auxilium.go

package auxilium

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"net/url"
	"sort"
	"strings"

	"github.com/google/go-querystring/query"
)

const (
	applicationIdentifier = "macropad"
)

// Client for Auxilium's API
type Client struct {
	client *http.Client

	baseURL *url.URL

	token string

	// Identifier used for requesting token and communicating with the API
	ApplicationIdentifier string

	// Login service
	Login *LoginService
	// TimeTrack service
	TimeTrack *TimeTrackService
}

// NewClient return a new Auxlium API Client. If a nil httpClient is
// provided, http.DefaultClient will be used. To use API methods which require
// authentication, provide a valid private token.
func NewClient(httpClient *http.Client, token string, baseURL string) *Client {
	if httpClient == nil {
		httpClient = http.DefaultClient
	}
	c := &Client{client: httpClient, token: token, ApplicationIdentifier: applicationIdentifier}
	c.Login = &LoginService{client: c}
	c.TimeTrack = &TimeTrackService{client: c}
	c.SetBaseURL(baseURL)
	return c
}

// BaseURL return a copy of the baseURL.
func (c *Client) BaseURL() *url.URL {
	u := *c.baseURL
	return &u
}

// SetBaseURL sets the base URL for API requests to a custom endpoint. urlStr
// should always be specified with a trailing slash.
func (c *Client) SetBaseURL(urlStr string) error {
	// Make sure the given URL end with a slash
	if !strings.HasSuffix(urlStr, "/") {
		urlStr += "/"
	}

	var err error
	c.baseURL, err = url.Parse(urlStr)
	return err
}

// 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. If v implements the io.Writer
// interface, the raw response body will be written to v, without attempting to
// first decode it.
func (c *Client) Do(req *http.Request, v interface{}) (*http.Response, error) {
	response, err := c.client.Do(req)
	if err != nil {
		return nil, err
	}
	defer response.Body.Close()

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

	if v != nil {
		if w, ok := v.(io.Writer); ok {
			_, err = io.Copy(w, response.Body)
		} else {
			err = json.NewDecoder(response.Body).Decode(v)
		}
	}
	return response, err
}

// An ErrorResponse reports one or more errors caused by an API request.
type ErrorResponse struct {
	Response *http.Response
	Message  string
}

func (e *ErrorResponse) Error() string {
	path, _ := url.QueryUnescape(e.Response.Request.URL.Opaque)
	u := fmt.Sprintf("%s://%s%s", e.Response.Request.URL.Scheme, e.Response.Request.URL.Host, path)
	return fmt.Sprintf("%s %s: %d %s", e.Response.Request.Method, u, e.Response.StatusCode, e.Message)
}

// CheckResponse checks the API response for errors, and returns them if present.
func CheckResponse(r *http.Response) error {
	switch r.StatusCode {
	case 200, 201, 304:
		return nil
	}

	errorResponse := &ErrorResponse{Response: r}
	data, err := ioutil.ReadAll(r.Body)
	if err == nil && data != nil {
		var raw interface{}
		if err := json.Unmarshal(data, &raw); err != nil {
			errorResponse.Message = "failed to parse unknown error format"
		}

		errorResponse.Message = parseError(raw)
	}

	return errorResponse
}

// NewRequest creates an API request. A relative URL path can be provided in
// urlStr, in which case it is resolved relative to the base URL of the Client.
// Relative URL paths should always be specified without a preceding slash. If
// specified, the value pointed to by body is JSON encoded and included as the
// request body.
func (c *Client) NewRequest(method, path string, opt interface{}) (*http.Request, error) {
	u := *c.baseURL
	// Set the encoded opaque data
	u.Opaque = c.baseURL.Path + path + ".json"

	if opt != nil {
		q, err := query.Values(opt)
		if err != nil {
			return nil, err
		}
		u.RawQuery = q.Encode()
	}

	req := &http.Request{
		Method:     method,
		URL:        &u,
		Proto:      "HTTP/1.1",
		ProtoMajor: 1,
		ProtoMinor: 1,
		Header:     make(http.Header),
		Host:       u.Host,
	}

	if method == "POST" || method == "PUT" {
		bodyBytes, err := json.Marshal(opt)
		if err != nil {
			return nil, err
		}
		bodyReader := bytes.NewReader(bodyBytes)

		u.RawQuery = ""
		req.Body = ioutil.NopCloser(bodyReader)
		req.ContentLength = int64(bodyReader.Len())
		req.Header.Set("Content-Type", "application/json")
	}

	req.Header.Set("Accept", "application/json")

	if len(c.token) > 0 {
		req.Header.Set("X-Token", c.token)
	}
	req.Header.Set("X-Identifier", c.ApplicationIdentifier)

	return req, nil
}

// Bool is a helper routine that allocates a new bool value
// to store v and returns a pointer to it.
func Bool(v bool) *bool {
	p := new(bool)
	*p = v
	return p
}

// Int is a helper routine that allocates a new int32 value
// to store v and returns a pointer to it, but unlike Int32
// its argument value is an int.
func Int(v int) *int {
	p := new(int)
	*p = v
	return p
}

// String is a helper routine that allocates a new string value
// to store v and returns a pointer to it.
func String(v string) *string {
	p := new(string)
	*p = v
	return p
}

// Format:
// {
//     "message": {
//         "<property-name>": [
//             "<error-message>",
//             "<error-message>",
//             ...
//         ],
//         "<embed-entity>": {
//             "<property-name>": [
//                 "<error-message>",
//                 "<error-message>",
//                 ...
//             ],
//         }
//     },
//     "error": "<error-message>"
// }
func parseError(raw interface{}) string {
	switch raw := raw.(type) {
	case string:
		return raw

	case []interface{}:
		var errs []string
		for _, v := range raw {
			errs = append(errs, parseError(v))
		}
		return fmt.Sprintf("[%s]", strings.Join(errs, ", "))

	case map[string]interface{}:
		var errs []string
		for k, v := range raw {
			errs = append(errs, fmt.Sprintf("{%s: %s}", k, parseError(v)))
		}
		sort.Strings(errs)
		return strings.Join(errs, ", ")

	default:
		return fmt.Sprintf("failed to parse unexpected error type: %T", raw)
	}
}