// Copyright (C) 2018 Storj Labs, Inc.
// See LICENSE for copying information.

package buckets

import (
	"bytes"
	"context"
	"strconv"
	"time"

	minio "github.com/minio/minio/cmd"
	monkit "gopkg.in/spacemonkeygo/monkit.v2"

	"storj.io/storj/pkg/storage/meta"
	"storj.io/storj/pkg/storage/objects"
	"storj.io/storj/pkg/storage/streams"
	"storj.io/storj/pkg/storj"
	"storj.io/storj/storage"
)

var mon = monkit.Package()

// Store creates an interface for interacting with buckets
type Store interface {
	Get(ctx context.Context, bucket string) (meta Meta, err error)
	Put(ctx context.Context, bucket string) (meta Meta, err error)
	Delete(ctx context.Context, bucket string) (err error)
	List(ctx context.Context, startAfter, endBefore string, limit int) (items []ListItem, more bool, err error)
	GetObjectStore(ctx context.Context, bucketName string) (store objects.Store, err error)
}

// ListItem is a single item in a listing
type ListItem struct {
	Bucket string
	Meta   Meta
}

// BucketStore contains objects store
type BucketStore struct {
	store      objects.Store
	stream     streams.Store
	pathCipher storj.Cipher
}

// Meta is the bucket metadata struct
type Meta struct {
	Created            time.Time
	PathEncryptionType storj.Cipher
}

// NewStore instantiates BucketStore
func NewStore(stream streams.Store, pathCipher storj.Cipher) Store {
	// root object store for storing the buckets with unencrypted names
	store := objects.NewStore(stream, storj.Unencrypted)
	return &BucketStore{store: store, stream: stream, pathCipher: pathCipher}
}

// GetObjectStore returns an implementation of objects.Store
func (b *BucketStore) GetObjectStore(ctx context.Context, bucket string) (objects.Store, error) {
	if bucket == "" {
		return nil, storj.ErrNoBucket.New("")
	}

	m, err := b.Get(ctx, bucket)
	if err != nil {
		if storage.ErrKeyNotFound.Has(err) {
			return nil, minio.BucketNotFound{Bucket: bucket}
		}
		return nil, err
	}
	prefixed := prefixedObjStore{
		store:  objects.NewStore(b.stream, m.PathEncryptionType),
		prefix: bucket,
	}
	return &prefixed, nil
}

// Get calls objects store Get
func (b *BucketStore) Get(ctx context.Context, bucket string) (meta Meta, err error) {
	defer mon.Task()(&ctx)(&err)

	if bucket == "" {
		return Meta{}, storj.ErrNoBucket.New("")
	}

	objMeta, err := b.store.Meta(ctx, bucket)
	if err != nil {
		return Meta{}, err
	}
	return convertMeta(objMeta)
}

// Put calls objects store Put
func (b *BucketStore) Put(ctx context.Context, bucket string) (meta Meta, err error) {
	defer mon.Task()(&ctx)(&err)

	if bucket == "" {
		return Meta{}, storj.ErrNoBucket.New("")
	}

	r := bytes.NewReader(nil)
	userMeta := map[string]string{
		"path-enc-type": strconv.Itoa(int(b.pathCipher)),
	}
	var exp time.Time
	m, err := b.store.Put(ctx, bucket, r, objects.SerializableMeta{UserDefined: userMeta}, exp)
	if err != nil {
		return Meta{}, err
	}
	return convertMeta(m)
}

// Delete calls objects store Delete
func (b *BucketStore) Delete(ctx context.Context, bucket string) (err error) {
	defer mon.Task()(&ctx)(&err)

	if bucket == "" {
		return storj.ErrNoBucket.New("")
	}

	return b.store.Delete(ctx, bucket)
}

// List calls objects store List
func (b *BucketStore) List(ctx context.Context, startAfter, endBefore string, limit int) (items []ListItem, more bool, err error) {
	defer mon.Task()(&ctx)(&err)

	objItems, more, err := b.store.List(ctx, "", startAfter, endBefore, false, limit, meta.Modified)
	if err != nil {
		return items, more, err
	}

	items = make([]ListItem, 0, len(objItems))
	for _, itm := range objItems {
		if itm.IsPrefix {
			continue
		}
		m, err := convertMeta(itm.Meta)
		if err != nil {
			return items, more, err
		}
		items = append(items, ListItem{
			Bucket: itm.Path,
			Meta:   m,
		})
	}
	return items, more, nil
}

// convertMeta converts stream metadata to object metadata
func convertMeta(m objects.Meta) (Meta, error) {
	var cipher storj.Cipher

	pathEncType := m.UserDefined["path-enc-type"]

	if pathEncType == "" {
		// backward compatibility for old buckets
		cipher = storj.AESGCM
	} else {
		pet, err := strconv.Atoi(pathEncType)
		if err != nil {
			return Meta{}, err
		}
		cipher = storj.Cipher(pet)
	}

	return Meta{
		Created:            m.Modified,
		PathEncryptionType: cipher,
	}, nil
}