[rget] first commit (base code)

Author: imura81gt

kadai3/imura81gt/rget/README.md

@@ -0,0 +1,9 @@
+rget
+=========================================================
+
+Command
+-----------------------------------------
+
+```
+go run cmd/rget/main.go https://upload.wikimedia.org/wikipedia/commons/1/16/Notocactus_minimus.jpg
+```

kadai3/imura81gt/rget/cmd/rget/main.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+
+	"github.com/gopherdojo/dojo7/kadai3/imura81gt/rget"
+)
+
+func main() {
+	option := rget.Option{
+		Concurrency: *flag.Int("c", 10, "concurrency"),
+	}
+	flag.Parse()
+	urls := flag.Args()
+	if len(urls) != 1 {
+		fmt.Fprintf(os.Stderr, "%s <url>\n", os.Args[0])
+		fmt.Fprintln(os.Stderr, "option:")
+		flag.PrintDefaults()
+		os.Exit(1)
+	}
+
+	option.Url = urls[0]
+	rget.Run(option)
+}

kadai3/imura81gt/rget/rget.go

@@ -0,0 +1,78 @@
+package rget
+
+import (
+	"fmt"
+	"net/http"
+	"os"
+)
+
+type Option struct {
+	Concurrency int
+	Url         string
+}
+
+type Unit struct {
+	RangeStart int64
+	RangeEnd   int64
+}
+
+type Units []Unit
+
+func Run(option Option) {
+	fmt.Printf("%+v\n", option)
+	cl, err := contentLength(option.Url)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+
+	units := divide(cl, option.Concurrency)
+
+	//TODO: check errors
+	download(units)
+
+}
+
+func contentLength(url string) (int64, error) {
+	resp, err := http.Head(url)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		return 0, err
+	}
+
+	if resp.Header.Get("Accept-Ranges") == "" {
+		err := fmt.Errorf("This URL cannot support Ranges Requests")
+		// fmt.Fprintln(os.Stderr, err)
+		return resp.ContentLength, err
+	}
+	if resp.Header["Accept-Ranges"][0] == "none" {
+		err := fmt.Errorf("This URL cannot support Ranges Requests")
+		// fmt.Fprintln(os.Stderr, err)
+		return resp.ContentLength, err
+	}
+	if resp.ContentLength == 0 {
+		err := fmt.Errorf("This URL size is %i", resp.Header["Content-Length"][0])
+		// fmt.Fprintln(os.Stderr, err)
+		return resp.ContentLength, err
+	}
+
+	return resp.ContentLength, nil
+}
+
+func divide(contentLength int64, concurrency int) Units {
+	var units []Unit
+
+	sbyte := contentLength / int64(concurrency)
+	for i := 0; i < concurrency; i++ {
+		units = append(units, Unit{
+			RangeStart: int64(i) * sbyte,
+			RangeEnd:   int64((i+1))*sbyte - 1,
+		})
+	}
+
+	return units
+}
+
+func download(units Units) {
+	fmt.Println(units)
+}