client.go

package yapi

import (
	"bytes"
	"encoding/json"
	"fmt"
	"github.com/google/go-querystring/query"
	"io"
	"net/http"
	"net/url"
	"reflect"
	"strings"
)

// httpClient defines an interface for an http.Client implementation so that alternative
// http Clients can be passed in for making requests
type httpClient interface {
	Do(request *http.Request) (response *http.Response, err error)
}

// AuthenticationService .
type AuthenticationService struct {
	client *Client

	// Authentication type
	authType int

	// Basic auth username
	username string

	// Basic auth password
	password string

	token string
}

// A Client manages communication with the API.
type Client struct {
	// HTTP client used to communicate with the API.
	client httpClient

	// Base URL for API requests.
	baseURL *url.URL

	// Services used for talking to different parts of the API.
	Authentication *AuthenticationService
	Interface      *InterfaceService
	Project        *ProjectService
	CatMenu        *CatMenuService
}

const (
	// HTTP Basic Authentication
	authTypeBasic = 1

	// HTTP Token Authentication
	authTypeToken = 2
)

// NewClient returns a new API client.
// If a nil httpClient is provided, http.DefaultClient will be used.
func NewClient(httpClient httpClient, baseURL string, apiToken string) (*Client, error) {
	if httpClient == nil {
		httpClient = http.DefaultClient
	}

	// ensure the baseURL contains a trailing slash so that all paths are preserved in later calls
	if !strings.HasSuffix(baseURL, "/") {
		baseURL += "/"
	}

	parsedBaseURL, err := url.Parse(baseURL)
	if err != nil {
		return nil, err
	}

	c := &Client{
		client:  httpClient,
		baseURL: parsedBaseURL,
	}

	c.Authentication = &AuthenticationService{client: c}
	c.Authentication.token = apiToken
	c.Project = &ProjectService{client: c}
	c.Interface = &InterfaceService{client: c}
	c.CatMenu = &CatMenuService{client: c}
	return c, nil
}

// NewRawRequest creates an API request.
// A relative URL can be provided in urlStr, in which case it is resolved relative to the baseURL of the Client.
// Allows using an optional native io.Reader for sourcing the request body.
func (c *Client) NewRawRequest(method, urlStr string, body io.Reader) (*http.Request, error) {
	rel, err := url.Parse(urlStr)
	if err != nil {
		return nil, err
	}
	// Relative URLs should be specified without a preceding slash since baseURL will have the trailing slash
	rel.Path = strings.TrimLeft(rel.Path, "/")

	u := c.baseURL.ResolveReference(rel)

	req, err := http.NewRequest(method, u.String(), body)
	if err != nil {
		return nil, err
	}

	if c.Authentication.authType == authTypeBasic {
		// Set basic auth information
		if c.Authentication.username != "" {
			req.SetBasicAuth(c.Authentication.username, c.Authentication.password)
		}
	}

	return req, nil
}

// NewRequest creates an API request.
// A relative URL can be provided in urlStr, in which case it is resolved relative to the baseURL of the Client.
// If specified, the value pointed to by body is JSON encoded and included as the request body.
func (c *Client) NewRequest(method, urlStr string, body interface{}) (*http.Request, error) {
	rel, err := url.Parse(urlStr)
	if err != nil {
		return nil, err
	}
	// Relative URLs should be specified without a preceding slash since baseURL will have the trailing slash
	rel.Path = strings.TrimLeft(rel.Path, "/")

	u := c.baseURL.ResolveReference(rel)

	var buf io.ReadWriter
	if body != nil {
		buf = new(bytes.Buffer)
		err = json.NewEncoder(buf).Encode(body)
		if err != nil {
			return nil, err
		}
	}

	req, err := http.NewRequest(method, u.String(), buf)
	if err != nil {
		return nil, err
	}

	if c.Authentication.authType == authTypeBasic {
		// Set basic auth information
		if c.Authentication.username != "" {
			req.SetBasicAuth(c.Authentication.username, c.Authentication.password)
		}
	}

	return req, nil
}

// addOptions adds the parameters in opt as URL query parameters to s.  opt
// must be a struct whose fields may contain "url" tags.
func addOptions(s string, opt interface{}) (string, error) {
	v := reflect.ValueOf(opt)
	if v.Kind() == reflect.Ptr && v.IsNil() {
		return s, nil
	}

