feat(ebooks): add support for mobi to pdf

pkg/files/ebooks/mobi.go

@@ -13,6 +13,8 @@ import (
 	"path/filepath"
 	"slices"
 	"strings"
+
+	"github.com/danvergara/morphos/pkg/files/documents"
 )
 
 type Mobi struct {
@@ -25,13 +27,19 @@ func NewMobi(filename string) Mobi {
 	m := Mobi{
 		filename: filename,
 		compatibleFormats: map[string][]string{
+			"Document": {
+				documents.PDF,
+			},
 			"Ebook": {
 				EPUB,
 			},
 		},
 		compatibleMIMETypes: map[string][]string{
+			"Document": {
+				documents.PDF,
+			},
 			"Ebook": {
-				EPUB,
+				EpubMimeType,
 			},
 		},
 	}
@@ -73,20 +81,150 @@ func (m Mobi) ConvertTo(fileType, subtype string, file io.Reader) (io.Reader, er
 	fileBytes := buf.Bytes()
 
 	switch strings.ToLower(fileType) {
+	case documentType:
+		switch subtype {
+		case PDF:
+			// Create a temporary empty file where the input is gonna be stored.
+			tmpInputMobi, err := os.CreateTemp("", fmt.Sprintf("*.%s", MOBI))
+			if err != nil {
+				return nil, fmt.Errorf("error creating temporary mobi file: %w", err)
+			}
+			defer os.Remove(tmpInputMobi.Name())
+
+			// Write the content of the input pdf into the temporary file.
+			if _, err = tmpInputMobi.Write(fileBytes); err != nil {
+				return nil, fmt.Errorf(
+					"error writting the input reader to the temporary mobi file",
+				)
+			}
+
+			if err := tmpInputMobi.Close(); err != nil {
+				return nil, err
+			}
+
+			pdfFileName := fmt.Sprintf(
+				"%s.%s",
+				strings.TrimSuffix(tmpInputMobi.Name(), filepath.Ext(tmpInputMobi.Name())),
+				PDF,
+			)
+
+			// Parses the file name of the Zip file.
+			zipFileName := fmt.Sprintf(
+				"%s.zip",
+				strings.TrimSuffix(m.filename, filepath.Ext(m.filename)),
+			)
+
+			// Parse the output file name.
+			outputPdfFilename := fmt.Sprintf(
+				"%s.%s",
+				strings.TrimSuffix(m.filename, filepath.Ext(m.filename)),
+				PDF,
+			)
+
+			cmd := exec.Command("ebook-convert", tmpInputMobi.Name(), pdfFileName)
+
+			// 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(pdfFileName)
+			if err != nil {
+				return nil, err
+			}
+			defer os.Remove(cf.Name())
+
+			// 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 epub 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(outputPdfFilename)
+			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 pdf 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 ebookType:
 		switch subtype {
 		case EPUB:
 			// Create a temporary empty file where the input is gonna be stored.
 			tmpInputMobi, err := os.CreateTemp("", fmt.Sprintf("*.%s", MOBI))
 			if err != nil {
-				return nil, fmt.Errorf("error creating temporary pdf file: %w", err)
+				return nil, fmt.Errorf("error creating temporary mobi file: %w", err)
 			}
 			defer os.Remove(tmpInputMobi.Name())
 
 			// Write the content of the input pdf into the temporary file.
 			if _, err = tmpInputMobi.Write(fileBytes); err != nil {
 				return nil, fmt.Errorf(
-					"error writting the input reader to the temporary pdf file",
+					"error writting the input reader to the temporary mobi file",
 				)
 			}