initial commit

internal/pkg/azure/communication/azcommunication.go

@@ -0,0 +1,143 @@
+package communication
+
+import (
+	"bytes"
+	"context"
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"html/template"
+	"net/http"
+	"net/url"
+	"time"
+
+	"github.com/rs/zerolog"
+
+	"base/config"
+	"base/pkg/email"
+)
+
+type client struct {
+	logger        zerolog.Logger
+	endpoint      string
+	accessKey     string
+	apiVersion    string
+	senderAddress string
+	templates     *template.Template
+}
+
+func New(logger zerolog.Logger, config *config.AppConfig) email.Email {
+	return &client{
+		logger:        logger,
+		endpoint:      config.AzureCommunicationConfig.Endpoint,
+		accessKey:     config.AzureCommunicationConfig.AccessKey,
+		apiVersion:    config.AzureCommunicationConfig.ApiVersion,
+		senderAddress: config.AzureCommunicationConfig.SenderAddress,
+	}
+}
+
+func (c client) Send(ctx context.Context, params email.Request) (*email.Response, error) {
+	var tpl bytes.Buffer
+	if err := c.templates.ExecuteTemplate(&tpl, generateTemplateName(params.Template.EmailTemplateName), params.Template.Data); err != nil {
+		return nil, err
+	}
+
+	html := tpl.String()
+
+	request := &ApiRequest{
+		SenderAddress: c.senderAddress,
+		Content: ApiContentDto{
+			Subject: params.Subject,
+			Html:    html,
+		},
+		Recipients: ApiRecipientDto{
+			To: []ApiRecipientDetailDto{
+				{
+					Address:     params.RecipientAddress,
+					DisplayName: params.UserFullName,
+				},
+			},
+			CC:  make([]ApiRecipientDetailDto, 0),
+			BCC: make([]ApiRecipientDetailDto, 0),
+		},
+	}
+	byteBody, err := json.Marshal(&request)
+	if err != nil {
+		return nil, errors.New("marshaling error")
+	}
+
+	method := "POST"
+	endpoint := c.endpoint
+	u, _ := url.Parse(endpoint)
+	snedPathAndQuery := fmt.Sprintf(
+		"/emails:send?api-version=%s",
+		c.apiVersion,
+	)
+	date := time.Now().In(time.FixedZone("GMT", 0)).Format("Mon, 02 Jan 2006 15:04:05 GMT")
+	host := u.Host
+
+	contentHash := computeContentHash(byteBody)
+
+	stringToSign := fmt.Sprintf("%s\n%s\n%s;%s;%s", method, snedPathAndQuery, date, host, contentHash)
+	signature, err := computeSignature(stringToSign, c.accessKey)
+	if err != nil {
+		return nil, err
+	}
+	authHeader := fmt.Sprintf("HMAC-SHA256 SignedHeaders=x-ms-date;host;x-ms-content-sha256&Signature=%s", signature)
+	fullURL := endpoint + snedPathAndQuery
+	req, _ := http.NewRequest(method, fullURL, bytes.NewReader(byteBody))
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("x-ms-date", date)
+	req.Header.Set("x-ms-content-sha256", contentHash)
+	req.Header.Set("Authorization", authHeader)
+	req.Header.Set("Host", host)
+	client := &http.Client{Timeout: 15 * time.Second}
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusAccepted {
+		response := &ApiErrorResponse{}
+		if err := json.NewDecoder(resp.Body).Decode(response); err != nil {
+			return nil, err
+		}
+		c.logger.Info().Msgf("email sending failed. %v", response)
+		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	c.logger.Info().Msgf("email sending done. %v", resp.Body)
+	response := &email.Response{}
+	if err := json.NewDecoder(resp.Body).Decode(response); err != nil {
+		return nil, err
+	}
+
+	return response, nil
+}
+
+func computeContentHash(body []byte) string {
+	sum := sha256.Sum256(body)
+	return base64.StdEncoding.EncodeToString(sum[:])
+}
+
+func computeSignature(stringToSign, base64AccessKey string) (string, error) {
+	key, err := base64.StdEncoding.DecodeString(base64AccessKey)
+	if err != nil {
+		return "", err
+	}
+	mac := hmac.New(sha256.New, key)
+	_, err = mac.Write([]byte(stringToSign))
+	if err != nil {
+		return "", err
+	}
+	sig := mac.Sum(nil)
+	return base64.StdEncoding.EncodeToString(sig), nil
+}
+
+func generateTemplateName(emailTemplateName email.Template) string {
+	return fmt.Sprintf("%s.html", emailTemplateName.String())
+}