/*
 * Copyright (C) 2016/2022 Litote
 *
 * 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 org.bson.codecs.pojo

import org.bson.BsonReader
import org.bson.BsonValue
import org.bson.BsonWriter
import org.bson.codecs.CollectibleCodec
import org.bson.codecs.DecoderContext
import org.bson.codecs.EncoderContext
import org.litote.kmongo.util.KMongoUtil.generateNewIdForIdClass
import org.litote.kmongo.util.KMongoUtil.getIdBsonValue

/**
 *
 */
internal class KMongoPojoCodec<T>(originalCodec: PojoCodec<T>) : PojoCodec<T>(),
    CollectibleCodec<T> {

    private val pojoCodec = originalCodec

    override fun getClassModel(): ClassModel<T> {
        return pojoCodec.classModel
    }

    override fun encode(writer: BsonWriter, value: T, encoderContext: EncoderContext) {
        pojoCodec.encode(writer, value, encoderContext)
    }

    override fun decode(reader: BsonReader, decoderContext: DecoderContext): T {
        return pojoCodec.decode(reader, decoderContext)
    }

    override fun getEncoderClass(): Class<T> {
        return pojoCodec.encoderClass
    }

    private fun retrieveDocumentId(document: T): Any? {
        return pojoCodec.classModel
            .idPropertyModel
            ?.propertyAccessor
            ?.get(document)
    }

    override fun getDocumentId(document: T): BsonValue {
        return retrieveDocumentId(document)
            ?.let { getIdBsonValue(it) }
                ?: error("unable to retrieve _id for $document")
    }

    override fun generateIdIfAbsentFromDocument(document: T): T {
        val idProperty = pojoCodec.classModel.idPropertyModel
        @Suppress("UNCHECKED_CAST")
        val propertyAccessor: PropertyAccessor<Any>? = idProperty?.propertyAccessor as PropertyAccessor<Any>?
        if (idProperty != null && propertyAccessor != null) {
            val idValue = propertyAccessor.get(document)
            if (idValue == null) {
                setPropertyValue(propertyAccessor, document, generateNewIdForIdClass(idProperty.typeData.type.kotlin))
            }
        }

        return document
    }

    private fun setPropertyValue(property: PropertyAccessor<Any>?, document: Any?, value: Any?) {
        val p = property as PropertyAccessorImpl
        val metadataField = p.javaClass.getDeclaredField("propertyMetadata")
        metadataField.isAccessible = true
        val metadata = metadataField.get(p) as PropertyMetadata<*>
        if (metadata.isDeserializable) {
            property.set(document, value)
        } else {
            val field = metadata.field
            field.isAccessible = true
            field.set(document, value)
        }
    }

    override fun documentHasId(document: T): Boolean {
        return retrieveDocumentId(document) != null
    }

    override fun getDiscriminatorLookup(): DiscriminatorLookup = pojoCodec.discriminatorLookup


}