// 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 csv

import (
	"context"
	"encoding/csv"
	"fmt"
	"io"
	"math/rand"
	"os"
	"strings"
	"testing"

	"github.com/stretchr/testify/mock"
	"github.com/stretchr/testify/suite"

	"github.com/milvus-io/milvus-proto/go-api/v3/commonpb"
	"github.com/milvus-io/milvus-proto/go-api/v3/schemapb"
	"github.com/milvus-io/milvus/internal/mocks"
	"github.com/milvus-io/milvus/internal/storage"
	importcommon "github.com/milvus-io/milvus/internal/util/importutilv2/common"
	"github.com/milvus-io/milvus/internal/util/testutil"
	"github.com/milvus-io/milvus/pkg/v3/common"
	"github.com/milvus-io/milvus/pkg/v3/objectstorage"
	"github.com/milvus-io/milvus/pkg/v3/util/merr"
	"github.com/milvus-io/milvus/pkg/v3/util/paramtable"
)

func init() {
	paramtable.Init()
}

type ReaderSuite struct {
	suite.Suite

	numRows     int
	pkDataType  schemapb.DataType
	vecDataType schemapb.DataType
}

func (suite *ReaderSuite) SetupTest() {
	suite.numRows = 100
	suite.pkDataType = schemapb.DataType_Int64
	suite.vecDataType = schemapb.DataType_FloatVector
}

func (suite *ReaderSuite) run(dataType schemapb.DataType, elemType schemapb.DataType, nullable bool, nullPercent int) {
	schema := &schemapb.CollectionSchema{
		Fields: []*schemapb.FieldSchema{
			{
				FieldID:      100,
				Name:         "pk",
				IsPrimaryKey: true,
				DataType:     suite.pkDataType,
				TypeParams: []*commonpb.KeyValuePair{
					{
						Key:   common.MaxLengthKey,
						Value: "128",
					},
				},
			},
			{
				FieldID:  101,
				Name:     "vec",
				DataType: suite.vecDataType,
				TypeParams: []*commonpb.KeyValuePair{
					{
						Key:   common.DimKey,
						Value: "8",
					},
				},
				Nullable: nullable,
			},
			{
				FieldID:     102,
				Name:        dataType.String(),
				DataType:    dataType,
				ElementType: elemType,
				TypeParams: []*commonpb.KeyValuePair{
					{
						Key:   common.MaxLengthKey,
						Value: "128",
					},
					{
						Key:   common.MaxCapacityKey,
						Value: "256",
					},
				},
				Nullable: nullable,
			},
		},
	}
	if dataType == schemapb.DataType_VarChar {
		// Add a BM25 function if data type is VarChar
		schema.Fields = append(schema.Fields, &schemapb.FieldSchema{
			FieldID:          103,
			Name:             "sparse",
			DataType:         schemapb.DataType_SparseFloatVector,
			IsFunctionOutput: true,
		})
		schema.Functions = append(schema.Functions, &schemapb.FunctionSchema{
			Id:               1000,
			Name:             "bm25",
			Type:             schemapb.FunctionType_BM25,
			InputFieldIds:    []int64{102},
			InputFieldNames:  []string{dataType.String()},
			OutputFieldIds:   []int64{103},
			OutputFieldNames: []string{"sparse"},
		})
	}

	// config
	// csv separator
	sep := ','
	// csv writer write null value as empty string
	nullkey := ""

	// generate csv data
	insertData, err := testutil.CreateInsertData(schema, suite.numRows, nullPercent)
	suite.NoError(err)
	csvData, err := testutil.CreateInsertDataForCSV(schema, insertData, nullkey)
	suite.NoError(err)

	// write to csv file
	filePath := fmt.Sprintf("/tmp/test_%d_reader.csv", rand.Int())
	defer os.Remove(filePath)
	wf, err := os.OpenFile(filePath, os.O_RDWR|os.O_CREATE, 0o666)
	suite.NoError(err)
	writer := csv.NewWriter(wf)
	writer.Comma = sep
	err = writer.WriteAll(csvData)
	suite.NoError(err)

