// 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 segments

import (
	"context"

	"github.com/milvus-io/milvus-proto/go-api/v3/msgpb"
	"github.com/milvus-io/milvus-proto/go-api/v3/schemapb"
	pkoracle "github.com/milvus-io/milvus/internal/querynodev2/pkoracle"
	"github.com/milvus-io/milvus/internal/storage"
	"github.com/milvus-io/milvus/internal/storagecommon"
	"github.com/milvus-io/milvus/internal/util/segcore"
	"github.com/milvus-io/milvus/pkg/v3/proto/datapb"
	"github.com/milvus-io/milvus/pkg/v3/proto/querypb"
	"github.com/milvus-io/milvus/pkg/v3/proto/segcorepb"
	"github.com/milvus-io/milvus/pkg/v3/util/metautil"
	"github.com/milvus-io/milvus/pkg/v3/util/typeutil"
)

// BinlogSaver is a minimal interface for saving binlog paths to DataCoord.
// This avoids depending on the full broker.Broker interface.
type BinlogSaver interface {
	SaveBinlogPaths(ctx context.Context, req *datapb.SaveBinlogPathsRequest) error
}

// ResourceUsage is used to estimate the resource usage of a sealed segment.
type ResourceUsage struct {
	MemorySize         uint64
	DiskSize           uint64
	MmapFieldCount     int
	FieldGpuMemorySize []uint64
}

// Segment is the interface of a segment implementation.
// Some methods can not apply to all segment types，such as LoadInfo, ResourceUsageEstimate.
// Add more interface to represent different segment types is a better implementation.
type Segment interface {
	// ResourceUsageEstimate() ResourceUsage

	// Properties
	ID() int64
	DatabaseName() string
	ResourceGroup() string
	Collection() int64
	Partition() int64
	Shard() metautil.Channel
	Version() int64
	CASVersion(int64, int64) bool
	StartPosition() *msgpb.MsgPosition
	Type() SegmentType
	Level() datapb.SegmentLevel
	IsSorted() bool
	LoadInfo() *querypb.SegmentLoadInfo
	// PinIfNotReleased the segment to prevent it from being released
	PinIfNotReleased() error
	// Unpin the segment to allow it to be released
	Unpin()

	// Stats related
	// InsertCount returns the number of inserted rows, not effected by deletion
	InsertCount() int64
	// RowNum returns the number of rows, it's slow, so DO NOT call it in a loop
	RowNum() int64
	MemSize() int64
	// ResourceUsageEstimate returns the estimated resource usage of the segment
	ResourceUsageEstimate() ResourceUsage

	// Index related
	GetIndexByID(indexID int64) *IndexedFieldInfo
	GetIndex(fieldID int64) []*IndexedFieldInfo
	ExistIndex(fieldID int64) bool
	Indexes() []*IndexedFieldInfo
	HasRawData(fieldID int64) bool
	DropIndex(ctx context.Context, indexID int64) error

	// Modification related
	Insert(ctx context.Context, rowIDs []int64, timestamps []typeutil.Timestamp, record *segcorepb.InsertRecord) error
	Delete(ctx context.Context, primaryKeys storage.PrimaryKeys, timestamps []typeutil.Timestamp) error
	LoadDeltaData(ctx context.Context, deltaData *storage.DeltaData) error
	LastDeltaTimestamp() uint64
	Load(ctx context.Context) error
	Release(ctx context.Context, opts ...releaseOption)
	Reopen(ctx context.Context, newLoadInfo *querypb.SegmentLoadInfo) error

	// PK candidate related (BloomFilterSet for regular segments, ExternalSegmentCandidate for external)
	// Segment implements pkoracle.Candidate: MayPkExist, BatchPkExist, ID, Partition, Type,
	// PkCandidateExist, UpdatePkCandidate, Stats, Charge, Refund — with protective guards (e.g. skipGrowingBF).
	SetPKCandidate(candidate pkoracle.Candidate)
	PkCandidateExist() bool
	UpdatePkCandidate(pks []storage.PrimaryKey)
	Stats() *storage.PkStatistics
	Charge()
	Refund()
	MayPkExist(lc *storage.LocationsCache) bool
	BatchPkExist(lc *storage.BatchLocationsCache) []bool

	// Get min/max
	GetMinPk() *storage.PrimaryKey
	GetMaxPk() *storage.PrimaryKey

	// BM25 stats
	UpdateBM25Stats(stats map[int64]*storage.BM25Stats)
	GetBM25Stats() map[int64]*storage.BM25Stats

