Add router for CLI interface to work with handlers and avoid switch-c…

…ase factories (#42)

Signed-off-by: Igor Shishkin <me@teran.dev>

cli/router/router.go

@@ -0,0 +1,51 @@
+package router
+
+import (
+	"context"
+	"sync"
+
+	"github.com/pkg/errors"
+	log "github.com/sirupsen/logrus"
+)
+
+var ErrNoSuchRoute = errors.New("no such route")
+
+type Router interface {
+	Register(command string, fn func(ctx context.Context) error)
+	Call(command string) error
+}
+
+type router struct {
+	ctx    context.Context
+	mutex  *sync.RWMutex
+	routes map[string]func(ctx context.Context) error
+}
+
+func New(ctx context.Context) Router {
+	return &router{
+		ctx:    ctx,
+		mutex:  &sync.RWMutex{},
+		routes: make(map[string]func(ctx context.Context) error),
+	}
+}
+
+func (r *router) Register(command string, fn func(ctx context.Context) error) {
+	r.mutex.Lock()
+	defer r.mutex.Unlock()
+
+	log.Debugf("route `%s` registered", command)
+
+	r.routes[command] = fn
+}
+
+func (r *router) Call(command string) error {
+	r.mutex.RLock()
+	defer r.mutex.RUnlock()
+
+	log.Tracef("route request: `%s`", command)
+
+	if fn, ok := r.routes[command]; ok {
+		return fn(r.ctx)
+	}
+	return ErrNoSuchRoute
+}

cli/router/router_test.go

@@ -0,0 +1,38 @@
+package router
+
+import (
+	"context"
+	"testing"
+
+	"github.com/pkg/errors"
+	"github.com/stretchr/testify/require"
+)
+
+func TestRouter(t *testing.T) {
+	r := require.New(t)
+
+	var (
+		test1Called = 0
+		test2Called = 0
+		errTest1    = errors.New("blah")
+	)
+
+	rt := New(context.Background())
+	rt.Register("test1", func(ctx context.Context) error {
+		test1Called++
+		return errTest1
+	})
+	rt.Register("test2", func(ctx context.Context) error {
+		test2Called++
+		return nil
+	})
+
+	err := rt.Call("test1")
+	r.Error(err)
+	r.Equal(errTest1, err)
+	r.Equal(1, test1Called)
+
+	err = rt.Call("test2")
+	r.NoError(err)
+	r.Equal(1, test2Called)
+}