	// read from csv file
	ctx := context.Background()
	f := storage.NewChunkManagerFactory("local", objectstorage.RootPath(suite.T().TempDir()+"/"))
	cm, err := f.NewPersistentStorageChunkManager(ctx)
	suite.NoError(err)

	// check reader separate fields by '\t'
	wrongSep := '\t'
	_, err = NewReader(ctx, cm, schema, filePath, 64*1024*1024, wrongSep, nullkey)
	suite.Error(err)
	suite.Contains(err.Error(), "value of field is missed:")

	// check data
	reader, err := NewReader(ctx, cm, schema, filePath, 64*1024*1024, sep, nullkey)
	suite.NoError(err)

	checkFn := func(actualInsertData *storage.InsertData, offsetBegin, expectRows int) {
		expectInsertData := insertData
		for fieldID, data := range actualInsertData.Data {
			suite.Equal(expectRows, data.RowNum())
			for i := 0; i < expectRows; i++ {
				expect := expectInsertData.Data[fieldID].GetRow(i + offsetBegin)
				actual := data.GetRow(i)
				suite.Equal(expect, actual)
			}
		}
	}

	res, err := reader.Read()
	suite.NoError(err)
	checkFn(res, 0, suite.numRows)
}

func (suite *ReaderSuite) TestReadScalarFields() {
	elementTypes := []schemapb.DataType{
		schemapb.DataType_Bool,
		schemapb.DataType_Int8,
		schemapb.DataType_Int16,
		schemapb.DataType_Int32,
		schemapb.DataType_Int64,
		schemapb.DataType_Float,
		schemapb.DataType_Double,
		schemapb.DataType_String,
	}
	scalarTypes := append(elementTypes, []schemapb.DataType{schemapb.DataType_VarChar, schemapb.DataType_JSON, schemapb.DataType_Array}...)

	for _, dataType := range scalarTypes {
		if dataType == schemapb.DataType_Array {
			for _, elementType := range elementTypes {
				suite.run(dataType, elementType, false, 0)
				for _, nullPercent := range []int{0, 50, 100} {
					suite.run(dataType, elementType, true, nullPercent)
				}
			}
		} else {
			suite.run(dataType, schemapb.DataType_None, false, 0)
			for _, nullPercent := range []int{0, 50, 100} {
				suite.run(dataType, schemapb.DataType_None, true, nullPercent)
			}
		}
	}
}

func (suite *ReaderSuite) TestStringPK() {
	suite.pkDataType = schemapb.DataType_VarChar
	suite.run(schemapb.DataType_Int32, schemapb.DataType_None, false, 0)
	for _, nullPercent := range []int{0, 50, 100} {
		suite.run(schemapb.DataType_Int32, schemapb.DataType_None, true, nullPercent)
	}
}

func (suite *ReaderSuite) TestVector() {
	dataTypes := []schemapb.DataType{
		schemapb.DataType_BinaryVector,
		schemapb.DataType_FloatVector,
		schemapb.DataType_Float16Vector,
		schemapb.DataType_BFloat16Vector,
		schemapb.DataType_SparseFloatVector,
		schemapb.DataType_Int8Vector,
	}

	for _, dataType := range dataTypes {
		suite.vecDataType = dataType
		suite.run(schemapb.DataType_Int32, schemapb.DataType_None, false, 0)
		for _, nullPercent := range []int{0, 50, 100} {
			suite.run(schemapb.DataType_Int32, schemapb.DataType_None, true, nullPercent)
		}
	}
}

