Add support for running a local debug server

debug-server.go

@@ -0,0 +1,143 @@
+package alexa
+
+import (
+	"context"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"log"
+	"net/http"
+
+	"github.com/aws/aws-lambda-go/lambda"
+	"nhooyr.io/websocket"
+	"nhooyr.io/websocket/wsjson"
+)
+
+// Run will start the associated Alexa instance to either handle requests from the AWS
+// Lambda service, or if run from the ASK CLI (via `ask run`) it will run in debug mode
+// against the development stage of the skill so that you can interact with your local
+// code from the live Alexa service
+func (alexa *Alexa) Run() {
+	var (
+		debugServer                  bool
+		accessToken, skillId, region string
+	)
+	flag.BoolVar(&debugServer, "debugServer", false, "Start an alexa debug server")
+	flag.StringVar(&accessToken, "accessToken", "", "The Alexa Developer lwa access token")
+	flag.StringVar(&skillId, "skillId", "", "The skill ID")
+	flag.StringVar(&region, "region", "NA", "The Alexa run region")
+	flag.Parse()
+
+	if debugServer {
+		debug(accessToken, alexa.ApplicationID, region, alexa.ProcessRequest)
+	} else {
+		lambda.Start(alexa.ProcessRequest)
+	}
+}
+
+type handlerFunc func(ctx context.Context, requestEnv *RequestEnvelope) (*ResponseEnvelope, error)
+
+var regionEndpoints = map[string]string{
+	"NA": "bob-dispatch-prod-na.amazon.com",
+	"FE": "bob-dispatch-prod-fe.amazon.com",
+	"EU": "bob-dispatch-prod-eu.amazon.com",
+}
+
+type skillRequest struct {
+	Version        string `json:"version"`
+	Type           string `json:"type"`
+	RequestID      string `json:"requestId"`
+	RequestPayload string `json:"requestPayload"`
+}
+
+type skillResponseType string
+
+const (
+	skillResponseTypeSuccess skillResponseType = "SkillResponseSuccessMessage"
+	skillResponseTypeFailure skillResponseType = "SkillResponseFailureMessage"
+)
+
+type skillResponse struct {
+	Version           string            `json:"version"`
+	Type              skillResponseType `json:"type"`
+	OriginalRequestID string            `json:"originalRequestId"`
+	ResponsePayload   string            `json:"responsePayload"`
+}
+
+func debug(accessToken, skillId, region string, handler handlerFunc) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	log.Print("Starting go alexa debug connection")
+
+	debugEndpointURL := fmt.Sprintf(
+		"wss://%s/v1/skills/%s/stages/development/connectCustomDebugEndpoint",
+		regionEndpoints[region],
+		skillId,
+	)
+
+	log.Print("Connecting to: ", debugEndpointURL)
+
+	headers := http.Header{}
+	// This MUST be set directly via the map instead of using the Header methods because
+	// the Alexa API hosts (i.e. bob-dispatch-prod-na.amazon.com) require it in lower case
+	// ಠ_ಠ
+	headers["authorization"] = []string{accessToken}
+
+	c, _, err := websocket.Dial(ctx, debugEndpointURL, &websocket.DialOptions{
+		CompressionMode: websocket.CompressionDisabled,
+		HTTPHeader:      headers,
+	})
+	if err != nil {
+		log.Fatal("Failed to connect to debug endpoint:", err)
+	}
+	defer c.Close(websocket.StatusNormalClosure, "bye")
+
+	log.Print("Debug session successfully started")
+	log.Print("This session is authorized for 1 hour")
+
+	for {
+		var (
+			req  *skillRequest
+			resp *skillResponse
+		)
+		err = wsjson.Read(ctx, c, &req)
+		if err != nil {
+			log.Fatal("Failed to read message: ", err)
+		}
+
+		log.Print("Received message: ", req)
+
+		var reqEnv *RequestEnvelope
+		err = json.Unmarshal([]byte(req.RequestPayload), &reqEnv)
+		if err != nil {
+			log.Fatal("Failed to unmarshal request payload: ", err)
+		}
+
+		resp = &skillResponse{
+			Type:              skillResponseTypeSuccess,
+			Version:           req.Version,
+			OriginalRequestID: req.RequestID,
+		}
+
+		r, err := handler(ctx, reqEnv)
+		if err != nil {
+			log.Print("Failed to handle skill request: ", err)
+			resp.Type = skillResponseTypeFailure
+		} else {
+			rb, err := json.Marshal(r)
+			if err != nil {
+				log.Print("Failed to marshal skill response: ", err)
+				resp.Type = skillResponseTypeFailure
+			} else {
+				resp.ResponsePayload = string(rb)
+			}
+		}
+
+		log.Print("Sending response: ", resp)
+		err = wsjson.Write(ctx, c, resp)
+		if err != nil {
+			log.Fatal("Failed to write response: ", err)
+		}
+	}
+}