// 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 vecindexmgr

/*
#cgo pkg-config: milvus_core

#include <stdlib.h>	// free
#include "segcore/vector_index_c.h"
*/
import "C"

import (
	"bytes"
	"context"
	"fmt"
	"sync"
	"unsafe"

	"github.com/milvus-io/milvus-proto/go-api/v3/schemapb"
	_ "github.com/milvus-io/milvus/internal/util/cgo"
	"github.com/milvus-io/milvus/pkg/v3/mlog"
)

const (
	BinaryFlag        uint64 = 1 << 0
	Float32Flag       uint64 = 1 << 1
	Float16Flag       uint64 = 1 << 2
	BFloat16Flag      uint64 = 1 << 3
	SparseFloat32Flag uint64 = 1 << 4
	Int8Flag          uint64 = 1 << 5

	EmbeddingListFlag uint64 = 1 << 15

	// NOTrainFlag This flag indicates that there is no need to create any index structure
	NOTrainFlag uint64 = 1 << 16
	// KNNFlag This flag indicates that the index defaults to KNN search, meaning the recall rate is 100%
	KNNFlag uint64 = 1 << 17
	// GpuFlag This flag indicates that the index is deployed on GPU (need GPU devices)
	GpuFlag uint64 = 1 << 18
	// MmapFlag This flag indicates that the index support using mmap manage its mainly memory, which can significant improve the capacity
	MmapFlag uint64 = 1 << 19
	// MvFlag This flag indicates that the index support using materialized view to accelerate filtering search
	MvFlag uint64 = 1 << 20
	// DiskFlag This flag indicates that the index need disk
	DiskFlag uint64 = 1 << 21
)

type IndexType = string

type VecIndexMgr interface {
	init()

	GetFeature(indexType IndexType) (uint64, bool)

	IsBinaryVectorSupport(indexType IndexType, isEmbeddingList bool) bool
	IsFloat32VectorSupport(indexType IndexType, isEmbeddingList bool) bool
	IsFloat16VectorSupport(indexType IndexType, isEmbeddingList bool) bool
	IsBFloat16VectorSupport(indexType IndexType, isEmbeddingList bool) bool
	IsSparseFloat32VectorSupport(indexType IndexType, isEmbeddingList bool) bool
	IsInt8VectorSupport(indexType IndexType, isEmbeddingList bool) bool
	IsDataTypeSupport(indexType IndexType, dataType schemapb.DataType, elementType schemapb.DataType) bool

	IsFlatVecIndex(indexType IndexType) bool
	IsNoTrainIndex(indexType IndexType) bool
	IsVecIndex(indexType IndexType) bool
	IsDiskANN(indexType IndexType) bool
	IsAISAQ(indexType IndexType) bool
	IsGPUVecIndex(indexType IndexType) bool
	IsDiskVecIndex(indexType IndexType) bool
	IsMMapSupported(indexType IndexType) bool
	IsMvSupported(indexType IndexType) bool
}

type vecIndexMgrImpl struct {
	features map[string]uint64
	once     sync.Once
}

func (mgr *vecIndexMgrImpl) GetFeature(indexType IndexType) (uint64, bool) {
	feature, ok := mgr.features[indexType]
	if !ok {
		return 0, false
	}
	return feature, true
}

func (mgr *vecIndexMgrImpl) IsNoTrainIndex(indexType IndexType) bool {
	feature, ok := mgr.GetFeature(indexType)
	if !ok {
		return false
	}
	return (feature & NOTrainFlag) == NOTrainFlag
}

func (mgr *vecIndexMgrImpl) IsDiskANN(indexType IndexType) bool {
	return indexType == "DISKANN"
}

func (mgr *vecIndexMgrImpl) IsAISAQ(indexType IndexType) bool {
	return indexType == "AISAQ"
}

func (mgr *vecIndexMgrImpl) init() {
	size := int(C.GetIndexListSize())
	if size == 0 {
		mlog.Error(context.TODO(), "get empty vector index features from vector index engine")
		return
	}
	vecIndexList := make([]unsafe.Pointer, size)
	vecIndexFeatures := make([]uint64, size)

	C.GetIndexFeatures(unsafe.Pointer(&vecIndexList[0]), (*C.uint64_t)(unsafe.Pointer(&vecIndexFeatures[0])))
	mgr.features = make(map[string]uint64)
	var featureLog bytes.Buffer
	for i := 0; i < size; i++ {
		key := C.GoString((*C.char)(vecIndexList[i]))
		mgr.features[key] = vecIndexFeatures[i]
		featureLog.WriteString(key + " : " + fmt.Sprintf("%d", vecIndexFeatures[i]) + ",")
	}
	mlog.Info(context.TODO(), "init vector indexes with features : "+featureLog.String())
}

func (mgr *vecIndexMgrImpl) isVectorTypeSupported(indexType IndexType, vectorFlag uint64, isEmbeddingList bool) bool {
	feature, ok := mgr.GetFeature(indexType)
	if !ok {
		return false
	}