func (suite *ReaderSuite) TestError() {
	testNewReaderErr := func(ioErr error, schema *schemapb.CollectionSchema, content string, bufferSize int) {
		cm := mocks.NewChunkManager(suite.T())
		cm.EXPECT().Reader(mock.Anything, mock.Anything).RunAndReturn(func(ctx context.Context, s string) (storage.FileReader, error) {
			if ioErr != nil {
				return nil, ioErr
			} else {
				r := importcommon.NewMockReader(content)
				return r, nil
			}
		})
		cm.EXPECT().Size(mock.Anything, "dummy path").Return(int64(len(content)), nil).Maybe()

		reader, err := NewReader(context.Background(), cm, schema, "dummy path", bufferSize, ',', "")
		suite.Error(err)
		suite.Nil(reader)
	}

	testNewReaderErr(merr.WrapErrImportFailed("error"), nil, "", 1)

	schema := &schemapb.CollectionSchema{
		Fields: []*schemapb.FieldSchema{
			{
				FieldID:      100,
				Name:         "pk",
				IsPrimaryKey: true,
				DataType:     schemapb.DataType_Int64,
			},
			{
				FieldID:  101,
				Name:     "int32",
				DataType: schemapb.DataType_Int32,
			},
		},
	}
	testNewReaderErr(nil, schema, "", -1)
	testNewReaderErr(nil, schema, "", 1)

	testReadErr := func(schema *schemapb.CollectionSchema, content string) {
		cm := mocks.NewChunkManager(suite.T())
		cm.EXPECT().Reader(mock.Anything, mock.Anything).RunAndReturn(func(ctx context.Context, s string) (storage.FileReader, error) {
			r := importcommon.NewMockReader(content)
			return r, nil
		})
		cm.EXPECT().Size(mock.Anything, mock.Anything).Return(128, nil)

		reader, err := NewReader(context.Background(), cm, schema, "dummy path", 1024, ',', "")
		suite.NoError(err)
		suite.NotNil(reader)

		size, err := reader.Size()
		suite.NoError(err)
		suite.Equal(int64(128), size)

		_, err = reader.Read()
		suite.Error(err)
	}
	content := "pk,int32\n1,A"
	testReadErr(schema, content)
}

func (suite *ReaderSuite) TestReadLoop() {
	schema := &schemapb.CollectionSchema{
		Fields: []*schemapb.FieldSchema{
			{
				FieldID:      100,
				Name:         "pk",
				IsPrimaryKey: true,
				DataType:     schemapb.DataType_Int64,
			},
			{
				FieldID:  101,
				Name:     "float",
				DataType: schemapb.DataType_Float,
			},
		},
	}
	content := "pk,float\n1,0.1\n2,0.2"

	cm := mocks.NewChunkManager(suite.T())
	cm.EXPECT().Reader(mock.Anything, mock.Anything).RunAndReturn(func(ctx context.Context, s string) (storage.FileReader, error) {
		r := importcommon.NewMockReader(content)
		return r, nil
	})
	cm.EXPECT().Size(mock.Anything, mock.Anything).Return(128, nil)

	reader, err := NewReader(context.Background(), cm, schema, "dummy path", 1, ',', "")
	suite.NoError(err)
	suite.NotNil(reader)
	defer reader.Close()

	size, err := reader.Size()
	suite.NoError(err)
	suite.Equal(int64(128), size)
	size2, err := reader.Size() // size is cached
	suite.NoError(err)
	suite.Equal(size, size2)

	reader.count = 1
	data, err := reader.Read()
	suite.NoError(err)
	suite.Equal(1, data.GetRowNum())

	data, err = reader.Read()
	suite.NoError(err)
	suite.Equal(1, data.GetRowNum())

	data, err = reader.Read()
	suite.EqualError(io.EOF, err.Error())
	suite.Nil(data)
}

