/*
Copyright 2015 The Kubernetes Authors All rights reserved.

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 chart

import (
	"errors"
	"fmt"
	"net/url"
	"regexp"
	"strings"
)

// ErrLocal indicates that a local URL was used as a remote URL.
var ErrLocal = errors.New("cannot use local Locator as remote")

// ErrRemote indicates that a remote URL was used as a local URL.
var ErrRemote = errors.New("cannot use remote Locator as local")

// Constants defining recognized URL schemes.
const (
	SchemeHTTP  = "http"
	SchemeHTTPS = "https"
	SchemeHelm  = "helm"
	SchemeFile  = "file"
)

// TarNameRegex parses the name component of a URI and breaks it into a name and version.
//
// This borrows liberally from github.com/Masterminds/semver.
const TarNameRegex = `([0-9A-Za-z\-_/]+)-(v?([0-9]+)(\.[0-9]+)?(\.[0-9]+)?` +
	`(-([0-9A-Za-z\-]+(\.[0-9A-Za-z\-]+)*))?` +
	`(\+([0-9A-Za-z\-]+(\.[0-9A-Za-z\-]+)*))?)(.tgz)?`

var tnregexp *regexp.Regexp

func init() {
	tnregexp = regexp.MustCompile("^" + TarNameRegex + "$")
}

// Locator describes the location of a Chart.
type Locator struct {
	// The scheme of the URL. Typically one of http, https, helm, or file.
	Scheme string
	// The host information, if applicable.
	Host string
	// The bucket name
	Bucket string
	// The chart name
	Name string
	// The version or version range.
	Version string

	// If this is a local chart, the path to the chart.
	LocalRef string

	isLocal bool

	original string
}

// Parse parses a URL into a Locator.
func Parse(path string) (*Locator, error) {
	u, err := url.Parse(path)
	if err != nil {
		return nil, err
	}

	switch u.Scheme {
	case SchemeHelm:
		parts := strings.SplitN(u.Opaque, "/", 3)
		if len(parts) < 3 {
			return nil, fmt.Errorf("both bucket and chart name are required in %s: %s", path, u.Path)
		}
		// Need to parse opaque data into bucket and chart.
		return &Locator{
			Scheme:   u.Scheme,
			Host:     parts[0],
			Bucket:   parts[1],
			Name:     parts[2],
			Version:  u.Fragment,
			original: path,
		}, nil

	case SchemeHTTP, SchemeHTTPS:
		// Long name
		parts := strings.SplitN(u.Path, "/", 3)
		if len(parts) < 3 {
			return nil, fmt.Errorf("both bucket and chart name are required in %s", path)
		}

		name, version, err := parseTarName(parts[2])
		if err != nil {
			return nil, err
		}

		return &Locator{
			Scheme:   u.Scheme,
			Host:     u.Host,
			Bucket:   parts[1],
			Name:     name,
			Version:  version,
			original: path,
		}, nil
	case SchemeFile:
		return &Locator{
			LocalRef: u.Path,
			isLocal:  true,
			original: path,
		}, nil
	default:
		// In this case...
		// - if the path is relative or absolute, return it as-is.
		// - if it's a URL of an unknown scheme, return it as is.
		return &Locator{
			LocalRef: path,
			isLocal:  true,
			original: path,
		}, nil

	}
}

// IsLocal returns true if this is a local path.
func (u *Locator) IsLocal() bool {
	return u.isLocal
}

// Local returns a local version of the path.
//
// This will return an error if the URL does not reference a local chart.
func (u *Locator) Local() (string, error) {
	return u.LocalRef, nil
}

// Short returns a short form URL.
//
// This will return an error if the URL references a local chart.
func (u *Locator) Short() (string, error) {
	if u.IsLocal() {
		return "", ErrLocal
	}
	fname := fmt.Sprintf("%s/%s/%s", u.Host, u.Bucket, u.Name)
	return (&url.URL{
		Scheme:   SchemeHelm,
		Opaque:   fname,
		Fragment: u.Version,
	}).String(), nil
}

// Long returns a long-form URL.
//
// If secure is true, this will return an HTTPS URL, otherwise HTTP.
//
// This will return an error if the URL references a local chart.
func (u *Locator) Long(secure bool) (string, error) {
	if u.IsLocal() {
		return "", ErrLocal
	}

	scheme := SchemeHTTPS
	if !secure {
		scheme = SchemeHTTP
	}
	fname := fmt.Sprintf("%s/%s-%s.tgz", u.Bucket, u.Name, u.Version)

	return (&url.URL{
		Scheme: scheme,
		Host:   u.Host,
		Path:   fname,
	}).String(), nil

}

// parseTarName parses a long-form tarfile name.
func parseTarName(name string) (string, string, error) {
	if strings.HasSuffix(name, ".tgz") {
		name = strings.TrimSuffix(name, ".tgz")
	}
	v := tnregexp.FindStringSubmatch(name)
	if v == nil {
		return name, "", fmt.Errorf("invalid name %s", name)
	}
	return v[1], v[2], nil
}