/*
 * 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 (
	"encoding/json"
	"io"
	"path"
	"path/filepath"
	"strings"
	"sync"

	"github.com/Sirupsen/logrus"
	"github.com/minio/minio/pkg/mimedb"
)

const (
	multipartSuffix   = ".minio.multipart"
	multipartMetaFile = "00000" + multipartSuffix
)

// xlObjects - Implements fs object layer.
type xlObjects struct {
	storage            StorageAPI
	listObjectMap      map[listParams][]*treeWalker
	listObjectMapMutex *sync.Mutex
}

func isLeafDirectory(disk StorageAPI, volume, leafPath string) bool {
	_, err := disk.StatFile(volume, pathJoin(leafPath, multipartMetaFile))
	return err == nil
}

// FIXME: constructor should return a pointer.
// newXLObjects - initialize new xl object layer.
func newXLObjects(exportPaths ...string) (ObjectLayer, error) {
	storage, err := newXL(exportPaths...)
	if err != nil {
		return nil, err
	}

	// Initialize object layer - like creating minioMetaBucket,
	// cleaning up tmp files etc.
	initObjectLayer(storage)

	// Return successfully initialized object layer.
	return xlObjects{
		storage:            storage,
		listObjectMap:      make(map[listParams][]*treeWalker),
		listObjectMapMutex: &sync.Mutex{},
	}, nil
}

/// Bucket operations

// MakeBucket - make a bucket.
func (xl xlObjects) MakeBucket(bucket string) error {
	return makeBucket(xl.storage, bucket)
}

// GetBucketInfo - get bucket info.
func (xl xlObjects) GetBucketInfo(bucket string) (BucketInfo, error) {
	return getBucketInfo(xl.storage, bucket)
}

// ListBuckets - list buckets.
func (xl xlObjects) ListBuckets() ([]BucketInfo, error) {
	return listBuckets(xl.storage)
}

// DeleteBucket - delete a bucket.
func (xl xlObjects) DeleteBucket(bucket string) error {
	return deleteBucket(xl.storage, bucket)
}

/// Object Operations

// GetObject - get an object.
func (xl xlObjects) GetObject(bucket, object string, startOffset int64) (io.ReadCloser, error) {
	// Verify if bucket is valid.
	if !IsValidBucketName(bucket) {
		return nil, BucketNameInvalid{Bucket: bucket}
	}
	// Verify if object is valid.
	if !IsValidObjectName(object) {
		return nil, ObjectNameInvalid{Bucket: bucket, Object: object}
	}
	if ok, err := isMultipartObject(xl.storage, bucket, object); err != nil {
		return nil, toObjectErr(err, bucket, object)
	} else if !ok {
		if _, err = xl.storage.StatFile(bucket, object); err == nil {
			var reader io.ReadCloser
			reader, err = xl.storage.ReadFile(bucket, object, startOffset)
			if err != nil {
				return nil, toObjectErr(err, bucket, object)
			}
			return reader, nil
		}
		return nil, toObjectErr(err, bucket, object)
	}
	fileReader, fileWriter := io.Pipe()
	info, err := getMultipartObjectInfo(xl.storage, bucket, object)
	if err != nil {
		return nil, toObjectErr(err, bucket, object)
	}
	partIndex, offset, err := info.GetPartNumberOffset(startOffset)
	if err != nil {
		return nil, toObjectErr(err, bucket, object)
	}
	go func() {
		for ; partIndex < len(info.Parts); partIndex++ {
			part := info.Parts[partIndex]
			r, err := xl.storage.ReadFile(bucket, pathJoin(object, partNumToPartFileName(part.PartNumber)), offset)
			if err != nil {
				fileWriter.CloseWithError(err)
				return
			}
			if _, err := io.Copy(fileWriter, r); err != nil {
				fileWriter.CloseWithError(err)
				return
			}
		}
		fileWriter.Close()
	}()
	return fileReader, nil
}

// Return the partsInfo of a special multipart object.
func getMultipartObjectInfo(storage StorageAPI, bucket, object string) (info MultipartObjectInfo, err error) {
	offset := int64(0)
	r, err := storage.ReadFile(bucket, pathJoin(object, multipartMetaFile), offset)
	if err != nil {
		return
	}
	decoder := json.NewDecoder(r)
	err = decoder.Decode(&info)
	return
}

