10 playlist download (#71)

* leveraging message queue for playlist entries DL

* playlist support implemented

It's a little bit slow but solid enough :D

server/internal/playlist.go

@@ -0,0 +1,81 @@
+package internal
+
+import (
+	"errors"
+	"log"
+	"os/exec"
+	"time"
+
+	"github.com/goccy/go-json"
+	"github.com/marcopeocchi/yt-dlp-web-ui/server/cli"
+)
+
+type metadata struct {
+	Entries []DownloadInfo `json:"entries"`
+	Count   int            `json:"playlist_count"`
+	Type    string         `json:"_type"`
+}
+
+func PlaylistDetect(req DownloadRequest, mq *MessageQueue, db *MemoryDB) error {
+	cmd := exec.Command(cfg.GetConfig().DownloaderPath, req.URL, "-J")
+
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		return err
+	}
+
+	m := metadata{}
+
+	err = cmd.Start()
+	if err != nil {
+		return err
+	}
+
+	log.Println(cli.BgRed, "Decoding metadata", cli.Reset, req.URL)
+
+	err = json.NewDecoder(stdout).Decode(&m)
+	if err != nil {
+		return err
+	}
+
+	log.Println(cli.BgGreen, "Decoded metadata", cli.Reset, req.URL)
+
+	if m.Type == "" {
+		cmd.Wait()
+		return errors.New("probably not a valid URL")
+	}
+
+	if m.Type == "playlist" {
+		log.Println(
+			cli.BgGreen, "Playlist detected", cli.Reset, m.Count, "entries",
+		)
+
+		for _, meta := range m.Entries {
+			proc := &Process{
+				Url:      meta.OriginalURL,
+				Progress: DownloadProgress{},
+				Output:   DownloadOutput{},
+				Info:     meta,
+				Params:   req.Params,
+			}
+
+			proc.Info.URL = meta.OriginalURL
+			proc.Info.CreatedAt = time.Now().Add(time.Second)
+
+			db.Set(proc)
+			proc.SetPending()
+			mq.PublishPlaylistEntry(proc)
+		}
+
+		err = cmd.Wait()
+		return err
+	}
+
+	proc := &Process{Url: req.URL, Params: req.Params}
+
+	mq.Publish(proc)
+	log.Println("Sending new process to message queue", proc.Url)
+
+	err = cmd.Wait()
+	return err
+}