress report and pass it to be used alongside the writer
+	counter := &WriteCounter{}
+	if _, err = io.Copy(out, io.TeeReader(resp.Body, counter)); err != nil {
+		out.Close()
 		return err
 	}
-	defer out.Close()
 
-	// Write the body to file
-	_, err = io.Copy(out, resp.Body)
-	return err
+	// The progress use the same line so print a new line once it's done.
+	fmt.Print("\n")
+
+	// Close the file without defer so it can happen before Rename()
+	out.Close()
+
+	if err = os.Rename(filepath+".tmp", filepath); err != nil {
+		return err
+	}
+	return nil
 }