package mailclient

import (
	"bytes"
	"encoding/base64"
	"fmt"
	"net/http"
	"os"
	"path/filepath"
	"strings"
)

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

type Attachment struct {
	Name string
	Data []byte
}

func NewMessage(subject, body string) *Message {
  if subject == "" {
    subject = "Вам пришла заявка с PenaQuiz"
  }
	return &Message{Subject: subject, Body: body, Attachments: []Attachment{}}
}

func (m *Message) AttachFile(src string) error {
	data, err := os.ReadFile(src)
	if err != nil {
		return err
	}

	_, filename := filepath.Split(src)
	m.Attachments = append(m.Attachments, Attachment{Name: filename, Data: data})

	return nil
}

func (m *Message) AttachBytesFile(filename string, data []byte) {
	m.Attachments = append(m.Attachments, Attachment{Name: filename, Data: data})
}

func (m *Message) ToBytes() []byte {
	buf := bytes.NewBuffer(nil)

	buf.WriteString("MIME-Version: 1.0\r\n")
	fmt.Fprintf(buf, "From: %s\r\n", m.From)
	fmt.Fprintf(buf, "Subject: %s\r\n", m.Subject)
	fmt.Fprintf(buf, "To: %s\r\n", strings.Join(m.To, ","))

	boundary := randomBoundary()

	if len(m.Attachments) > 0 {
		buf.WriteString("Content-Type: multipart/mixed;\r\n")

		fmt.Fprintf(buf, "	boundary=\"%s\"\r\n", boundary)

		fmt.Fprintf(buf, "\r\n--%s", boundary)
		for _, attachment := range m.Attachments {
			buf.WriteString("\r\n")
			switch strings.Split(attachment.Name, ".")[1] {
			case "htmlmsg":

				buf.WriteString("Content-Type: text/html; charset=\"utf-8\"\r\n")
				buf.WriteString("Content-Transfer-Encoding: base64\r\n")
			case "docx":

				buf.WriteString("Content-Type: application/vnd.openxmlformats-officedocument.wordprocessingml.document\r\n")
				buf.WriteString("Content-Transfer-Encoding: base64\r\n")
				fmt.Fprintf(buf, "Content-Disposition: attachment; filename=\"%s\"\r\n", attachment.Name)
			default:
				fmt.Fprintf(buf, "Content-Type: %s\r\n", http.DetectContentType(attachment.Data))
				buf.WriteString("Content-Transfer-Encoding: base64\r\n")
				fmt.Fprintf(buf, "Content-Disposition: attachment; filename=\"%s\"\r\n", attachment.Name)
			}

			buf.WriteString("\r\n")

			b := make([]byte, base64.StdEncoding.EncodedLen(len(attachment.Data)))
			base64.StdEncoding.Encode(b, attachment.Data)

			writer := NewLineWriter(buf, 76)
			_, err := writer.Write(b)
			if err != nil {
				fmt.Println("mailclient-client err:", err)
			}

			fmt.Fprintf(buf, "\r\n\r\n--%s", boundary)
		}

		buf.WriteString("--")
	} else {
		buf.WriteString("Content-Type: text/plain; charset=utf-8\r\n")
		buf.WriteString(m.Body)
	}

	return buf.Bytes()
}