	// Read operations
	// Search executes a search on the segment.
	// If searchReq.FilterOnly() is true, only executes the filter and returns valid_count (Stage 1 of two-stage search).
	Search(ctx context.Context, searchReq *segcore.SearchRequest) (*segcore.SearchResult, error)
	Retrieve(ctx context.Context, plan *segcore.RetrievePlan) (*segcorepb.RetrieveResults, error)
	RetrieveByOffsets(ctx context.Context, plan *segcore.RetrievePlanWithOffsets) (*segcorepb.RetrieveResults, error)

	// FlushData flushes data from segment memory directly to storage via C++ milvus-storage.
	// This is a unified interface that combines data extraction and writing:
	//   - C++ side extracts data directly from ConcurrentVector (no query engine overhead)
	//   - C++ side writes data to storage (TEXT fields via TextColumnWriter, others via PackedWriter)
	//   - Returns binlog paths and metadata (all processing in C++ side)
	// Go layer only provides thin wrapper for FFI call - no business logic.
	// TODO: Implement C++ FlushData interface (Phase 1.3, 1.4, 2.3)
	FlushData(ctx context.Context, startOffset, endOffset int64, config *FlushConfig) (*FlushResult, error)
	IsLazyLoad() bool
	ResetIndexesLazyLoad(lazyState bool)

	// lazy load related
	NeedUpdatedVersion() int64
	RemoveUnusedFieldFiles() error

	GetFieldJSONIndexStats() map[int64]*querypb.JsonStatsInfo
}

// FlushConfig contains configuration for flushing segment data.
// All paths and settings are passed to C++ side via FFI.
type FlushConfig struct {
	// Segment base path for binlog storage
	SegmentBasePath string
	// Partition base path for LOB storage (TEXT fields)
	PartitionBasePath string
	// Collection ID
	CollectionID int64
	// Partition ID
	PartitionID int64
	// Schema is the flush-task schema for the offset range being flushed.
	// It must not be inferred from the mutable growing segment runtime schema.
	Schema *schemapb.CollectionSchema
	// TEXT column field IDs
	TextFieldIDs []int64
	// LOB base paths for each TEXT field (same order as TextFieldIDs)
	// Format: {partition_path}/lobs/{field_id}
	TextLobPaths []string
	// TEXT LOB writer thresholds, aligned with DataNode writer settings.
	TextInlineThreshold     int64
	TextMaxLobFileBytes     int64
	TextFlushThresholdBytes int64
	// BM25 output sparse vector field IDs whose stats should be collected for
	// the flushed offset range.
	BM25FieldIDs []int64
	// BM25 stats log IDs, in the same order as BM25FieldIDs.
	BM25StatsLogIDs []int64
	// WriteMergedBM25Stats writes a compound BM25 stats file in the same
	// manifest transaction. It should be true only for the final flush.
	WriteMergedBM25Stats bool
	// ReadVersion is the manifest version to read from.
	// Must be set to the last version acknowledged by DataCoord (via SaveBinlogPaths).
	// Use ManifestEarliest for the first flush so retries never append to latest.
	ReadVersion int64
	// WriterFormat is passed as writer.format. For incremental growing flushes,
	// it may be resolved from the acknowledged manifest to keep appends
	// compatible with existing column groups.
	WriterFormat string
	// SchemaBasedPattern is passed as writer.split.schema_based.patterns.
	// When set, C++ uses schema_based writer policy instead of single.
	SchemaBasedPattern string
	// SchemaBasedFormats is passed as writer.split.schema_based.formats.
	// It preserves per-column-group formats when appending to existing manifests.
	SchemaBasedFormats string
	// AllowedFieldIDs limits growing flush output to fields compatible with
	// the target segment layout.
	AllowedFieldIDs []int64
	ColumnGroups    []storagecommon.ColumnGroup
}

// FlushResult contains the result of flushing segment data.
// All data is returned from C++ side via FFI. In Storage V3 FFI mode,
// ManifestPath points to the physical files while the summary fields are used
// to build DataCoord binlog metadata.
type FlushResult struct {
	// Manifest path (Storage V3 - contains all file information).
	// The committed version is encoded in the path and can be extracted
	// via packed.UnmarshalManifestPath when needed.
	ManifestPath string
	// Number of rows flushed
	NumRows       int64
	TimestampFrom uint64
	TimestampTo   uint64
	// FlushedFieldIDs is the authoritative set of columns the flush actually
	// wrote; non-materialized function-output columns are skipped and absent.
	FlushedFieldIDs        []int64
	ColumnGroupMemorySizes map[int64]int64
	FieldNullCounts        map[int64]int64
	BM25Stats              map[int64]*storage.BM25Stats
}