	// check if the vector type is supported
	if (feature & vectorFlag) != vectorFlag {
		return false
	}

	// if it is embedding list, also check EmbeddingListFlag
	if isEmbeddingList && (feature&EmbeddingListFlag) != EmbeddingListFlag {
		return false
	}

	return true
}

func (mgr *vecIndexMgrImpl) IsBinaryVectorSupport(indexType IndexType, isEmbeddingList bool) bool {
	return mgr.isVectorTypeSupported(indexType, BinaryFlag, isEmbeddingList)
}

func (mgr *vecIndexMgrImpl) IsFloat32VectorSupport(indexType IndexType, isEmbeddingList bool) bool {
	return mgr.isVectorTypeSupported(indexType, Float32Flag, isEmbeddingList)
}

func (mgr *vecIndexMgrImpl) IsFloat16VectorSupport(indexType IndexType, isEmbeddingList bool) bool {
	return mgr.isVectorTypeSupported(indexType, Float16Flag, isEmbeddingList)
}

func (mgr *vecIndexMgrImpl) IsBFloat16VectorSupport(indexType IndexType, isEmbeddingList bool) bool {
	return mgr.isVectorTypeSupported(indexType, BFloat16Flag, isEmbeddingList)
}

func (mgr *vecIndexMgrImpl) IsSparseFloat32VectorSupport(indexType IndexType, isEmbeddingList bool) bool {
	return mgr.isVectorTypeSupported(indexType, SparseFloat32Flag, isEmbeddingList)
}

func (mgr *vecIndexMgrImpl) IsInt8VectorSupport(indexType IndexType, isEmbeddingList bool) bool {
	return mgr.isVectorTypeSupported(indexType, Int8Flag, isEmbeddingList)
}

func (mgr *vecIndexMgrImpl) IsDataTypeSupport(indexType IndexType, dataType schemapb.DataType, elementType schemapb.DataType) bool {
	isEmbeddingList := dataType == schemapb.DataType_ArrayOfVector
	if isEmbeddingList {
		dataType = elementType
	}

	switch dataType {
	case schemapb.DataType_BinaryVector:
		return mgr.IsBinaryVectorSupport(indexType, isEmbeddingList)
	case schemapb.DataType_FloatVector:
		return mgr.IsFloat32VectorSupport(indexType, isEmbeddingList)
	case schemapb.DataType_BFloat16Vector:
		return mgr.IsBFloat16VectorSupport(indexType, isEmbeddingList)
	case schemapb.DataType_Float16Vector:
		return mgr.IsFloat16VectorSupport(indexType, isEmbeddingList)
	case schemapb.DataType_SparseFloatVector:
		return mgr.IsSparseFloat32VectorSupport(indexType, isEmbeddingList)
	case schemapb.DataType_Int8Vector:
		return mgr.IsInt8VectorSupport(indexType, isEmbeddingList)
	default:
		return false
	}
}

func (mgr *vecIndexMgrImpl) IsFlatVecIndex(indexType IndexType) bool {
	feature, ok := mgr.features[indexType]
	if !ok {
		return false
	}
	return (feature & KNNFlag) == KNNFlag
}

func (mgr *vecIndexMgrImpl) IsMvSupported(indexType IndexType) bool {
	feature, ok := mgr.GetFeature(indexType)
	if !ok {
		return false
	}
	return (feature & MvFlag) == MvFlag
}

func (mgr *vecIndexMgrImpl) IsGPUVecIndex(indexType IndexType) bool {
	feature, ok := mgr.GetFeature(indexType)
	if !ok {
		return false
	}
	return (feature & GpuFlag) == GpuFlag
}

func (mgr *vecIndexMgrImpl) IsMMapSupported(indexType IndexType) bool {
	feature, ok := mgr.GetFeature(indexType)
	if !ok {
		return false
	}
	return (feature & MmapFlag) == MmapFlag
}

func (mgr *vecIndexMgrImpl) IsVecIndex(indexType IndexType) bool {
	_, ok := mgr.GetFeature(indexType)
	return ok
}

func (mgr *vecIndexMgrImpl) IsDiskVecIndex(indexType IndexType) bool {
	feature, ok := mgr.GetFeature(indexType)
	if !ok {
		return false
	}
	return (feature & DiskFlag) == DiskFlag
}

func newVecIndexMgr() *vecIndexMgrImpl {
	mgr := &vecIndexMgrImpl{}
	mgr.once.Do(mgr.init)
	return mgr
}

var vecIndexMgr VecIndexMgr

var getVecIndexMgrOnce sync.Once

// GetVecIndexMgrInstance gets the instance of VecIndexMgrInstance.
func GetVecIndexMgrInstance() VecIndexMgr {
	getVecIndexMgrOnce.Do(func() {
		vecIndexMgr = newVecIndexMgr()
	})
	return vecIndexMgr
}
