worker/clients/mailclient/utils.go

package mailclient

import (
	"crypto/rand"
	"encoding/json"
	"fmt"
	"html/template"
	"io"
	"penahub.gitlab.yandexcloud.net/backend/quiz/common.git/model"
)

type LineWriter struct {
	w      io.Writer
	length int
}

func NewLineWriter(w io.Writer, length int) *LineWriter {
	return &LineWriter{
		w:      w,
		length: length,
	}
}

func (r *LineWriter) Write(p []byte) (n int, err error) {
	for i := 0; i < len(p); i += r.length {
		end := i + r.length

		if end > len(p) {
			end = len(p) - 1
		}

		var chunk []byte
		chunk = append(chunk, p[i:end]...)

		if len(p) >= end+r.length {
			chunk = append(chunk, []byte("\r\n")...)
		}

		addN, err := r.w.Write(chunk)
		if err != nil {
			return n, err
		}
		n += addN
	}

	return n, nil
}

func (r *LineWriter) WriteString(s string) (n int, err error) {
	p := []byte(s)
	return r.Write(p)
}

func (r *LineWriter) WriteFormatString(format string, a ...any) (n int, err error) {
	p := []byte(fmt.Sprintf(format, a...))
	return r.Write(p)
}

func randomBoundary() string {
	var buf [30]byte
	_, err := io.ReadFull(rand.Reader, buf[:])
	if err != nil {
		panic(err)
	}
	return fmt.Sprintf("%x", buf[:])
}

var tmplFuncs = template.FuncMap{
	"renderImage": RenderImage,
}

func RenderImage(content string) template.HTML {
	var res model.ImageContent
	err := json.Unmarshal([]byte(content), &res)
	if err != nil {
		return template.HTML(fmt.Sprintf("%s", template.HTMLEscapeString(content)))
	}
	tpl := template.HTML(fmt.Sprintf("<td>%s<br><img class=\"image\" style=\"width:100%%; max-width:250px; max-height:250px\" src=\"%s\"/></td>", res.Description, res.Image))
	fmt.Println(tpl)
	return tpl
}