package httpserver import ( "encoding/json" "errors" "log" "net/http" "strconv" "strings" "time" "go.dev.pztrn.name/metricator/internal/common" "go.dev.pztrn.name/metricator/internal/models" ) var ( errInvalidAPIVersion = errors.New("invalid API version") errInvalidApplication = errors.New("invalid application") errInvalidPath = errors.New("invalid path") errNoAppsRegistered = errors.New("no applications registered") errNoData = errors.New("no data") supportedAPIVersions = []int{1} ) // HTTP requests handler. type handler struct { handlers map[string]common.HTTPHandlerFunc } // Gets applications list from handlers map. func (h *handler) getAppsList() ([]byte, error) { apps := make([]string, 0, len(h.handlers)) for appName := range h.handlers { apps = append(apps, appName) } appsList, err := json.Marshal(apps) if err != nil { // ToDo: log error return nil, errNoAppsRegistered } return appsList, nil } // Gets request information from URL. Returns a structure with filled request // info and error if it occurs. func (h *handler) getRequestInfo(r *http.Request) (*models.RequestInfo, error) { // Request isn't for API or isn't versioned. if !strings.HasPrefix(r.URL.Path, "/api/v") { return nil, errInvalidPath } // Note: first element will always be empty! pathSplitted := strings.Split(r.URL.Path, "/") // Request is for API but not enough items in URL was passed. if len(pathSplitted) < 4 { return nil, errInvalidPath } var ( appName string metricName string requestType string ) // Parse API version. apiVersionRaw := strings.TrimLeft(pathSplitted[2], "v") apiVersion, err := strconv.Atoi(apiVersionRaw) if err != nil { // ToDo: log error return nil, errInvalidAPIVersion } // Check used API version. var supportedAPIVersionUsed bool for _, version := range supportedAPIVersions { if apiVersion == version { supportedAPIVersionUsed = true break } } if !supportedAPIVersionUsed { return nil, errInvalidAPIVersion } // Get request type and key. requestType = pathSplitted[3] if len(pathSplitted) >= 5 { appName = pathSplitted[4] } if len(pathSplitted) >= 6 { metricName = strings.Join(pathSplitted[5:], "/") } reqInfo := &models.RequestInfo{ APIVersion: apiVersion, Application: appName, Metric: metricName, RequestType: requestType, } return reqInfo, nil } // Registers request's handler. func (h *handler) register(appName string, hndl common.HTTPHandlerFunc) { h.handlers[appName] = hndl } // ServeHTTP handles every HTTP request. func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) { startTime := time.Now() defer func() { requestDuration := time.Since(startTime) log.Printf("[HTTP Request] from %s to %s, duration %.4fs\n", r.RemoteAddr, r.URL.Path, requestDuration.Seconds()) }() // Validate request and extract needed info. rInfo, err := h.getRequestInfo(r) if err != nil { w.WriteHeader(http.StatusBadRequest) _, _ = w.Write([]byte("400 bad request - " + err.Error())) return } // Process request type. Here we process only known requests types, // by default request should go to specific application's handler. switch rInfo.RequestType { // ToDo: move to constants. case "apps_list": appsList, err := h.getAppsList() if err != nil { w.WriteHeader(http.StatusBadRequest) _, _ = w.Write([]byte("400 bad request - " + err.Error())) return } w.WriteHeader(http.StatusOK) _, _ = w.Write(appsList) return case "info": infoData := struct { Branch string Build string CommitHash string Version string }{ Branch: common.Branch, Build: common.Build, CommitHash: common.CommitHash, Version: common.Version, } infoBytes, _ := json.Marshal(infoData) w.WriteHeader(http.StatusOK) _, _ = w.Write(infoBytes) return case "metrics": handler, found := h.handlers[rInfo.Application] if !found { w.WriteHeader(http.StatusBadRequest) _, _ = w.Write([]byte("400 bad request - " + errInvalidApplication.Error())) return } // Get data from handler. data := handler(rInfo) if data == "" { w.WriteHeader(http.StatusBadRequest) _, _ = w.Write([]byte("400 bad request - " + errNoData.Error())) } w.WriteHeader(http.StatusOK) _, _ = w.Write([]byte(data)) return } w.WriteHeader(http.StatusBadRequest) _, _ = w.Write([]byte("400 bad request - " + errInvalidPath.Error())) }