//  Copyright (c) 2016 Couchbase, 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 moss

import (
	"fmt"

	"github.com/blevesearch/bleve/index/store"

	"github.com/couchbase/moss"
)

type Writer struct {
	s *Store
}

func (w *Writer) NewBatch() store.KVBatch {
	b, err := w.s.ms.NewBatch(0, 0)
	if err != nil {
		return nil
	}

	return &Batch{
		store:   w.s,
		merge:   store.NewEmulatedMerge(w.s.mo),
		batch:   b,
		alloced: false,
	}
}

func (w *Writer) NewBatchEx(options store.KVBatchOptions) (
	[]byte, store.KVBatch, error) {
	numOps := options.NumSets + options.NumDeletes + options.NumMerges

	b, err := w.s.ms.NewBatch(numOps, options.TotalBytes)
	if err != nil {
		return nil, nil, err
	}

	buf, err := b.Alloc(options.TotalBytes)
	if err != nil {
		return nil, nil, err
	}

	return buf, &Batch{
		store:   w.s,
		merge:   store.NewEmulatedMerge(w.s.mo),
		batch:   b,
		alloced: true,
	}, nil
}

func (w *Writer) ExecuteBatch(b store.KVBatch) error {
	batch, ok := b.(*Batch)
	if !ok {
		return fmt.Errorf("wrong type of batch")
	}

	for kStr, mergeOps := range batch.merge.Merges {
		k := []byte(kStr)

		for _, v := range mergeOps {
			err := batch.batch.Merge(k, v)
			if err != nil {
				return err
			}
		}
	}

	return w.s.ms.ExecuteBatch(batch.batch, moss.WriteOptions{})
}

func (w *Writer) Close() error {
	w.s = nil
	return nil
}