Adding upstream version 0.8.9.

Signed-off-by: Daniel Baumann <daniel@debian.org>

pkg/util/jsonclient/jsonclient.go

@@ -0,0 +1,165 @@
+package jsonclient
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+)
+
+// ContentType defines the default MIME type for JSON requests.
+const ContentType = "application/json"
+
+// HTTPClientErrorThreshold specifies the status code threshold for client errors (400+).
+const HTTPClientErrorThreshold = 400
+
+// ErrUnexpectedStatus indicates an unexpected HTTP response status.
+var (
+	ErrUnexpectedStatus = errors.New("got unexpected HTTP status")
+)
+
+// DefaultClient provides a singleton JSON client using http.DefaultClient.
+var DefaultClient = NewClient()
+
+// Client wraps http.Client for JSON operations.
+type client struct {
+	httpClient *http.Client
+	headers    http.Header
+	indent     string
+}
+
+// Get fetches a URL using GET and unmarshals the response into the provided object using DefaultClient.
+func Get(url string, response any) error {
+	if err := DefaultClient.Get(url, response); err != nil {
+		return fmt.Errorf("getting JSON from %q: %w", url, err)
+	}
+
+	return nil
+}
+
+// Post sends a request as JSON and unmarshals the response into the provided object using DefaultClient.
+func Post(url string, request any, response any) error {
+	if err := DefaultClient.Post(url, request, response); err != nil {
+		return fmt.Errorf("posting JSON to %q: %w", url, err)
+	}
+
+	return nil
+}
+
+// NewClient creates a new JSON client using the default http.Client.
+func NewClient() Client {
+	return NewWithHTTPClient(http.DefaultClient)
+}
+
+// NewWithHTTPClient creates a new JSON client using the specified http.Client.
+func NewWithHTTPClient(httpClient *http.Client) Client {
+	return &client{
+		httpClient: httpClient,
+		headers: http.Header{
+			"Content-Type": []string{ContentType},
+		},
+	}
+}
+
+// Headers returns the default headers for requests.
+func (c *client) Headers() http.Header {
+	return c.headers
+}
+
+// Get fetches a URL using GET and unmarshals the response into the provided object.
+func (c *client) Get(url string, response any) error {
+	req, err := http.NewRequestWithContext(context.Background(), http.MethodGet, url, nil)
+	if err != nil {
+		return fmt.Errorf("creating GET request for %q: %w", url, err)
+	}
+
+	for key, val := range c.headers {
+		req.Header.Set(key, val[0])
+	}
+
+	res, err := c.httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("executing GET request to %q: %w", url, err)
+	}
+
+	return parseResponse(res, response)
+}
+
+// Post sends a request as JSON and unmarshals the response into the provided object.
+func (c *client) Post(url string, request any, response any) error {
+	var err error
+
+	var body []byte
+
+	if strReq, ok := request.(string); ok {
+		// If the request is a string, pass it through without serializing
+		body = []byte(strReq)
+	} else {
+		body, err = json.MarshalIndent(request, "", c.indent)
+		if err != nil {
+			return fmt.Errorf("marshaling request to JSON: %w", err)
+		}
+	}
+
+	req, err := http.NewRequestWithContext(
+		context.Background(),
+		http.MethodPost,
+		url,
+		bytes.NewReader(body),
+	)
+	if err != nil {
+		return fmt.Errorf("creating POST request for %q: %w", url, err)
+	}
+
+	for key, val := range c.headers {
+		req.Header.Set(key, val[0])
+	}
+
+	res, err := c.httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("sending POST request to %q: %w", url, err)
+	}
+
+	return parseResponse(res, response)
+}
+
+// ErrorResponse checks if an error is a JSON error and unmarshals its body into the response.
+func (c *client) ErrorResponse(err error, response any) bool {
+	var errMsg Error
+	if errors.As(err, &errMsg) {
+		return json.Unmarshal([]byte(errMsg.Body), response) == nil
+	}
+
+	return false
+}
+
+// parseResponse parses the HTTP response and unmarshals it into the provided object.
+func parseResponse(res *http.Response, response any) error {
+	defer res.Body.Close()
+	body, err := io.ReadAll(res.Body)
+
+	if res.StatusCode >= HTTPClientErrorThreshold {
+		err = fmt.Errorf("%w: %v", ErrUnexpectedStatus, res.Status)
+	}
+
+	if err == nil {
+		err = json.Unmarshal(body, response)
+	}
+
+	if err != nil {
+		if body == nil {
+			body = []byte{}
+		}
+
+		return Error{
+			StatusCode: res.StatusCode,
+			Body:       string(body),
+			err:        err,
+		}
+	}
+
+	return nil
+}