package repo

import (
	"crypto/sha1"
	"errors"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"strings"
	"time"

	"gopkg.in/yaml.v2"

	"github.com/kubernetes/helm/pkg/chart"
)

// ChartRepository represents a chart repository
type ChartRepository struct {
	RootPath   string
	URL        string // URL of repository
	ChartPaths []string
	IndexFile  *IndexFile
}

// RepoFile represents the repositories.yaml file in $HELM_HOME
type RepoFile struct {
	Repositories map[string]string
}

// LoadRepositoriesFile takes a file at the given path and returns a RepoFile object
func LoadRepositoriesFile(path string) (*RepoFile, error) {
	b, err := ioutil.ReadFile(path)
	if err != nil {
		return nil, err
	}

	var r RepoFile
	err = yaml.Unmarshal(b, &r)
	if err != nil {
		return nil, err
	}

	return &r, nil
}

// UnmarshalYAML unmarshals the repo file
func (rf *RepoFile) UnmarshalYAML(unmarshal func(interface{}) error) error {
	var repos map[string]string
	if err := unmarshal(&repos); err != nil {
		if _, ok := err.(*yaml.TypeError); !ok {
			return err
		}
	}
	rf.Repositories = repos
	return nil
}

// LoadChartRepository takes in a path to a local chart repository
//      which contains packaged charts and an index.yaml file
//
// This function evaluates the contents of the directory and
// returns a ChartRepository
func LoadChartRepository(dir, url string) (*ChartRepository, error) {
	dirInfo, err := os.Stat(dir)
	if err != nil {
		return nil, err
	}

	if !dirInfo.IsDir() {
		return nil, errors.New(dir + "is not a directory")
	}

	r := &ChartRepository{RootPath: dir, URL: url}

	filepath.Walk(dir, func(path string, f os.FileInfo, err error) error {
		if !f.IsDir() {
			if strings.Contains(f.Name(), "index.yaml") {
				i, err := LoadIndexFile(path)
				if err != nil {
					return nil
				}
				r.IndexFile = i
			} else {
				// TODO: check for tgz extension
				r.ChartPaths = append(r.ChartPaths, path)
			}
		}
		return nil
	})

	return r, nil
}

func (r *ChartRepository) saveIndexFile() error {
	index, err := yaml.Marshal(&r.IndexFile.Entries)
	if err != nil {
		return err
	}

	if err = ioutil.WriteFile(filepath.Join(r.RootPath, indexPath), index, 0644); err != nil {
		return err
	}

	return nil
}

func (r *ChartRepository) Index() error {
	if r.IndexFile == nil {
		r.IndexFile = &IndexFile{Entries: make(map[string]*ChartRef)}
	}

	for _, path := range r.ChartPaths {
		ch, err := chart.Load(path)
		if err != nil {
			return err
		}

		chartfile := ch.Chartfile()
		hash, err := generateChecksum(path)
		if err != nil {
			return err
		}

		key := chartfile.Name + "-" + chartfile.Version
		if r.IndexFile.Entries == nil {
			r.IndexFile.Entries = make(map[string]*ChartRef)
		}

		ref, ok := r.IndexFile.Entries[key]
		var created string
		if ok && ref.Created != "" {
			created = ref.Created
		} else {
			created = time.Now().UTC().String()
		}

		url := filepath.Join(r.URL, key+".tgz")

		entry := &ChartRef{Chartfile: *chartfile, Name: chartfile.Name, URL: url, Created: created, Checksum: hash, Removed: false}

		r.IndexFile.Entries[key] = entry

	}

	if err := r.saveIndexFile(); err != nil {
		return err
	}

	return nil
}

func generateChecksum(path string) (string, error) {
	f, err := os.Open(path)
	if err != nil {
		return "", err
	}

	b, err := ioutil.ReadAll(f)
	if err != nil {
		return "", err
	}

	result := sha1.Sum(b)

	return fmt.Sprintf("%x", result), nil
}