/*
   Copyright (c) 2016 VMware, Inc. 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 auth

import (
	"crypto/tls"
	"fmt"
	"net/http"

	au "github.com/docker/distribution/registry/client/auth"
	"github.com/vmware/harbor/utils/registry/utils"
)

// Authorizer authorizes requests according to the schema
type Authorizer interface {
	// Scheme : basic, bearer
	Scheme() string
	//Authorize adds basic auth or token auth to the header of request
	Authorize(req *http.Request, params map[string]string) error
}

// AuthorizerStore holds a authorizer list, which will authorize request.
// And it implements interface Modifier
type AuthorizerStore struct {
	authorizers []Authorizer
	challenges  []au.Challenge
}

// NewAuthorizerStore ...
func NewAuthorizerStore(endpoint string, insecure bool, authorizers ...Authorizer) (*AuthorizerStore, error) {
	endpoint = utils.FormatEndpoint(endpoint)

	client := &http.Client{
		Transport: &http.Transport{
			TLSClientConfig: &tls.Config{
				InsecureSkipVerify: insecure,
			},
		},
	}

	resp, err := client.Get(buildPingURL(endpoint))
	if err != nil {
		return nil, err
	}

	challenges := ParseChallengeFromResponse(resp)
	return &AuthorizerStore{
		authorizers: authorizers,
		challenges:  challenges,
	}, nil
}

func buildPingURL(endpoint string) string {
	return fmt.Sprintf("%s/v2/", endpoint)
}

// Modify adds authorization to the request
func (a *AuthorizerStore) Modify(req *http.Request) error {
	for _, challenge := range a.challenges {
		for _, authorizer := range a.authorizers {
			if authorizer.Scheme() == challenge.Scheme {
				if err := authorizer.Authorize(req, challenge.Parameters); err != nil {
					return err
				}
			}
		}
	}

	return nil
}