// Licensed to the LF AI & Data foundation under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you 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 storage

import (
	"bytes"
	"encoding/binary"
	"fmt"

	"github.com/milvus-io/milvus-proto/go-api/schemapb"
	"github.com/milvus-io/milvus/internal/common"
	"github.com/milvus-io/milvus/internal/util/typeutil"
)

// BinlogType is to distinguish different files saving different data.
type BinlogType int32

const (
	// InsertBinlog BinlogType for insert data
	InsertBinlog BinlogType = iota
	// DeleteBinlog BinlogType for delete data
	DeleteBinlog
	// DDLBinlog BinlogType for DDL
	DDLBinlog
	// IndexFileBinlog BinlogType for index
	IndexFileBinlog
	// StatsBinlog BinlogType for stats data
	StatsBinlog
)
const (
	// MagicNumber used in binlog
	MagicNumber int32 = 0xfffabc
)

type baseBinlogWriter struct {
	descriptorEvent
	magicNumber  int32
	binlogType   BinlogType
	eventWriters []EventWriter
	buffer       *bytes.Buffer
	length       int32
}

func (writer *baseBinlogWriter) isClosed() bool {
	return writer.buffer != nil
}

// GetEventNums returns the number of event writers
func (writer *baseBinlogWriter) GetEventNums() int32 {
	return int32(len(writer.eventWriters))
}

// GetRowNums returns writer's number of rows
func (writer *baseBinlogWriter) GetRowNums() (int32, error) {
	if writer.isClosed() {
		return writer.length, nil
	}

	length := 0
	for _, e := range writer.eventWriters {
		rows, err := e.GetPayloadLengthFromWriter()
		if err != nil {
			return 0, err
		}
		length += rows
	}
	return int32(length), nil
}

// GetBinlogType returns writer's binlogType
func (writer *baseBinlogWriter) GetBinlogType() BinlogType {
	return writer.binlogType
}

// GetBuffer gets binlog buffer. Return nil if binlog is not finished yet.
func (writer *baseBinlogWriter) GetBuffer() ([]byte, error) {
	if writer.buffer == nil {
		return nil, fmt.Errorf("please close binlog before get buffer")
	}
	return writer.buffer.Bytes(), nil
}

// Finish allocates buffer and releases resource
func (writer *baseBinlogWriter) Finish() error {
	if writer.buffer != nil {
		return nil
	}
	if writer.StartTimestamp == 0 || writer.EndTimestamp == 0 {
		return fmt.Errorf("invalid start/end timestamp")
	}

	var offset int32
	writer.buffer = new(bytes.Buffer)
	if err := binary.Write(writer.buffer, common.Endian, MagicNumber); err != nil {
		return err
	}
	offset += int32(binary.Size(MagicNumber))
	if err := writer.descriptorEvent.Write(writer.buffer); err != nil {
		return err
	}
	offset += writer.descriptorEvent.GetMemoryUsageInBytes()

	writer.length = 0
	for _, w := range writer.eventWriters {
		w.SetOffset(offset)
		if err := w.Finish(); err != nil {
			return err
		}
		if err := w.Write(writer.buffer); err != nil {
			return err
		}
		length, err := w.GetMemoryUsageInBytes()
		if err != nil {
			return err
		}
		offset += length
		rows, err := w.GetPayloadLengthFromWriter()
		if err != nil {
			return err
		}
		writer.length += int32(rows)
	}
	return nil
}

func (writer *baseBinlogWriter) Close() {
	for _, e := range writer.eventWriters {
		e.Close()
	}
}

// InsertBinlogWriter is an object to write binlog file which saves insert data.
type InsertBinlogWriter struct {
	baseBinlogWriter
}

// NextInsertEventWriter returns an event writer to write insert data to an event.
func (writer *InsertBinlogWriter) NextInsertEventWriter(dim ...int) (*insertEventWriter, error) {
	if writer.isClosed() {
		return nil, fmt.Errorf("binlog has closed")
	}

	var event *insertEventWriter
	var err error
	if typeutil.IsVectorType(writer.PayloadDataType) {
		if len(dim) != 1 {
			return nil, fmt.Errorf("incorrect input numbers")
		}
		event, err = newInsertEventWriter(writer.PayloadDataType, dim[0])
	} else {
		event, err = newInsertEventWriter(writer.PayloadDataType)
	}
	if err != nil {
		return nil, err
	}

	writer.eventWriters = append(writer.eventWriters, event)
	return event, nil
}

// DeleteBinlogWriter is an object to write binlog file which saves delete data.
type DeleteBinlogWriter struct {
	baseBinlogWriter
}

// NextDeleteEventWriter returns an event writer to write delete data to an event.
func (writer *DeleteBinlogWriter) NextDeleteEventWriter() (*deleteEventWriter, error) {
	if writer.isClosed() {
		return nil, fmt.Errorf("binlog has closed")
	}
	event, err := newDeleteEventWriter(writer.PayloadDataType)
	if err != nil {
		return nil, err
	}
	writer.eventWriters = append(writer.eventWriters, event)
	return event, nil
}

