// Copyright 2022-2023 EMQ Technologies Co., Ltd.
//
// 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 protobuf

import (
	"fmt"

	// TODO: replace with `google.golang.org/protobuf/proto` pkg.
	"github.com/golang/protobuf/proto" //nolint:staticcheck
	dpb "github.com/golang/protobuf/protoc-gen-go/descriptor"
	"github.com/jhump/protoreflect/desc"
	"github.com/jhump/protoreflect/dynamic"

	"github.com/lf-edge/ekuiper/pkg/cast"
)

const (
	WrapperBool   = "google.protobuf.BoolValue"
	WrapperBytes  = "google.protobuf.BytesValue"
	WrapperDouble = "google.protobuf.DoubleValue"
	WrapperFloat  = "google.protobuf.FloatValue"
	WrapperInt32  = "google.protobuf.Int32Value"
	WrapperInt64  = "google.protobuf.Int64Value"
	WrapperString = "google.protobuf.StringValue"
	WrapperUInt32 = "google.protobuf.UInt32Value"
	WrapperUInt64 = "google.protobuf.UInt64Value"
	WrapperVoid   = "google.protobuf.EMPTY"
)

var WRAPPER_TYPES = map[string]struct{}{
	WrapperBool:   {},
	WrapperBytes:  {},
	WrapperDouble: {},
	WrapperFloat:  {},
	WrapperInt32:  {},
	WrapperInt64:  {},
	WrapperString: {},
	WrapperUInt32: {},
	WrapperUInt64: {},
}

var (
	fieldConverterIns = &FieldConverter{}
	mf                = dynamic.NewMessageFactoryWithDefaults()
)

type FieldConverter struct{}

func GetFieldConverter() *FieldConverter {
	return fieldConverterIns
}

func (fc *FieldConverter) encodeMap(im *desc.MessageDescriptor, i interface{}) (*dynamic.Message, error) {
	result := mf.NewDynamicMessage(im)
	fields := im.GetFields()
	if m, ok := i.(map[string]interface{}); ok {
		for _, field := range fields {
			v, ok := m[field.GetName()]
			if !ok {
				if field.IsRequired() {
					return nil, fmt.Errorf("field %s not found", field.GetName())
				} else {
					continue
				}
			}
			fv, err := fc.EncodeField(field, v)
			if err != nil {
				return nil, err
			}
			result.SetFieldByName(field.GetName(), fv)
		}
	}
	return result, nil
}

func (fc *FieldConverter) EncodeField(field *desc.FieldDescriptor, v interface{}) (interface{}, error) {
	fn := field.GetName()
	ft := field.GetType()
	if field.IsRepeated() {
		var (
			result interface{}
			err    error
		)
		switch ft {
		case dpb.FieldDescriptorProto_TYPE_DOUBLE:
			result, err = cast.ToFloat64Slice(v, cast.CONVERT_SAMEKIND)
		case dpb.FieldDescriptorProto_TYPE_FLOAT:
			result, err = cast.ToTypedSlice(v, func(input interface{}, sn cast.Strictness) (interface{}, error) {
				r, err := cast.ToFloat32(input, sn)
				if err != nil {
					return 0, nil
				} else {
					return r, nil
				}
			}, "float", cast.CONVERT_SAMEKIND)
		case dpb.FieldDescriptorProto_TYPE_INT32, dpb.FieldDescriptorProto_TYPE_SFIXED32, dpb.FieldDescriptorProto_TYPE_SINT32:
			result, err = cast.ToTypedSlice(v, func(input interface{}, sn cast.Strictness) (interface{}, error) {
				r, err := cast.ToInt(input, sn)
				if err != nil {
					return 0, nil
				} else {
					return int32(r), nil
				}
			}, "int", cast.CONVERT_SAMEKIND)
		case dpb.FieldDescriptorProto_TYPE_INT64, dpb.FieldDescriptorProto_TYPE_SFIXED64, dpb.FieldDescriptorProto_TYPE_SINT64:
			result, err = cast.ToInt64Slice(v, cast.CONVERT_SAMEKIND)
		case dpb.FieldDescriptorProto_TYPE_FIXED32, dpb.FieldDescriptorProto_TYPE_UINT32:
			result, err = cast.ToTypedSlice(v, func(input interface{}, sn cast.Strictness) (interface{}, error) {
				r, err := cast.ToUint64(input, sn)
				if err != nil {
					return 0, nil
				} else {
					return uint32(r), nil
				}
			}, "uint", cast.CONVERT_SAMEKIND)
		case dpb.FieldDescriptorProto_TYPE_FIXED64, dpb.FieldDescriptorProto_TYPE_UINT64:
			result, err = cast.ToUint64Slice(v, cast.CONVERT_SAMEKIND)
		case dpb.FieldDescriptorProto_TYPE_BOOL:
			result, err = cast.ToBoolSlice(v, cast.CONVERT_SAMEKIND)
		case dpb.FieldDescriptorProto_TYPE_STRING:
			result, err = cast.ToStringSlice(v, cast.CONVERT_SAMEKIND)
		case dpb.FieldDescriptorProto_TYPE_BYTES:
			result, err = cast.ToBytesSlice(v, cast.CONVERT_SAMEKIND)
		case dpb.FieldDescriptorProto_TYPE_MESSAGE:
			result, err = cast.ToTypedSlice(v, func(input interface{}, sn cast.Strictness) (interface{}, error) {
				r, err := cast.ToStringMap(input)
				if err == nil {
					return fc.encodeMap(field.GetMessageType(), r)
				} else {
					return nil, fmt.Errorf("invalid type for map type field '%s': %v", fn, err)
				}
			}, "map", cast.CONVERT_SAMEKIND)
		default:
			return nil, fmt.Errorf("invalid type for field '%s'", fn)
		}
		if err != nil {
			err = fmt.Errorf("failed to encode field '%s':%v", fn, err)
		}
		return result, err
	} else {
		return fc.encodeSingleField(field, v)
	}
}

