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`.

lib/staticgen/jekyll.go

@@ -0,0 +1,125 @@
+package staticgen
+
+import (
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+
+	fb "github.com/filebrowser/filebrowser/lib"
+)
+
+// Jekyll is the Jekyll static website generator.
+type Jekyll struct {
+	// Website root
+	Root string `name:"Website Root"`
+	// Public folder
+	Public string `name:"Public Directory"`
+	// Jekyll executable path
+	Exe string `name:"Executable"`
+	// Jekyll arguments
+	Args []string `name:"Arguments"`
+	// Indicates if we should clean public before a new publish.
+	CleanPublic bool `name:"Clean Public"`
+	// previewPath is the temporary path for a preview
+	previewPath string
+}
+
+// Name is the plugin's name.
+func (j Jekyll) Name() string {
+	return "jekyll"
+}
+
+// SettingsPath retrieves the correct settings path.
+func (j Jekyll) SettingsPath() string {
+	return "/_config.yml"
+}
+
+// Hook is the pre-api handler.
+func (j Jekyll) Hook(c *fb.Context, w http.ResponseWriter, r *http.Request) (int, error) {
+	return 0, nil
+}
+
+// Publish publishes a post.
+func (j Jekyll) Publish(c *fb.Context, w http.ResponseWriter, r *http.Request) (int, error) {
+	filename := filepath.Join(c.User.Scope, r.URL.Path)
+
+	// We only run undraft command if it is a file.
+	if err := j.undraft(filename); err != nil {
+		return http.StatusInternalServerError, err
+	}
+
+	// Regenerates the file
+	j.run()
+
+	return 0, nil
+}
+
+// Preview handles the preview path.
+func (j *Jekyll) Preview(c *fb.Context, w http.ResponseWriter, r *http.Request) (int, error) {
+	// Get a new temporary path if there is none.
+	if j.previewPath == "" {
+		path, err := ioutil.TempDir("", "")
+		if err != nil {
+			return http.StatusInternalServerError, err
+		}
+
+		j.previewPath = path
+	}
+
+	// Build the arguments to execute Hugo: change the base URL,
+	// build the drafts and update the destination.
+	args := j.Args
+	args = append(args, "--baseurl", c.RootURL()+"/preview/")
+	args = append(args, "--drafts")
+	args = append(args, "--destination", j.previewPath)
+
+	// Builds the preview.
+	if err := runCommand(j.Exe, args, j.Root); err != nil {
+		return http.StatusInternalServerError, err
+	}
+
+	// Serves the temporary path with the preview.
+	http.FileServer(http.Dir(j.previewPath)).ServeHTTP(w, r)
+	return 0, nil
+}
+
+func (j Jekyll) run() {
+	// If the CleanPublic option is enabled, clean it.
+	if j.CleanPublic {
+		os.RemoveAll(j.Public)
+	}
+
+	if err := runCommand(j.Exe, j.Args, j.Root); err != nil {
+		log.Println(err)
+	}
+}
+
+func (j Jekyll) undraft(file string) error {
+	if !strings.Contains(file, "_drafts") {
+		return nil
+	}
+
+	return os.Rename(file, strings.Replace(file, "_drafts", "_posts", 1))
+}
+
+// Setup sets up the plugin.
+func (j *Jekyll) Setup() error {
+	var err error
+	if j.Exe, err = exec.LookPath("jekyll"); err != nil {
+		return err
+	}
+
+	if len(j.Args) == 0 {
+		j.Args = []string{"build"}
+	}
+
+	if j.Args[0] != "build" {
+		j.Args = append([]string{"build"}, j.Args...)
+	}
+
+	return nil
+}