Implemented doRequest helper method (#557)

* Implemented doRequest helper method and added unit tests

* Added more detailed response for HTTP errors

* Addressed pr comments

* Addressed more pr comments

client.go

@@ -1,8 +1,11 @@
 package linodego
 
 import (
+	"bytes"
 	"context"
+	"encoding/json"
 	"fmt"
+	"io"
 	"log"
 	"net/http"
 	"net/url"
@@ -110,6 +113,67 @@ func (c *Client) SetUserAgent(ua string) *Client {
 	return c
 }
 
+type RequestParams struct {
+	Body     any
+	Response any
+}
+
+// Generic helper to execute HTTP requests using the
+//
+//nolint:unused
+func (c *httpClient) doRequest(ctx context.Context, method, url string, params RequestParams, mutators ...func(req *http.Request) error) error {
+	// Create a new HTTP request
+	var bodyReader io.Reader
+	if params.Body != nil {
+		buf := new(bytes.Buffer)
+		if err := json.NewEncoder(buf).Encode(params.Body); err != nil {
+			return fmt.Errorf("failed to encode body: %w", err)
+		}
+		bodyReader = buf
+	}
+
+	req, err := http.NewRequestWithContext(ctx, method, url, bodyReader)
+	if err != nil {
+		return fmt.Errorf("failed to create request: %w", err)
+	}
+
+	// Set default headers
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Accept", "application/json")
+	if c.userAgent != "" {
+		req.Header.Set("User-Agent", c.userAgent)
+	}
+
+	// Apply mutators
+	for _, mutate := range mutators {
+		if err := mutate(req); err != nil {
+			return fmt.Errorf("failed to mutate request: %w", err)
+		}
+	}
+
+	// Send the request
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("failed to send request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	// Check for HTTP errors
+	resp, err = coupleAPIErrorsHTTP(resp, err)
+	if err != nil {
+		return err
+	}
+
+	// Decode the response body
+	if params.Response != nil {
+		if err := json.NewDecoder(resp.Body).Decode(params.Response); err != nil {
+			return fmt.Errorf("failed to decode response: %w", err)
+		}
+	}
+
+	return nil
+}
+
 // R wraps resty's R method
 func (c *Client) R(ctx context.Context) *resty.Request {
 	return c.resty.R().

client_http.go

@@ -0,0 +1,48 @@
+package linodego
+
+import (
+	"net/http"
+	"sync"
+	"time"
+)
+
+// Client is a wrapper around the Resty client
+//
+//nolint:unused
+type httpClient struct {
+	//nolint:unused
+	httpClient *http.Client
+	//nolint:unused
+	userAgent string
+	//nolint:unused
+	debug bool
+	//nolint:unused
+	retryConditionals []RetryConditional
+
+	//nolint:unused
+	pollInterval time.Duration
+
+	//nolint:unused
+	baseURL string
+	//nolint:unused
+	apiVersion string
+	//nolint:unused
+	apiProto string
+	//nolint:unused
+	selectedProfile string
+	//nolint:unused
+	loadedProfile string
+
+	//nolint:unused
+	configProfiles map[string]ConfigProfile
+
+	// Fields for caching endpoint responses
+	//nolint:unused
+	shouldCache bool
+	//nolint:unused
+	cacheExpiration time.Duration
+	//nolint:unused
+	cachedEntries map[string]clientCacheEntry
+	//nolint:unused
+	cachedEntryLock *sync.RWMutex
+}

