feat: callback service

internal/server/http/callback.go

@@ -0,0 +1,96 @@
+package http
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"log"
+	"net/http"
+	"sync"
+	"time"
+)
+
+// CallbackMap is a map of all the callbacks
+type callbackMap map[*time.Ticker]*Callback
+
+var mutex = &sync.Mutex{}
+
+// Callback represent the structure of real callback
+// with additional delay
+type Callback struct {
+	Ticker  *time.Ticker  `json:"-"`
+	Request Request       `json:"request" yaml:"request"`
+	Delay   ResponseDelay `json:"delay" yaml:"delay"`
+}
+
+func (c Callback) Call() {
+	log.Println("Initiated Callback")
+	buf := new(bytes.Buffer)
+
+	req, err := http.NewRequest(c.Request.Method, c.Request.Endpoint, buf)
+	if err != nil {
+		return
+	}
+
+	if c.Request.Body != nil {
+		json.NewEncoder(buf).Encode(c.Request.Body)
+	}
+
+	if c.Request.Headers != nil {
+		for key, val := range *c.Request.Headers {
+			req.Header.Set(key, val)
+		}
+	}
+	req.Header.Set("User-Agent", "Killgrave")
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		log.Println("there's error in your defined callback service: ", err.Error())
+		return
+	}
+	if resp.StatusCode != http.StatusOK {
+		log.Printf("Callback service returned non-OK status code: %d\n", resp.StatusCode)
+
+		// Read and log the response body if it's available.
+		responseBody, readErr := io.ReadAll(resp.Body)
+		if readErr != nil {
+			log.Println("Error reading response body:", readErr.Error())
+		} else {
+			log.Printf("Response Body: %s\n", responseBody)
+		}
+
+		resp.Body.Close()
+		return
+	}
+
+	log.Println("Callback completed successfully - ", req.URL.String())
+}
+
+// global variable to store all the callbacks
+var callbackMapInstance = make(callbackMap)
+
+// remove a callback from the map
+func (c callbackMap) Remove(t *time.Ticker) {
+	delete(c, t)
+}
+
+// add a callback to the map
+func (c callbackMap) Add(t *time.Ticker, callback *Callback) {
+	mutex.Lock()
+	c[t] = callback
+	mutex.Unlock()
+}
+
+func (s *Server) callbackCron() {
+	for {
+		for ticker, callback := range callbackMapInstance {
+			select {
+			case <-ticker.C:
+				callback.Call()
+				callbackMapInstance.Remove(ticker)
+			default:
+				continue
+			}
+		}
+	}
+}

internal/server/http/callback_test.go

@@ -0,0 +1,119 @@
+package http
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/gorilla/mux"
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+)
+
+var iitermutex = new(sync.Mutex)
+
+func TestCallback(t *testing.T) {
+	router := mux.NewRouter()
+	httpServer := &http.Server{Handler: router}
+	imposterFs := NewImposterFS(afero.NewOsFs())
+	server := NewServer("test/testdata/imposters", router, httpServer, &Proxy{}, false, imposterFs)
+
+	testCases := map[string]struct {
+		imposter           Imposter
+		expectedStatusCode int
+		expectedError      bool
+	}{
+		"valid callback": {
+			imposter: Imposter{
+				Request: Request{
+					Method:   "POST",
+					Endpoint: "/gophers",
+				},
+				Callback: &Callback{
+					Request: Request{
+						Method:   "GET",
+						Endpoint: "http://localhost:8080/test",
+					},
+					Delay: ResponseDelay{
+						delay:  2 * int64(time.Second),
+						offset: 0,
+					},
+				},
+				Response: Response{
+					Status: http.StatusOK,
+					Body:   "hello",
+				},
+			},
+			expectedStatusCode: 200,
+		},
+		"default callback": {
+			imposter: Imposter{
+				Request: Request{
+					Method:   "POST",
+					Endpoint: "/gophers",
+				},
+				Callback: &Callback{
+					Request: Request{
+						Method:   "GET",
+						Endpoint: "http://localhost:8080/test",
+					},
+					Delay: ResponseDelay{
+						delay:  0,
+						offset: 0,
+					},
+				},
+				Response: Response{
+					Status: http.StatusOK,
+					Body:   "hello",
+				},
+			},
+			expectedStatusCode: 200,
+		},
+	}
+
+	for key, tt := range testCases {
+		wg := new(sync.WaitGroup)
+		wg.Add(1)
+		t.Run(key, func(t *testing.T) {
+			defer func() {
+				if tt.expectedError {
+					rec := recover()
+					assert.NotNil(t, rec)
+				}
+			}()
+
+			go func() {
+				router := http.NewServeMux()
+
+				router.HandleFunc("/test", helloHandler(wg))
+				http.ListenAndServe(":8080", router)
+			}()
+
+			rec := httptest.NewRecorder()
+			handler := http.HandlerFunc(ImposterHandler(tt.imposter))
+
+			err := server.Build()
+			assert.Nil(t, err)
+
+			// due the caller service were ahead 1 seconds for the default.
+			handler.ServeHTTP(rec, httptest.NewRequest(tt.imposter.Request.Method, tt.imposter.Request.Endpoint, nil))
+			assert.Equal(t, tt.expectedStatusCode, rec.Code)
+		})
+		wg.Wait()
+	}
+
+
+}
+
+// if this function were called then we knew this function were called from the callback
+func helloHandler(wg *sync.WaitGroup) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		w.Write([]byte("hello"))
+
+		wg.Done()
+		// done <- struct{}{}
+	}
+}

