/*
Copyright The Helm Authors.

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.
*/

package util

import (
	"archive/tar"
	"compress/gzip"
	"encoding/json"
	"errors"
	"fmt"
	"io/fs"
	"os"
	"path/filepath"
	"time"

	"sigs.k8s.io/yaml"

	chart "helm.sh/helm/v4/internal/chart/v3"
	"helm.sh/helm/v4/pkg/chart/common"
)

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

// SaveDir saves a chart as files in a directory.
//
// This takes the chart name, and creates a new subdirectory inside of the given dest
// directory, writing the chart's contents to that subdirectory.
func SaveDir(c *chart.Chart, dest string) error {
	// Create the chart directory
	err := validateName(c.Name())
	if err != nil {
		return err
	}
	outdir := filepath.Join(dest, c.Name())
	if fi, err := os.Stat(outdir); err == nil && !fi.IsDir() {
		return fmt.Errorf("file %s already exists and is not a directory", outdir)
	}
	if err := os.MkdirAll(outdir, 0o755); err != nil {
		return err
	}

	// Save the chart file.
	if err := SaveChartfile(filepath.Join(outdir, ChartfileName), c.Metadata); err != nil {
		return err
	}

	// Save values.yaml
	for _, f := range c.Raw {
		if f.Name == ValuesfileName {
			vf := filepath.Join(outdir, ValuesfileName)
			if err := writeFile(vf, f.Data); err != nil {
				return err
			}
		}
	}

	// Save values.schema.json if it exists
	if c.Schema != nil {
		filename := filepath.Join(outdir, SchemafileName)
		if err := writeFile(filename, c.Schema); err != nil {
			return err
		}
	}

	// Save templates and files
	for _, o := range [][]*common.File{c.Templates, c.Files} {
		for _, f := range o {
			n := filepath.Join(outdir, f.Name)
			if err := writeFile(n, f.Data); err != nil {
				return err
			}
		}
	}

	// Save dependencies
	base := filepath.Join(outdir, ChartsDir)
	for _, dep := range c.Dependencies() {
		// Here, we write each dependency as a tar file.
		if _, err := Save(dep, base); err != nil {
			return fmt.Errorf("saving %s: %w", dep.ChartFullPath(), err)
		}
	}
	return nil
}

// 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) {
	if err := c.Validate(); err != nil {
		return "", fmt.Errorf("chart validation: %w", err)
	}

	filename := fmt.Sprintf("%s-%s.tgz", c.Name(), c.Metadata.Version)
	filename = filepath.Join(outDir, filename)
	dir := filepath.Dir(filename)
	if stat, err := os.Stat(dir); err != nil {
		if !errors.Is(err, fs.ErrNotExist) {
			return "", fmt.Errorf("stat %s: %w", dir, err)
		}
		if err2 := os.MkdirAll(dir, 0o755); err2 != nil {
			return "", err2
		}
	} else if !stat.IsDir() {
		return "", fmt.Errorf("is not a directory: %s", dir)
	}

	f, err := os.Create(filename)
	if err != nil {
		return "", err
	}

	// Wrap in gzip writer
	zipper := gzip.NewWriter(f)
	zipper.Extra = headerBytes
	zipper.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
	}
	return filename, nil
}

func writeTarContents(out *tar.Writer, c *chart.Chart, prefix string) error {
	err := validateName(c.Name())
	if err != nil {
		return err
	}
	base := filepath.Join(prefix, c.Name())

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

	// Save Chart.lock
	if c.Lock != nil {
		ldata, err := yaml.Marshal(c.Lock)
		if err != nil {
			return err
		}
		if err := writeToTar(out, filepath.Join(base, "Chart.lock"), ldata, c.Lock.Generated); err != nil {
			return err
		}
	}

	// Save values.yaml
	for _, f := range c.Raw {
		if f.Name == ValuesfileName {
			if err := writeToTar(out, filepath.Join(base, ValuesfileName), f.Data, f.ModTime); err != nil {
				return err
			}
		}
	}

	// Save values.schema.json if it exists
	if c.Schema != nil {
		if !json.Valid(c.Schema) {
			return errors.New("invalid JSON in " + SchemafileName)
		}
		if err := writeToTar(out, filepath.Join(base, SchemafileName), c.Schema, c.SchemaModTime); err != nil {
			return err
		}
	}

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

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

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

// writeToTar writes a single file to a tar archive.
func writeToTar(out *tar.Writer, name string, body []byte, modTime time.Time) error {
	// TODO: Do we need to create dummy parent directory names if none exist?
	h := &tar.Header{
		Name:    filepath.ToSlash(name),
		Mode:    0o644,
		Size:    int64(len(body)),
		ModTime: modTime,
	}
	if h.ModTime.IsZero() {
		h.ModTime = time.Now()
	}
	if err := out.WriteHeader(h); err != nil {
		return err
	}
	_, err := out.Write(body)
	return err
}

// If the name has directory name has characters which would change the location
// they need to be removed.
func validateName(name string) error {
	nname := filepath.Base(name)

	if nname != name {
		return common.ErrInvalidChartName{Name: name}
	}

	return nil
}