Add HTTP Request and Response to debug logs (#271)

* initial implementation

* remove unused body close

* add comment explaing the body closure

* add testing

* remove reduntant comments

* address PR comments, refactor reading the body

* fix linting

* simplify implementation

* extend other clients with debug middleware

internal/pkg/print/debug.go

@@ -1,12 +1,20 @@
 package print
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
+	"io"
+	"net/http"
+	"slices"
 	"sort"
 	"strings"
+
+	"github.com/stackitcloud/stackit-sdk-go/core/config"
 )
 
+var defaultHTTPHeaders = []string{"Accept", "Content-Type", "Content-Length", "User-Agent", "Date", "Referrer-Policy"}
+
 // BuildDebugStrFromInputModel converts an input model to a user-friendly string representation.
 // This function converts the input model to a map, removes empty values, and generates a string representation of the map.
 // The purpose of this function is to provide a more readable output than the default JSON representation.
@@ -31,6 +39,9 @@ func BuildDebugStrFromInputModel(model any) (string, error) {
 // The string representation is in the format: [key1: value1, key2: value2, ...]
 // The keys are ordered alphabetically to make the output deterministic.
 func BuildDebugStrFromMap(inputMap map[string]any) string {
+	if inputMap == nil {
+		return "[]"
+	}
 	// Sort the keys to make the output deterministic
 	keys := make([]string, 0, len(inputMap))
 	for key := range inputMap {
@@ -44,7 +55,25 @@ func BuildDebugStrFromMap(inputMap map[string]any) string {
 		if isEmpty(value) {
 			continue
 		}
-		keyValues = append(keyValues, fmt.Sprintf("%s: %v", key, value))
+
+		valueStr := fmt.Sprintf("%v", value)
+
+		switch value := value.(type) {
+		case map[string]any:
+			valueStr = BuildDebugStrFromMap(value)
+		case []any:
+			sliceStr := make([]string, len(value))
+			for i, item := range value {
+				if itemMap, ok := item.(map[string]any); ok {
+					sliceStr[i] = BuildDebugStrFromMap(itemMap)
+				} else {
+					sliceStr[i] = fmt.Sprintf("%v", item)
+				}
+			}
+			valueStr = BuildDebugStrFromSlice(sliceStr)
+		}
+
+		keyValues = append(keyValues, fmt.Sprintf("%s: %v", key, valueStr))
 	}
 
 	result := strings.Join(keyValues, ", ")
@@ -57,6 +86,174 @@ func BuildDebugStrFromSlice(inputSlice []string) string {
 	return fmt.Sprintf("[%s]", sliceStr)
 }
 
