forked from mattermost/mattermost
/
mmpreview.go
81 lines (71 loc) · 2.27 KB
/
mmpreview.go
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// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.
package docextractor
// MMPreview is a micro-service to convert from any libreoffice supported
// format into a PDF file, and then we use the regular pdf extractor to convert
// it into plain text.
import (
"bytes"
"io"
"mime/multipart"
"net/http"
"path"
"strings"
"github.com/pkg/errors"
)
type mmPreviewExtractor struct {
url string
secret string
pdfExtractor pdfExtractor
}
var mmpreviewSupportedExtensions = map[string]bool{
"ppt": true,
"odp": true,
"xls": true,
"xlsx": true,
"ods": true,
}
func newMMPreviewExtractor(url string, secret string, pdfExtractor pdfExtractor) *mmPreviewExtractor {
return &mmPreviewExtractor{url: url, secret: secret, pdfExtractor: pdfExtractor}
}
func (mpe *mmPreviewExtractor) Match(filename string) bool {
extension := strings.TrimPrefix(path.Ext(filename), ".")
return mmpreviewSupportedExtensions[extension]
}
func (mpe *mmPreviewExtractor) Extract(filename string, file io.Reader) (string, error) {
b, w, err := createMultipartFormData("file", filename, file)
if err != nil {
return "", errors.Wrap(err, "Unable to generate file preview using mmpreview.")
}
req, err := http.NewRequest("POST", mpe.url+"/toPDF", &b)
if err != nil {
return "", errors.Wrap(err, "Unable to generate file preview using mmpreview.")
}
req.Header.Set("Content-Type", w.FormDataContentType())
if mpe.secret != "" {
req.Header.Add("Authentication", mpe.secret)
}
resp, err := http.DefaultClient.Do(req)
if err != nil {
return "", errors.Wrap(err, "Unable to generate file preview using mmpreview.")
}
defer resp.Body.Close()
if resp.StatusCode != 200 {
return "", errors.New("Unable to generate file preview using mmpreview (The server has replied with an error)")
}
return mpe.pdfExtractor.Extract(filename, resp.Body)
}
func createMultipartFormData(fieldName, fileName string, fileData io.Reader) (bytes.Buffer, *multipart.Writer, error) {
var b bytes.Buffer
var err error
w := multipart.NewWriter(&b)
var fw io.Writer
if fw, err = w.CreateFormFile(fieldName, fileName); err != nil {
return b, nil, err
}
if _, err = io.Copy(fw, fileData); err != nil {
return b, nil, err
}
w.Close()
return b, w, nil
}