stripe.go

// Package stripe provides the binding for Stripe REST APIs.
package stripe

import (
	"bytes"
	"encoding/json"
	"errors"
	"io"
	"io/ioutil"
	"log"
	"net/http"
	"net/url"
	"os"
	"strings"
	"time"
)

const (
	apiURL     = "https://api.stripe.com/v1"
	uploadsURL = "https://uploads.stripe.com/v1"
)

// apiversion is the currently supported API version
const apiversion = "2015-07-13"

// clientversion is the binding version
const clientversion = "12.0.0"

// defaultHTTPTimeout is the default timeout on the http.Client used by the library.
// This is chosen to be consistent with the other Stripe language libraries and
// to coordinate with other timeouts configured in the Stripe infrastructure.
const defaultHTTPTimeout = 80 * time.Second

// Totalbackends is the total number of Stripe API endpoints supported by the binding.
const TotalBackends = 2

// Backend is an interface for making calls against a Stripe service.
// This interface exists to enable mocking for during testing if needed.
type Backend interface {
	Call(method, path, key string, body *url.Values, params *Params, v interface{}) error
	CallMultipart(method, path, key, boundary string, body io.Reader, params *Params, v interface{}) error
}

// BackendConfiguration is the internal implementation for making HTTP calls to Stripe.
type BackendConfiguration struct {
	Type       SupportedBackend
	URL        string
	HTTPClient *http.Client
}

// SupportedBackend is an enumeration of supported Stripe endpoints.
// Currently supported values are "api" and "uploads".
type SupportedBackend string

const (
	APIBackend     SupportedBackend = "api"
	UploadsBackend SupportedBackend = "uploads"
)

// Backends are the currently supported endpoints.
type Backends struct {
	API, Uploads Backend
}

// Key is the Stripe API key used globally in the binding.
var Key string

// LogLevel is the logging level for this library.
// 0: no logging
// 1: errors only
// 2: errors + informational (default)
// 3: errors + informational + debug
var LogLevel = 2

// Logger controls how stripe performs logging at a package level. It is useful
// to customise if you need it prefixed for your application to meet other
// requirements
var Logger *log.Logger

func init() {
	// setup the logger
	Logger = log.New(os.Stderr, "", log.LstdFlags)
}

var httpClient = &http.Client{Timeout: defaultHTTPTimeout}
var backends Backends

// SetHTTPClient overrides the default HTTP client.
// This is useful if you're running in a Google AppEngine environment
// where the http.DefaultClient is not available.
func SetHTTPClient(client *http.Client) {
	httpClient = client
}

// NewBackends creates a new set of backends with the given HTTP client. You
// should only need to use this for testing purposes or on App Engine.
func NewBackends(httpClient *http.Client) *Backends {
	return &Backends{
		API: BackendConfiguration{
			APIBackend, "https://api.stripe.com/v1", httpClient},
		Uploads: BackendConfiguration{
			UploadsBackend, "https://uploads.stripe.com/v1", httpClient},
	}
}

// GetBackend returns the currently used backend in the binding.
func GetBackend(backend SupportedBackend) Backend {
	var ret Backend
	switch backend {
	case APIBackend:
		if backends.API == nil {
			backends.API = BackendConfiguration{backend, apiURL, httpClient}
		}

		ret = backends.API
	case UploadsBackend:
		if backends.Uploads == nil {
			backends.Uploads = BackendConfiguration{backend, uploadsURL, httpClient}
		}
		ret = backends.Uploads
	}

	return ret
}

// SetBackend sets the backend used in the binding.
func SetBackend(backend SupportedBackend, b Backend) {
	switch backend {
	case APIBackend:
		backends.API = b
	case UploadsBackend:
		backends.Uploads = b
	}
}

