// Copyright 2021 PingCAP, Inc.
//
// Licensed 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 aggregation

import (
	"testing"

	"github.com/pingcap/tidb/pkg/expression"
	"github.com/pingcap/tidb/pkg/parser/ast"
	"github.com/pingcap/tidb/pkg/parser/mysql"
	"github.com/pingcap/tidb/pkg/types"
	"github.com/pingcap/tidb/pkg/util/mock"
	"github.com/stretchr/testify/require"
)

func TestClone(t *testing.T) {
	ctx := mock.NewContext()
	col := &expression.Column{
		UniqueID: 0,
		RetType:  types.NewFieldType(mysql.TypeLonglong),
	}
	desc, err := newBaseFuncDesc(ctx, ast.AggFuncFirstRow, []expression.Expression{col})
	require.NoError(t, err)
	cloned := desc.clone()
	require.True(t, desc.equal(ctx, cloned))

	col1 := &expression.Column{
		UniqueID: 1,
		RetType:  types.NewFieldType(mysql.TypeVarchar),
	}
	cloned.Args[0] = col1

	require.Equal(t, col, desc.Args[0])
	require.False(t, desc.equal(ctx, cloned))
}

func TestBaseFunc_InferAggRetType(t *testing.T) {
	ctx := mock.NewContext()
	doubleType := types.NewFieldType(mysql.TypeDouble)
	bitType := types.NewFieldType(mysql.TypeBit)

	funcNames := []string{
		ast.AggFuncMax, ast.AggFuncMin,
	}
	dataTypes := []*types.FieldType{
		doubleType, bitType,
	}

	for _, dataType := range dataTypes {
		notNullType := dataType.Clone()
		notNullType.AddFlag(mysql.NotNullFlag)
		col := &expression.Column{
			UniqueID: 0,
			RetType:  notNullType,
		}
		for _, name := range funcNames {
			desc, err := newBaseFuncDesc(ctx, name, []expression.Expression{col})
			require.NoError(t, err)
			err = desc.TypeInfer(ctx)
			require.NoError(t, err)
			require.Equal(t, dataType, desc.RetTp)
		}
	}
}

func TestTypeInfer4AvgSum(t *testing.T) {
	ctx := mock.NewContext()

	// sum(col)
	{
		argCol := &expression.Column{
			UniqueID: 0,
			RetType:  types.NewFieldType(mysql.TypeNewDecimal),
		}
		argColFlen := 15
		argCol.RetType.SetFlen(argColFlen)
		argCol.RetType.SetDecimal(2)

		avgFunc, err := newBaseFuncDesc(ctx, ast.AggFuncAvg, []expression.Expression{argCol})
		require.NoError(t, err)
		err = avgFunc.TypeInfer(ctx)
		require.NoError(t, err)

		partialSumFunc := avgFunc
		partialSumFunc.Name = ast.AggFuncSum
		err = partialSumFunc.TypeInfer4AvgSum(ctx.GetEvalCtx(), avgFunc.RetTp)
		require.NoError(t, err)

		require.Equal(t, partialSumFunc.RetTp.GetFlen(), argColFlen+22)
		require.Equal(t, partialSumFunc.RetTp.GetDecimal(), 2)
	}

	// sum(div(col/col))
	{
		divArgCol1 := &expression.Column{
			UniqueID: 0,
			RetType:  types.NewFieldType(mysql.TypeNewDecimal),
		}
		divArgCol1.RetType.SetFlen(20)
		divArgCol1.RetType.SetDecimal(0)

		divArgCol2 := &expression.Column{
			UniqueID: 0,
			RetType:  types.NewFieldType(mysql.TypeNewDecimal),
		}
		divArgCol2.RetType.SetFlen(5)
		divArgCol2.RetType.SetDecimal(0)

		mockDivRetType := types.NewFieldType(mysql.TypeUnspecified)
		divExpr, err := expression.NewFunction(ctx, ast.Div, mockDivRetType, divArgCol1, divArgCol2)
		require.NoError(t, err)
		require.Equal(t, divExpr.GetType(ctx.GetEvalCtx()).GetFlen(), 25)
		require.Equal(t, divExpr.GetType(ctx.GetEvalCtx()).GetDecimal(), 4)

		avgFunc, err := newBaseFuncDesc(ctx, ast.AggFuncAvg, []expression.Expression{divExpr})
		require.NoError(t, err)
		err = avgFunc.TypeInfer(ctx)
		require.NoError(t, err)
		require.Equal(t, avgFunc.RetTp.GetFlen(), 29)
		require.Equal(t, avgFunc.RetTp.GetDecimal(), 8)

		partialSumFunc := avgFunc
		partialSumFunc.Name = ast.AggFuncSum
		err = partialSumFunc.TypeInfer4AvgSum(ctx.GetEvalCtx(), avgFunc.RetTp)
		require.NoError(t, err)
		require.Equal(t, partialSumFunc.RetTp.GetFlen(), 51)
		require.Equal(t, partialSumFunc.RetTp.GetDecimal(), 8)
	}
}