admin: Implement sychronization backends

We are now able, depending on configuration, to retrieve files from either WebDAV or local file system.

admin/sync/importer_cloud.go

@@ -0,0 +1,96 @@
+package sync
+
+import (
+	"bufio"
+	"errors"
+	"net/http"
+	"net/url"
+	"path"
+
+	"github.com/studio-b12/gowebdav"
+)
+
+var CloudDAVBase string = "https://srs.epita.fr/owncloud/remote.php/webdav/FIC 2018"
+var CloudUsername string = "fic"
+var CloudPassword string = ""
+
+type CloudImporter struct {
+	baseDAV url.URL
+	username string
+	password string
+}
+
+func NewCloudImporter(baseDAV string, username string, password string) (*CloudImporter, error) {
+	if r, err := url.Parse(baseDAV); err != nil {
+		return nil, err
+	} else {
+		return &CloudImporter{*r, username, password}, nil
+	}
+}
+
+func (i CloudImporter) Kind() string {
+	return "cloud file importer: " + i.baseDAV.String()
+}
+
+func (i CloudImporter) exists(filename string) bool {
+	fullURL := i.baseDAV
+	fullURL.Path = path.Join(fullURL.Path, filename)
+
+	client := http.Client{}
+	if req, err := http.NewRequest("HEAD", fullURL.String(), nil); err == nil {
+		req.SetBasicAuth(i.username, i.password)
+
+		if resp, err := client.Do(req); err == nil {
+			defer resp.Body.Close()
+
+			return resp.StatusCode == http.StatusOK
+		}
+	}
+	return false
+}
+
+func (i CloudImporter) toURL(filename string) string {
+	fullURL := i.baseDAV
+	fullURL.Path = path.Join(fullURL.Path, filename)
+	return fullURL.String()
+}
+
+func (i CloudImporter) getFile(filename string, writer *bufio.Writer) error {
+	fullURL := i.baseDAV
+	fullURL.Path = path.Join(fullURL.Path, filename)
+
+	client := http.Client{}
+	if req, err := http.NewRequest("GET", fullURL.String(), nil); err != nil {
+		return err
+	} else {
+		req.SetBasicAuth(i.username, i.password)
+		if resp, err := client.Do(req); err != nil {
+			return err
+		} else {
+			defer resp.Body.Close()
+
+			if resp.StatusCode != http.StatusOK {
+				return errors.New(resp.Status)
+			} else {
+				reader := bufio.NewReader(resp.Body)
+				reader.WriteTo(writer)
+				writer.Flush()
+			}
+		}
+	}
+	return nil
+}
+
+func (i CloudImporter) listDir(filename string) ([]string, error) {
+	client := gowebdav.NewClient(i.baseDAV.String(), i.username, i.password)
+
+	if files, err := client.ReadDir(filename); err != nil {
+		return nil, err
+	} else {
+		res := make([]string, 0)
+		for _, file := range files {
+			res = append(res, file.Name())
+		}
+		return res, nil
+	}
+}