package autorest

// Copyright 2017 Microsoft Corporation

//

//  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.

import (

	"fmt"

	"net/http"

	"strings"

)

// SASTokenAuthorizer implements an authorization for SAS Token Authentication

// this can be used for interaction with Blob Storage Endpoints

type SASTokenAuthorizer struct {

	sasToken string

}

// NewSASTokenAuthorizer creates a SASTokenAuthorizer using the given credentials

func NewSASTokenAuthorizer(sasToken string) (*SASTokenAuthorizer, error) {

	if strings.TrimSpace(sasToken) == "" {

		return nil, fmt.Errorf("sasToken cannot be empty")

	}

	token := sasToken

	if strings.HasPrefix(sasToken, "?") {

		token = strings.TrimPrefix(sasToken, "?")

	}

	return &SASTokenAuthorizer{

		sasToken: token,

	}, nil

}

// WithAuthorization returns a PrepareDecorator that adds a shared access signature token to the

// URI's query parameters.  This can be used for the Blob, Queue, and File Services.

//

// See https://docs.microsoft.com/en-us/rest/api/storageservices/delegate-access-with-shared-access-signature

func (sas *SASTokenAuthorizer) WithAuthorization() PrepareDecorator {

	return func(p Preparer) Preparer {

		return PreparerFunc(func(r *http.Request) (*http.Request, error) {

			r, err := p.Prepare(r)

			if err != nil {

				return r, err

			}

			if r.URL.RawQuery != "" {

				r.URL.RawQuery = fmt.Sprintf("%s&%s", r.URL.RawQuery, sas.sasToken)

			} else {

				r.URL.RawQuery = sas.sasToken

			}

			r.RequestURI = r.URL.String()

			return Prepare(r)

		})

	}

}