func (fc *FieldConverter) encodeSingleField(field *desc.FieldDescriptor, v interface{}) (interface{}, error) {
	fn := field.GetName()
	switch field.GetType() {
	case dpb.FieldDescriptorProto_TYPE_DOUBLE:
		r, err := cast.ToFloat64(v, cast.CONVERT_SAMEKIND)
		if err == nil {
			return r, nil
		} else {
			return nil, fmt.Errorf("invalid type for float type field '%s': %v", fn, err)
		}
	case dpb.FieldDescriptorProto_TYPE_FLOAT:
		r, err := cast.ToFloat32(v, cast.CONVERT_SAMEKIND)
		if err == nil {
			return r, nil
		} else {
			return nil, fmt.Errorf("invalid type for float type field '%s': %v", fn, err)
		}
	case dpb.FieldDescriptorProto_TYPE_INT32, dpb.FieldDescriptorProto_TYPE_SFIXED32, dpb.FieldDescriptorProto_TYPE_SINT32, dpb.FieldDescriptorProto_TYPE_ENUM:
		r, err := cast.ToInt(v, cast.CONVERT_SAMEKIND)
		if err == nil {
			return int32(r), nil
		} else {
			return nil, fmt.Errorf("invalid type for int type field '%s': %v", fn, err)
		}
	case dpb.FieldDescriptorProto_TYPE_INT64, dpb.FieldDescriptorProto_TYPE_SFIXED64, dpb.FieldDescriptorProto_TYPE_SINT64:
		r, err := cast.ToInt64(v, cast.CONVERT_SAMEKIND)
		if err == nil {
			return r, nil
		} else {
			return nil, fmt.Errorf("invalid type for int type field '%s': %v", fn, err)
		}
	case dpb.FieldDescriptorProto_TYPE_FIXED32, dpb.FieldDescriptorProto_TYPE_UINT32:
		r, err := cast.ToUint64(v, cast.CONVERT_SAMEKIND)
		if err == nil {
			return uint32(r), nil
		} else {
			return nil, fmt.Errorf("invalid type for uint type field '%s': %v", fn, err)
		}
	case dpb.FieldDescriptorProto_TYPE_FIXED64, dpb.FieldDescriptorProto_TYPE_UINT64:
		r, err := cast.ToUint64(v, cast.CONVERT_SAMEKIND)
		if err == nil {
			return r, nil
		} else {
			return nil, fmt.Errorf("invalid type for uint type field '%s': %v", fn, err)
		}
	case dpb.FieldDescriptorProto_TYPE_BOOL:
		r, err := cast.ToBool(v, cast.CONVERT_SAMEKIND)
		if err == nil {
			return r, nil
		} else {
			return nil, fmt.Errorf("invalid type for bool type field '%s': %v", fn, err)
		}
	case dpb.FieldDescriptorProto_TYPE_STRING:
		r, err := cast.ToString(v, cast.CONVERT_SAMEKIND)
		if err == nil {
			return r, nil
		} else {
			return nil, fmt.Errorf("invalid type for string type field '%s': %v", fn, err)
		}
	case dpb.FieldDescriptorProto_TYPE_BYTES:
		r, err := cast.ToBytes(v, cast.CONVERT_SAMEKIND)
		if err == nil {
			return r, nil
		} else {
			return nil, fmt.Errorf("invalid type for bytes type field '%s': %v", fn, err)
		}
	case dpb.FieldDescriptorProto_TYPE_MESSAGE:
		r, err := cast.ToStringMap(v)
		if err == nil {
			return fc.encodeMap(field.GetMessageType(), r)
		} else {
			return nil, fmt.Errorf("invalid type for map type field '%s': %v", fn, err)
		}
	default:
		return nil, fmt.Errorf("invalid type for field '%s'", fn)
	}
}

