// 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 proxy

import (
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"

	"github.com/milvus-io/milvus-proto/go-api/v3/commonpb"
	"github.com/milvus-io/milvus-proto/go-api/v3/milvuspb"
	"github.com/milvus-io/milvus-proto/go-api/v3/schemapb"
	"github.com/milvus-io/milvus/internal/util/function/chain/types"
)

func TestValidateFunctionChainSearchRequest(t *testing.T) {
	t.Run("ordinary function chains", func(t *testing.T) {
		err := validateFunctionChainSearchRequest(&milvuspb.SearchRequest{
			FunctionChains: []*schemapb.FunctionChain{l2FunctionChain(mapOp(types.ScoreFieldName, "expr", columnArg(types.ScoreFieldName)))},
		}, false)
		require.NoError(t, err)
	})

	t.Run("ordinary request without function chains", func(t *testing.T) {
		err := validateFunctionChainSearchRequest(&milvuspb.SearchRequest{}, false)
		require.NoError(t, err)
	})

	t.Run("function score and function chains", func(t *testing.T) {
		err := validateFunctionChainSearchRequest(&milvuspb.SearchRequest{
			FunctionScore:  &schemapb.FunctionScore{},
			FunctionChains: []*schemapb.FunctionChain{l2FunctionChain(mapOp(types.ScoreFieldName, "expr", columnArg(types.ScoreFieldName)))},
		}, false)
		require.Error(t, err)
		assert.Contains(t, err.Error(), "function_score and function_chains cannot be used together")
	})

	t.Run("hybrid function chains", func(t *testing.T) {
		err := validateFunctionChainSearchRequest(&milvuspb.SearchRequest{
			FunctionChains: []*schemapb.FunctionChain{l2FunctionChain(mapOp(types.ScoreFieldName, "expr", columnArg(types.ScoreFieldName)))},
		}, true)
		require.Error(t, err)
		assert.Contains(t, err.Error(), "function_chains is not supported for hybrid search yet")
	})
}

func TestSplitFunctionChainsByStage(t *testing.T) {
	t.Run("split l0 and l2 chains", func(t *testing.T) {
		l0Chain := l0FunctionChain()
		l2Chain := l2FunctionChain(mapOp(types.ScoreFieldName, "expr", columnArg(types.ScoreFieldName)))

		l2Chains, querynodeChains, err := splitFunctionChainsByStage([]*schemapb.FunctionChain{l0Chain, l2Chain})
		require.NoError(t, err)
		assert.Equal(t, []*schemapb.FunctionChain{l2Chain}, l2Chains)
		assert.Equal(t, []*schemapb.FunctionChain{l0Chain}, querynodeChains)
	})

	t.Run("l0 chain is shallow routed without op validation", func(t *testing.T) {
		l0Chain := l0FunctionChain()

		l2Chains, querynodeChains, err := splitFunctionChainsByStage([]*schemapb.FunctionChain{l0Chain})
		require.NoError(t, err)
		assert.Empty(t, l2Chains)
		assert.Equal(t, []*schemapb.FunctionChain{l0Chain}, querynodeChains)
	})

	t.Run("nil chain", func(t *testing.T) {
		_, _, err := splitFunctionChainsByStage([]*schemapb.FunctionChain{nil})
		require.Error(t, err)
		assert.Contains(t, err.Error(), "function chain[0] is nil")
	})

	t.Run("duplicate stage", func(t *testing.T) {
		_, _, err := splitFunctionChainsByStage([]*schemapb.FunctionChain{
			l0FunctionChain(),
			l0FunctionChain(),
		})
		require.Error(t, err)
		assert.Contains(t, err.Error(), "appears more than once")
	})

	t.Run("l1 is not supported yet", func(t *testing.T) {
		_, _, err := splitFunctionChainsByStage([]*schemapb.FunctionChain{{
			Stage: schemapb.FunctionChainStage_FunctionChainStageL1Rerank,
		}})
		require.Error(t, err)
		assert.Contains(t, err.Error(), "is not supported yet")
	})
}

func TestNewFunctionChainRerankMeta(t *testing.T) {
	schema := newFunctionChainTestSchema()

	t.Run("empty chains", func(t *testing.T) {
		meta, err := newFunctionChainRerankMeta(nil, schema)
		require.NoError(t, err)
		assert.Nil(t, meta)
	})

	t.Run("score only chain", func(t *testing.T) {
		chainPB := l2FunctionChain(mapOp(types.ScoreFieldName, "expr", columnArg(types.ScoreFieldName)))

