Implement internal mail skill MVP
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赵义仑
228
internal/parser/parser.go
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228
internal/parser/parser.go
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@@ -0,0 +1,228 @@
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package parser
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import (
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"bytes"
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"encoding/base64"
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"fmt"
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"io"
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"mime"
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"mime/multipart"
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"mime/quotedprintable"
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"net/mail"
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"path/filepath"
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"strings"
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"time"
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"golang.org/x/net/html/charset"
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"internal-mail-skill/internal/model"
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)
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func Parse(raw []byte) (model.ParsedEmail, error) {
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msg, err := mail.ReadMessage(bytes.NewReader(raw))
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if err != nil {
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return model.ParsedEmail{}, fmt.Errorf("read message: %w", err)
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}
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parsed := model.ParsedEmail{
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MessageIDHeader: strings.TrimSpace(msg.Header.Get("Message-ID")),
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InReplyTo: strings.TrimSpace(msg.Header.Get("In-Reply-To")),
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References: strings.TrimSpace(msg.Header.Get("References")),
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Subject: decodeHeader(msg.Header.Get("Subject")),
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DateHeader: strings.TrimSpace(msg.Header.Get("Date")),
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}
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if sentAt, err := mail.ParseDate(parsed.DateHeader); err == nil {
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parsed.SentAt = &sentAt
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}
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if from, err := mail.ParseAddress(msg.Header.Get("From")); err == nil {
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parsed.SenderName = decodeHeader(from.Name)
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parsed.SenderEmail = strings.ToLower(from.Address)
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}
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parsed.To = parseAddressList(msg.Header.Get("To"))
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parsed.Cc = parseAddressList(msg.Header.Get("Cc"))
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if err := parsePart(mail.Header(msg.Header), msg.Body, &parsed); err != nil {
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return model.ParsedEmail{}, err
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}
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return parsed, nil
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}
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func parsePart(header mail.Header, body io.Reader, out *model.ParsedEmail) error {
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mediaType, params, err := mime.ParseMediaType(header.Get("Content-Type"))
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if err != nil || mediaType == "" {
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mediaType = "text/plain"
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}
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mediaType = strings.ToLower(mediaType)
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if strings.HasPrefix(mediaType, "multipart/") {
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boundary := params["boundary"]
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if boundary == "" {
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return fmt.Errorf("multipart message missing boundary")
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}
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mr := multipart.NewReader(body, boundary)
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for {
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part, err := mr.NextPart()
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if err == io.EOF {
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return nil
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}
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if err != nil {
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return fmt.Errorf("read multipart: %w", err)
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}
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if err := parsePart(mail.Header(part.Header), part, out); err != nil {
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return err
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}
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}
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}
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decoded := transferDecodedReader(header, body)
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filename := partFilename(header)
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disposition := strings.ToLower(header.Get("Content-Disposition"))
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isAttachment := filename != "" || strings.Contains(disposition, "attachment")
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if !isAttachment && strings.HasPrefix(mediaType, "text/") {
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text, err := readText(decoded, params["charset"])
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if err != nil {
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return fmt.Errorf("read text part: %w", err)
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}
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switch mediaType {
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case "text/html":
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appendText(&out.BodyHTML, text)
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default:
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appendText(&out.BodyText, text)
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}
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return nil
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}
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data, err := io.ReadAll(decoded)
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if err != nil {
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return fmt.Errorf("read attachment: %w", err)
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}
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if filename == "" {
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filename = "attachment.bin"
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}
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out.Attachments = append(out.Attachments, model.ParsedAttachment{
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Filename: sanitizeFilename(filename),
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ContentType: mediaType,
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ContentID: trimAngle(header.Get("Content-ID")),
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SizeBytes: int64(len(data)),
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Data: data,
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})
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return nil
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}
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func decodeHeader(value string) string {
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value = strings.TrimSpace(value)
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if value == "" {
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return ""
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}
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decoder := &mime.WordDecoder{CharsetReader: charset.NewReaderLabel}
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decoded, err := decoder.DecodeHeader(value)
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if err != nil {
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return value
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}
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return decoded
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}
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func parseAddressList(value string) []model.Address {
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value = strings.TrimSpace(value)
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if value == "" {
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return nil
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}
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list, err := mail.ParseAddressList(value)
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if err != nil {
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decoded := decodeHeader(value)
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list, err = mail.ParseAddressList(decoded)
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if err != nil {
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return nil
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}
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}
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out := make([]model.Address, 0, len(list))
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for _, addr := range list {
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out = append(out, model.Address{
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Name: decodeHeader(addr.Name),
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Email: strings.ToLower(addr.Address),
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})
