introduce donut engine

internal/controllers/engine/donut_engine_controller.go

@@ -0,0 +1,85 @@
+package engine
+
+import (
+	"fmt"
+
+	"github.com/flavioribeiro/donut/internal/controllers/probers"
+	"github.com/flavioribeiro/donut/internal/controllers/streamers"
+	"github.com/flavioribeiro/donut/internal/entities"
+	"go.uber.org/fx"
+)
+
+type DonutEngine interface {
+	Prober() probers.DonutProber
+	Streamer() streamers.DonutStreamer
+	CompatibleStreamsFor(server, client *entities.StreamInfo) []entities.Stream
+}
+
+type DonutEngineParams struct {
+	fx.In
+	Streamers []streamers.DonutStreamer `group:"streamers"`
+	Probers   []probers.DonutProber     `group:"probers"`
+}
+
+type DonutEngineController struct {
+	p DonutEngineParams
+}
+
+func NewDonutEngineController(p DonutEngineParams) *DonutEngineController {
+	return &DonutEngineController{p}
+}
+
+func (c *DonutEngineController) EngineFor(req *entities.RequestParams) (DonutEngine, error) {
+	prober := c.selectProberFor(req)
+	if prober == nil {
+		return nil, fmt.Errorf("request %v: not fulfilled error %v", req, entities.ErrMissingProber)
+	}
+
+	streamer := c.selectStreamerFor(req)
+	if prober == nil {
+		return nil, fmt.Errorf("request %v: not fulfilled error %v", req, entities.ErrMissingStreamer)
+	}
+
+	return &donutEngine{
+		prober:   prober,
+		streamer: streamer,
+	}, nil
+}
+
+// TODO: try to use generics
+func (c *DonutEngineController) selectProberFor(req *entities.RequestParams) probers.DonutProber {
+	for _, p := range c.p.Probers {
+		if p.Match(req) {
+			return p
+		}
+	}
+	return nil
+}
+
+// TODO: try to use generics
+func (c *DonutEngineController) selectStreamerFor(req *entities.RequestParams) streamers.DonutStreamer {
+	for _, p := range c.p.Streamers {
+		if p.Match(req) {
+			return p
+		}
+	}
+	return nil
+}
+
+type donutEngine struct {
+	prober   probers.DonutProber
+	streamer streamers.DonutStreamer
+}
+
+func (d *donutEngine) Prober() probers.DonutProber {
+	return d.prober
+}
+
+func (d *donutEngine) Streamer() streamers.DonutStreamer {
+	return d.streamer
+}
+
+func (d *donutEngine) CompatibleStreamsFor(server, client *entities.StreamInfo) []entities.Stream {
+	// TODO: implement proper matching
+	return server.Streams
+}