SFM-loan-Rest-Api/UploadsOnDisk.go

package main

import (
	"biukop.com/sfm/loan"
	"errors"
	log "github.com/sirupsen/logrus"
	"io/ioutil"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"
)

type uploadsOnDisk struct {
	Upload loan.Uploads
}

func (m *uploadsOnDisk) convertUploadsToPDF() (e error) {
	return convertUploadsToPDF(m.Upload)
}
func convertUploadsToPDF(ul loan.Uploads) (e error) {
	m := uploadsOnDisk{}
	m.Upload = ul

	if strings.Contains(strings.ToLower(ul.Format), "excel") ||
		strings.Contains(strings.ToLower(ul.Format), "spreadsheet") {
		e = m.convertExcelToPDF()
		return // excel is converted
	}

	if strings.Contains(strings.ToLower(ul.Format), "/pdf") {
		return // no need to convert
	}

	e = errors.New("don't know how to convert file to PDF")
	log.Error("don't know how to convert file to PDF", ul)
	return
}

func (m *uploadsOnDisk) convertUploadsToJpg() (e error) {
	return convertUploadsToJpg(m.Upload)
}

func convertUploadsToJpg(ul loan.Uploads) (e error) {
	m := uploadsOnDisk{}
	m.Upload = ul

	if strings.Contains(strings.ToLower(ul.Format), "excel") ||
		strings.Contains(strings.ToLower(ul.Format), "spreadsheet") {
		e = m.convertExcelToJpg()
		return // excel is converted
	}
	if strings.Contains(strings.ToLower(ul.Format), "/pdf") {
		e = m.convertPDFToJpg()
		return // excel is converted
	}

	e = errors.New("don't know how to convert file to image")
	log.Error("don't know how to convert file to image", ul)
	return
}

func (m *uploadsOnDisk) convertUploadsToThumb() (e error) {
	return convertUploadsToThumb(m.Upload)
}
func convertUploadsToThumb(ul loan.Uploads) (e error) {
	m := uploadsOnDisk{}
	m.Upload = ul
	if !fileExists(m.jpgPath()) {
		e = m.convertUploadsToJpg()
		if e != nil {
			return
		}
	}

	e = ConvertImageToThumbnail(m.jpgPath(), m.thumbPath(), 256)
	if e != nil {
		log.Error("cannot create thumbnail for uploads", m.Upload, e)
		return
	}
	return
}

func (m *uploadsOnDisk) filePath() string {
	return config.UploadsDir.FileDir + strconv.Itoa(int(m.Upload.Id)) + ".uploads"
}

func (m *uploadsOnDisk) jpgPath() string {
	return config.UploadsDir.JpgDir + strconv.Itoa(int(m.Upload.Id)) + ".jpg"
}

func (m *uploadsOnDisk) thumbPath() string {
	return config.UploadsDir.ThumbDir + strconv.Itoa(int(m.Upload.Id)) + ".webp"
}

func (m *uploadsOnDisk) pdfPath() string {
	return config.UploadsDir.PdfDir + strconv.Itoa(int(m.Upload.Id)) + ".pdf"
}
func (m *uploadsOnDisk) convertExcelToPDF() (e error) {
	if fileExists(m.pdfPath()) {
		log.Info("Skip conversion excel to PDF , already exists", m)
		return
	}
	return m.convertExcelTo("pdf")
}

func (m *uploadsOnDisk) convertExcelToJpg() (e error) {
	if fileExists(m.jpgPath()) {
		log.Info("Skip conversion excel to Jpg , already exists", m)
		return
	}
	return m.convertExcelTo("jpg")
}

func (m *uploadsOnDisk) convertExcelTo(format string) (e error) {
	if format != "pdf" && format != "jpg" {
		e = errors.New("unsupported format")
		return
	}

	dst := m.jpgPath()
	if format == "pdf" {
		dst = m.pdfPath()
	}

	dir, e := ioutil.TempDir(config.TempDir, "tmp-convert-xls-to-"+format+"-")
	if e != nil {
		log.Error("cannot create tmp dir for converting image", m.Upload, e)
		return
	}
	defer os.RemoveAll(dir)

	cmd := exec.Command("libreoffice", "--convert-to", format, "--outdir", dir, m.filePath())
	strCmd := cmd.String()
	log.Debug("command is ", strCmd)
	out, e := cmd.Output()
	if e != nil {
		log.Error("cannot converting Excel to "+format+":", m.Upload, e)
		return
	} else { // success
		log.Info("convert to "+format, m.Upload, " output: ", string(out))
	}