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}
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return out
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}
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func transferDecodedReader(header mail.Header, r io.Reader) io.Reader {
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switch strings.ToLower(strings.TrimSpace(header.Get("Content-Transfer-Encoding"))) {
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case "base64":
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return base64.NewDecoder(base64.StdEncoding, r)
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case "quoted-printable":
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return quotedprintable.NewReader(r)
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default:
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return r
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}
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}
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func readText(r io.Reader, label string) (string, error) {
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if label != "" {
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cr, err := charset.NewReaderLabel(label, r)
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if err == nil {
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r = cr
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}
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}
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data, err := io.ReadAll(r)
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if err != nil {
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return "", err
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}
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return string(data), nil
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}
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func partFilename(header mail.Header) string {
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if disp := header.Get("Content-Disposition"); disp != "" {
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_, params, err := mime.ParseMediaType(disp)
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if err == nil && params["filename"] != "" {
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return decodeHeader(params["filename"])
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}
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}
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if ct := header.Get("Content-Type"); ct != "" {
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_, params, err := mime.ParseMediaType(ct)
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if err == nil && params["name"] != "" {
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return decodeHeader(params["name"])
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}
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}
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return ""
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}
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func appendText(dst *string, value string) {
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if strings.TrimSpace(value) == "" {
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return
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}
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if strings.TrimSpace(*dst) == "" {
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*dst = value
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return
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}
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*dst += "\n" + value
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}
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func sanitizeFilename(name string) string {
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name = filepath.Base(strings.TrimSpace(name))
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name = strings.ReplaceAll(name, "\x00", "")
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name = strings.ReplaceAll(name, "/", "_")
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name = strings.ReplaceAll(name, "\\", "_")
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if name == "." || name == "" {
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return "attachment.bin"
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}
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return name
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}
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func trimAngle(value string) string {
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value = strings.TrimSpace(value)
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value = strings.TrimPrefix(value, "<")
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value = strings.TrimSuffix(value, ">")
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return value
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}
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func ParseTimeRFC3339(value string) *time.Time {
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if value == "" {
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return nil
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}
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t, err := time.Parse(time.RFC3339Nano, value)
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if err != nil {
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return nil
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}
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return &t
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}
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63
internal/parser/parser_test.go
Normal file
63
internal/parser/parser_test.go
Normal file
@@ -0,0 +1,63 @@
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package parser
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import (
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"strings"
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"testing"
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)
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func TestParseMultipartEmailWithAttachment(t *testing.T) {
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raw := strings.Join([]string{
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"Message-ID: <m1@example.com>",
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"Subject: =?UTF-8?B?5rWL6K+V6YKu5Lu2?=",
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"From: =?UTF-8?B?5byg5LiJ?= <sender@example.com>",
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"To: receiver@example.com",
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"Cc: cc@example.com",
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"Date: Tue, 04 Jun 2024 12:00:00 +0800",
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"MIME-Version: 1.0",
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"Content-Type: multipart/mixed; boundary=mix",
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"",
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"--mix",
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"Content-Type: multipart/alternative; boundary=alt",
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"",
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"--alt",
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"Content-Type: text/plain; charset=utf-8",
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"",
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"plain body",
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"--alt",
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"Content-Type: text/html; charset=utf-8",
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"",
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"<p>html body</p>",
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"--alt--",
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"--mix",
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"Content-Type: text/plain; name=\"note.txt\"",
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"Content-Disposition: attachment; filename=\"note.txt\"",
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"Content-Transfer-Encoding: base64",
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"",
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"YXR0YWNobWVudA==",
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"--mix--",
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"",
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}, "\r\n")
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msg, err := Parse([]byte(raw))
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if err != nil {
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t.Fatalf("Parse() error = %v", err)
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}
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if msg.Subject != "测试邮件" {
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t.Fatalf("Subject = %q", msg.Subject)
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}
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if msg.SenderName != "张三" || msg.SenderEmail != "sender@example.com" {
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t.Fatalf("sender = %q <%s>", msg.SenderName, msg.SenderEmail)
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}
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if strings.TrimSpace(msg.BodyText) != "plain body" {
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t.Fatalf("BodyText = %q", msg.BodyText)
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}
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if !strings.Contains(msg.BodyHTML, "html body") {
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t.Fatalf("BodyHTML = %q", msg.BodyHTML)
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}
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if len(msg.Attachments) != 1 {
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t.Fatalf("attachments = %d", len(msg.Attachments))
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}
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if msg.Attachments[0].Filename != "note.txt" || string(msg.Attachments[0].Data) != "attachment" {
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t.Fatalf("attachment = %#v", msg.Attachments[0])
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}
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}
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