	u, err := url.Parse(s)
	if err != nil {
		return s, err
	}

	qs, err := query.Values(opt)
	if err != nil {
		return s, err
	}

	u.RawQuery = qs.Encode()
	return u.String(), nil
}

// NewMultiPartRequest creates an API request including a multi-part file.
// A relative URL can be provided in urlStr, in which case it is resolved relative to the baseURL of the Client.
// If specified, the value pointed to by buf is a multipart form.
func (c *Client) NewMultiPartRequest(method, urlStr string, buf *bytes.Buffer) (*http.Request, error) {
	rel, err := url.Parse(urlStr)
	if err != nil {
		return nil, err
	}
	// Relative URLs should be specified without a preceding slash since baseURL will have the trailing slash
	rel.Path = strings.TrimLeft(rel.Path, "/")

	u := c.baseURL.ResolveReference(rel)

	req, err := http.NewRequest(method, u.String(), buf)
	if err != nil {
		return nil, err
	}

	if c.Authentication.authType == authTypeBasic {
		// Set basic auth information
		if c.Authentication.username != "" {
			req.SetBasicAuth(c.Authentication.username, c.Authentication.password)
		}
	}

	return req, nil
}

// Do sends an API request and returns the API response.
// The API response is JSON decoded and stored in the value pointed to by v, or returned as an error if an API error has occurred.
func (c *Client) Do(req *http.Request, v interface{}) (*http.Response, error) {
	httpResp, err := c.client.Do(req)
	if err != nil {
		return nil, err
	}

	err = CheckResponse(httpResp)
	if err != nil {
		// Even though there was an error, we still return the response
		// in case the caller wants to inspect it further
		return httpResp, err
	}

	if v != nil {
		// Open a NewDecoder and defer closing the reader only if there is a provided interface to decode to
		defer httpResp.Body.Close()
		err = json.NewDecoder(httpResp.Body).Decode(v)
	}

	return httpResp, err
}

// CheckResponse checks the API response for errors, and returns them if present.
// A response is considered an error if it has a status code outside the 200 range.
// The caller is responsible to analyze the response body.
// The body can contain JSON (if the error is intended) or xml.
func CheckResponse(r *http.Response) error {
	if c := r.StatusCode; 200 <= c && c <= 299 {
		return nil
	}

	err := fmt.Errorf("Request failed. Please analyze the request body for more details. Status code: %d", r.StatusCode)
	return err
}

// GetBaseURL will return you the Base URL.
// This is the same URL as in the NewClient constructor
func (c *Client) GetBaseURL() url.URL {
	return *c.baseURL
}

// cloneRequest returns a clone of the provided *http.Request.
// The clone is a shallow copy of the struct and its Header map.
func cloneRequest(r *http.Request) *http.Request {
	// shallow copy of the struct
	r2 := new(http.Request)
	*r2 = *r
	// deep copy of the Header
	r2.Header = make(http.Header, len(r.Header))
	for k, s := range r.Header {
		r2.Header[k] = append([]string(nil), s...)
	}
	return r2
}

// BasicAuthTransport is an http.RoundTripper that authenticates all requests
// using HTTP Basic Authentication with the provided username and password.
type BasicAuthTransport struct {
	Username string
	Password string

	// Transport is the underlying HTTP transport to use when making requests.
	// It will default to http.DefaultTransport if nil.
	Transport http.RoundTripper
}

// RoundTrip implements the RoundTripper interface.  We just add the
// basic auth and return the RoundTripper for this transport type.
func (t *BasicAuthTransport) RoundTrip(req *http.Request) (*http.Response, error) {
	req2 := cloneRequest(req) // per RoundTripper contract

	req2.SetBasicAuth(t.Username, t.Password)
	return t.transport().RoundTrip(req2)
}

// Client returns an *http.Client that makes requests that are authenticated
// using HTTP Basic Authentication.  This is a nice little bit of sugar
// so we can just get the client instead of creating the client in the calling code.
// If it's necessary to send more information on client init, the calling code can
// always skip this and set the transport itself.
func (t *BasicAuthTransport) Client() *http.Client {
	return &http.Client{Transport: t}
}

func (t *BasicAuthTransport) transport() http.RoundTripper {
	if t.Transport != nil {
		return t.Transport
	}
	return http.DefaultTransport
}