// 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"
	"context"
	"encoding/binary"

	"github.com/milvus-io/milvus-proto/go-api/v3/hook"
	"github.com/milvus-io/milvus-proto/go-api/v3/schemapb"
	"github.com/milvus-io/milvus/pkg/v3/common"
	"github.com/milvus-io/milvus/pkg/v3/mlog"
	"github.com/milvus-io/milvus/pkg/v3/util/merr"
)

// 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
	// BM25 BinlogType for bm25 stats data
	BM25Binlog
)

const (
	// MagicNumber used in binlog
	MagicNumber int32 = 0xfffabc
)

func (b BinlogType) String() string {
	switch b {
	case InsertBinlog:
		return "InsertBinlog"
	case DeleteBinlog:
		return "DeleteBinlog"
	case DDLBinlog:
		return "DDLBinlog"
	case IndexFileBinlog:
		return "IndexFileBinlog"
	case StatsBinlog:
		return "StatsBinlog"
	case BM25Binlog:
		return "BM25"
	}
	return "BinlogType"
}

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

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, merr.WrapErrServiceInternalMsg("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 merr.WrapErrServiceInternalMsg("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.Write(writer.buffer); err != nil {
		return err
	}
	offset += writer.GetMemoryUsageInBytes()

	eventBuffer := writer.buffer
	if writer.encryptor != nil {
		eventBuffer = new(bytes.Buffer)
	}
	writer.length = 0
	for _, w := range writer.eventWriters {
		w.SetOffset(offset)
		if err := w.Finish(); err != nil {
			return err
		}
		if err := w.Write(eventBuffer); 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)
	}

	if writer.encryptor != nil {
		encrypted, err := writer.encryptor.Encrypt(eventBuffer.Bytes())
		if err != nil {
			return err
		}
		mlog.Debug(context.TODO(), "Binlog writer encrypted plain text",
			mlog.String("writer type", writer.binlogType.String()),
			mlog.Int("plain size", eventBuffer.Len()),
			mlog.Int("cipher size", len(encrypted)))
		if err := binary.Write(writer.buffer, common.Endian, encrypted); err != nil {
			return err
		}
	}
	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(opts ...PayloadWriterOptions) (*insertEventWriter, error) {
	if writer.isClosed() {
		return nil, merr.WrapErrServiceInternalMsg("binlog has closed")
	}

	event, err := newInsertEventWriter(writer.PayloadDataType, opts...)
	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(opts ...PayloadWriterOptions) (*deleteEventWriter, error) {
	if writer.isClosed() {
		return nil, merr.WrapErrServiceInternalMsg("binlog has closed")
	}
	event, err := newDeleteEventWriter(writer.PayloadDataType, opts...)
	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, merr.WrapErrServiceInternalMsg("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, nullable bool,
	opts ...BinlogWriterOptions,
) *InsertBinlogWriter {
	descriptorEvent := newDescriptorEvent()
	descriptorEvent.PayloadDataType = dataType
	descriptorEvent.CollectionID = collectionID
	descriptorEvent.PartitionID = partitionID
	descriptorEvent.SegmentID = segmentID
	descriptorEvent.FieldID = FieldID
	// store nullable in extra for compatible
	descriptorEvent.AddExtra(nullableKey, nullable)

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

	for _, opt := range opts {
		opt(&baseWriter)
	}

	w := &InsertBinlogWriter{
		baseBinlogWriter: baseWriter,
	}
	return w
}

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

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

	for _, opt := range opts {
		opt(&baseWriter)
	}
	w := &DeleteBinlogWriter{
		baseBinlogWriter: baseWriter,
	}
	return w
}

type BinlogWriterOptions func(base *baseBinlogWriter)

func WithWriterEncryptionContext(ezID int64, edek []byte, encryptor hook.Encryptor) BinlogWriterOptions {
	return func(base *baseBinlogWriter) {
		base.AddExtra(edekKey, string(edek))
		base.AddExtra(ezIDKey, ezID)
		base.encryptor = encryptor
	}
}
