notifier/internal/clients/mail.go

package clients

import (
	"bytes"
	"fmt"
	"github.com/gofiber/fiber/v2"
	"go.uber.org/zap"
	"html/template"
	"mime/multipart"
	"os"
)

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

type MailClient struct {
	deps Deps
}

func NewMailClient(deps Deps) *MailClient {
	if deps.FiberClient == nil {
		deps.FiberClient = fiber.AcquireClient()
	}
	return &MailClient{
		deps: deps,
	}
}

type SenderDeps struct {
	Subject  string
	Email    string
	TmplPath string
}

func (m *MailClient) MailSender(data SenderDeps) error {
	tmplContent, err := os.ReadFile(data.TmplPath)
	if err != nil {
		m.deps.Logger.Error("Error reading template file", zap.Error(err))
		return err
	}

	tmpl, err := template.New("email").Parse(string(tmplContent))
	if err != nil {
		m.deps.Logger.Error("Error parsing HTML template", zap.Error(err))
		return err
	}

	var buf bytes.Buffer
	if err := tmpl.Execute(&buf, nil); err != nil {
		m.deps.Logger.Error("Error executing template", zap.Error(err))
		return err
	}

	htmlBody := buf.String()

	form := new(bytes.Buffer)
	writer := multipart.NewWriter(form)
	defer writer.Close()

	fields := map[string]string{
		"from":    m.deps.SmtpSender,
		"to":      data.Email,
		"subject": data.Subject,
		"html":    htmlBody,
	}

	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.deps.FiberClient.Post(m.deps.SmtpApiUrl).Body(form.Bytes()).ContentType(writer.FormDataContentType())
	if m.deps.ApiKey != "" {
		req.Set("Authorization", m.deps.ApiKey)
	}

	statusCode, body, errs := req.Bytes()
	if errs != nil {
		m.deps.Logger.Error("Error sending request", zap.Error(errs[0]))
		return errs[0]
	}

	if statusCode != fiber.StatusOK {
		err := fmt.Errorf("the SMTP service returned an error: %s Response body: %s", statusCode, body)
		m.deps.Logger.Error("Error sending email", zap.Error(err))
		return err
	}

	return nil
}