feat: use cobra to provide subcommands, move sources to lib (#506)

- Use cobra in order to provide subcommands `serve` and `db`.
  - Subdir `cmd` is removed.
  - Subdir `cli` is created, which is a standard cobra structure.
- Sources related to the core are moved to subdir `lib`.
- #497 and #504 are merged.
- Deprecated flags are added. See https://github.com/filebrowser/filebrowser/pull/497#discussion_r209428120.
- [`viper.BindPFlags`](https://godoc.org/github.com/spf13/viper#BindPFlags) is used in order to reduce the verbosity in `serve.go`.


Former-commit-id: 4b37ad82e91e01f7718cd389469814674bdf7032 [formerly c84d7fcf9c362b2aa1f9e5b57196152f53835e61] [formerly 2fef43c0382f3cc7d13e0297ccb467e38fac6982 [formerly 69a3f853bd2821d2c52a435277aaac68a468d39b]]
Former-commit-id: 2f7dc1b8ee6735382cedae2053f40c546c21de45 [formerly b438417178b47ad5f7caf9cb728f4a5011a09f5e]
Former-commit-id: 07bc58ab2e1ab10c30be8d0a5e760288bfc4d4dc

lib/http/subtitle.go

@@ -0,0 +1,83 @@
+package http
+
+import (
+	"bytes"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"path/filepath"
+	"regexp"
+
+	fb "github.com/filebrowser/filebrowser/lib"
+)
+
+func subtitlesHandler(c *fb.Context, w http.ResponseWriter, r *http.Request) (int, error) {
+	files, err := readDir(filepath.Dir(c.File.Path))
+	if err != nil {
+		return http.StatusInternalServerError, err
+	}
+	subtitles := make([]map[string]string, 0)
+	for _, file := range files {
+		ext := filepath.Ext(file.Name())
+		if ext == ".vtt" || ext == ".srt" {
+			sub := make(map[string]string)
+			sub["src"] = filepath.Dir(c.File.Path) + "/" + file.Name()
+			sub["kind"] = "subtitles"
+			sub["label"] = file.Name()
+			subtitles = append(subtitles, sub)
+		}
+	}
+	return renderJSON(w, subtitles)
+}
+
+func subtitleHandler(c *fb.Context, w http.ResponseWriter, r *http.Request) (int, error) {
+	str, err := cleanSubtitle(c.File.Path)
+	if err != nil {
+		return http.StatusInternalServerError, err
+	}
+
+	file, err := os.Open(c.File.Path)
+	if err != nil {
+		return http.StatusInternalServerError, err
+	}
+	defer file.Close()
+
+	stat, err := file.Stat()
+	if err != nil {
+		return http.StatusInternalServerError, err
+	}
+
+	w.Header().Set("Content-Disposition", "inline")
+	w.Header().Set("Content-Type", "text/vtt")
+	http.ServeContent(w, r, stat.Name(), stat.ModTime(), bytes.NewReader([]byte(str)))
+
+	return 0, nil
+
+}
+
+func cleanSubtitle(filename string) (string, error) {
+	b, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return "", err
+	}
+	str := string(b) // convert content to a 'string'
+	ext := filepath.Ext(filename)
+	if ext == ".srt" {
+		re := regexp.MustCompile("([0-9]{2}:[0-9]{2}:[0-9]{2}),([0-9]{3})")
+		str = "WEBVTT\n\n" + re.ReplaceAllString(str, "$1.$2")
+	}
+	return str, err
+}
+
+func readDir(dirname string) ([]os.FileInfo, error) {
+	f, err := os.Open(dirname)
+	if err != nil {
+		return nil, err
+	}
+	list, err := f.Readdir(-1)
+	f.Close()
+	if err != nil {
+		return nil, err
+	}
+	return list, nil
+}