move providers into providers subdirectory

providers/questrade/client.go

@@ -0,0 +1,132 @@
+package questrade
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strconv"
+	"time"
+)
+
+const loginServerURL = "https://login.questrade.com/oauth2/"
+
+type LoginCredentials struct {
+	AccessToken  string `json:"access_token"`
+	TokenType    string `json:"token_type"`
+	ExpiresIn    int    `json:"expires_in"`
+	RefreshToken string `json:"refresh_token"`
+	ApiServer    string `json:"api_server"`
+}
+
+// A client is the structure that will be used to consume the API
+// endpoints. It holds the login credentials, http client/transport,
+// rate limit information, and the login session timer.
+type client struct {
+	Credentials        LoginCredentials
+	SessionTimer       *time.Timer
+	RateLimitRemaining int
+	RateLimitReset     time.Time
+	httpClient         *http.Client
+	transport          *http.Transport
+}
+
+// authHeader is a shortcut that returns a string to be placed
+// in the authorization header of API calls
+func (l LoginCredentials) authHeader() string {
+	return l.TokenType + " " + l.AccessToken
+}
+
+// Send an HTTP GET request, and return the processed response
+func (c *client) get(endpoint string, out interface{}, query url.Values) error {
+	req, err := http.NewRequest("GET", c.Credentials.ApiServer+endpoint+"?"+query.Encode(), nil)
+	if err != nil {
+		return err
+	}
+	req.Header.Add("Authorization", c.Credentials.authHeader())
+
+	res, err := c.httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("http get request failed: %v", err)
+	}
+
+	err = c.processResponse(res, out)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// processResponse takes the body of an HTTP response, and either returns
+// the error code, or unmarshalls the JSON response, extracts
+// rate limit info, and places it into the object
+// output parameter. This function closes the response body after reading it.
+func (c *client) processResponse(res *http.Response, out interface{}) error {
+	body, err := io.ReadAll(res.Body)
+	res.Body.Close()
+	if err != nil {
+		return err
+	}
+
+	if res.StatusCode != 200 {
+		return newQuestradeError(res, body)
+	}
+
+	err = json.Unmarshal(body, out)
+	if err != nil {
+		return err
+	}
+
+	reset, _ := strconv.Atoi(res.Header.Get("X-RateLimit-Reset"))
+	c.RateLimitReset = time.Unix(int64(reset), 0)
+	c.RateLimitRemaining, _ = strconv.Atoi(res.Header.Get("X-RateLimit-Remaining"))
+	return nil
+}
+
+// Login takes the refresh token from the client login credentials
+// and exchanges it for an access token. Returns a timer that
+// expires when the login session is over.
+// TODO - Return a proper error when login fails with HTTP 400 - Bad Request
+func (c *client) login() error {
+	vars := url.Values{"grant_type": {"refresh_token"}, "refresh_token": {c.Credentials.RefreshToken}}
+	res, err := c.httpClient.PostForm(loginServerURL+"token", vars)
+
+	if err != nil {
+		return err
+	}
+
+	err = c.processResponse(res, &c.Credentials)
+	if err != nil {
+		return err
+	}
+
+	c.SessionTimer = time.NewTimer(time.Duration(c.Credentials.ExpiresIn) * time.Second)
+	return nil
+}
+
+// newClient is the factory function for clients - takes a refresh token and logs in
+func newClient(refreshToken string) (*client, error) {
+	transport := &http.Transport{
+		ResponseHeaderTimeout: 5 * time.Second,
+	}
+
+	httpClient := &http.Client{
+		Transport: transport,
+	}
+
+	// Create a new client
+	c := &client{
+		Credentials: LoginCredentials{
+			RefreshToken: refreshToken,
+		},
+		httpClient: httpClient,
+		transport:  transport,
+	}
+
+	err := c.login()
+	if err != nil {
+		return nil, err
+	}
+	return c, nil
+}