Read pdf image via tesseract

pdf.go

@@ -3,12 +3,110 @@ package docconv
 import (
 	"fmt"
 	"io"
+	"io/ioutil"
 	"log"
+	"os"
 	"os/exec"
+	"path/filepath"
 	"strings"
+	"sync"
 	"time"
 )
 
+var (
+	exts = []string{".jpg", ".tif", ".tiff", ".png"}
+)
+
+var pdfMutex struct {
+	sync.Mutex
+}
+
+func compareExt(ext string, exts []string) bool {
+	for _, e := range exts {
+		if ext == e {
+			return true
+		}
+	}
+	return false
+}
+
+func PDFImages(path string) (string, map[string]string, error) {
+	tmp, err := ioutil.TempDir("/tmp", "tmp-imgs-")
+	if err != nil {
+		log.Println(err)
+		return "", nil, err
+	}
+	tmpDir := fmt.Sprintf("%s/", tmp)
+	defer os.RemoveAll(tmpDir)
+
+	_, err = exec.Command("pdfimages", "-j", path, tmpDir).Output()
+	if err != nil {
+		return "", nil, err
+	}
+
+	files := []string{}
+
+	walkFunc := func(path string, info os.FileInfo, err error) error {
+		path, err = filepath.Abs(path)
+		if err != nil {
+			return err
+		}
+
+		if compareExt(filepath.Ext(path), exts) == true {
+			files = append(files, path)
+		}
+		return nil
+	}
+	filepath.Walk(tmpDir, walkFunc)
+
+	var wg sync.WaitGroup
+	m := make(map[int]string)
+
+	wg.Add(len(files))
+	for indx, p := range files {
+		go func(idx int, pathFile string, m map[int]string, ww *sync.WaitGroup) {
+			defer ww.Done()
+			f, err := os.Open(pathFile)
+			if err != nil {
+				log.Println(err)
+			}
+			out, _, err := ConvertImage(f)
+			if err != nil {
+				log.Println(err)
+			}
+
+			pdfMutex.Lock()
+			m[idx] = out
+			pdfMutex.Unlock()
+
+			f.Close()
+		}(indx, p, m, &wg)
+	}
+	wg.Wait()
+
+	o := make([]string, len(m))
+
+	for i := 0; i < len(m); i++ {
+		o = append(o, m[i])
+	}
+
+	return strings.Join(o, " "), nil, nil
+}
+
+// PdfHasImage verify if `path` (PDF) has images
+func PDFHasImage(path string) bool {
+	cmd := "pdffonts -l 5 %s | tail -n +3 | cut -d' ' -f1 | sort | uniq"
+	out, err := exec.Command("bash", "-c", fmt.Sprintf(cmd, path)).Output()
+	if err != nil {
+		log.Println(err)
+		return false
+	}
+	if string(out) == "" {
+		return true
+	}
+	return false
+}
+
 // Convert PDF
 func ConvertPDF(r io.Reader) (string, map[string]string, error) {
 	f, err := NewLocalFile(r, "/tmp", "sajari-convert-")
@@ -17,6 +115,11 @@ func ConvertPDF(r io.Reader) (string, map[string]string, error) {
 	}
 	defer f.Done()
 
+	// Verify if pdf has images or is pdf only-text
+	if PDFHasImage(f.Name()) {
+		return PDFImages(f.Name())
+	}
+
 	// Meta data
 	mc := make(chan map[string]string, 1)
 	go func() {
@@ -52,7 +155,6 @@ func ConvertPDF(r io.Reader) (string, map[string]string, error) {
 
 		mc <- meta
 	}()
-
 	// Document body
 	bc := make(chan string, 1)
 	go func() {