func (suite *ReaderSuite) TestReadRecoversFromPrematureEOF() {
	schema := &schemapb.CollectionSchema{
		Fields: []*schemapb.FieldSchema{
			{
				FieldID:      100,
				Name:         "pk",
				IsPrimaryKey: true,
				DataType:     schemapb.DataType_Int64,
			},
			{
				FieldID:  101,
				Name:     "int32",
				DataType: schemapb.DataType_Int32,
			},
		},
	}
	var contentBuilder strings.Builder
	contentBuilder.WriteString("pk,int32\n")
	for i := 1; i <= 100; i++ {
		fmt.Fprintf(&contentBuilder, "%d,%d\n", i, i*10)
	}
	content := contentBuilder.String()
	openCount := 0

	cm := mocks.NewChunkManager(suite.T())
	cm.EXPECT().Reader(mock.Anything, "dummy path").RunAndReturn(func(ctx context.Context, path string) (storage.FileReader, error) {
		openCount++
		if openCount == 1 {
			return importcommon.NewPrematureEOFReader(content, 18), nil
		}
		return importcommon.NewMockReader(content), nil
	})

	reader, err := NewReader(context.Background(), cm, schema, "dummy path", 1024, ',', "")
	suite.NoError(err)
	defer reader.Close()

	data, err := reader.Read()
	suite.NoError(err)
	suite.Equal(100, data.GetRowNum())
	suite.Equal(int64(1), data.Data[100].GetRow(0))
	suite.Equal(int32(1000), data.Data[101].GetRow(99))
	suite.GreaterOrEqual(openCount, 2)
}

func TestCsvReader(t *testing.T) {
	suite.Run(t, new(ReaderSuite))
}

func (suite *ReaderSuite) TestAllowInsertAutoID_KeepUserPK() {
	schema := &schemapb.CollectionSchema{
		Fields: []*schemapb.FieldSchema{
			{
				FieldID:      100,
				Name:         "pk",
				IsPrimaryKey: true,
				DataType:     schemapb.DataType_Int64,
				AutoID:       true,
			},
			{
				FieldID:    101,
				Name:       "vec",
				DataType:   schemapb.DataType_FloatVector,
				TypeParams: []*commonpb.KeyValuePair{{Key: common.DimKey, Value: "8"}},
			},
		},
	}

	// prepare csv content with header including pk
	content := "pk,vec\n"
	// one row is enough; vec must be a quoted JSON array to avoid CSV splitting
	content += "1,\"[0,1,2,3,4,5,6,7]\"\n"

	// allow_insert_autoid=false, providing PK in header should error
	{
		cm := mocks.NewChunkManager(suite.T())
		cm.EXPECT().Reader(mock.Anything, mock.Anything).RunAndReturn(func(ctx context.Context, s string) (storage.FileReader, error) {
			r := importcommon.NewMockReader(content)
			return r, nil
		})
		_, err := NewReader(context.Background(), cm, schema, "dummy path", 1024, ',', "")
		suite.Error(err)
		suite.Contains(err.Error(), "is auto-generated, no need to provide")
	}

	// allow_insert_autoid=true, providing PK in header should be allowed
	{
		schema.Properties = []*commonpb.KeyValuePair{{Key: common.AllowInsertAutoIDKey, Value: "true"}}
		cm := mocks.NewChunkManager(suite.T())
		cm.EXPECT().Reader(mock.Anything, mock.Anything).RunAndReturn(func(ctx context.Context, s string) (storage.FileReader, error) {
			r := importcommon.NewMockReader(content)
			return r, nil
		})
		reader, err := NewReader(context.Background(), cm, schema, "dummy path", 1024, ',', "")
		suite.NoError(err)
		// call Read once to ensure parsing proceeds
		_, err = reader.Read()
		suite.NoError(err)
	}
}

