package gzip

import (
	"compress/gzip"
	"fmt"
	"io"
	"io/fs"
	"os"
	"strings"

	zipper "git.sa-roci.de/oss/go_zipper"
)

const ArchiveExt = ".gz"

// NewZipper makes a new Zipper.
func NewGZipper(gzipFilename string, multiFile bool) zipper.Zipper {
	if !strings.HasSuffix(strings.ToLower(gzipFilename), ArchiveExt) {
		gzipFilename += ArchiveExt
	}
	gzipper := gZipper{
		Zipper:    zipper.NewBaseZipper(gzipFilename),
		multiFile: multiFile,
	}
	gzipper.SetCompressor(&gzipper)
	return gzipper
}

type gZipper struct {
	zipper.Zipper
	output    io.Writer
	multiFile bool
}

func (gz *gZipper) OpenWriter(zipFile *os.File) error {
	gz.SetWriter(gzip.NewWriter(zipFile))
	gz.output = zipFile
	return nil
}

func (gz *gZipper) MultiFileSupported() bool {
	return gz.multiFile
}

func (gz *gZipper) Compress(fileToZip *os.File, pathInArchive string) (err error) {
	// Get the file information
	var info fs.FileInfo
	if info, err = fileToZip.Stat(); err != nil {
		return err
	}

	filename := info.Name()

	if writer, ok := gz.GetWriter().(*gzip.Writer); ok {
		writer.ModTime = info.ModTime()

		// Using FileInfoHeader() above only uses the basename of the file. If we want
		// to preserve the folder structure we can overwrite this with the full path.
		if len(pathInArchive) > 0 || strings.Contains(filename, "/") || strings.Contains(filename, "\\") {
			writer.Name = zipper.PrependPath(filename, pathInArchive)
		} else {
			writer.Name = filename
		}

		if _, err = io.Copy(writer, fileToZip); err == nil {
			flushErr := writer.Flush()
			if err = writer.Close(); err != nil {
				err = flushErr
			} else {
				writer.Reset(gz.output)
			}
		}
	} else {
		err = fmt.Errorf("unable to access compressor")
	}

	return
}