internal/server/http/handler.go

@@ -14,6 +14,18 @@ func ImposterHandler(imposter Imposter) http.HandlerFunc {
 		if imposter.Delay() > 0 {
 			time.Sleep(imposter.Delay())
 		}
+
+		if imposter.Callback != nil {
+			tickerTime := imposter.Callback.Delay.Delay()
+			if tickerTime <= 0 {
+				tickerTime = time.Second
+			}
+
+			tickerInstance := time.NewTicker(tickerTime)
+			imposter.Callback.Ticker = tickerInstance
+			callbackMapInstance.Add(tickerInstance, imposter.Callback)
+		}
+
 		writeHeaders(imposter, w)
 		w.WriteHeader(imposter.Response.Status)
 		writeBody(imposter, w)

internal/server/http/imposter.go

@@ -38,10 +38,11 @@ type ImposterConfig struct {
 
 // Imposter define an imposter structure
 type Imposter struct {
-	BasePath string   `json:"-" yaml:"-"`
-	Path     string   `json:"-" yaml:"-"`
-	Request  Request  `json:"request"`
-	Response Response `json:"response"`
+	BasePath string    `json:"-" yaml:"-"`
+	Path     string    `json:"-" yaml:"-"`
+	Request  Request   `json:"request"`
+	Callback *Callback `json:"callback"`
+	Response Response  `json:"response"`
 }
 
 // Delay returns delay for response that user can specify in imposter config
@@ -60,6 +61,7 @@ type Request struct {
 	Endpoint   string             `json:"endpoint"`
 	SchemaFile *string            `json:"schemaFile"`
 	Params     *map[string]string `json:"params"`
+	Body       *map[string]string `json:"body"`
 	Headers    *map[string]string `json:"headers"`
 }
 
@@ -132,7 +134,7 @@ func (i ImposterFs) unmarshalImposters(imposterConfig ImposterConfig) ([]Imposte
 		return nil, fmt.Errorf("%w: error while unmarshalling imposter's file %s", parseError, imposterConfig.FilePath)
 	}
 
-	for i, _ := range imposters {
+	for i := range imposters {
 		imposters[i].BasePath = filepath.Dir(imposterConfig.FilePath)
 		imposters[i].Path = imposterConfig.FilePath
 	}

internal/server/http/server.go

@@ -92,8 +92,9 @@ func (s *Server) Build() error {
 	if _, err := os.Stat(s.impostersPath); os.IsNotExist(err) {
 		return fmt.Errorf("%w: the directory %s doesn't exists", err, s.impostersPath)
 	}
-	var impostersCh = make(chan []Imposter)
-	var done = make(chan struct{})
+	impostersCh := make(chan []Imposter)
+	done := make(chan struct{})
+	go s.callbackCron()
 
 	go func() {
 		s.imposterFs.FindImposters(s.impostersPath, impostersCh)

internal/server/http/test/testdata/imposters/test_request_with_callback.imp.json

@@ -0,0 +1,26 @@
+[
+    {
+        "request": {
+            "method": "GET",
+            "endpoint": "/testRequest"
+        },
+        "callback": {
+            "request":{
+                "method": "POST",
+                "endpoint": "http://localhost:3000/users",
+                "headers": {
+                    "Content-Type": "application/json"
+                },
+                "body": {
+                    "email":"[email protected]",
+                    "password":"ngab"                
+                }
+            },
+            "delay": "1s:1s"
+        },
+        "response": {
+            "status": 200,
+            "body": "test"
+        }
+    }
+]