package Archive

import (
	"PackageManager/Variables"
	"archive/tar"
	"compress/gzip"
	"io"
	"os"
	"strings"
)

func CreateArchive(files []string, target string) error {
	var (
		outFile    *os.File
		gzipWriter *gzip.Writer
		tarWriter  *tar.Writer
		file       string
		err        error
	)

	// Create output file
	outFile, err = os.Create(target)
	if err != nil {
		return err
	}
	defer outFile.Close()

	gzipWriter = gzip.NewWriter(outFile)
	defer gzipWriter.Close()
	tarWriter = tar.NewWriter(gzipWriter)
	defer tarWriter.Close()

	// Iterate over files and add them to the tar archive

	for _, file = range files {
		err = addToArchive(tarWriter, file)
		if err != nil {
			return err
		}
	}

	return nil
}

func addToArchive(tarWriter *tar.Writer, filename string) error {
	var (
		file   *os.File
		info   os.FileInfo
		header *tar.Header
		err    error
	)

	// Get FileInfo about our file providing file size, mode, etc.
	info, err = os.Lstat(filename)
	if err != nil {
		return err
	}

	// Create a tar Header from the FileInfo data
	header, err = tar.FileInfoHeader(info, info.Name())
	if err != nil {
		return err
	}

	isSymlink := info.Mode()&os.ModeSymlink != 0
	if isSymlink {
		header.Typeflag = tar.TypeSymlink
	}

	// Use full path as name (FileInfoHeader only takes the basename)
	// If we don't do this the directory strucuture would
	// not be preserved
	// https://golang.org/src/archive/tar/common.go?#L626
	header.Name = strings.TrimPrefix(
		strings.TrimPrefix(
			filename,
			Variables.RootDir,
		),
		"/",
	)

	// Write file header to the tar archive
	err = tarWriter.WriteHeader(header)
	if err != nil {
		return err
	}

	// Do not write file if it is a symlink
	if isSymlink {
		return nil
	}

	// Open the file which will be written into the archive
	file, err = os.Open(filename)
	if err != nil {
		return err
	}
	defer file.Close()

	// Copy file content to tar archive
	_, err = io.Copy(tarWriter, file)
	if err != nil {
		return err
	}

	return nil
}