feat: add smtp send mail

.env

@@ -1,2 +1,2 @@
-JSON_OBJ={"key":"value"}
-JSON_ARRAY=["value1","value2"]
+JSON_OBJ={"key":"value"}
+JSON_ARRAY=["value1","value2"]

smtp.go

@@ -0,0 +1,82 @@
+package helpers
+
+import (
+	"bytes"
+	"encoding/base64"
+	"fmt"
+	"net/smtp"
+	"strings"
+)
+
+type Mail struct {
+	Host           string
+	Port           int
+	User           string
+	Password       string
+	From           string
+	To             []string
+	Cc             []string
+	Bcc            []string
+	Subject        string
+	Msg            []byte
+	AttachmentName string
+	Attachment     []byte
+}
+
+func (m Mail) Builder() (body []byte) {
+	buf := new(bytes.Buffer)
+
+	// Mail Header
+	buf.WriteString(fmt.Sprintf("From: %s\r\n", m.From))
+	buf.WriteString(fmt.Sprintf("To: %s\r\n", strings.Join(m.To, ";")))
+	buf.WriteString(fmt.Sprintf("Subject: %s\r\n", m.Subject))
+
+	if len(m.Cc) != 0 {
+		buf.WriteString(fmt.Sprintf("Cc: %s\r\n", strings.Join(m.Cc, ";")))
+	}
+
+	if len(m.Bcc) != 0 {
+		buf.WriteString(fmt.Sprintf("Bcc: %s\r\n", strings.Join(m.Bcc, ";")))
+	}
+
+	boundary := "zercle-boundary-779"
+	buf.WriteString("MIME-Version: 1.0\r\n")
+	buf.WriteString(fmt.Sprintf("Content-Type: multipart/mixed; boundary=%s\n", boundary))
+
+	// Mail Body
+	buf.WriteString(fmt.Sprintf("\r\n--%s\r\n", boundary))
+	buf.WriteString("Content-Type: text/plain; charset=\"utf-8\"\r\n")
+	buf.WriteString(fmt.Sprintf("\r\n%s", m.Msg))
+
+	// Mail Attachment
+	if len(m.Attachment) != 0 {
+		buf.WriteString(fmt.Sprintf("\r\n--%s\r\n", boundary))
+		buf.WriteString("Content-Type: text/plain; charset=\"utf-8\"\r\n")
+		buf.WriteString("Content-Transfer-Encoding: base64\r\n")
+		buf.WriteString("Content-Disposition: attachment; filename=" + m.AttachmentName + "\r\n")
+		buf.WriteString("Content-ID: <" + m.AttachmentName + ">\r\n\r\n")
+
+		attachmentByte := make([]byte, base64.StdEncoding.EncodedLen(len(m.Attachment)))
+		base64.StdEncoding.Encode(attachmentByte, m.Attachment)
+		buf.Write(attachmentByte)
+	}
+	buf.WriteString(fmt.Sprintf("\r\n--%s", boundary))
+
+	// Mail End
+	buf.WriteString("--")
+
+	return buf.Bytes()
+}
+
+func (m Mail) Send() (err error) {
+	if m.Port == 0 {
+		m.Port = 587
+	}
+
+	addr := fmt.Sprintf("%s:%d", m.Host, m.Port)
+
+	auth := smtp.PlainAuth("", m.User, m.Password, m.Host)
+
+	err = smtp.SendMail(addr, auth, m.From, m.To, m.Builder())
+	return
+}