Add multi-disk copy workflow

internal/copier/copier.go

@@ -31,38 +31,46 @@ type Options struct {
 type Copier struct {
 	tasks *task.Store
 
-	mu     sync.Mutex
-	cancel context.CancelFunc
+	mu      sync.Mutex
+	cancels map[string]context.CancelFunc
 
 	dbMu sync.RWMutex
-	db   *db.DB
+	dbs  map[string]*db.DB
 }
 
 func New(tasks *task.Store) *Copier {
-	return &Copier{tasks: tasks}
+	return &Copier{
+		tasks:   tasks,
+		cancels: make(map[string]context.CancelFunc),
+		dbs:     make(map[string]*db.DB),
+	}
 }
 
-func (c *Copier) SetDB(d *db.DB) {
+func (c *Copier) SetDB(diskID string, d *db.DB) {
 	c.dbMu.Lock()
-	c.db = d
+	if d == nil {
+		delete(c.dbs, diskID)
+	} else {
+		c.dbs[diskID] = d
+	}
 	c.dbMu.Unlock()
 }
 
-func (c *Copier) getDB() *db.DB {
+func (c *Copier) getDB(diskID string) *db.DB {
 	c.dbMu.RLock()
 	defer c.dbMu.RUnlock()
-	return c.db
+	return c.dbs[diskID]
 }
 
 func (c *Copier) Start(ctx context.Context, opts Options) (string, error) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
-	if _, active := c.tasks.ActiveTask(); active {
+	if _, active := c.cancels[opts.DiskID]; active {
 		return "", errors.New("copy already running")
 	}
 
-	database := c.getDB()
+	database := c.getDB(opts.DiskID)
 	if database == nil {
 		return "", errors.New("no disk database available")
 	}
@@ -71,23 +79,29 @@ func (c *Copier) Start(ctx context.Context, opts Options) (string, error) {
 		opts.DestFolder = "media"
 	}
 
-	t := c.tasks.Create("copy")
+	t := c.tasks.Create("copy", opts.DiskID)
 	copyCtx, cancel := context.WithCancel(ctx)
-	c.cancel = cancel
+	c.cancels[opts.DiskID] = cancel
 
 	go c.run(copyCtx, t.ID, opts, database)
 	return t.ID, nil
 }
 
-func (c *Copier) Cancel() {
+func (c *Copier) Cancel(diskID string) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
-	if c.cancel != nil {
-		c.cancel()
+	if cancel, ok := c.cancels[diskID]; ok {
+		cancel()
 	}
 }
 
 func (c *Copier) run(ctx context.Context, taskID string, opts Options, database *db.DB) {
+	defer func() {
+		c.mu.Lock()
+		delete(c.cancels, opts.DiskID)
+		c.mu.Unlock()
+	}()
+
 	setStatus := func(s task.Status, msg string, prog int) {
 		c.tasks.Update(taskID, func(t *task.Task) {
 			t.Status = s