// 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"

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

// Data types used for returning dummy access control
// policy XML, these variables shouldn't be used elsewhere
// they are only defined to be used in this file alone.
type grantee struct {
	XMLNS       string `xml:"xmlns:xsi,attr"`
	XMLXSI      string `xml:"xsi:type,attr"`
	Type        string `xml:"Type"`
	ID          string `xml:"ID,omitempty"`
	DisplayName string `xml:"DisplayName,omitempty"`
	URI         string `xml:"URI,omitempty"`
}

type grant struct {
	Grantee    grantee `xml:"Grantee"`
	Permission string  `xml:"Permission"`
}

type accessControlPolicy struct {
	XMLName           xml.Name `xml:"AccessControlPolicy"`
	Owner             Owner    `xml:"Owner"`
	AccessControlList struct {
		Grants []grant `xml:"Grant"`
	} `xml:"AccessControlList"`
}

// PutBucketACLHandler - PUT Bucket ACL
// -----------------
// This operation uses the ACL subresource
// to set ACL for a bucket, this is a dummy call
// only responds success if the ACL is private.
func (api objectAPIHandlers) PutBucketACLHandler(w http.ResponseWriter, r *http.Request) {
	ctx := newContext(r, w, "PutBucketACL")

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

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

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

	// Allow putBucketACL if policy action is set, since this is a dummy call
	// we are simply re-purposing the bucketPolicyAction.
	if s3Error := checkRequestAuthType(ctx, r, policy.PutBucketPolicyAction, bucket, ""); s3Error != ErrNone {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(s3Error), r.URL)
		return
	}

	// Before proceeding validate if bucket exists.
	_, err := objAPI.GetBucketInfo(ctx, bucket, BucketOptions{})
	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

	aclHeader := r.Header.Get(xhttp.AmzACL)
	if aclHeader == "" {
		acl := &accessControlPolicy{}
		if err = xmlDecoder(r.Body, acl, r.ContentLength); err != nil {
			if err == io.EOF {
				writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrMissingSecurityHeader),
					r.URL)
				return
			}
			writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
			return
		}

		if len(acl.AccessControlList.Grants) == 0 {
			writeErrorResponse(ctx, w, toAPIError(ctx, NotImplemented{}), r.URL)
			return
		}

		if acl.AccessControlList.Grants[0].Permission != "FULL_CONTROL" {
			writeErrorResponse(ctx, w, toAPIError(ctx, NotImplemented{}), r.URL)
			return
		}
	}

	if aclHeader != "" && aclHeader != "private" {
		writeErrorResponse(ctx, w, toAPIError(ctx, NotImplemented{}), r.URL)
		return
	}
}

// GetBucketACLHandler - GET Bucket ACL
// -----------------
// This operation uses the ACL
// subresource to return the ACL of a specified bucket.
func (api objectAPIHandlers) GetBucketACLHandler(w http.ResponseWriter, r *http.Request) {
	ctx := newContext(r, w, "GetBucketACL")

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

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

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

	// Allow getBucketACL if policy action is set, since this is a dummy call
	// we are simply re-purposing the bucketPolicyAction.
	if s3Error := checkRequestAuthType(ctx, r, policy.GetBucketPolicyAction, bucket, ""); s3Error != ErrNone {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(s3Error), r.URL)
		return
	}

	// Before proceeding validate if bucket exists.
	_, err := objAPI.GetBucketInfo(ctx, bucket, BucketOptions{})
	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

	acl := &accessControlPolicy{}
	acl.AccessControlList.Grants = append(acl.AccessControlList.Grants, grant{
		Grantee: grantee{
			XMLNS:  "http://www.w3.org/2001/XMLSchema-instance",
			XMLXSI: "CanonicalUser",
			Type:   "CanonicalUser",
		},
		Permission: "FULL_CONTROL",
	})

	if err := xml.NewEncoder(w).Encode(acl); err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}
}

// PutObjectACLHandler - PUT Object ACL
// -----------------
// This operation uses the ACL subresource
// to set ACL for a bucket, this is a dummy call
// only responds success if the ACL is private.
func (api objectAPIHandlers) PutObjectACLHandler(w http.ResponseWriter, r *http.Request) {
	ctx := newContext(r, w, "PutObjectACL")

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

	vars := mux.Vars(r)
	bucket := vars["bucket"]
	object, err := unescapePath(vars["object"])
	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

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

	// Allow putObjectACL if policy action is set, since this is a dummy call
	// we are simply re-purposing the bucketPolicyAction.
	if s3Error := checkRequestAuthType(ctx, r, policy.PutBucketPolicyAction, bucket, ""); s3Error != ErrNone {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(s3Error), r.URL)
		return
	}

	// Before proceeding validate if object exists.
	_, err = objAPI.GetObjectInfo(ctx, bucket, object, ObjectOptions{})
	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

	aclHeader := r.Header.Get(xhttp.AmzACL)
	if aclHeader == "" {
		acl := &accessControlPolicy{}
		if err = xmlDecoder(r.Body, acl, r.ContentLength); err != nil {
			writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
			return
		}

		if len(acl.AccessControlList.Grants) == 0 {
			writeErrorResponse(ctx, w, toAPIError(ctx, NotImplemented{}), r.URL)
			return
		}

		if acl.AccessControlList.Grants[0].Permission != "FULL_CONTROL" {
			writeErrorResponse(ctx, w, toAPIError(ctx, NotImplemented{}), r.URL)
			return
		}
	}

	if aclHeader != "" && aclHeader != "private" {
		writeErrorResponse(ctx, w, toAPIError(ctx, NotImplemented{}), r.URL)
		return
	}
}

// GetObjectACLHandler - GET Object ACL
// -----------------
// This operation uses the ACL
// subresource to return the ACL of a specified object.
func (api objectAPIHandlers) GetObjectACLHandler(w http.ResponseWriter, r *http.Request) {
	ctx := newContext(r, w, "GetObjectACL")

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

	vars := mux.Vars(r)
	bucket := vars["bucket"]
	object, err := unescapePath(vars["object"])
	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

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

	// Allow getObjectACL if policy action is set, since this is a dummy call
	// we are simply re-purposing the bucketPolicyAction.
	if s3Error := checkRequestAuthType(ctx, r, policy.GetBucketPolicyAction, bucket, ""); s3Error != ErrNone {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(s3Error), r.URL)
		return
	}

	// Before proceeding validate if object exists.
	_, err = objAPI.GetObjectInfo(ctx, bucket, object, ObjectOptions{})
	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

	acl := &accessControlPolicy{}
	acl.AccessControlList.Grants = append(acl.AccessControlList.Grants, grant{
		Grantee: grantee{
			XMLNS:  "http://www.w3.org/2001/XMLSchema-instance",
			XMLXSI: "CanonicalUser",
			Type:   "CanonicalUser",
		},
		Permission: "FULL_CONTROL",
	})
	if err := xml.NewEncoder(w).Encode(acl); err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}
}
