package bitcoin import ( "encoding/json" "fmt" "io" "net/http" "net/url" "time" ) const apiBaseURL = "https://blockstream.info/api/" // 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 { httpClient *http.Client transport *http.Transport } // 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", apiBaseURL+endpoint+"?"+query.Encode(), nil) if err != nil { return fmt.Errorf("failed to create new GET request: %v", err) } 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 fmt.Errorf("failed to process response: %v", 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 fmt.Errorf("failed to read response body: %v", err) } if res.StatusCode != 200 && res.StatusCode != 201 { return fmt.Errorf("unexpected http status code '%d': %v", res.StatusCode, err) } err = json.Unmarshal(body, out) if err != nil { return fmt.Errorf("failed to unmarshal response body: %v", err) } return nil } // newClient is the factory function for clients func newClient() (*client, error) { transport := &http.Transport{ ResponseHeaderTimeout: 5 * time.Second, } httpClient := &http.Client{ Transport: transport, } // Create a new client c := &client{ httpClient: httpClient, transport: transport, } return c, nil }