		meta, err := newFunctionChainRerankMeta([]*schemapb.FunctionChain{chainPB}, schema)
		require.NoError(t, err)
		require.NotNil(t, meta)
		assert.Empty(t, meta.GetInputFieldNames())
		assert.Empty(t, meta.GetInputFieldIDs())
		assert.Equal(t, chainPB, meta.chainPB)
		assert.NotNil(t, meta.repr)
	})

	t.Run("schema field and score", func(t *testing.T) {
		chainPB := l2FunctionChain(
			mapOp("score1", "decay", columnArg("ts")),
			mapOp(types.ScoreFieldName, "sum", columnArg("score1"), columnArg(types.ScoreFieldName)),
		)

		meta, err := newFunctionChainRerankMeta([]*schemapb.FunctionChain{chainPB}, schema)
		require.NoError(t, err)
		require.NotNil(t, meta)
		assert.Equal(t, []string{"ts"}, meta.GetInputFieldNames())
		assert.Equal(t, []int64{101}, meta.GetInputFieldIDs())
	})

	t.Run("duplicate schema input is planned once", func(t *testing.T) {
		chainPB := l2FunctionChain(
			mapOp("score1", "expr", columnArg("ts"), columnArg(types.ScoreFieldName)),
			mapOp(types.ScoreFieldName, "expr", columnArg("ts"), columnArg("score1")),
		)

		meta, err := newFunctionChainRerankMeta([]*schemapb.FunctionChain{chainPB}, schema)
		require.NoError(t, err)
		require.NotNil(t, meta)
		assert.Equal(t, []string{"ts"}, meta.GetInputFieldNames())
		assert.Equal(t, []int64{101}, meta.GetInputFieldIDs())
	})

	t.Run("struct array sub field input is unsupported", func(t *testing.T) {
		structSchema := newFunctionChainStructTestSchema()
		chainPB := l2FunctionChain(mapOp("score1", "expr", columnArg("struct_scalar_array")))

		_, err := newFunctionChainRerankMeta([]*schemapb.FunctionChain{chainPB}, structSchema)
		require.Error(t, err)
		assert.Contains(t, err.Error(), "unsupported field type")
		assert.Contains(t, err.Error(), "Array")
	})

	t.Run("nil schema", func(t *testing.T) {
		_, _, err := getFunctionChainInputField(nil, "ts")
		require.Error(t, err)
		assert.Contains(t, err.Error(), "neither a previous output nor a collection field")
	})

	t.Run("duplicate stage", func(t *testing.T) {
		_, err := newFunctionChainRerankMeta([]*schemapb.FunctionChain{
			l2FunctionChain(mapOp(types.ScoreFieldName, "expr", columnArg(types.ScoreFieldName))),
			l2FunctionChain(mapOp(types.ScoreFieldName, "expr", columnArg(types.ScoreFieldName))),
		}, schema)
		require.Error(t, err)
		assert.Contains(t, err.Error(), "appears more than once")
	})

	t.Run("non l2 stage", func(t *testing.T) {
		_, err := newFunctionChainRerankMeta([]*schemapb.FunctionChain{
			{
				Stage: schemapb.FunctionChainStage_FunctionChainStageL1Rerank,
				Ops:   []*schemapb.FunctionChainOp{mapOp(types.ScoreFieldName, "expr", columnArg(types.ScoreFieldName))},
			},
		}, schema)
		require.Error(t, err)
		assert.Contains(t, err.Error(), "is not supported in search request")
	})

	t.Run("empty l2 chain", func(t *testing.T) {
		_, err := newFunctionChainRerankMeta([]*schemapb.FunctionChain{
			l2FunctionChain(),
		}, schema)
		require.Error(t, err)
		assert.Contains(t, err.Error(), "function chain[0] must contain at least one op")
	})

	t.Run("unknown field", func(t *testing.T) {
		_, err := newFunctionChainRerankMeta([]*schemapb.FunctionChain{
			l2FunctionChain(mapOp("score1", "decay", columnArg("unknown"))),
		}, schema)
		require.Error(t, err)
		assert.Contains(t, err.Error(), "unknown")
		assert.Contains(t, err.Error(), "neither a previous output nor a collection field")
	})

	t.Run("unsupported system input", func(t *testing.T) {
		_, err := newFunctionChainRerankMeta([]*schemapb.FunctionChain{
			l2FunctionChain(mapOp("score1", "expr", columnArg("$timestamp"))),
		}, schema)
		require.Error(t, err)
		assert.Contains(t, err.Error(), "system input \"$timestamp\" is not supported")
	})

