chore: added client files

Makefile

@@ -1,4 +1,4 @@
-.PHONY: test install test-integ test-docker
+.PHONY: test install test-integ test-docker goimports
 
 install:
 	go get -t -v ./...
@@ -13,3 +13,8 @@ version ?= latest
 test-docker:
 	curl -s https://raw.githubusercontent.com/sendgrid/sendgrid-oai/HEAD/prism/prism.sh -o prism.sh
 	version=$(version) bash ./prism.sh
+
+goimports:
+	go install golang.org/x/tools/cmd/goimports@latest
+	goimports -w .
+	go mod tidy

client/base_client.go

@@ -0,0 +1,13 @@
+package client
+
+import (
+	"net/http"
+	"net/url"
+	"time"
+)
+
+type BaseClient interface {
+	SetTimeout(timeout time.Duration)
+	SendRequest(method string, rawURL string, data url.Values,
+		headers map[string]interface{}, body ...byte) (*http.Response, error)
+}

client/client.go

@@ -0,0 +1,180 @@
+// Package client provides internal utilities for the twilio-go client library.
+package client
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"regexp"
+	"runtime"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/pkg/errors"
+	"github.com/sendgrid/sendgrid-go/client/form"
+)
+
+var alphanumericRegex *regexp.Regexp
+var delimitingRegex *regexp.Regexp
+
+func init() {
+	alphanumericRegex = regexp.MustCompile(`^[a-zA-Z0-9]*$`)
+	delimitingRegex = regexp.MustCompile(`\.\d+`)
+}
+
+// Credentials store user authentication credentials.
+type Credentials struct {
+	Apikey string
+}
+
+func NewCredentials(apikey string) *Credentials {
+	return &Credentials{Apikey: apikey}
+}
+
+// Client encapsulates a standard HTTP backend with authorization.
+type Client struct {
+	*Credentials
+	HTTPClient          *http.Client
+	UserAgentExtensions []string
+}
+
+// default http Client should not follow redirects and return the most recent response.
+func defaultHTTPClient() *http.Client {
+	return &http.Client{
+		CheckRedirect: func(req *http.Request, via []*http.Request) error {
+			return http.ErrUseLastResponse
+		},
+		Timeout: time.Second * 10,
+	}
+}
+
+func (c *Client) basicAuth() (string, string) {
+	return c.Credentials.Apikey, ""
+}
+
+func (c *Client) bearerAuth() string {
+	return c.Credentials.Apikey
+}
+
+// SetTimeout sets the Timeout for HTTP requests.
+func (c *Client) SetTimeout(timeout time.Duration) {
+	if c.HTTPClient == nil {
+		c.HTTPClient = defaultHTTPClient()
+	}
+	c.HTTPClient.Timeout = timeout
+}
+
+func extractContentTypeHeader(headers map[string]interface{}) (cType string) {
+	headerType, ok := headers["Content-Type"]
+	if !ok {
+		return urlEncodedContentType
+	}
+	return headerType.(string)
+}
+
+const (
+	urlEncodedContentType = "application/x-www-form-urlencoded"
+	jsonContentType       = "application/json"
+	keepZeros             = true
+	delimiter             = '.'
+	escapee               = '\\'
+)
+
+func (c *Client) doWithErr(req *http.Request) (*http.Response, error) {
+	client := c.HTTPClient
+
+	if client == nil {
+		client = defaultHTTPClient()
+	}
+
+	res, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	// Note that 3XX response codes are allowed for fetches
+	if res.StatusCode < 200 || res.StatusCode >= 400 {
+		err = &SendgridRestError{}
+		decodeErrs := json.NewDecoder(res.Body)
+		decodeErr := decodeErrs.Decode(err)
+		if decodeErr != nil {
+			err = errors.Wrap(decodeErr, "error decoding the response for an HTTP error code: "+strconv.Itoa(res.StatusCode))
+			return nil, err
+		}
+
+		return nil, err
+	}
+	return res, nil
+}
+
+func setBearerToken(req *http.Request, token string) {
+	req.Header.Set("Authorization", "Bearer "+token)
+}
+
+// SendRequest verifies, constructs, and authorizes an HTTP request.
+func (c *Client) SendRequest(method string, rawURL string, data url.Values,
+	headers map[string]interface{}, body ...byte) (*http.Response, error) {
+
+	contentType := extractContentTypeHeader(headers)
+
+	u, err := url.Parse(rawURL)
+	if err != nil {
+		return nil, err
+	}
+
+	valueReader := &strings.Reader{}
+	goVersion := runtime.Version()
+	var req *http.Request
+
+	//For HTTP GET Method there are no body parameters. All other parameters like query, path etc
+	// are added as information in the url itself. Also while Content-Type is json, we are sending
+	// json body. In that case, data variable contains all other parameters than body, which is the
+	//same case as GET method. In that case as well all parameters will be added to url
+	if method == http.MethodGet || contentType == jsonContentType {
+		if data != nil {
+			v, _ := form.EncodeToStringWith(data, delimiter, escapee, keepZeros)
+			s := delimitingRegex.ReplaceAllString(v, "")
+
+			u.RawQuery = s
+		}
+	}
+
+	//data is already processed and information will be added to u(the url) in the
+	//previous step. Now body will solely contain json payload
+	if contentType == jsonContentType {
+		req, err = http.NewRequest(method, u.String(), bytes.NewBuffer(body))
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		//Here the HTTP POST methods which is not having json content type are processed
+		//All the values will be added in data and encoded (all body, query, path parameters)
+		if method == http.MethodPost || method == http.MethodPut {
+			valueReader = strings.NewReader(data.Encode())
+		}
+		req, err = http.NewRequest(method, u.String(), valueReader)
+		if err != nil {
+			return nil, err
+		}
+
+	}
+
+	setBearerToken(req, c.bearerAuth())
+
+	// E.g. "User-Agent": "twilio-go/1.0.0 (darwin amd64) go/go1.17.8"
+	userAgent := fmt.Sprintf("sendgrid-go/%s (%s %s) go/%s", LibraryVersion, runtime.GOOS, runtime.GOARCH, goVersion)
+
+	if len(c.UserAgentExtensions) > 0 {
+		userAgent += " " + strings.Join(c.UserAgentExtensions, " ")
+	}
+
+	req.Header.Add("User-Agent", userAgent)
+
+	for k, v := range headers {
+		req.Header.Add(k, fmt.Sprint(v))
+	}
+	return c.doWithErr(req)
+}