// Call is the Backend.Call implementation for invoking Stripe APIs.
func (s BackendConfiguration) Call(method, path, key string, form *url.Values, params *Params, v interface{}) error {
	var body io.Reader
	if form != nil && len(*form) > 0 {
		data := form.Encode()
		if strings.ToUpper(method) == "GET" {
			path += "?" + data
		} else {
			body = bytes.NewBufferString(data)
		}
	}

	req, err := s.NewRequest(method, path, key, "application/x-www-form-urlencoded", body, params)
	if err != nil {
		return err
	}

	if err := s.Do(req, v); err != nil {
		return err
	}

	return nil
}

// CallMultipart is the Backend.CallMultipart implementation for invoking Stripe APIs.
func (s BackendConfiguration) CallMultipart(method, path, key, boundary string, body io.Reader, params *Params, v interface{}) error {
	contentType := "multipart/form-data; boundary=" + boundary

	req, err := s.NewRequest(method, path, key, contentType, body, params)
	if err != nil {
		return err
	}

	if err := s.Do(req, v); err != nil {
		return err
	}

	return nil
}

// NewRequest is used by Call to generate an http.Request. It handles encoding
// parameters and attaching the appropriate headers.
func (s *BackendConfiguration) NewRequest(method, path, key, contentType string, body io.Reader, params *Params) (*http.Request, error) {
	if !strings.HasPrefix(path, "/") {
		path = "/" + path
	}

	path = s.URL + path

	req, err := http.NewRequest(method, path, body)
	if err != nil {
		if LogLevel > 0 {
			Logger.Printf("Cannot create Stripe request: %v\n", err)
		}
		return nil, err
	}

	req.SetBasicAuth(key, "")

	if params != nil {
		if idempotency := strings.TrimSpace(params.IdempotencyKey); idempotency != "" {
			if len(idempotency) > 255 {
				return nil, errors.New("Cannot use an IdempotencyKey longer than 255 characters long.")
			}

			req.Header.Add("Idempotency-Key", idempotency)
		}

		if account := strings.TrimSpace(params.Account); account != "" {
			req.Header.Add("Stripe-Account", account)
		}
	}

	req.Header.Add("Stripe-Version", apiversion)
	req.Header.Add("User-Agent", "Stripe/v1 GoBindings/"+clientversion)
	req.Header.Add("Content-Type", contentType)

	return req, nil
}

// Do is used by Call to execute an API request and parse the response. It uses
// the backend's HTTP client to execute the request and unmarshals the response
// into v. It also handles unmarshaling errors returned by the API.
func (s *BackendConfiguration) Do(req *http.Request, v interface{}) error {
	if LogLevel > 1 {
		Logger.Printf("Requesting %v %v%v\n", req.Method, req.URL.Host, req.URL.Path)
	}

	start := time.Now()

	res, err := s.HTTPClient.Do(req)

	if LogLevel > 2 {
		Logger.Printf("Completed in %v\n", time.Since(start))
	}

	if err != nil {
		if LogLevel > 0 {
			Logger.Printf("Request to Stripe failed: %v\n", err)
		}
		return err
	}
	defer res.Body.Close()

	resBody, err := ioutil.ReadAll(res.Body)
	if err != nil {
		if LogLevel > 0 {
			Logger.Printf("Cannot parse Stripe response: %v\n", err)
		}
		return err
	}

	if res.StatusCode >= 400 {
		// for some odd reason, the Erro structure doesn't unmarshal
		// initially I thought it was because it's a struct inside of a struct
		// but even after trying that, it still didn't work
		// so unmarshalling to a map for now and parsing the results manually
		// but should investigate later
		var errMap map[string]interface{}
		json.Unmarshal(resBody, &errMap)

		if e, found := errMap["error"]; !found {
			err := errors.New(string(resBody))
			if LogLevel > 0 {
				Logger.Printf("Unparsable error returned from Stripe: %v\n", err)
			}
			return err
		} else {
			root := e.(map[string]interface{})
			err := &Error{
				Type:           ErrorType(root["type"].(string)),
				Msg:            root["message"].(string),
				HTTPStatusCode: res.StatusCode,
				RequestID:      res.Header.Get("Request-Id"),
			}

			if code, found := root["code"]; found {
				err.Code = ErrorCode(code.(string))
			}

			if param, found := root["param"]; found {
				err.Param = param.(string)
			}

			if charge, found := root["charge"]; found {
				err.ChargeID = charge.(string)
			}

			if LogLevel > 0 {
				Logger.Printf("Error encountered from Stripe: %v\n", err)
			}
			return err
		}
	}

	if LogLevel > 2 {
		Logger.Printf("Stripe Response: %q\n", resBody)
	}

	if v != nil {
		return json.Unmarshal(resBody, v)
	}

	return nil
}