	t.Run("unsupported system output", func(t *testing.T) {
		_, err := newFunctionChainRerankMeta([]*schemapb.FunctionChain{
			l2FunctionChain(mapOp(types.IDFieldName, "expr", columnArg(types.ScoreFieldName), columnArg("ts"))),
		}, schema)
		require.Error(t, err)
		assert.Contains(t, err.Error(), "system output \"$id\" is not writable")
	})

	t.Run("reserved temporary system output", func(t *testing.T) {
		_, err := newFunctionChainRerankMeta([]*schemapb.FunctionChain{
			l2FunctionChain(mapOp("$tmp_score", "expr", columnArg(types.ScoreFieldName), columnArg("ts"))),
		}, schema)
		require.Error(t, err)
		assert.Contains(t, err.Error(), "system output \"$tmp_score\" is not writable")
	})

	t.Run("score system output is writable", func(t *testing.T) {
		_, err := newFunctionChainRerankMeta([]*schemapb.FunctionChain{
			l2FunctionChain(mapOp(types.ScoreFieldName, "expr", columnArg(types.ScoreFieldName), columnArg("ts"))),
		}, schema)
		require.NoError(t, err)
	})

	t.Run("unsupported field type", func(t *testing.T) {
		_, err := newFunctionChainRerankMeta([]*schemapb.FunctionChain{
			l2FunctionChain(mapOp("score1", "expr", columnArg("vec"))),
		}, schema)
		require.Error(t, err)
		assert.Contains(t, err.Error(), "unsupported field type")
		assert.Contains(t, err.Error(), "FloatVector")
	})
}

func newFunctionChainTestSchema() *schemaInfo {
	return mustNewSchemaInfo(&schemapb.CollectionSchema{
		Fields: []*schemapb.FieldSchema{
			{FieldID: 100, Name: "pk", DataType: schemapb.DataType_Int64, IsPrimaryKey: true},
			{FieldID: 101, Name: "ts", DataType: schemapb.DataType_Int64},
			{FieldID: 102, Name: "tag", DataType: schemapb.DataType_VarChar},
			{FieldID: 103, Name: "vec", DataType: schemapb.DataType_FloatVector, TypeParams: []*commonpb.KeyValuePair{{Key: "dim", Value: "4"}}},
			{FieldID: 104, Name: "flag", DataType: schemapb.DataType_Bool},
			{FieldID: 105, Name: "price", DataType: schemapb.DataType_Double},
		},
	})
}

func newFunctionChainStructTestSchema() *schemaInfo {
	return mustNewSchemaInfo(&schemapb.CollectionSchema{
		Fields: []*schemapb.FieldSchema{
			{FieldID: 100, Name: "pk", DataType: schemapb.DataType_Int64, IsPrimaryKey: true},
		},
		StructArrayFields: []*schemapb.StructArrayFieldSchema{
			{
				Name: "structArray",
				Fields: []*schemapb.FieldSchema{
					{FieldID: 201, Name: "struct_scalar_array", DataType: schemapb.DataType_Array, ElementType: schemapb.DataType_Int32},
				},
			},
		},
	})
}

func l2FunctionChain(ops ...*schemapb.FunctionChainOp) *schemapb.FunctionChain {
	return &schemapb.FunctionChain{
		Stage: schemapb.FunctionChainStage_FunctionChainStageL2Rerank,
		Ops:   ops,
	}
}

func l0FunctionChain(ops ...*schemapb.FunctionChainOp) *schemapb.FunctionChain {
	return &schemapb.FunctionChain{
		Stage: schemapb.FunctionChainStage_FunctionChainStageL0Rerank,
		Ops:   ops,
	}
}

func l2LimitFunctionChain(limit int64) *schemapb.FunctionChain {
	return l2FunctionChain(&schemapb.FunctionChainOp{
		Op: types.OpTypeLimit,
		Params: map[string]*schemapb.FunctionParamValue{
			"limit": {Value: &schemapb.FunctionParamValue_Int64Value{Int64Value: limit}},
		},
	})
}

func mapOp(output string, exprName string, args ...*schemapb.FunctionChainExprArg) *schemapb.FunctionChainOp {
	return &schemapb.FunctionChainOp{
		Op:      types.OpTypeMap,
		Outputs: []string{output},
		Expr: &schemapb.FunctionChainExpr{
			Name:   exprName,
			Args:   args,
			Params: map[string]*schemapb.FunctionParamValue{},
		},
	}
}

func columnArg(name string) *schemapb.FunctionChainExprArg {
	return &schemapb.FunctionChainExprArg{Arg: &schemapb.FunctionChainExprArg_Column{Column: &schemapb.FunctionChainColumnArg{Name: name}}}
}