+// buildHeaderMap converts a map to a user-friendly string representation.
+// This function also filters the headers based on the includeHeaders parameter.
+// If includeHeaders is empty, the default header filters are used.
+func buildHeaderMap(headers http.Header, includeHeaders []string) map[string]any {
+	headersMap := make(map[string]any)
+	for key, values := range headers {
+		headersMap[key] = strings.Join(values, ", ")
+	}
+
+	headersToInclude := defaultHTTPHeaders
+	if len(includeHeaders) != 0 {
+		headersToInclude = includeHeaders
+	}
+	for key := range headersMap {
+		if !slices.Contains(headersToInclude, key) {
+			delete(headersMap, key)
+		}
+	}
+
+	return headersMap
+}
+
+// drainBody reads all of b to memory and then returns two equivalent
+// ReadClosers yielding the same bytes.
+//
+// It returns an error if the initial slurp of all bytes fails. It does not attempt
+// to make the returned ReadClosers have identical error-matching behavior.
+// Taken directly from the httputil package
+// https://cs.opensource.google/go/go/+/refs/tags/go1.22.2:src/net/http/httputil/dump.go;drc=1d45a7ef560a76318ed59dfdb178cecd58caf948;l=25
+func drainBody(b io.ReadCloser) (r1, r2 io.ReadCloser, err error) {
+	if b == nil || b == http.NoBody {
+		// No copying needed. Preserve the magic sentinel meaning of NoBody.
+		return http.NoBody, http.NoBody, nil
+	}
+	var buf bytes.Buffer
+	if _, err = buf.ReadFrom(b); err != nil {
+		return nil, b, err
+	}
+	if err := b.Close(); err != nil {
+		return nil, b, err
+	}
+	return io.NopCloser(&buf), io.NopCloser(bytes.NewReader(buf.Bytes())), nil
+}
+
+// BuildDebugStrFromHTTPRequest converts an HTTP request to a user-friendly string representation.
+// This function also receives a list of headers to include in the output, if empty, the default headers are used.
+// The return value is a list of strings that should be printed separately.
+func BuildDebugStrFromHTTPRequest(req *http.Request, includeHeaders []string) ([]string, error) {
+	if req == nil {
+		return nil, fmt.Errorf("request is nil")
+	}
+	if req.URL == nil || req.Proto == "" || req.Method == "" {
+		return nil, fmt.Errorf("request is invalid")
+	}
+
+	status := fmt.Sprintf("request to %s: %s %s", req.URL, req.Method, req.Proto)
+
+	headersMap := buildHeaderMap(req.Header, includeHeaders)
+	headers := fmt.Sprintf("request headers: %v", BuildDebugStrFromMap(headersMap))
+
+	var save io.ReadCloser
+	var err error
+
+	save, req.Body, err = drainBody(req.Body)
+	if err != nil {
+		return []string{status, headers}, fmt.Errorf("drain response body: %w", err)
+	}
+	bodyBytes, err := io.ReadAll(req.Body)
+	if err != nil {
+		return []string{status, headers}, fmt.Errorf("read response body: %w", err)
+	}
+	req.Body = save
+	var bodyMap map[string]any
+	if len(bodyBytes) != 0 {
+		if err := json.Unmarshal(bodyBytes, &bodyMap); err != nil {
+			return nil, fmt.Errorf("unmarshal response body: %w", err)
+		}
+	}
+	if len(bodyMap) == 0 {
+		return []string{status, headers}, nil
+	}
+	body := fmt.Sprintf("request body: %s", BuildDebugStrFromMap(bodyMap))
+
+	return []string{status, headers, body}, nil
+}
+
+// BuildDebugStrFromHTTPResponse converts an HTTP response to a user-friendly string representation.
+// This function also receives a list of headers to include in the output, if empty, the default headers are used.
+// The return value is a list of strings that should be printed separately.
+func BuildDebugStrFromHTTPResponse(resp *http.Response, includeHeaders []string) ([]string, error) {
+	if resp == nil {
+		return nil, fmt.Errorf("response is nil")
+	}
+
+	if resp.Request == nil || resp.Proto == "" || resp.Status == "" {
+		return nil, fmt.Errorf("response is invalid")
+	}
+
+	status := fmt.Sprintf("response from %s: %s %s", resp.Request.URL, resp.Proto, resp.Status)
+
+	headersMap := buildHeaderMap(resp.Header, includeHeaders)
+	headers := fmt.Sprintf("response headers: %v", BuildDebugStrFromMap(headersMap))
+
+	var save io.ReadCloser
+	var err error
+
+	save, resp.Body, err = drainBody(resp.Body)
+	if err != nil {
+		return []string{status, headers}, fmt.Errorf("drain response body: %w", err)
+	}
+	bodyBytes, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return []string{status, headers}, fmt.Errorf("read response body: %w", err)
+	}
+	resp.Body = save
+	var bodyMap map[string]any
+	if len(bodyBytes) != 0 {
+		if err := json.Unmarshal(bodyBytes, &bodyMap); err != nil {
+			return nil, fmt.Errorf("unmarshal response body: %w", err)
+		}
+	}
+	if len(bodyMap) == 0 {
+		return []string{status, headers}, nil
+	}
+	body := fmt.Sprintf("response body: %s", BuildDebugStrFromMap(bodyMap))
+
+	return []string{status, headers, body}, nil
+}
+
+// RequestResponseCapturer is a middleware that captures the request and response of an HTTP request.
+// Receives a printer and a list of headers to include in the output
+// If the list of headers is empty, the default headers are used.
+// The printer is used to print the captured data.
+func RequestResponseCapturer(p *Printer, includeHeaders []string) config.Middleware {
+	return func(rt http.RoundTripper) http.RoundTripper {
+		return &roundTripperWithCapture{rt, p, includeHeaders}
+	}
+}
+
+type roundTripperWithCapture struct {
+	transport        http.RoundTripper
+	p                *Printer
+	debugHttpHeaders []string
+}
+
+func (rt roundTripperWithCapture) RoundTrip(req *http.Request) (*http.Response, error) {
+	reqStr, err := BuildDebugStrFromHTTPRequest(req, rt.debugHttpHeaders)
+	if err != nil {
+		rt.p.Debug(ErrorLevel, "printing request to debug logs: %v", err)
+	}
+	for _, line := range reqStr {
+		rt.p.Debug(DebugLevel, line)
+	}
+	resp, err := rt.transport.RoundTrip(req)
+	defer func() {
+		if err == nil {
+			respStrSlice, tempErr := BuildDebugStrFromHTTPResponse(resp, rt.debugHttpHeaders)
+			if tempErr != nil {
+				rt.p.Debug(ErrorLevel, "printing HTTP response to debug logs: %v", tempErr)
+			}
+			for _, line := range respStrSlice {
+				rt.p.Debug(DebugLevel, line)
+			}
+		}
+	}()
+	return resp, err
+}
+
 // isEmpty checks if a value is empty (nil, empty string, zero value for other types)
 func isEmpty(value interface{}) bool {
 	if value == nil {