// GetObjectInfo - get object info.
func (xl xlObjects) GetObjectInfo(bucket, object string) (ObjectInfo, error) {
	// Verify if bucket is valid.
	if !IsValidBucketName(bucket) {
		return ObjectInfo{}, BucketNameInvalid{Bucket: bucket}
	}
	// Verify if object is valid.
	if !IsValidObjectName(object) {
		return ObjectInfo{}, ObjectNameInvalid{Bucket: bucket, Object: object}
	}
	fi, err := xl.storage.StatFile(bucket, object)
	if err != nil {
		if err == errFileNotFound {
			var info MultipartObjectInfo
			info, err = getMultipartObjectInfo(xl.storage, bucket, object)
			if err != nil {
				return ObjectInfo{}, toObjectErr(err, bucket, object)
			}
			fi.Size = info.Size
			fi.ModTime = info.ModTime
			fi.MD5Sum = info.MD5Sum
		}
		return ObjectInfo{}, toObjectErr(err, bucket, object)
	}
	contentType := "application/octet-stream"
	if objectExt := filepath.Ext(object); objectExt != "" {
		content, ok := mimedb.DB[strings.ToLower(strings.TrimPrefix(objectExt, "."))]
		if ok {
			contentType = content.ContentType
		}
	}
	return ObjectInfo{
		Bucket:      bucket,
		Name:        object,
		ModTime:     fi.ModTime,
		Size:        fi.Size,
		IsDir:       fi.Mode.IsDir(),
		ContentType: contentType,
		MD5Sum:      fi.MD5Sum,
	}, nil
}

// PutObject - create an object.
func (xl xlObjects) PutObject(bucket string, object string, size int64, data io.Reader, metadata map[string]string) (string, error) {
	return putObjectCommon(xl.storage, bucket, object, size, data, metadata)
}

// isMultipartObject - verifies if an object is special multipart file.
func isMultipartObject(storage StorageAPI, bucket, object string) (bool, error) {
	_, err := storage.StatFile(bucket, pathJoin(object, multipartMetaFile))
	if err != nil {
		if err == errFileNotFound {
			return false, nil
		}
		return false, err
	}
	return true, nil
}

func (xl xlObjects) DeleteObject(bucket, object string) error {
	// Verify if bucket is valid.
	if !IsValidBucketName(bucket) {
		return BucketNameInvalid{Bucket: bucket}
	}
	if !IsValidObjectName(object) {
		return ObjectNameInvalid{Bucket: bucket, Object: object}
	}
	// Verify if the object is a multipart object.
	if ok, err := isMultipartObject(xl.storage, bucket, object); err != nil {
		return toObjectErr(err, bucket, object)
	} else if !ok {
		if err := xl.storage.DeleteFile(bucket, object); err != nil {
			return toObjectErr(err, bucket, object)
		}
	}
	// Get parts info.
	info, err := getMultipartObjectInfo(xl.storage, bucket, object)
	if err != nil {
		return toObjectErr(err, bucket, object)
	}
	// Range through all files and delete it.
	for _, part := range info.Parts {
		err = xl.storage.DeleteFile(bucket, pathJoin(object, partNumToPartFileName(part.PartNumber)))
		if err != nil {
			return toObjectErr(err, bucket, object)
		}
	}
	err = xl.storage.DeleteFile(bucket, pathJoin(object, multipartMetaFile))
	if err != nil {
		return toObjectErr(err, bucket, object)
	}
	return nil
}

func (xl xlObjects) ListObjects(bucket, prefix, marker, delimiter string, maxKeys int) (ListObjectsInfo, error) {
	// Verify if bucket is valid.
	if !IsValidBucketName(bucket) {
		return ListObjectsInfo{}, BucketNameInvalid{Bucket: bucket}
	}
	// Verify whether the bucket exists.
	if isExist, err := isBucketExist(xl.storage, bucket); err != nil {
		return ListObjectsInfo{}, err
	} else if !isExist {
		return ListObjectsInfo{}, BucketNotFound{Bucket: bucket}
	}
	if !IsValidObjectPrefix(prefix) {
		return ListObjectsInfo{}, ObjectNameInvalid{Bucket: bucket, Object: prefix}
	}
	// Verify if delimiter is anything other than '/', which we do not support.
	if delimiter != "" && delimiter != slashSeparator {
		return ListObjectsInfo{}, UnsupportedDelimiter{
			Delimiter: delimiter,
		}
	}
	// Verify if marker has prefix.
	if marker != "" {
		if !strings.HasPrefix(marker, prefix) {
			return ListObjectsInfo{}, InvalidMarkerPrefixCombination{
				Marker: marker,
				Prefix: prefix,
			}
		}
	}

