/*
Copyright IBM Corp. 2017 All Rights Reserved.

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 protolator

import (
	"reflect"

	"github.com/golang/protobuf/proto"
	"github.com/golang/protobuf/ptypes/timestamp"
)

func nestedFrom(value interface{}, destType reflect.Type) (reflect.Value, error) {
	tree := value.(map[string]interface{}) // Safe, already checked
	result := reflect.New(destType.Elem())
	nMsg := result.Interface().(proto.Message) // Safe, already checked
	if err := recursivelyPopulateMessageFromTree(tree, nMsg); err != nil {
		return reflect.Value{}, err
	}
	return result, nil
}

func nestedTo(value reflect.Value) (interface{}, error) {
	nMsg := value.Interface().(proto.Message) // Safe, already checked
	return recursivelyCreateTreeFromMessage(nMsg)
}

var timestampType = reflect.TypeOf(&timestamp.Timestamp{})

type nestedFieldFactory struct{}

func (nff nestedFieldFactory) Handles(msg proto.Message, fieldName string, fieldType reflect.Type, fieldValue reflect.Value) bool {
	// Note, we skip recursing into the field if it is a proto native timestamp, because there is other custom marshaling this conflicts with
	// this should probably be revisited more generally to prevent custom marshaling of 'well known messages'
	return fieldType.Kind() == reflect.Ptr && fieldType.AssignableTo(protoMsgType) && !fieldType.AssignableTo(timestampType)
}

func (nff nestedFieldFactory) NewProtoField(msg proto.Message, fieldName string, fieldType reflect.Type, fieldValue reflect.Value) (protoField, error) {
	return &plainField{
		baseField: baseField{
			msg:   msg,
			name:  fieldName,
			fType: mapStringInterfaceType,
			vType: fieldType,
			value: fieldValue,
		},
		populateFrom: nestedFrom,
		populateTo:   nestedTo,
	}, nil
}

type nestedMapFieldFactory struct{}

func (nmff nestedMapFieldFactory) Handles(msg proto.Message, fieldName string, fieldType reflect.Type, fieldValue reflect.Value) bool {
	return fieldType.Kind() == reflect.Map && fieldType.Elem().AssignableTo(protoMsgType) && !fieldType.Elem().AssignableTo(timestampType) && fieldType.Key().Kind() == reflect.String
}

func (nmff nestedMapFieldFactory) NewProtoField(msg proto.Message, fieldName string, fieldType reflect.Type, fieldValue reflect.Value) (protoField, error) {
	return &mapField{
		baseField: baseField{
			msg:   msg,
			name:  fieldName,
			fType: mapStringInterfaceType,
			vType: fieldType,
			value: fieldValue,
		},
		populateFrom: func(k string, v interface{}, dT reflect.Type) (reflect.Value, error) {
			return nestedFrom(v, dT)
		},
		populateTo: func(k string, v reflect.Value) (interface{}, error) {
			return nestedTo(v)
		},
	}, nil
}

type nestedSliceFieldFactory struct{}

func (nmff nestedSliceFieldFactory) Handles(msg proto.Message, fieldName string, fieldType reflect.Type, fieldValue reflect.Value) bool {
	return fieldType.Kind() == reflect.Slice && fieldType.Elem().AssignableTo(protoMsgType) && !fieldType.Elem().AssignableTo(timestampType)
}

func (nmff nestedSliceFieldFactory) NewProtoField(msg proto.Message, fieldName string, fieldType reflect.Type, fieldValue reflect.Value) (protoField, error) {
	return &sliceField{
		baseField: baseField{
			msg:   msg,
			name:  fieldName,
			fType: mapStringInterfaceType,
			vType: fieldType,
			value: fieldValue,
		},
		populateFrom: func(i int, v interface{}, dT reflect.Type) (reflect.Value, error) {
			return nestedFrom(v, dT)
		},
		populateTo: func(i int, v reflect.Value) (interface{}, error) {
			return nestedTo(v)
		},
	}, nil
}