client_test.go

@@ -3,7 +3,10 @@ package linodego
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
+	"net/http"
+	"net/http/httptest"
 	"reflect"
 	"strings"
 	"testing"
@@ -198,3 +201,138 @@ func TestDebugLogSanitization(t *testing.T) {
 		t.Fatalf("actual response does not equal desired response: %s", cmp.Diff(result, testResponse))
 	}
 }
+
+func TestDoRequest_Success(t *testing.T) {
+	handler := func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{"message":"success"}`))
+	}
+	server := httptest.NewServer(http.HandlerFunc(handler))
+	defer server.Close()
+
+	client := &httpClient{
+		httpClient: server.Client(),
+	}
+
+	params := RequestParams{
+		Response: &map[string]string{},
+	}
+
+	err := client.doRequest(context.Background(), http.MethodGet, server.URL, params)
+	if err != nil {
+		t.Fatal(cmp.Diff(nil, err))
+	}
+
+	expected := "success"
+	actual := (*params.Response.(*map[string]string))["message"]
+	if diff := cmp.Diff(expected, actual); diff != "" {
+		t.Fatalf("response mismatch (-expected +actual):\n%s", diff)
+	}
+}
+
+func TestDoRequest_FailedEncodeBody(t *testing.T) {
+	client := &httpClient{
+		httpClient: http.DefaultClient,
+	}
+
+	params := RequestParams{
+		Body: map[string]interface{}{
+			"invalid": func() {},
+		},
+	}
+
+	err := client.doRequest(context.Background(), http.MethodPost, "http://example.com", params)
+	expectedErr := "failed to encode body"
+	if err == nil || !strings.Contains(err.Error(), expectedErr) {
+		t.Fatalf("expected error %q, got: %v", expectedErr, err)
+	}
+}
+
+func TestDoRequest_FailedCreateRequest(t *testing.T) {
+	client := &httpClient{
+		httpClient: http.DefaultClient,
+	}
+
+	// Create a request with an invalid URL to simulate a request creation failure
+	err := client.doRequest(context.Background(), http.MethodGet, "http://invalid url", RequestParams{})
+	expectedErr := "failed to create request"
+	if err == nil || !strings.Contains(err.Error(), expectedErr) {
+		t.Fatalf("expected error %q, got: %v", expectedErr, err)
+	}
+}
+
+func TestDoRequest_Non2xxStatusCode(t *testing.T) {
+	handler := func(w http.ResponseWriter, r *http.Request) {
+		http.Error(w, "error", http.StatusInternalServerError)
+	}
+	server := httptest.NewServer(http.HandlerFunc(handler))
+	defer server.Close()
+
+	client := &httpClient{
+		httpClient: server.Client(),
+	}
+
+	err := client.doRequest(context.Background(), http.MethodGet, server.URL, RequestParams{})
+	if err == nil {
+		t.Fatal("expected error, got nil")
+	}
+	httpError, ok := err.(Error)
+	if !ok {
+		t.Fatalf("expected error to be of type Error, got %T", err)
+	}
+	if httpError.Code != http.StatusInternalServerError {
+		t.Fatalf("expected status code %d, got %d", http.StatusInternalServerError, httpError.Code)
+	}
+	if !strings.Contains(httpError.Message, "error") {
+		t.Fatalf("expected error message to contain %q, got %v", "error", httpError.Message)
+	}
+}
+
+func TestDoRequest_FailedDecodeResponse(t *testing.T) {
+	handler := func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`invalid json`))
+	}
+	server := httptest.NewServer(http.HandlerFunc(handler))
+	defer server.Close()
+
+	client := &httpClient{
+		httpClient: server.Client(),
+	}
+
+	params := RequestParams{
+		Response: &map[string]string{},
+	}
+
+	err := client.doRequest(context.Background(), http.MethodGet, server.URL, params)
+	expectedErr := "failed to decode response"
+	if err == nil || !strings.Contains(err.Error(), expectedErr) {
+		t.Fatalf("expected error %q, got: %v", expectedErr, err)
+	}
+}
+
+func TestDoRequest_MutatorError(t *testing.T) {
+	handler := func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{"message":"success"}`))
+	}
+	server := httptest.NewServer(http.HandlerFunc(handler))
+	defer server.Close()
+
+	client := &httpClient{
+		httpClient: server.Client(),
+	}
+
+	mutator := func(req *http.Request) error {
+		return errors.New("mutator error")
+	}
+
+	err := client.doRequest(context.Background(), http.MethodGet, server.URL, RequestParams{}, mutator)
+	expectedErr := "failed to mutate request"
+	if err == nil || !strings.Contains(err.Error(), expectedErr) {
+		t.Fatalf("expected error %q, got: %v", expectedErr, err)
+	}
+}

errors.go

@@ -1,8 +1,10 @@
 package linodego
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
 	"net/http"
 	"reflect"
 	"strings"
@@ -46,6 +48,11 @@ type APIError struct {
 	Errors []APIErrorReason `json:"errors"`
 }
 
+// String returns the error reason in a formatted string
+func (r APIErrorReason) String() string {
+	return fmt.Sprintf("[%s] %s", r.Field, r.Reason)
+}
+
 func coupleAPIErrors(r *resty.Response, err error) (*resty.Response, error) {
 	if err != nil {
 		// an error was raised in go code, no need to check the resty Response
@@ -66,7 +73,7 @@ func coupleAPIErrors(r *resty.Response, err error) (*resty.Response, error) {
 	// If the upstream Linode API server being fronted fails to respond to the request,
 	// the http server will respond with a default "Bad Gateway" page with Content-Type
 	// "text/html".
-	if r.StatusCode() == http.StatusBadGateway && responseContentType == "text/html" {
+	if r.StatusCode() == http.StatusBadGateway && responseContentType == "text/html" { //nolint:goconst
 		return nil, Error{Code: http.StatusBadGateway, Message: http.StatusText(http.StatusBadGateway)}
 	}
 
@@ -89,6 +96,52 @@ func coupleAPIErrors(r *resty.Response, err error) (*resty.Response, error) {
 	return nil, NewError(r)
 }
 
+//nolint:unused
+func coupleAPIErrorsHTTP(resp *http.Response, err error) (*http.Response, error) {
+	if err != nil {
+		// an error was raised in go code, no need to check the http.Response
+		return nil, NewError(err)
+	}
+
+	if resp == nil || resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		// Check that response is of the correct content-type before unmarshalling
+		expectedContentType := resp.Request.Header.Get("Accept")
+		responseContentType := resp.Header.Get("Content-Type")
+
+		// If the upstream server fails to respond to the request,
+		// the http server will respond with a default error page with Content-Type "text/html".
+		if resp.StatusCode == http.StatusBadGateway && responseContentType == "text/html" { //nolint:goconst
+			return nil, Error{Code: http.StatusBadGateway, Message: http.StatusText(http.StatusBadGateway)}
+		}
+
+		if responseContentType != expectedContentType {
+			bodyBytes, _ := io.ReadAll(resp.Body)
+			msg := fmt.Sprintf(
+				"Unexpected Content-Type: Expected: %v, Received: %v\nResponse body: %s",
+				expectedContentType,
+				responseContentType,
+				string(bodyBytes),
+			)
+
+			return nil, Error{Code: resp.StatusCode, Message: msg}
+		}
+
+		var apiError APIError
+		if err := json.NewDecoder(resp.Body).Decode(&apiError); err != nil {
+			return nil, NewError(fmt.Errorf("failed to decode response body: %w", err))
+		}
+
+		if len(apiError.Errors) == 0 {
+			return resp, nil
+		}
+
+		return nil, Error{Code: resp.StatusCode, Message: apiError.Errors[0].String()}
+	}
+
+	// no error in the http.Response
+	return resp, nil
+}
+
 func (e APIError) Error() string {
 	x := []string{}
 	for _, msg := range e.Errors {