common/clients/smtp.go

package clients

import (
	"bytes"
	"encoding/json"
	"fmt"
	"github.com/gofiber/fiber/v2"
	"mime/multipart"
)

type Deps struct {
	SmtpApiUrl  string
	SmtpHost    string
	SmtpPort    string
	SmtpSender  string
	Username    string
	Password    string
	ApiKey      string
	FiberClient *fiber.Client
}

type SmtpClient struct {
	smtpApiUrl  string
	smtpHost    string
	smtpPort    string
	smtpSender  string
	username    string
	password    string
	apiKey      string
	fiberClient *fiber.Client
}

func NewSmtpClient(deps Deps) *SmtpClient {
	if deps.FiberClient == nil {
		deps.FiberClient = fiber.AcquireClient()
	}
	return &SmtpClient{
		smtpApiUrl:  deps.SmtpApiUrl,
		smtpHost:    deps.SmtpHost,
		smtpPort:    deps.SmtpPort,
		smtpSender:  deps.SmtpSender,
		username:    deps.Username,
		password:    deps.Password,
		apiKey:      deps.ApiKey,
		fiberClient: deps.FiberClient,
	}
}

type Message struct {
	To          string
	Subject     string
	HtmlBody    string
	Attachments []Attachment
}

type Attachment struct {
	Name string `json:"name"`
	Data string `json:"body"`
}

func (m *SmtpClient) MailSender(data Message) error {
	form := new(bytes.Buffer)
	writer := multipart.NewWriter(form)

	fields := map[string]string{
		"from":    m.smtpSender,
		"to":      data.To,
		"subject": data.Subject,
		"html":    data.HtmlBody,
	}

	if data.Attachments != nil && len(data.Attachments) > 0 {
		attachmentJson, err := json.Marshal(data.Attachments)
		if err != nil {
			return err
		}
		fields["files"] = string(attachmentJson)
	}

	for key, value := range fields {
		if err := writer.WriteField(key, value); err != nil {
			return err
		}
	}

	if err := writer.Close(); err != nil {
		return err
	}

	req := m.fiberClient.Post(m.smtpApiUrl).Body(form.Bytes()).ContentType(writer.FormDataContentType())
	if m.apiKey != "" {
		req.Set("Authorization", m.apiKey)
	}

	statusCode, body, errs := req.Bytes()
	if errs != nil {
		return errs[0]
	}

	if statusCode != fiber.StatusOK {
		err := fmt.Errorf("the SMTP service returned an error: %d Response body: %s", statusCode, body)
		return err
	}

	return nil
}