10 feat download queue (#59)

* testing message queue

* better mq syncronisation

* major code refactoring, concern separation.

* bugfix

* code refactoring

* queuesize configurable via flags

* code refactoring

* comments

* code refactoring, updated readme

server/internal/memory_db.go

@@ -0,0 +1,125 @@
+package internal
+
+import (
+	"errors"
+	"fmt"
+	"log"
+	"os"
+	"sync"
+
+	"github.com/goccy/go-json"
+
+	"github.com/google/uuid"
+	"github.com/marcopeocchi/yt-dlp-web-ui/server/cli"
+)
+
+// In-Memory Thread-Safe Key-Value Storage with optional persistence
+type MemoryDB struct {
+	table sync.Map
+}
+
+// Get a process pointer given its id
+func (m *MemoryDB) Get(id string) (*Process, error) {
+	entry, ok := m.table.Load(id)
+	if !ok {
+		return nil, errors.New("no process found for the given key")
+	}
+	return entry.(*Process), nil
+}
+
+// Store a pointer of a process and return its id
+func (m *MemoryDB) Set(process *Process) string {
+	id := uuid.Must(uuid.NewRandom()).String()
+	m.table.Store(id, process)
+	return id
+}
+
+// Update a process info/metadata, given the process id
+//
+// Deprecated: will be removed anytime soon.
+func (m *MemoryDB) UpdateInfo(id string, info DownloadInfo) error {
+	entry, ok := m.table.Load(id)
+	if ok {
+		entry.(*Process).Info = info
+		m.table.Store(id, entry)
+		return nil
+	}
+	return fmt.Errorf("can't update row with id %s", id)
+}
+
+// Update a process progress data, given the process id
+// Used for updating completition percentage or ETA.
+//
+// Deprecated: will be removed anytime soon.
+func (m *MemoryDB) UpdateProgress(id string, progress DownloadProgress) error {
+	entry, ok := m.table.Load(id)
+	if ok {
+		entry.(*Process).Progress = progress
+		m.table.Store(id, entry)
+		return nil
+	}
+	return fmt.Errorf("can't update row with id %s", id)
+}
+
+// Removes a process progress, given the process id
+func (m *MemoryDB) Delete(id string) {
+	m.table.Delete(id)
+}
+
+func (m *MemoryDB) Keys() *[]string {
+	running := []string{}
+	m.table.Range(func(key, value any) bool {
+		running = append(running, key.(string))
+		return true
+	})
+	return &running
+}
+
+// Returns a slice of all currently stored processes progess
+func (m *MemoryDB) All() *[]ProcessResponse {
+	running := []ProcessResponse{}
+	m.table.Range(func(key, value any) bool {
+		running = append(running, ProcessResponse{
+			Id:       key.(string),
+			Info:     value.(*Process).Info,
+			Progress: value.(*Process).Progress,
+		})
+		return true
+	})
+	return &running
+}
+
+// WIP: Persist the database in a single file named "session.dat"
+func (m *MemoryDB) Persist() {
+	running := m.All()
+
+	session, err := json.Marshal(Session{
+		Processes: *running,
+	})
+	if err != nil {
+		log.Println(cli.Red, "Failed to persist database", cli.Reset)
+		return
+	}
+
+	err = os.WriteFile("session.dat", session, 0700)
+	if err != nil {
+		log.Println(cli.Red, "Failed to persist database", cli.Reset)
+	}
+}
+
+// WIP: Restore a persisted state
+func (m *MemoryDB) Restore() {
+	feed, _ := os.ReadFile("session.dat")
+	session := Session{}
+	json.Unmarshal(feed, &session)
+
+	for _, proc := range session.Processes {
+		m.table.Store(proc.Id, &Process{
+			Id:       proc.Id,
+			Url:      proc.Info.URL,
+			Info:     proc.Info,
+			Progress: proc.Progress,
+			DB:       m,
+		})
+	}
+}