	if maxKeys == 0 {
		return ListObjectsInfo{}, nil
	}

	// Default is recursive, if delimiter is set then list non recursive.
	recursive := true
	if delimiter == slashSeparator {
		recursive = false
	}

	walker := lookupTreeWalk(xl, listParams{bucket, recursive, marker, prefix})
	if walker == nil {
		walker = startTreeWalk(xl, bucket, prefix, marker, recursive)
	}
	var fileInfos []FileInfo
	var eof bool
	var err error
	var nextMarker string
	log.Debugf("Reading from the tree walk channel has begun.")
	for i := 0; i < maxKeys; {
		walkResult, ok := <-walker.ch
		if !ok {
			// Closed channel.
			eof = true
			break
		}
		// For any walk error return right away.
		if walkResult.err != nil {
			log.WithFields(logrus.Fields{
				"bucket":    bucket,
				"prefix":    prefix,
				"marker":    marker,
				"recursive": recursive,
			}).Debugf("Walk resulted in an error %s", walkResult.err)
			// File not found is a valid case.
			if walkResult.err == errFileNotFound {
				return ListObjectsInfo{}, nil
			}
			return ListObjectsInfo{}, toObjectErr(walkResult.err, bucket, prefix)
		}
		fileInfo := walkResult.fileInfo
		if strings.HasSuffix(fileInfo.Name, slashSeparator) && isLeafDirectory(xl.storage, bucket, fileInfo.Name) {
			// Code flow reaches here for non-recursive listing.

			var info MultipartObjectInfo
			info, err = getMultipartObjectInfo(xl.storage, bucket, fileInfo.Name)
			if err == nil {
				// Set the Mode to a "regular" file.
				fileInfo.Mode = 0
				fileInfo.Name = strings.TrimSuffix(fileInfo.Name, slashSeparator)
				fileInfo.Size = info.Size
				fileInfo.MD5Sum = info.MD5Sum
				fileInfo.ModTime = info.ModTime
			} else if err != errFileNotFound {
				return ListObjectsInfo{}, toObjectErr(err, bucket, fileInfo.Name)
			}
		} else if strings.HasSuffix(fileInfo.Name, multipartMetaFile) {
			// Code flow reaches here for recursive listing.

			// for object/00000.minio.multipart, strip the base name
			// and calculate get the object size.
			fileInfo.Name = path.Dir(fileInfo.Name)
			var info MultipartObjectInfo
			info, err = getMultipartObjectInfo(xl.storage, bucket, fileInfo.Name)
			if err != nil {
				return ListObjectsInfo{}, toObjectErr(err, bucket, fileInfo.Name)
			}
			fileInfo.Size = info.Size
		} else if strings.HasSuffix(fileInfo.Name, multipartSuffix) {
			// Ignore the part files like object/00001.minio.multipart
			continue
		}
		nextMarker = fileInfo.Name
		fileInfos = append(fileInfos, fileInfo)
		if walkResult.end {
			eof = true
			break
		}
		i++
	}
	params := listParams{bucket, recursive, nextMarker, prefix}
	log.WithFields(logrus.Fields{
		"bucket":    params.bucket,
		"recursive": params.recursive,
		"marker":    params.marker,
		"prefix":    params.prefix,
	}).Debugf("Save the tree walk into map for subsequent requests.")
	if !eof {
		saveTreeWalk(xl, params, walker)
	}

	result := ListObjectsInfo{IsTruncated: !eof}

	for _, fileInfo := range fileInfos {
		// With delimiter set we fill in NextMarker and Prefixes.
		if delimiter == slashSeparator {
			result.NextMarker = fileInfo.Name
			if fileInfo.Mode.IsDir() {
				result.Prefixes = append(result.Prefixes, fileInfo.Name)
				continue
			}
		}
		result.Objects = append(result.Objects, ObjectInfo{
			Name:    fileInfo.Name,
			ModTime: fileInfo.ModTime,
			Size:    fileInfo.Size,
			IsDir:   false,
		})
	}
	return result, nil
}