stamp.go

package fillpdf

/*
 *  FillPDF - Fill PDF forms, with extentions
 *  Copyright
 *  PKG Author: Roland Singer
 *  File Author: Alexander Félix
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

import (
	"bytes"
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"os/exec"
	"path/filepath"
)

// Multistamp stamps one PDF ontop of another, returns a reader to bytes generated.
func Multistamp(stampontoPDFFile, stampPDFFile string) (io.Reader, error) {
	var err error

	// Check if the pdftk utility exists.
	if _, err := exec.LookPath("pdftk"); err != nil {
		return nil, err
	}

	if stampontoPDFFile, err = getAbs(stampontoPDFFile); err != nil {
		return nil, err
	}

	stampPDFFile, err = getAbs(stampPDFFile)
	if err != nil {
		return nil, err
	}

	// Create a temporary directory.
	tmpDir, err := ioutil.TempDir("", "fillpdf-")
	if err != nil {
		return nil, err
	}

	// Remove the temporary directory on defer again.
	defer func() {
		os.RemoveAll(tmpDir)
	}()

	// Create the temporary output file path.
	outputFile := filepath.Clean(tmpDir + "/output.pdf")

	// Create the pdftk command line arguments.
	args := []string{
		stampontoPDFFile,
		"multistamp", stampPDFFile,
		"output", outputFile,
	}

	// Run the pdftk utility.
	err = runCommandInPath(tmpDir, "pdftk", args...)
	if err != nil {
		return nil, fmt.Errorf("pdftk error: %v", err)
	}

	fb, err := ioutil.ReadFile(outputFile)
	if err != nil {
		return nil, err
	}

	return bytes.NewReader(fb), nil
}