// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package cmd

import (
	"encoding/xml"
	"io"
	"net/http"
	"reflect"

	"github.com/gorilla/mux"
	"github.com/minio/minio/internal/event"
	"github.com/minio/minio/internal/logger"
	"github.com/minio/pkg/bucket/policy"
)

const (
	bucketConfigPrefix       = "buckets"
	bucketNotificationConfig = "notification.xml"
)

// GetBucketNotificationHandler - This HTTP handler returns event notification configuration
// as per http://docs.aws.amazon.com/AmazonS3/latest/dev/NotificationHowTo.html.
// It returns empty configuration if its not set.
func (api objectAPIHandlers) GetBucketNotificationHandler(w http.ResponseWriter, r *http.Request) {
	ctx := newContext(r, w, "GetBucketNotification")

	defer logger.AuditLog(ctx, w, r, mustGetClaimsFromToken(r))

	vars := mux.Vars(r)
	bucketName := vars["bucket"]

	objAPI := api.ObjectAPI()
	if objAPI == nil {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrServerNotInitialized), r.URL)
		return
	}

	if !objAPI.IsNotificationSupported() {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrNotImplemented), r.URL)
		return
	}

	if s3Error := checkRequestAuthType(ctx, r, policy.GetBucketNotificationAction, bucketName, ""); s3Error != ErrNone {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(s3Error), r.URL)
		return
	}

	_, err := objAPI.GetBucketInfo(ctx, bucketName)
	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

	config, err := globalBucketMetadataSys.GetNotificationConfig(bucketName)
	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}
	config.SetRegion(globalServerRegion)
	if err = config.Validate(globalServerRegion, globalNotificationSys.targetList); err != nil {
		arnErr, ok := err.(*event.ErrARNNotFound)
		if ok {
			for i, queue := range config.QueueList {
				// Remove ARN not found queues, because we previously allowed
				// adding unexpected entries into the config.
				//
				// With newer config disallowing changing / turning off
				// notification targets without removing ARN in notification
				// configuration we won't see this problem anymore.
				if reflect.DeepEqual(queue.ARN, arnErr.ARN) && i < len(config.QueueList) {
					config.QueueList = append(config.QueueList[:i],
						config.QueueList[i+1:]...)
				}
				// This is a one time activity we shall do this
				// here and allow stale ARN to be removed. We shall
				// never reach a stage where we will have stale
				// notification configs.
			}
		} else {
			writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
			return
		}
	}

	configData, err := xml.Marshal(config)
	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

	writeSuccessResponseXML(w, configData)
}

// PutBucketNotificationHandler - This HTTP handler stores given notification configuration as per
// http://docs.aws.amazon.com/AmazonS3/latest/dev/NotificationHowTo.html.
func (api objectAPIHandlers) PutBucketNotificationHandler(w http.ResponseWriter, r *http.Request) {
	ctx := newContext(r, w, "PutBucketNotification")

	defer logger.AuditLog(ctx, w, r, mustGetClaimsFromToken(r))

	objectAPI := api.ObjectAPI()
	if objectAPI == nil {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrServerNotInitialized), r.URL)
		return
	}

	if !objectAPI.IsNotificationSupported() {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrNotImplemented), r.URL)
		return
	}

	vars := mux.Vars(r)
	bucketName := vars["bucket"]

	if s3Error := checkRequestAuthType(ctx, r, policy.PutBucketNotificationAction, bucketName, ""); s3Error != ErrNone {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(s3Error), r.URL)
		return
	}

	_, err := objectAPI.GetBucketInfo(ctx, bucketName)
	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

	// PutBucketNotification always needs a Content-Length.
	if r.ContentLength <= 0 {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrMissingContentLength), r.URL)
		return
	}

	config, err := event.ParseConfig(io.LimitReader(r.Body, r.ContentLength), globalServerRegion, globalNotificationSys.targetList)
	if err != nil {
		apiErr := errorCodes.ToAPIErr(ErrMalformedXML)
		if event.IsEventError(err) {
			apiErr = toAPIError(ctx, err)
		}
		writeErrorResponse(ctx, w, apiErr, r.URL)
		return
	}

	configData, err := xml.Marshal(config)
	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

	if err = globalBucketMetadataSys.Update(bucketName, bucketNotificationConfig, configData); err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

	rulesMap := config.ToRulesMap()
	globalNotificationSys.AddRulesMap(bucketName, rulesMap)

	writeSuccessResponseHeadersOnly(w)
}
