/*
 * Minio Cloud Storage, (C) 2016 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 main

import (
	"path"
	"sort"
)

/// Common object layer functions.

// makeBucket - create a bucket, is a common function for both object layers.
func makeBucket(storage StorageAPI, bucket string) error {
	// Verify if bucket is valid.
	if !IsValidBucketName(bucket) {
		return BucketNameInvalid{Bucket: bucket}
	}
	if err := storage.MakeVol(bucket); err != nil {
		return toObjectErr(err, bucket)
	}
	// This happens for the first time, but keep this here since this
	// is the only place where it can be made expensive optimizing all
	// other calls.
	// Create minio meta volume, if it doesn't exist yet.
	if err := storage.MakeVol(minioMetaBucket); err != nil {
		if err != errVolumeExists {
			return toObjectErr(err, minioMetaBucket)
		}
	}
	return nil
}

// getBucketInfo - fetch bucket info, is a common function for both object layers.
func getBucketInfo(storage StorageAPI, bucket string) (BucketInfo, error) {
	// Verify if bucket is valid.
	if !IsValidBucketName(bucket) {
		return BucketInfo{}, BucketNameInvalid{Bucket: bucket}
	}
	vi, err := storage.StatVol(bucket)
	if err != nil {
		return BucketInfo{}, toObjectErr(err, bucket)
	}
	return BucketInfo{
		Name:    bucket,
		Created: vi.Created,
		Total:   vi.Total,
		Free:    vi.Free,
	}, nil
}

// listBuckets - list all buckets, is a common function for both object layers.
func listBuckets(storage StorageAPI) ([]BucketInfo, error) {
	var bucketInfos []BucketInfo
	vols, err := storage.ListVols()
	if err != nil {
		return nil, toObjectErr(err)
	}
	for _, vol := range vols {
		// StorageAPI can send volume names which are incompatible
		// with buckets, handle it and skip them.
		if !IsValidBucketName(vol.Name) {
			continue
		}
		bucketInfos = append(bucketInfos, BucketInfo{
			Name:    vol.Name,
			Created: vol.Created,
			Total:   vol.Total,
			Free:    vol.Free,
		})
	}
	sort.Sort(byBucketName(bucketInfos))
	return bucketInfos, nil
}

// deleteBucket - deletes a bucket, is a common function for both the layers.
func deleteBucket(storage StorageAPI, bucket string) error {
	// Verify if bucket is valid.
	if !IsValidBucketName(bucket) {
		return BucketNameInvalid{Bucket: bucket}
	}
	if err := storage.DeleteVol(bucket); err != nil {
		return toObjectErr(err)
	}
	return nil
}

// isUploadIDExists - verify if a given uploadID exists and is valid.
func isUploadIDExists(storage StorageAPI, bucket, object, uploadID string) (bool, error) {
	uploadIDPath := path.Join(bucket, object, uploadID)
	st, err := storage.StatFile(minioMetaBucket, uploadIDPath)
	if err != nil {
		// Upload id does not exist.
		if err == errFileNotFound {
			return false, nil
		}
		return false, err
	}
	// Upload id exists and is a regular file.
	return st.Mode.IsRegular(), nil
}

// checks whether bucket exists.
func isBucketExist(storage StorageAPI, bucketName string) (bool, error) {
	// Check whether bucket exists.
	if _, e := storage.StatVol(bucketName); e != nil {
		if e == errVolumeNotFound {
			return false, nil
		}
		return false, e
	}
	return true, nil
}