/*
 * Minio Cloud 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 fs

import (
	"os"
	"path/filepath"
	"sync"
	"time"

	"github.com/minio/minio-xl/pkg/probe"
)

// Filesystem - local variables
type Filesystem struct {
	path             string
	minFreeDisk      int64
	maxBuckets       int
	rwLock           *sync.RWMutex
	multiparts       *Multiparts
	buckets          *Buckets
	listServiceReqCh chan<- listServiceReq
	timeoutReqCh     chan<- uint32
}

// Buckets holds acl information
type Buckets struct {
	Version  string `json:"version"`
	Metadata map[string]*BucketMetadata
}

// MultipartSession holds active session information
type MultipartSession struct {
	TotalParts int
	ObjectName string
	UploadID   string
	Initiated  time.Time
	Parts      []PartMetadata
}

// Multiparts collection of many parts
type Multiparts struct {
	Version       string                       `json:"version"`
	ActiveSession map[string]*MultipartSession `json:"activeSessions"`
}

// New instantiate a new donut
func New(rootPath string, minFreeDisk int64, maxBuckets int) (Filesystem, *probe.Error) {
	setFSBucketsMetadataPath(filepath.Join(rootPath, "$buckets.json"))
	setFSMultipartsMetadataPath(filepath.Join(rootPath, "$multiparts-session.json"))

	var err *probe.Error
	// load multiparts session from disk
	var multiparts *Multiparts
	multiparts, err = loadMultipartsSession()
	if err != nil {
		if os.IsNotExist(err.ToGoError()) {
			multiparts = &Multiparts{
				Version:       "1",
				ActiveSession: make(map[string]*MultipartSession),
			}
			if err := saveMultipartsSession(*multiparts); err != nil {
				return Filesystem{}, err.Trace()
			}
		} else {
			return Filesystem{}, err.Trace()
		}
	}

	var buckets *Buckets
	buckets, err = loadBucketsMetadata()
	if err != nil {
		if os.IsNotExist(err.ToGoError()) {
			buckets = &Buckets{
				Version:  "1",
				Metadata: make(map[string]*BucketMetadata),
			}
			if err := saveBucketsMetadata(*buckets); err != nil {
				return Filesystem{}, err.Trace()
			}
		} else {
			return Filesystem{}, err.Trace()
		}
	}
	fs := Filesystem{
		rwLock: &sync.RWMutex{},
	}
	fs.path = rootPath
	fs.multiparts = multiparts
	fs.buckets = buckets
	/// Defaults

	// maximum buckets to be listed from list buckets.
	fs.maxBuckets = maxBuckets
	// minium free disk required for i/o operations to succeed.
	fs.minFreeDisk = minFreeDisk

	// Start list goroutine.
	if err = fs.listObjectsService(); err != nil {
		return Filesystem{}, err.Trace(rootPath)
	}
	// Return here.
	return fs, nil
}