func (fc *FieldConverter) DecodeField(src interface{}, field *desc.FieldDescriptor, sn cast.Strictness) (interface{}, error) {
	var (
		r interface{}
		e error
	)
	fn := field.GetName()
	switch field.GetType() {
	case dpb.FieldDescriptorProto_TYPE_DOUBLE, dpb.FieldDescriptorProto_TYPE_FLOAT:
		if field.IsRepeated() {
			r, e = cast.ToFloat64Slice(src, sn)
		} else {
			r, e = cast.ToFloat64(src, sn)
		}
	case dpb.FieldDescriptorProto_TYPE_INT32, dpb.FieldDescriptorProto_TYPE_SFIXED32, dpb.FieldDescriptorProto_TYPE_SINT32, dpb.FieldDescriptorProto_TYPE_INT64, dpb.FieldDescriptorProto_TYPE_SFIXED64, dpb.FieldDescriptorProto_TYPE_SINT64, dpb.FieldDescriptorProto_TYPE_FIXED32, dpb.FieldDescriptorProto_TYPE_UINT32, dpb.FieldDescriptorProto_TYPE_FIXED64, dpb.FieldDescriptorProto_TYPE_UINT64, dpb.FieldDescriptorProto_TYPE_ENUM:
		if field.IsRepeated() {
			r, e = cast.ToInt64Slice(src, sn)
		} else {
			r, e = cast.ToInt64(src, sn)
		}
	case dpb.FieldDescriptorProto_TYPE_BOOL:
		if field.IsRepeated() {
			r, e = cast.ToBoolSlice(src, sn)
		} else {
			r, e = cast.ToBool(src, sn)
		}
	case dpb.FieldDescriptorProto_TYPE_STRING:
		if field.IsRepeated() {
			r, e = cast.ToStringSlice(src, sn)
		} else {
			r, e = cast.ToString(src, sn)
		}
	case dpb.FieldDescriptorProto_TYPE_BYTES:
		if field.IsRepeated() {
			r, e = cast.ToBytesSlice(src, sn)
		} else {
			r, e = cast.ToBytes(src, sn)
		}
	case dpb.FieldDescriptorProto_TYPE_MESSAGE:
		if field.IsRepeated() {
			r, e = cast.ToTypedSlice(src, func(input interface{}, ssn cast.Strictness) (interface{}, error) {
				return fc.decodeSubMessage(input, field.GetMessageType(), ssn)
			}, "map", sn)
		} else {
			r, e = fc.decodeSubMessage(src, field.GetMessageType(), sn)
		}
	default:
		return nil, fmt.Errorf("unsupported type for %s", fn)
	}
	if e != nil {
		e = fmt.Errorf("invalid type of return value for '%s': %v", fn, e)
	}
	return r, e
}

func (fc *FieldConverter) decodeSubMessage(input interface{}, ft *desc.MessageDescriptor, sn cast.Strictness) (interface{}, error) {
	m := map[string]interface{}{}
	switch v := input.(type) {
	case map[interface{}]interface{}:
		for k, val := range v {
			m[cast.ToStringAlways(k)] = val
		}
		return fc.DecodeMap(m, ft, sn)
	case map[string]interface{}:
		return fc.DecodeMap(v, ft, sn)
	case proto.Message:
		message, err := dynamic.AsDynamicMessage(v)
		if err != nil {
			return nil, err
		}
		return fc.DecodeMessage(message, ft), nil
	default:
		return nil, fmt.Errorf("cannot decode %[1]T(%[1]v) to map", input)
	}
}

func (fc *FieldConverter) DecodeMap(src map[string]interface{}, ft *desc.MessageDescriptor, sn cast.Strictness) (map[string]interface{}, error) {
	result := make(map[string]interface{})
	for _, field := range ft.GetFields() {
		val, ok := src[field.GetName()]
		if !ok {
			continue
		}
		err := fc.decodeMessageField(val, field, result, sn)
		if err != nil {
			return nil, err
		}
	}
	return result, nil
}

func (fc *FieldConverter) decodeMessageField(src interface{}, field *desc.FieldDescriptor, result map[string]interface{}, sn cast.Strictness) error {
	if f, err := fc.DecodeField(src, field, sn); err != nil {
		return err
	} else {
		result[field.GetName()] = f
		return nil
	}
}

func (fc *FieldConverter) DecodeMessage(message *dynamic.Message, outputType *desc.MessageDescriptor) interface{} {
	if _, ok := WRAPPER_TYPES[outputType.GetFullyQualifiedName()]; ok {
		return message.GetFieldByNumber(1)
	} else if WrapperVoid == outputType.GetFullyQualifiedName() {
		return nil
	} else if message == nil {
		return nil
	}
	result := make(map[string]interface{})
	for _, field := range outputType.GetFields() {
		fc.decodeMessageField(message.GetField(field), field, result, cast.CONVERT_SAMEKIND)
	}
	return result
}