core/features/content/server/src/jvmMain/kotlin/dev/inmo/postssystem/features/content/server/ServerContentStorageAggregator.kt

package dev.inmo.postssystem.features.content.server

import dev.inmo.micro_utils.pagination.*
import dev.inmo.micro_utils.repos.UpdatedValuePair
import dev.inmo.postssystem.features.content.common.*
import dev.inmo.postssystem.features.content.server.storage.ServerContentStorage
import kotlinx.coroutines.*
import kotlinx.coroutines.flow.Flow

class ServerContentStorageAggregator(
    private val storages: List<ServerContentStorageWrapper<*>>,
    private val scope: CoroutineScope
) : ServerContentStorage<Content> {
    override val deletedObjectsIdsFlow: Flow<ContentId>
        get() = TODO("Not yet implemented")
    override val newObjectsFlow: Flow<RegisteredContent>
        get() = TODO("Not yet implemented")
    override val updatedObjectsFlow: Flow<RegisteredContent>
        get() = TODO("Not yet implemented")

    override suspend fun create(values: List<Content>): List<RegisteredContent> {
        return values.groupBy {
            storages.firstOrNull { storage -> storage.mayHandle(it) }
        }.let {
            (it - null) as Map<ServerContentStorageWrapper<*>, List<Content>>
        }.flatMap { (storage, content) ->
            storage.create(content)
        }
    }

    override suspend fun deleteById(ids: List<ContentId>) {
        storages.map {
            scope.launch { it.deleteById(ids) }
        }.joinAll()
    }

    override suspend fun update(id: ContentId, value: Content): RegisteredContent? {
        return storages.mapNotNull {
            it.takeIf { it.mayHandle(value) }
        }.firstNotNullOfOrNull { it.update(id, value) }
    }

    override suspend fun update(values: List<UpdatedValuePair<ContentId, Content>>): List<RegisteredContent> {
        return values.groupBy { (_, content) ->
            storages.firstOrNull { storage -> storage.mayHandle(content) }
        }.let {
            (it - null) as Map<ServerContentStorageWrapper<*>, List<UpdatedValuePair<ContentId, Content>>>
        }.flatMap { (storage, values) ->
            storage.update(values)
        }
    }

    override suspend fun contains(id: ContentId): Boolean {
        val contains = CompletableDeferred<Boolean>()
        storages.map {
            scope.launch {
                if (it.contains(id)) {
                    contains.complete(true)
                }
            }.also { job ->
                contains.invokeOnCompletion { job.cancel() }
            }
        }.joinAll()
        return if (contains.isCompleted) {
            contains.getCompleted()
        } else {
            return false
        }
    }

    override suspend fun count(): Long {
        return storages.map {
            scope.async {
                it.count()
            }
        }.awaitAll().sum()
    }

    override suspend fun getById(id: ContentId): RegisteredContent? {
        val result = CompletableDeferred<RegisteredContent>()

        storages.map {
            scope.launch {
                val content = it.getById(id)
                if (content != null) {
                    result.complete(content)
                }
            }.also { job ->
                result.invokeOnCompletion { job.cancel() }
            }
        }.joinAll()

        return if (result.isCompleted) {
            result.getCompleted()
        } else {
            return null
        }
    }

    override suspend fun getByPagination(
        pagination: Pagination
    ): PaginationResult<RegisteredContent> {
        val currentResults = mutableListOf<RegisteredContent>()

        for (it in storages) {
            val currentPagination = PaginationByIndexes((currentResults.size + pagination.firstIndex), pagination.lastIndex)
            val wrapperResults = it.getByPagination(currentPagination)

            currentResults.addAll(wrapperResults.results)

            if (currentResults.size >= pagination.size) {
                break
            }
        }

        return currentResults.createPaginationResult(pagination, count())
    }

    override suspend fun getContentPreview(id: ContentId): RegisteredContent? {
        val result = CompletableDeferred<RegisteredContent>()

        storages.map {
            scope.launch {
                val content = it.getContentPreview(id)
                if (content != null) {
                    result.complete(content)
                }
            }.also { job ->
                result.invokeOnCompletion { job.cancel() }
            }
        }.joinAll()

        return if (result.isCompleted) {
            result.getCompleted()
        } else {
            return null
        }
    }
}