/*
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 loader

import (
	"bytes"
	"os"
	"path/filepath"
	"strings"

	"github.com/ghodss/yaml"
	"github.com/pkg/errors"

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

// ChartLoader loads a chart.
type ChartLoader interface {
	Load() (*chart.Chart, error)
}

// Loader returns a new ChartLoader appropriate for the given chart name
func Loader(name string) (ChartLoader, error) {
	fi, err := os.Stat(name)
	if err != nil {
		return nil, err
	}
	if fi.IsDir() {
		return DirLoader(name), nil
	}
	return FileLoader(name), nil

}

// Load takes a string name, tries to resolve it to a file or directory, and then loads it.
//
// This is the preferred way to load a chart. It will discover the chart encoding
// and hand off to the appropriate chart reader.
//
// If a .helmignore file is present, the directory loader will skip loading any files
// matching it. But .helmignore is not evaluated when reading out of an archive.
func Load(name string) (*chart.Chart, error) {
	l, err := Loader(name)
	if err != nil {
		return nil, err
	}
	return l.Load()
}

// BufferedFile represents an archive file buffered for later processing.
type BufferedFile struct {
	Name string
	Data []byte
}

// LoadFiles loads from in-memory files.
func LoadFiles(files []*BufferedFile) (*chart.Chart, error) {
	c := new(chart.Chart)
	subcharts := make(map[string][]*BufferedFile)

	for _, f := range files {
		switch {
		case f.Name == "Chart.yaml":
			c.Metadata = new(chart.Metadata)
			if err := yaml.Unmarshal(f.Data, c.Metadata); err != nil {
				return c, errors.Wrap(err, "cannot load Chart.yaml")
			}
		case f.Name == "Chart.lock":
			c.Lock = new(chart.Lock)
			if err := yaml.Unmarshal(f.Data, &c.Lock); err != nil {
				return c, errors.Wrap(err, "cannot load Chart.lock")
			}
		case f.Name == "values.yaml":
			c.Values = make(map[string]interface{})
			if err := yaml.Unmarshal(f.Data, &c.Values); err != nil {
				return c, errors.Wrap(err, "cannot load values.yaml")
			}
			c.RawValues = f.Data
		case strings.HasPrefix(f.Name, "templates/"):
			c.Templates = append(c.Templates, &chart.File{Name: f.Name, Data: f.Data})
		case strings.HasPrefix(f.Name, "charts/"):
			if filepath.Ext(f.Name) == ".prov" {
				c.Files = append(c.Files, &chart.File{Name: f.Name, Data: f.Data})
				continue
			}

			fname := strings.TrimPrefix(f.Name, "charts/")
			cname := strings.SplitN(fname, "/", 2)[0]
			subcharts[cname] = append(subcharts[cname], &BufferedFile{Name: fname, Data: f.Data})
		default:
			c.Files = append(c.Files, &chart.File{Name: f.Name, Data: f.Data})
		}
	}

	// Ensure that we got a Chart.yaml file
	if c.Metadata == nil {
		return c, errors.New("chart metadata (Chart.yaml) missing")
	}
	if c.Name() == "" {
		return c, errors.New("invalid chart (Chart.yaml): name must not be empty")
	}

	for n, files := range subcharts {
		var sc *chart.Chart
		var err error
		switch {
		case strings.IndexAny(n, "_.") == 0:
			continue
		case filepath.Ext(n) == ".tgz":
			file := files[0]
			if file.Name != n {
				return c, errors.Errorf("error unpacking tar in %s: expected %s, got %s", c.Name(), n, file.Name)
			}
			// Untar the chart and add to c.Dependencies
			sc, err = LoadArchive(bytes.NewBuffer(file.Data))
		default:
			// We have to trim the prefix off of every file, and ignore any file
			// that is in charts/, but isn't actually a chart.
			buff := make([]*BufferedFile, 0, len(files))
			for _, f := range files {
				parts := strings.SplitN(f.Name, "/", 2)
				if len(parts) < 2 {
					continue
				}
				f.Name = parts[1]
				buff = append(buff, f)
			}
			sc, err = LoadFiles(buff)
		}

		if err != nil {
			return c, errors.Wrapf(err, "error unpacking %s in %s", n, c.Name())
		}
		c.AddDependency(sc)
	}

	return c, nil
}