Provide download functionality for documents

Addressing: #7

Uses existing function to find a list of matching filenames, if only one
entry matches, downloads it to current dir, if there are multiple
matches provide an indexed list to select from

cmd/download.go

@@ -0,0 +1,35 @@
+package cmd
+
+import (
+	"fmt"
+
+	log "github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+)
+
+var downloadCmd = &cobra.Command{
+	Use:   "download",
+	Short: "Download a Document",
+	Long:  "Download a remote document from a paperless server",
+
+	Run: func(cmd *cobra.Command, args []string) {
+		log.Debugf("Called Download with args %v", args)
+		if len(args) < 1 {
+			log.Debugf("Missing filename to download")
+		}
+		if viper.ConfigFileUsed() == "" {
+			fmt.Println("No configuration file found! Try 'config create'")
+		} else {
+			fmt.Println(PaperInst)
+			for index := range args {
+				PaperInst.DownloadFiles(args[index])
+			}
+		}
+		log.Debug("Done downloading")
+	},
+}
+
+func init() {
+	documentsCmd.AddCommand(downloadCmd)
+}

paperless/downloadfile.go

@@ -0,0 +1,80 @@
+package paperless
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"strconv"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+)
+
+var documentselection int
+
+func (p Paperless) setFullDownloadURL(location string) string {
+	switch p.UseHTTPS {
+	case true:
+		return "https://" + p.Hostname + location
+	case false:
+		return "http://" + p.Hostname + location
+	}
+	return ""
+}
+
+func (p Paperless) writeFile(document Document) {
+	downloadURL := p.setFullDownloadURL(document.DownloadURL)
+
+	client := http.Client{Timeout: time.Second * 5}
+	log.Debugf("downloading from: %v", downloadURL)
+	req, _ := http.NewRequest("GET", downloadURL, nil)
+	req.Header.Set("User-Agent", "paperless-cli")
+	req.SetBasicAuth(p.Username, p.Password)
+
+	resp, err := client.Do(req)
+	if err != nil {
+		log.Errorf("Error downloading file: %v", err)
+	}
+	defer resp.Body.Close()
+
+	out, err := os.Create(document.FileName)
+	if err != nil {
+		log.Panicln(err)
+	}
+	defer out.Close()
+
+	_, err = io.Copy(out, resp.Body)
+	if err != nil {
+		log.Panicln(err)
+	}
+}
+
+// DownloadFiles pulls either a paperless document or allows selection from a list
+func (p Paperless) DownloadFiles(filename string) {
+	documents, err := Paperless.GetDocument(p, filename, true)
+	if err != nil {
+		log.Errorf("Error finding file")
+		return
+	}
+	if len(documents) == 0 {
+		log.Panicln("No matches for", filename)
+		return
+	}
+	if len(documents) > 1 {
+		fmt.Println("Multiple files found. Please select from:")
+		for index, element := range documents {
+			fmt.Println(strconv.Itoa(index) + ": " + element.FileName)
+		}
+		var selection string
+		fmt.Scanln(&selection)
+		documentselection, err = strconv.Atoi(selection)
+		if err != nil {
+			log.Error("Please pass a number back for selection")
+			return
+		}
+	}
+
+	document := documents[documentselection]
+	p.writeFile(document)
+}