initial commit

ynab/client.go

@@ -0,0 +1,143 @@
+package ynab
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"time"
+)
+
+// Reference: https://api.ynab.com/
+
+const apiBaseURL = "https://api.ynab.com/v1/budgets/"
+
+// 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 {
+	BearerToken string
+	BudgetID    string
+	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+c.BudgetID+endpoint+"?"+query.Encode(), nil)
+	if err != nil {
+		return fmt.Errorf("failed to create new GET request: %v", err)
+	}
+	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", c.BearerToken))
+
+	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
+}
+
+// Format the message body, send an HTTP POST request, and return the processed response
+func (c *Client) post(endpoint string, out interface{}, body interface{}) error {
+	// Attempt to marshall the body as JSON
+	json, err := json.Marshal(body)
+	if err != nil {
+		return fmt.Errorf("failed to marshal body to json: %v", err)
+	}
+
+	req, err := http.NewRequest("POST", apiBaseURL+c.BudgetID+endpoint, bytes.NewBuffer(json))
+	if err != nil {
+		return fmt.Errorf("failed to create new POST request: %v", err)
+	}
+	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", c.BearerToken))
+	req.Header.Add("Content-Type", "application/json")
+
+	res, err := c.httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("http POST request failed: %v", err)
+	}
+
+	err = c.processResponse(res, out)
+	if err != nil {
+		return fmt.Errorf("failed to process response: %v", err)
+	}
+	return nil
+}
+
+// Format the message body, send an HTTP POST request, and return the processed response
+func (c *Client) put(endpoint string, out interface{}, body interface{}) error {
+	// Attempt to marshall the body as JSON
+	json, err := json.Marshal(body)
+	if err != nil {
+		return fmt.Errorf("failed to marshal body to json: %v", err)
+	}
+
+	req, err := http.NewRequest("PUT", apiBaseURL+c.BudgetID+endpoint, bytes.NewBuffer(json))
+	if err != nil {
+		return fmt.Errorf("failed to create new POST request: %v", err)
+	}
+	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", c.BearerToken))
+	req.Header.Add("Content-Type", "application/json")
+
+	res, err := c.httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("http POST 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 - takes a bearer token
+func NewClient(budgetID, bearerToken string) (*Client, error) {
+	transport := &http.Transport{
+		ResponseHeaderTimeout: 5 * time.Second,
+	}
+
+	client := &http.Client{
+		Transport: transport,
+	}
+
+	// Create a new client
+	c := &Client{
+		BudgetID:    budgetID,
+		BearerToken: bearerToken,
+		httpClient:  client,
+		transport:   transport,
+	}
+
+	return c, nil
+}