/*
 * MinIO Cloud Storage, (C) 2018 MinIO, Inc.
 *
 * 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 cmd

import (
	"context"
	"encoding/xml"
	"fmt"
	"net/http"

	xhttp "github.com/minio/minio/cmd/http"
	"github.com/minio/minio/cmd/logger"
)

// writeSTSErrorRespone writes error headers
func writeSTSErrorResponse(ctx context.Context, w http.ResponseWriter, errCode STSErrorCode, errCtxt error) {
	err := stsErrCodes.ToSTSErr(errCode)
	// Generate error response.
	stsErrorResponse := STSErrorResponse{}
	stsErrorResponse.Error.Code = err.Code
	stsErrorResponse.RequestID = w.Header().Get(xhttp.AmzRequestID)
	stsErrorResponse.Error.Message = err.Description
	if errCtxt != nil {
		stsErrorResponse.Error.Message = fmt.Sprintf("%v", errCtxt)
	}
	logKind := logger.All
	switch errCode {
	case ErrSTSInternalError, ErrSTSNotInitialized:
		logKind = logger.Minio
	default:
		logKind = logger.Application
	}
	logger.LogIf(ctx, errCtxt, logKind)
	encodedErrorResponse := encodeResponse(stsErrorResponse)
	writeResponse(w, err.HTTPStatusCode, encodedErrorResponse, mimeXML)
}

// STSError structure
type STSError struct {
	Code           string
	Description    string
	HTTPStatusCode int
}

// STSErrorResponse - error response format
type STSErrorResponse struct {
	XMLName xml.Name `xml:"https://sts.amazonaws.com/doc/2011-06-15/ ErrorResponse" json:"-"`
	Error   struct {
		Type    string `xml:"Type"`
		Code    string `xml:"Code"`
		Message string `xml:"Message"`
	} `xml:"Error"`
	RequestID string `xml:"RequestId"`
}

// STSErrorCode type of error status.
type STSErrorCode int

// Error codes, non exhaustive list - http://docs.aws.amazon.com/STS/latest/APIReference/API_AssumeRoleWithSAML.html
const (
	ErrSTSNone STSErrorCode = iota
	ErrSTSAccessDenied
	ErrSTSMissingParameter
	ErrSTSInvalidParameterValue
	ErrSTSWebIdentityExpiredToken
	ErrSTSClientGrantsExpiredToken
	ErrSTSInvalidClientGrantsToken
	ErrSTSMalformedPolicyDocument
	ErrSTSNotInitialized
	ErrSTSInternalError
)

type stsErrorCodeMap map[STSErrorCode]STSError

func (e stsErrorCodeMap) ToSTSErr(errCode STSErrorCode) STSError {
	apiErr, ok := e[errCode]
	if !ok {
		return e[ErrSTSInternalError]
	}
	return apiErr
}

// error code to STSError structure, these fields carry respective
// descriptions for all the error responses.
var stsErrCodes = stsErrorCodeMap{
	ErrSTSAccessDenied: {
		Code:           "AccessDenied",
		Description:    "Generating temporary credentials not allowed for this request.",
		HTTPStatusCode: http.StatusForbidden,
	},
	ErrSTSMissingParameter: {
		Code:           "MissingParameter",
		Description:    "A required parameter for the specified action is not supplied.",
		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrSTSInvalidParameterValue: {
		Code:           "InvalidParameterValue",
		Description:    "An invalid or out-of-range value was supplied for the input parameter.",
		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrSTSWebIdentityExpiredToken: {
		Code:           "ExpiredToken",
		Description:    "The web identity token that was passed is expired or is not valid. Get a new identity token from the identity provider and then retry the request.",
		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrSTSClientGrantsExpiredToken: {
		Code:           "ExpiredToken",
		Description:    "The client grants that was passed is expired or is not valid. Get a new client grants token from the identity provider and then retry the request.",
		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrSTSInvalidClientGrantsToken: {
		Code:           "InvalidClientGrantsToken",
		Description:    "The client grants token that was passed could not be validated by MinIO.",
		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrSTSMalformedPolicyDocument: {
		Code:           "MalformedPolicyDocument",
		Description:    "The request was rejected because the policy document was malformed.",
		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrSTSNotInitialized: {
		Code:           "STSNotInitialized",
		Description:    "STS API not initialized, please try again.",
		HTTPStatusCode: http.StatusServiceUnavailable,
	},
	ErrSTSInternalError: {
		Code:           "InternalError",
		Description:    "We encountered an internal error generating credentials, please try again.",
		HTTPStatusCode: http.StatusInternalServerError,
	},
}

// getSTSErrorResponse gets in standard error and
// provides a encodable populated response values
func getSTSErrorResponse(err STSError, requestID string) STSErrorResponse {
	errRsp := STSErrorResponse{}
	errRsp.Error.Code = err.Code
	errRsp.Error.Message = err.Description
	errRsp.RequestID = requestID
	return errRsp
}