// DDLBinlogWriter is an object to write binlog file which saves ddl information.
type DDLBinlogWriter struct {
	baseBinlogWriter
}

// NextCreateCollectionEventWriter returns an event writer to write CreateCollection
// information to an event.
func (writer *DDLBinlogWriter) NextCreateCollectionEventWriter() (*createCollectionEventWriter, error) {
	if writer.isClosed() {
		return nil, fmt.Errorf("binlog has closed")
	}
	event, err := newCreateCollectionEventWriter(writer.PayloadDataType)
	if err != nil {
		return nil, err
	}
	writer.eventWriters = append(writer.eventWriters, event)
	return event, nil
}

// NextDropCollectionEventWriter returns an event writer to write DropCollection
// information to an event.
func (writer *DDLBinlogWriter) NextDropCollectionEventWriter() (*dropCollectionEventWriter, error) {
	if writer.isClosed() {
		return nil, fmt.Errorf("binlog has closed")
	}
	event, err := newDropCollectionEventWriter(writer.PayloadDataType)
	if err != nil {
		return nil, err
	}
	writer.eventWriters = append(writer.eventWriters, event)
	return event, nil
}

// NextCreatePartitionEventWriter returns an event writer to write CreatePartition
// information to an event.
func (writer *DDLBinlogWriter) NextCreatePartitionEventWriter() (*createPartitionEventWriter, error) {
	if writer.isClosed() {
		return nil, fmt.Errorf("binlog has closed")
	}
	event, err := newCreatePartitionEventWriter(writer.PayloadDataType)
	if err != nil {
		return nil, err
	}
	writer.eventWriters = append(writer.eventWriters, event)
	return event, nil
}

// NextDropPartitionEventWriter returns an event writer to write DropPartition
// information to an event.
func (writer *DDLBinlogWriter) NextDropPartitionEventWriter() (*dropPartitionEventWriter, error) {
	if writer.isClosed() {
		return nil, fmt.Errorf("binlog has closed")
	}
	event, err := newDropPartitionEventWriter(writer.PayloadDataType)
	if err != nil {
		return nil, err
	}
	writer.eventWriters = append(writer.eventWriters, event)
	return event, nil
}

// IndexFileBinlogWriter is an object to write binlog file which saves index files
type IndexFileBinlogWriter struct {
	baseBinlogWriter
}

// NextIndexFileEventWriter return next available EventWriter
func (writer *IndexFileBinlogWriter) NextIndexFileEventWriter() (*indexFileEventWriter, error) {
	if writer.isClosed() {
		return nil, fmt.Errorf("binlog has closed")
	}
	event, err := newIndexFileEventWriter(writer.PayloadDataType)
	if err != nil {
		return nil, err
	}
	writer.eventWriters = append(writer.eventWriters, event)
	return event, nil
}

// NewInsertBinlogWriter creates InsertBinlogWriter to write binlog file.
func NewInsertBinlogWriter(dataType schemapb.DataType, collectionID, partitionID, segmentID, FieldID int64) *InsertBinlogWriter {
	descriptorEvent := newDescriptorEvent()
	descriptorEvent.PayloadDataType = dataType
	descriptorEvent.CollectionID = collectionID
	descriptorEvent.PartitionID = partitionID
	descriptorEvent.SegmentID = segmentID
	descriptorEvent.FieldID = FieldID

	w := &InsertBinlogWriter{
		baseBinlogWriter: baseBinlogWriter{
			descriptorEvent: *descriptorEvent,
			magicNumber:     MagicNumber,
			binlogType:      InsertBinlog,
			eventWriters:    make([]EventWriter, 0),
			buffer:          nil,
		},
	}

	return w
}

// NewDeleteBinlogWriter creates DeleteBinlogWriter to write binlog file.
func NewDeleteBinlogWriter(dataType schemapb.DataType, collectionID, partitionID, segmentID int64) *DeleteBinlogWriter {
	descriptorEvent := newDescriptorEvent()
	descriptorEvent.PayloadDataType = dataType
	descriptorEvent.CollectionID = collectionID
	descriptorEvent.PartitionID = partitionID
	descriptorEvent.SegmentID = segmentID
	w := &DeleteBinlogWriter{
		baseBinlogWriter: baseBinlogWriter{
			descriptorEvent: *descriptorEvent,
			magicNumber:     MagicNumber,
			binlogType:      DeleteBinlog,
			eventWriters:    make([]EventWriter, 0),
			buffer:          nil,
		},
	}
	return w
}

// NewDDLBinlogWriter creates DDLBinlogWriter to write binlog file.
func NewDDLBinlogWriter(dataType schemapb.DataType, collectionID int64) *DDLBinlogWriter {
	descriptorEvent := newDescriptorEvent()
	descriptorEvent.PayloadDataType = dataType
	descriptorEvent.CollectionID = collectionID
	w := &DDLBinlogWriter{
		baseBinlogWriter: baseBinlogWriter{
			descriptorEvent: *descriptorEvent,
			magicNumber:     MagicNumber,
			binlogType:      DDLBinlog,
			eventWriters:    make([]EventWriter, 0),
			buffer:          nil,
		},
	}
	return w
}