feat(documents): add support for pdf to mobi

pkg/files/documents/documents.go

@@ -11,6 +11,9 @@ const (
 	EpubMimeType = "epub+zip"
 	EPUB         = "epub"
 
+	MOBI         = "mobi"
+	MobiMimeType = "x-mobipocket-ebook"
+
 	imageMimeType = "image/"
 	imageType     = "image"
 

pkg/files/documents/documents_test.go

@@ -38,6 +38,19 @@ func TestPDFTConvertTo(t *testing.T) {
 		input    input
 		expected expected
 	}{
+		{
+			name: "pdf to mobi",
+			input: input{
+				filename:       "testdata/bitcoin.pdf",
+				mimetype:       "application/pdf",
+				targetFileType: "Ebook",
+				targetFormat:   "mobi",
+				documenter:     documents.NewPdf("bitcoin.pdf"),
+			},
+			expected: expected{
+				mimetype: "application/zip",
+			},
+		},
 		{
 			name: "pdf to epub",
 			input: input{

pkg/files/documents/pdf.go

@@ -52,6 +52,7 @@ func NewPdf(filename string) Pdf {
 			},
 			"Ebook": {
 				EPUB,
+				MOBI,
 			},
 		},
 		compatibleMIMETypes: map[string][]string{
@@ -66,10 +67,10 @@ func NewPdf(filename string) Pdf {
 			},
 			"Document": {
 				DOCXMIMEType,
-				EpubMimeType,
 			},
 			"Ebook": {
 				EpubMimeType,
+				MobiMimeType,
 			},
 		},
 	}
@@ -110,6 +111,7 @@ func (p Pdf) ConvertTo(fileType, subType string, file io.Reader) (io.Reader, err
 			err,
 		)
 	}
+
 	fileBytes := buf.Bytes()
 
 	// If the file type is valid, figures out how to go ahead.
@@ -514,7 +516,140 @@ func (p Pdf) ConvertTo(fileType, subType string, file io.Reader) (io.Reader, err
 
 			if _, err := io.Copy(w1, cf); err != nil {
 				return nil, fmt.Errorf(
-					"error at writing the docx file content to the zip writer: %w",
+					"error at writing the epub file content to the zip writer: %w",
+					err,
+				)
+			}
+
+			// Closes both zip writer and the zip file after its done with the writing.
+			zipWriter.Close()
+			archive.Close()
+
+			// Reads the zip file as an slice of bytes.
+			zipFile, err := os.ReadFile(archive.Name())
+			if err != nil {
+				return nil, fmt.Errorf("error reading zip file: %v", err)
+			}
+
+			return bytes.NewReader(zipFile), nil
+		case MOBI:
+			// Create a temporary empty file where the input pdf is gonna be stored.
+			tmpInputPDF, err := os.Create(
+				fmt.Sprintf(
+					"/tmp/%s.%s",
+					strings.TrimSuffix(p.filename, filepath.Ext(p.filename)),
+					PDF,
+				),
+			)
+			if err != nil {
+				return nil, fmt.Errorf("error creating temporary pdf file: %w", err)
+			}
+			defer os.Remove(tmpInputPDF.Name())
+
+			// Write the content of the input pdf into the temporary file.
+			if _, err = tmpInputPDF.Write(fileBytes); err != nil {
+				return nil, fmt.Errorf(
+					"error writting the input reader to the temporary pdf file",
+				)
+			}
+
+			if err := tmpInputPDF.Close(); err != nil {
+				return nil, err
+			}
+
+			mobiName := fmt.Sprintf(
+				"%s.%s",
+				strings.TrimSuffix(tmpInputPDF.Name(), filepath.Ext(tmpInputPDF.Name())),
+				MOBI,
+			)
+
+			cmd := exec.Command("ebook-convert", tmpInputPDF.Name(), mobiName)
+
+			// Capture stdout.
+			stdout, err := cmd.StdoutPipe()
+			if err != nil {
+				return nil, err
+			}
+
+			// Capture stderr.
+			stderr, err := cmd.StderrPipe()
+			if err != nil {
+				return nil, err
+			}
+
+			// Start the command.
+			if err := cmd.Start(); err != nil {
+				return nil, err
+			}
+			// Create readers to read stdout and stderr.
+			stdoutScanner := bufio.NewScanner(stdout)
+			stderrScanner := bufio.NewScanner(stderr)
+
+			// Read stdout line by line.
+			go func() {
+				for stdoutScanner.Scan() {
+					log.Println("STDOUT:", stdoutScanner.Text())
+				}
+			}()
+
+			// Read stderr line by line.
+			go func() {
+				for stderrScanner.Scan() {
+					log.Println("STDERR:", stderrScanner.Text())
+				}
+			}()
+
+			// Wait for the command to finish.
+			if err := cmd.Wait(); err != nil {
+				return nil, err
+			}
+
+			// Open the converted file to get the bytes out of it,
+			// and then turning them into a io.Reader.
+			cf, err := os.Open(mobiName)
+			if err != nil {
+				return nil, err
+			}
+			defer os.Remove(cf.Name())
+
+			// Parse the file name of the Zip file.
+			zipFileName := fmt.Sprintf(
+				"%s.zip",
+				strings.TrimSuffix(p.filename, filepath.Ext(p.filename)),
+			)
+
+			// Parse the output file name.
+			outputMobiFilename := fmt.Sprintf(
+				"%s.%s",
+				strings.TrimSuffix(p.filename, filepath.Ext(p.filename)),
+				MOBI,
+			)
+
+			// Creates the zip file that will be returned.
+			archive, err := os.CreateTemp("", zipFileName)
+			if err != nil {
+				return nil, fmt.Errorf(
+					"error at creating the zip file to store the mobi file: %w",
+					err,
+				)
+			}
+			defer os.Remove(archive.Name())
+
+			// Creates a Zip Writer to add files later on.
+			zipWriter := zip.NewWriter(archive)
+
+			// Adds the image to the zip file.
+			w1, err := zipWriter.Create(outputMobiFilename)
+			if err != nil {
+				return nil, fmt.Errorf(
+					"error creating the zip writer: %w",
+					err,
+				)
+			}
+
+			if _, err := io.Copy(w1, cf); err != nil {
+				return nil, fmt.Errorf(
+					"error at writing the epub file content to the zip writer: %w",
 					err,
 				)
 			}

pkg/files/ebooks/epub.go

@@ -40,7 +40,7 @@ func NewEpub(filename string) Epub {
 				documents.PDF,
 			},
 			"Ebook": {
-				MOBI,
+				MobiMimeType,
 			},
 		},
 	}