	_, name := filepath.Split(m.filePath())

	src := dir + string(os.PathSeparator) + fileNameWithoutExtTrimSuffix(name) + "." + format
	e = os.Rename(src, dst) // there should be only one jpg

	return
}

// first page to thumbnail
// all page to single jpg
func (m *uploadsOnDisk) convertPDFToJpg() (e error) {

	if fileExists(m.jpgPath()) {
		// no need to reconvert it again
		log.Info("PDF to JPG skipped it already exists ", m)
		return
	}

	dir, e := ioutil.TempDir(config.TempDir, "tmp-convert-pdf-to-jpg-")
	if e != nil {
		log.Error("cannot create tmp dir for converting image", m.Upload, e)
		return
	}
	defer os.RemoveAll(dir)

	// convert -density 3000  abc.pdf  path/tmp/result.png
	// could be path/tmp/result-0, result-1, result-2, ... png
	target := dir + string(os.PathSeparator) + "result.jpg" //.jpg suffix is important
	cmd := exec.Command("convert", "-density", "300", m.filePath(), target)
	strCmd := cmd.String()
	log.Debug("command is ", strCmd)
	out, e := cmd.Output()
	if e != nil {
		log.Error("cannot create png file for PDF", m.Upload, e)
		return
	} else {
		log.Info("convert ", m.Upload, " output: ", string(out))
	}

	// montage -mode concatenate -tile 1x 30*png 30.jpg
	if fileExists(target) { // single file,
		e = os.Rename(target, m.jpgPath()) // there should be only one jpg
		_ = ConvertImageToThumbnail(target, m.thumbPath(), 256)
	} else { // multi-page, we have -0 -1 -2 -3 -4  files
		firstPage := dir + string(os.PathSeparator) + "result-0.jpg"
		_ = ConvertImageToThumbnail(firstPage, m.thumbPath(), 256)

		batch := dir + string(os.PathSeparator) + "result*jpg" // result* is important
		target = dir + string(os.PathSeparator) + "final.jpg"  // .jpg suffix is important
		cmd = exec.Command("montage", "-mode", "concatenate", "-tile", "1x", batch, target)

		strCmd = cmd.String()
		log.Debug("command is ", strCmd)
		out, e = cmd.Output()
		if e != nil {
			return
		} else {
			log.Info("montage ", m, " output: ", string(out))
		}
		e = os.Rename(target, m.jpgPath()) // give combined file to target
	}
	return
}

func (m *uploadsOnDisk) GetFileType() (ret string, e error) {
	strMime, e := GetFileContentType(m.filePath())
	if e != nil {
		return
	}

	if strings.ToLower(strMime) == "application/pdf" {
		return "pdf", nil
	}

	if strings.ToLower(strMime) == "application/vnd.ms-excel" {
		return "excel", nil
	}

	if strings.ToLower(strMime) == "application/zip" &&
		strings.ToLower(m.Upload.Format) ==
			"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" {
		return "opensheet", nil
	}

	return "", nil
}

// tested, not accurate with xls, xlsx, it becomes zip and octstream sometime.
func GetFileContentType(filename string) (contentType string, e error) {
	contentType = ""
	input, e := os.OpenFile(filename, os.O_RDONLY, 0755)
	// Only the first 512 bytes are used to sniff the content type.
	buffer := make([]byte, 512)

	_, e = input.Read(buffer)
	if e != nil {
		return
	}

	// Use the net/http package's handy DectectContentType function. Always returns a valid
	// content-type by returning "application/octet-stream" if no others seemed to match.
	contentType = http.DetectContentType(buffer)
	return
}

func ConvertImageToThumbnail(srcPath string, dstPath string, size int) (e error) {
	if fileExists(dstPath) {
		log.Info("skip converting thumbnail it exists", dstPath)
		return
	}
	if size <= 0 {
		size = 256
	}
	// convert -thumbnail 200 abc.png thumb.abc.png
	cmd := exec.Command("convert", "-thumbnail", strconv.Itoa(size), srcPath, dstPath)
	strCmd := cmd.String()
	log.Debug("create thumbnail: ", strCmd)

	out, e := cmd.Output()
	if e != nil {
		return
	} else { // success
		log.Info("success output: \n: ", string(out))
	}
	return
}

func fileNameWithoutExtTrimSuffix(fileName string) string {
	return strings.TrimSuffix(fileName, filepath.Ext(fileName))
}