package chartutil

import (
	"archive/tar"
	"compress/gzip"
	"errors"
	"fmt"
	"os"
	"path/filepath"

	"github.com/ghodss/yaml"

	"k8s.io/helm/pkg/proto/hapi/chart"
)

var headerBytes = []byte("+aHR0cHM6Ly95b3V0dS5iZS96OVV6MWljandyTQo=")

// Save creates an archived chart to the given directory.
//
// This takes an existing chart and a destination directory.
//
// If the directory is /foo, and the chart is named bar, with version 1.0.0, this
// will generate /foo/bar-1.0.0.tgz.
//
// This returns the absolute path to the chart archive file.
func Save(c *chart.Chart, outDir string) (string, error) {
	// Create archive
	if fi, err := os.Stat(outDir); err != nil {
		return "", err
	} else if !fi.IsDir() {
		return "", fmt.Errorf("location %s is not a directory", outDir)
	}

	if c.Metadata == nil {
		return "", errors.New("no Chart.yaml data")
	}

	cfile := c.Metadata
	if cfile.Name == "" {
		return "", errors.New("no chart name specified (Chart.yaml)")
	} else if cfile.Version == "" {
		return "", errors.New("no chart version specified (Chart.yaml)")
	}

	filename := fmt.Sprintf("%s-%s.tgz", cfile.Name, cfile.Version)
	filename = filepath.Join(outDir, filename)
	f, err := os.Create(filename)
	if err != nil {
		return "", err
	}

	// Wrap in gzip writer
	zipper := gzip.NewWriter(f)
	zipper.Header.Extra = headerBytes
	zipper.Header.Comment = "Helm"

	// Wrap in tar writer
	twriter := tar.NewWriter(zipper)
	rollback := false
	defer func() {
		twriter.Close()
		zipper.Close()
		f.Close()
		if rollback {
			os.Remove(filename)
		}
	}()

	if err := writeTarContents(twriter, c, ""); err != nil {
		rollback = true
	}
	return filename, err
}

func writeTarContents(out *tar.Writer, c *chart.Chart, prefix string) error {
	base := filepath.Join(prefix, c.Metadata.Name)

	// Save Chart.yaml
	cdata, err := yaml.Marshal(c.Metadata)
	if err != nil {
		return err
	}
	if err := writeToTar(out, base+"/Chart.yaml", cdata); err != nil {
		return err
	}

	// Save values.yaml
	if c.Values != nil && len(c.Values.Raw) > 0 {
		if err := writeToTar(out, base+"/values.yaml", []byte(c.Values.Raw)); err != nil {
			return err
		}
	}

	// Save templates
	for _, f := range c.Templates {
		n := filepath.Join(base, f.Name)
		if err := writeToTar(out, n, f.Data); err != nil {
			return err
		}
	}

	// Save files
	for _, f := range c.Files {
		n := filepath.Join(base, f.TypeUrl)
		if err := writeToTar(out, n, f.Value); err != nil {
			return err
		}
	}

	// Save dependencies
	for _, dep := range c.Dependencies {
		if err := writeTarContents(out, dep, base+"/charts"); err != nil {
			return err
		}
	}
	return nil
}

// writeToTar writes a single file to a tar archive.
func writeToTar(out *tar.Writer, name string, body []byte) error {
	// TODO: Do we need to create dummy parent directory names if none exist?
	h := &tar.Header{
		Name: name,
		Mode: 0755,
		Size: int64(len(body)),
	}
	if err := out.WriteHeader(h); err != nil {
		return err
	}
	if _, err := out.Write(body); err != nil {
		return err
	}
	return nil
}