Implement routes to list, get and delete execution environments

* #9 Implement routes to list, get and delete execution environments.
A refactoring was required to introduce the ExecutionEnvironment interface.

* Fix MR comments, linting issues and bug that lead to e2e test failure

* Add e2e tests

* Add unit tests

internal/api/environments.go

@@ -9,11 +9,16 @@ import (
 	"github.com/openHPI/poseidon/internal/runner"
 	"github.com/openHPI/poseidon/pkg/dto"
 	"net/http"
+	"strconv"
 )
 
 const (
 	executionEnvironmentIDKey = "executionEnvironmentId"
+	fetchEnvironmentKey       = "fetch"
+	listRouteName             = "list"
+	getRouteName              = "get"
 	createOrUpdateRouteName   = "createOrUpdate"
+	deleteRouteName           = "delete"
 )
 
 var ErrMissingURLParameter = errors.New("url parameter missing")
@@ -22,10 +27,82 @@ type EnvironmentController struct {
 	manager environment.Manager
 }
 
+type ExecutionEnvironmentsResponse struct {
+	ExecutionEnvironments []runner.ExecutionEnvironment `json:"executionEnvironments"`
+}
+
 func (e *EnvironmentController) ConfigureRoutes(router *mux.Router) {
 	environmentRouter := router.PathPrefix(EnvironmentsPath).Subrouter()
+	environmentRouter.HandleFunc("", e.list).Methods(http.MethodGet).Name(listRouteName)
+
 	specificEnvironmentRouter := environmentRouter.Path(fmt.Sprintf("/{%s:[0-9]+}", executionEnvironmentIDKey)).Subrouter()
+	specificEnvironmentRouter.HandleFunc("", e.get).Methods(http.MethodGet).Name(getRouteName)
 	specificEnvironmentRouter.HandleFunc("", e.createOrUpdate).Methods(http.MethodPut).Name(createOrUpdateRouteName)
+	specificEnvironmentRouter.HandleFunc("", e.delete).Methods(http.MethodDelete).Name(deleteRouteName)
+}
+
+// list returns all information about available execution environments.
+func (e *EnvironmentController) list(writer http.ResponseWriter, request *http.Request) {
+	fetch, err := parseFetchParameter(request)
+	if err != nil {
+		writeBadRequest(writer, err)
+		return
+	}
+
+	environments, err := e.manager.List(fetch)
+	if err != nil {
+		writeInternalServerError(writer, err, dto.ErrorUnknown)
+		return
+	}
+
+	sendJSON(writer, ExecutionEnvironmentsResponse{environments}, http.StatusOK)
+}
+
+// get returns all information about the requested execution environment.
+func (e *EnvironmentController) get(writer http.ResponseWriter, request *http.Request) {
+	environmentID, err := parseEnvironmentID(request)
+	if err != nil {
+		// This case is never used as the router validates the id format
+		writeBadRequest(writer, err)
+		return
+	}
+	fetch, err := parseFetchParameter(request)
+	if err != nil {
+		writeBadRequest(writer, err)
+		return
+	}
+
+	executionEnvironment, err := e.manager.Get(environmentID, fetch)
+	if errors.Is(err, runner.ErrUnknownExecutionEnvironment) {
+		writer.WriteHeader(http.StatusNotFound)
+		return
+	} else if err != nil {
+		writeInternalServerError(writer, err, dto.ErrorUnknown)
+		return
+	}
+
+	sendJSON(writer, executionEnvironment, http.StatusOK)
+}
+
+// delete removes the specified execution environment.
+func (e *EnvironmentController) delete(writer http.ResponseWriter, request *http.Request) {
+	environmentID, err := parseEnvironmentID(request)
+	if err != nil {
+		// This case is never used as the router validates the id format
+		writeBadRequest(writer, err)
+		return
+	}
+
+	found, err := e.manager.Delete(environmentID)
+	if err != nil {
+		writeInternalServerError(writer, err, dto.ErrorUnknown)
+		return
+	} else if !found {
+		writer.WriteHeader(http.StatusNotFound)
+		return
+	}
+
+	writer.WriteHeader(http.StatusNoContent)
 }
 
 // createOrUpdate creates/updates an execution environment on the executor.
@@ -35,17 +112,12 @@ func (e *EnvironmentController) createOrUpdate(writer http.ResponseWriter, reque
 		writeBadRequest(writer, err)
 		return
 	}
-
-	id, ok := mux.Vars(request)[executionEnvironmentIDKey]
-	if !ok {
-		writeBadRequest(writer, fmt.Errorf("could not find %s: %w", executionEnvironmentIDKey, ErrMissingURLParameter))
-		return
-	}
-	environmentID, err := runner.NewEnvironmentID(id)
+	environmentID, err := parseEnvironmentID(request)
 	if err != nil {
-		writeBadRequest(writer, fmt.Errorf("could not update environment: %w", err))
+		writeBadRequest(writer, err)
 		return
 	}
+
 	created, err := e.manager.CreateOrUpdate(environmentID, *req)
 	if err != nil {
 		writeInternalServerError(writer, err, dto.ErrorUnknown)
@@ -57,3 +129,26 @@ func (e *EnvironmentController) createOrUpdate(writer http.ResponseWriter, reque
 		writer.WriteHeader(http.StatusNoContent)
 	}
 }
+
+func parseEnvironmentID(request *http.Request) (dto.EnvironmentID, error) {
+	id, ok := mux.Vars(request)[executionEnvironmentIDKey]
+	if !ok {
+		return 0, fmt.Errorf("could not find %s: %w", executionEnvironmentIDKey, ErrMissingURLParameter)
+	}
+	environmentID, err := dto.NewEnvironmentID(id)
+	if err != nil {
+		return 0, fmt.Errorf("could not update environment: %w", err)
+	}
+	return environmentID, nil
+}
+
+func parseFetchParameter(request *http.Request) (fetch bool, err error) {
+	fetchString := request.FormValue(fetchEnvironmentKey)
+	if len(fetchString) > 0 {
+		fetch, err = strconv.ParseBool(fetchString)
+		if err != nil {
+			return false, fmt.Errorf("could not parse fetch parameter: %w", err)
+		}
+	}
+	return fetch, nil
+}