Feat livestream support (#180)

* experimental livestrea support

* test livestream

* update wait time detection

* update livestream functions

* persist and restore livestreams monitor session

* fan-in logging

* deps update

* added live time display

* livestream monitor prototype

* changed to default logger instead of passing *slog.Logger everywhere

* code refactoring, comments

server/internal/livestream/monitor.go

@@ -0,0 +1,118 @@
+package livestream
+
+import (
+	"encoding/gob"
+	"log/slog"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/marcopeocchi/yt-dlp-web-ui/server/config"
+)
+
+type Monitor struct {
+	streams map[string]*LiveStream // keeps track of the livestreams
+	done    chan *LiveStream       // to signal individual processes completition
+	logs    chan []byte            // to signal individual processes completition
+}
+
+func NewMonitor() *Monitor {
+	return &Monitor{
+		streams: make(map[string]*LiveStream),
+		done:    make(chan *LiveStream),
+	}
+}
+
+// Detect each livestream completition, if done remove it from the monitor.
+func (m *Monitor) Schedule() {
+	for l := range m.done {
+		delete(m.streams, l.url)
+	}
+}
+
+func (m *Monitor) Add(url string) {
+	ls := New(url, m.logs, m.done)
+
+	go ls.Start()
+	m.streams[url] = ls
+}
+
+func (m *Monitor) Remove(url string) error {
+	return m.streams[url].Kill()
+}
+
+func (m *Monitor) RemoveAll() error {
+	for _, v := range m.streams {
+		if err := v.Kill(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (m *Monitor) Status() LiveStreamStatus {
+	status := make(LiveStreamStatus)
+
+	for k, v := range m.streams {
+		// wt, ok := <-v.WaitTime()
+		// if !ok {
+		// 	continue
+		// }
+
+		status[k] = struct {
+			Status   int
+			WaitTime time.Duration
+			LiveDate time.Time
+		}{
+			Status:   v.status,
+			WaitTime: v.waitTime,
+			LiveDate: v.liveDate,
+		}
+	}
+
+	return status
+}
+
+// Persist the monitor current state to a file.
+// The file is located in the configured config directory
+func (m *Monitor) Persist() error {
+	fd, err := os.Create(filepath.Join(config.Instance().Dir(), "livestreams.dat"))
+	if err != nil {
+		return err
+	}
+
+	defer fd.Close()
+
+	slog.Debug("persisting livestream monitor state")
+
+	return gob.NewEncoder(fd).Encode(m.streams)
+}
+
+// Restore a saved state and resume the monitored livestreams
+func (m *Monitor) Restore() error {
+	fd, err := os.Open(filepath.Join(config.Instance().Dir(), "livestreams.dat"))
+	if err != nil {
+		return err
+	}
+
+	defer fd.Close()
+
+	restored := make(map[string]*LiveStream)
+
+	if err := gob.NewDecoder(fd).Decode(&restored); err != nil {
+		return err
+	}
+
+	for k := range restored {
+		m.Add(k)
+	}
+
+	slog.Debug("restored livestream monitor state")
+
+	return nil
+}
+
+// Return a fan-in logs channel
+func (m *Monitor) Logs() <-chan []byte {
+	return m.logs
+}