package planparserv2

import (
	"fmt"

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

	"github.com/antlr/antlr4/runtime/Go/antlr"
)

func handleExpr(schema *typeutil.SchemaHelper, exprStr string) interface{} {
	if exprStr == "" {
		return nil
	}

	inputStream := antlr.NewInputStream(exprStr)
	errorListener := &errorListener{}

	lexer := getLexer(inputStream, errorListener)
	if errorListener.err != nil {
		return errorListener.err
	}

	parser := getParser(lexer, errorListener)
	if errorListener.err != nil {
		return errorListener.err
	}

	ast := parser.Expr()
	if errorListener.err != nil {
		return errorListener.err
	}

	// lexer & parser won't be used by this thread, can be put into pool.
	putLexer(lexer)
	putParser(parser)

	visitor := NewParserVisitor(schema)
	return ast.Accept(visitor)
}

func ParseExpr(schema *typeutil.SchemaHelper, exprStr string) (*planpb.Expr, error) {
	if len(exprStr) <= 0 {
		return nil, nil
	}

	ret := handleExpr(schema, exprStr)

	if err := getError(ret); err != nil {
		return nil, fmt.Errorf("cannot parse expression: %s, error: %s", exprStr, err)
	}

	predicate := getExpr(ret)
	if predicate == nil {
		return nil, fmt.Errorf("cannot parse expression: %s", exprStr)
	}

	if !typeutil.IsBoolType(predicate.dataType) {
		return nil, fmt.Errorf("predicate is not a boolean expression: %s, data type: %s", exprStr, predicate.dataType)
	}

	return predicate.expr, nil
}

func CreateRetrievePlan(schemaPb *schemapb.CollectionSchema, exprStr string) (*planpb.PlanNode, error) {
	schema, err := typeutil.CreateSchemaHelper(schemaPb)
	if err != nil {
		return nil, err
	}

	expr, err := ParseExpr(schema, exprStr)
	if err != nil {
		return nil, err
	}

	planNode := &planpb.PlanNode{
		Node: &planpb.PlanNode_Query{
			Query: &planpb.QueryPlanNode{
				Predicates: expr,
			},
		},
	}
	return planNode, nil
}

func CreateSearchPlan(schemaPb *schemapb.CollectionSchema, exprStr string, vectorFieldName string, queryInfo *planpb.QueryInfo) (*planpb.PlanNode, error) {
	schema, err := typeutil.CreateSchemaHelper(schemaPb)
	if err != nil {
		return nil, err
	}

	expr, err := ParseExpr(schema, exprStr)
	if err != nil {
		return nil, err
	}
	vectorField, err := schema.GetFieldFromName(vectorFieldName)
	if err != nil {
		return nil, err
	}
	fieldID := vectorField.FieldID
	dataType := vectorField.DataType

	if !typeutil.IsVectorType(dataType) {
		return nil, fmt.Errorf("field (%s) to search is not of vector data type", vectorFieldName)
	}

	planNode := &planpb.PlanNode{
		Node: &planpb.PlanNode_VectorAnns{
			VectorAnns: &planpb.VectorANNS{
				IsBinary:       dataType == schemapb.DataType_BinaryVector,
				Predicates:     expr,
				QueryInfo:      queryInfo,
				PlaceholderTag: "$0",
				FieldId:        fieldID,
			},
		},
	}
	return planNode, nil
}