func (suite *ReaderSuite) TestFunctionOutputField() {
	// Test 1: BM25 function output NOT in CSV should be excluded from result,
	// but nullable non-function-output field not in CSV should be retained (filled with nil).
	{
		schema := &schemapb.CollectionSchema{
			Fields: []*schemapb.FieldSchema{
				{FieldID: 100, Name: "pk", IsPrimaryKey: true, DataType: schemapb.DataType_Int64},
				{
					FieldID: 101, Name: "text", DataType: schemapb.DataType_VarChar,
					TypeParams: []*commonpb.KeyValuePair{{Key: common.MaxLengthKey, Value: "128"}},
				},
				{FieldID: 102, Name: "sparse", DataType: schemapb.DataType_SparseFloatVector, IsFunctionOutput: true},
				{FieldID: 103, Name: "score", DataType: schemapb.DataType_Float, Nullable: true},
			},
			Functions: []*schemapb.FunctionSchema{
				{
					Id: 1000, Name: "bm25", Type: schemapb.FunctionType_BM25,
					InputFieldIds: []int64{101}, InputFieldNames: []string{"text"},
					OutputFieldIds: []int64{102}, OutputFieldNames: []string{"sparse"},
				},
			},
		}
		// CSV does NOT provide "sparse" (function output) or "score" (nullable)
		content := "pk,text\n1,hello\n2,world"
		cm := mocks.NewChunkManager(suite.T())
		cm.EXPECT().Reader(mock.Anything, mock.Anything).RunAndReturn(func(ctx context.Context, s string) (storage.FileReader, error) {
			return importcommon.NewMockReader(content), nil
		})

		reader, err := NewReader(context.Background(), cm, schema, "dummy path", 1024, ',', "")
		suite.NoError(err)
		res, err := reader.Read()
		suite.NoError(err)
		suite.Equal(2, res.GetRowNum())
		// BM25 function output field should be removed (not populated from CSV)
		_, hasSparse := res.Data[102]
		suite.False(hasSparse)
		// Nullable non-function-output field should be retained (filled with nil, not removed)
		scoreData, hasScore := res.Data[103]
		suite.True(hasScore)
		suite.Equal(2, scoreData.RowNum())
	}

	// Test 2: Non-BM25 function output in CSV with property enabled should be included
	{
		schema := &schemapb.CollectionSchema{
			Fields: []*schemapb.FieldSchema{
				{FieldID: 100, Name: "pk", IsPrimaryKey: true, DataType: schemapb.DataType_Int64},
				{
					FieldID: 101, Name: "text", DataType: schemapb.DataType_VarChar,
					TypeParams: []*commonpb.KeyValuePair{{Key: common.MaxLengthKey, Value: "128"}},
				},
				{
					FieldID: 102, Name: "embedding", DataType: schemapb.DataType_FloatVector, IsFunctionOutput: true,
					TypeParams: []*commonpb.KeyValuePair{{Key: common.DimKey, Value: "2"}},
				},
			},
			Functions: []*schemapb.FunctionSchema{
				{
					Id: 1000, Name: "text_embedding", Type: schemapb.FunctionType_TextEmbedding,
					InputFieldIds: []int64{101}, InputFieldNames: []string{"text"},
					OutputFieldIds: []int64{102}, OutputFieldNames: []string{"embedding"},
				},
			},
			Properties: []*commonpb.KeyValuePair{
				{Key: common.CollectionAllowInsertNonBM25FunctionOutputs, Value: "true"},
			},
		}
		content := "pk,text,embedding\n1,hello,\"[0.1, 0.2]\"\n2,world,\"[0.3, 0.4]\""
		cm := mocks.NewChunkManager(suite.T())
		cm.EXPECT().Reader(mock.Anything, mock.Anything).RunAndReturn(func(ctx context.Context, s string) (storage.FileReader, error) {
			return importcommon.NewMockReader(content), nil
		})

		reader, err := NewReader(context.Background(), cm, schema, "dummy path", 1024, ',', "")
		suite.NoError(err)
		res, err := reader.Read()
		suite.NoError(err)
		suite.Equal(2, res.GetRowNum())
		// embedding field should be present with correct data
		suite.NotNil(res.Data[102])
		suite.Equal(2, res.Data[102].RowNum())
	}
}