/*
 * Minimalist Object Storage, (C) 2015 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 api

import (
	"net/http"

	"github.com/gorilla/mux"
	"github.com/minio-io/minio/pkg/iodine"
	"github.com/minio-io/minio/pkg/storage/drivers"
	"github.com/minio-io/minio/pkg/utils/log"
)

func (server *minioAPI) isValidOp(w http.ResponseWriter, req *http.Request, acceptsContentType contentType) bool {
	vars := mux.Vars(req)
	bucket := vars["bucket"]

	bucketMetadata, err := server.driver.GetBucketMetadata(bucket)
	switch iodine.ToError(err).(type) {
	case drivers.BucketNotFound:
		{
			writeErrorResponse(w, req, NoSuchBucket, acceptsContentType, req.URL.Path)
			return false
		}
	case drivers.BucketNameInvalid:
		{
			writeErrorResponse(w, req, InvalidBucketName, acceptsContentType, req.URL.Path)
			return false
		}
	case nil:
		if stripAccessKey(req) == "" && bucketMetadata.ACL.IsPrivate() {
			writeErrorResponse(w, req, AccessDenied, acceptsContentType, req.URL.Path)
			return false
		}
		if bucketMetadata.ACL.IsPublicRead() && req.Method == "PUT" {
			writeErrorResponse(w, req, AccessDenied, acceptsContentType, req.URL.Path)
			return false
		}
	}
	return true
}

// GET Bucket (List Objects)
// -------------------------
// This implementation of the GET operation returns some or all (up to 1000)
// of the objects in a bucket. You can use the request parameters as selection
// criteria to return a subset of the objects in a bucket.
//
func (server *minioAPI) listObjectsHandler(w http.ResponseWriter, req *http.Request) {
	acceptsContentType := getContentType(req)
	if acceptsContentType == unknownContentType {
		writeErrorResponse(w, req, NotAcceptable, acceptsContentType, req.URL.Path)
		return
	}
	// verify if bucket allows this operation
	if !server.isValidOp(w, req, acceptsContentType) {
		return
	}

	resources := getBucketResources(req.URL.Query())
	if resources.Maxkeys == 0 {
		resources.Maxkeys = maxObjectList
	}

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

	objects, resources, err := server.driver.ListObjects(bucket, resources)
	switch err := iodine.ToError(err).(type) {
	case nil: // success
		{
			// write headers
			setCommonHeaders(w, getContentTypeString(acceptsContentType))
			w.WriteHeader(http.StatusOK)
			// write body
			response := generateObjectsListResult(bucket, objects, resources)
			encodedSuccessResponse := encodeSuccessResponse(response, acceptsContentType)
			w.Write(encodedSuccessResponse)
		}
	case drivers.ObjectNotFound:
		{
			writeErrorResponse(w, req, NoSuchKey, acceptsContentType, req.URL.Path)
		}
	case drivers.ObjectNameInvalid:
		{
			writeErrorResponse(w, req, NoSuchKey, acceptsContentType, req.URL.Path)
		}
	default:
		{
			log.Error.Println(iodine.New(err, nil))
			writeErrorResponse(w, req, InternalError, acceptsContentType, req.URL.Path)
		}
	}
}

// GET Service
// -----------
// This implementation of the GET operation returns a list of all buckets
// owned by the authenticated sender of the request.
func (server *minioAPI) listBucketsHandler(w http.ResponseWriter, req *http.Request) {
	acceptsContentType := getContentType(req)
	if acceptsContentType == unknownContentType {
		writeErrorResponse(w, req, NotAcceptable, acceptsContentType, req.URL.Path)
		return
	}

	buckets, err := server.driver.ListBuckets()
	// cannot fallthrough in (type) switch :(
	switch err := iodine.ToError(err).(type) {
	case nil:
		{
			response := generateBucketsListResult(buckets)
			// write headers
			setCommonHeaders(w, getContentTypeString(acceptsContentType))
			w.WriteHeader(http.StatusOK)
			// write response
			encodedSuccessResponse := encodeSuccessResponse(response, acceptsContentType)
			w.Write(encodedSuccessResponse)
		}
	default:
		{
			log.Error.Println(iodine.New(err, nil))
			writeErrorResponse(w, req, InternalError, acceptsContentType, req.URL.Path)
		}
	}
}

// PUT Bucket
// ----------
// This implementation of the PUT operation creates a new bucket for authenticated request
func (server *minioAPI) putBucketHandler(w http.ResponseWriter, req *http.Request) {
	acceptsContentType := getContentType(req)
	if acceptsContentType == unknownContentType {
		writeErrorResponse(w, req, NotAcceptable, acceptsContentType, req.URL.Path)
		return
	}

	// read from 'x-amz-acl'
	aclType := getACLType(req)
	if aclType == unsupportedACLType {
		writeErrorResponse(w, req, NotImplemented, acceptsContentType, req.URL.Path)
		return
	}

	vars := mux.Vars(req)
	bucket := vars["bucket"]
	err := server.driver.CreateBucket(bucket, getACLTypeString(aclType))
	switch iodine.ToError(err).(type) {
	case nil:
		{
			w.Header().Set("Server", "Minio")
			w.Header().Set("Connection", "close")
			w.WriteHeader(http.StatusOK)
		}
	case drivers.BucketNameInvalid:
		{
			writeErrorResponse(w, req, InvalidBucketName, acceptsContentType, req.URL.Path)
		}
	case drivers.BucketExists:
		{
			writeErrorResponse(w, req, BucketAlreadyExists, acceptsContentType, req.URL.Path)
		}
	default:
		{
			log.Error.Println(iodine.New(err, nil))
			writeErrorResponse(w, req, InternalError, acceptsContentType, req.URL.Path)
		}
	}
}

// HEAD Bucket
// ----------
// This operation is useful to determine if a bucket exists.
// The operation returns a 200 OK if the bucket exists and you
// have permission to access it. Otherwise, the operation might
// return responses such as 404 Not Found and 403 Forbidden.
func (server *minioAPI) headBucketHandler(w http.ResponseWriter, req *http.Request) {
	acceptsContentType := getContentType(req)
	if acceptsContentType == unknownContentType {
		writeErrorResponse(w, req, NotAcceptable, acceptsContentType, req.URL.Path)
		return
	}

	// verify if bucket allows this operation
	if !server.isValidOp(w, req, acceptsContentType) {
		return
	}

	// Always a success if isValidOp succeeds
	w.Header().Set("Server", "Minio")
	w.Header().Set("Connection", "close")
	w.WriteHeader(http.StatusOK)
}