client.go

package rabbithole

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"time"
)

// Client for interaction with RabbitMQ HTTP API.
type Client struct {
	// URI of a RabbitMQ node to use, not including the path, e.g. http://127.0.0.1:15672.
	Endpoint string
	// Username to use. This RabbitMQ user must have the "management" tag.
	Username string
	// Password to use.
	Password  string
	host      string
	transport http.RoundTripper
	timeout   time.Duration
}

// NewClient instantiates a client.
func NewClient(uri string, username string, password string) (me *Client, err error) {
	u, err := url.Parse(uri)
	if err != nil {
		return nil, err
	}

	me = &Client{
		Endpoint: uri,
		host:     u.Host,
		Username: username,
		Password: password,
	}

	return me, nil
}

// NewTLSClient instantiates a client with a transport; it is up to the developer to make that layer secure.
func NewTLSClient(uri string, username string, password string, transport http.RoundTripper) (me *Client, err error) {
	u, err := url.Parse(uri)
	if err != nil {
		return nil, err
	}

	me = &Client{
		Endpoint:  uri,
		host:      u.Host,
		Username:  username,
		Password:  password,
		transport: transport,
	}

	return me, nil
}

// SetTransport changes the Transport Layer that the Client will use.
func (c *Client) SetTransport(transport http.RoundTripper) {
	c.transport = transport
}

// SetTimeout changes the HTTP timeout that the Client will use.
// By default there is no timeout.
func (c *Client) SetTimeout(timeout time.Duration) {
	c.timeout = timeout
}

func newGETRequest(client *Client, path string) (*http.Request, error) {
	s := client.Endpoint + "/api/" + path
	req, err := http.NewRequest("GET", s, nil)
	if err != nil {
		return nil, err
	}

	req.Close = true
	req.SetBasicAuth(client.Username, client.Password)

	return req, err
}

func newGETRequestWithParameters(client *Client, path string, qs url.Values) (*http.Request, error) {
	s := client.Endpoint + "/api/" + path + "?" + qs.Encode()

	req, err := http.NewRequest("GET", s, nil)
	if err != nil {
		return nil, err
	}

	req.Close = true
	req.SetBasicAuth(client.Username, client.Password)

	return req, err
}

func newRequestWithBody(client *Client, method string, path string, body []byte) (*http.Request, error) {
	s := client.Endpoint + "/api/" + path

	req, err := http.NewRequest(method, s, bytes.NewReader(body))
	if err != nil {
		return nil, err
	}

	req.Close = true
	req.SetBasicAuth(client.Username, client.Password)

	req.Header.Add("Content-Type", "application/json")

	return req, err
}

func executeRequest(client *Client, req *http.Request) (resp *http.Response, err error) {
	httpc := &http.Client{
		Timeout: client.timeout,
	}
	if client.transport != nil {
		httpc.Transport = client.transport
	}
	resp, err = httpc.Do(req)
	if err != nil {
		return nil, err
	}

	if err = parseResponseErrors(resp); err != nil {
		if resp.Body != nil {
			resp.Body.Close()
		}
		return nil, err
	}

	return resp, err
}

func executeAndParseRequest(client *Client, req *http.Request, rec interface{}) (err error) {
	res, err := executeRequest(client, req)
	if err != nil {
		return err
	}
	defer res.Body.Close()

	if err = json.NewDecoder(res.Body).Decode(&rec); err != nil {
		return err
	}

	return nil
}

func parseResponseErrors(res *http.Response) (err error) {
	if res.StatusCode == http.StatusUnauthorized {
		return errors.New("Error: API responded with a 401 Unauthorized")
	}

	// handle a "404 Not Found" response for a DELETE request as success.
	if res.Request.Method == http.MethodDelete && res.StatusCode == http.StatusNotFound {
		return nil
	}

	if res.StatusCode >= http.StatusBadRequest {
		rme := ErrorResponse{}
		if err = json.NewDecoder(res.Body).Decode(&rme); err != nil {
			rme.Message = fmt.Sprintf("Error %d from RabbitMQ: %s", res.StatusCode, err)
		}
		rme.StatusCode = res.StatusCode
		return rme
	}
	return nil
}