package world.respect.datalayer.db.school.opds

import androidx.room.Transactor
import androidx.room.useReaderConnection
import androidx.room.useWriterConnection
import com.ustadmobile.ihttp.headers.IHttpHeaders
import io.ktor.http.Url
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.map
import kotlinx.serialization.json.Json
import world.respect.datalayer.AuthenticatedUserPrincipalId
import world.respect.lib.dataloadstate.DataLoadMetaInfo
import world.respect.lib.dataloadstate.DataLoadParams
import world.respect.lib.dataloadstate.DataLoadState
import world.respect.lib.dataloadstate.DataReadyState
import world.respect.lib.dataloadstate.NoDataLoadedState
import world.respect.datalayer.UidNumberMapper
import world.respect.datalayer.db.RespectSchoolDatabase
import world.respect.datalayer.db.school.opds.adapters.OpdsFeedEntities
import world.respect.datalayer.db.school.opds.adapters.asEntities
import world.respect.datalayer.db.school.opds.adapters.asModel
import world.respect.datalayer.db.school.opds.entities.OpdsFeedEntity
import world.respect.datalayer.db.shared.adapters.asNetworkValidationInfo
import world.respect.datalayer.ext.EPOCH
import world.respect.datalayer.networkvalidation.NetworkValidationInfo
import world.respect.datalayer.school.opds.ext.requireSelfUrl
import world.respect.datalayer.school.opds.OpdsFeedDataSourceLocal
import world.respect.datalayer.school.opds.ext.dataLoadMetaInfoForPlaylist
import world.respect.lib.opds.model.OpdsFeed
import world.respect.lib.primarykeygen.PrimaryKeyGenerator
import kotlin.time.Clock

class OpdsFeedDataSourceDb(
    private val schoolDb: RespectSchoolDatabase,
    private val uidNumberMapper: UidNumberMapper,
    @Suppress("unused")
    private val authenticatedUser: AuthenticatedUserPrincipalId,
    private val json: Json,
    private val primaryKeyGenerator: PrimaryKeyGenerator,
) : OpdsFeedDataSourceLocal{

    private suspend fun OpdsFeedEntity.loadModel(): OpdsFeed {
        return OpdsFeedEntities(
            opdsFeed = this,
            feedMetaData = schoolDb.getOpdsFeedMetadataEntityDao().findByFeedUid(this.ofeUid),
            langMapEntities = schoolDb.getLangMapEntityDao().findAllByFeedUid(this.ofeUid),
            linkEntities =schoolDb.getReadiumLinkEntityDao().findAllByFeedUid(this.ofeUid),
            publications = schoolDb.getOpdsPublicationEntityDao().findByFeedUid(
                this.ofeUid),
            groups = schoolDb.getOpdsGroupEntityDao().findByFeedUid(this.ofeUid),
            subjects = schoolDb.getReadiumSubjectEntityDao().findAllByFeedUid(this.ofeUid),
        ).asModel(json)
    }

    override fun getByUrlAsFlow(
        url: Url,
        params: DataLoadParams
    ): Flow<DataLoadState<OpdsFeed>> {
        return schoolDb.getOpdsFeedEntityDao().findByUrlHashAsFlow(
            uidNumberMapper(url.toString())
        ).map { feedEntity ->
            schoolDb.takeIf { feedEntity != null }?.useReaderConnection {
                feedEntity?.loadModel()?.let { opdsFeed ->
                    DataReadyState(
                        data = opdsFeed
                    )
                }
            } ?: NoDataLoadedState.notFound()
        }
    }

    override suspend fun getByUrl(
        url: Url,
        params: DataLoadParams
    ): DataLoadState<OpdsFeed> {
        return schoolDb.getOpdsFeedEntityDao().findByUrlHash(
            urlHash = uidNumberMapper(url.toString())
        )?.let { feedEntity ->
            schoolDb.useReaderConnection {
                DataReadyState(
                    data = feedEntity.loadModel()
                )
            }
        } ?: NoDataLoadedState.notFound()
    }

    override suspend fun getValidationInfo(
        url: Url,
        requestHeaders: IHttpHeaders
    ): NetworkValidationInfo? {
        return schoolDb.getOpdsFeedEntityDao().getNetworkValidationInfo(
            urlHash = uidNumberMapper(url.toString()),
        )?.asNetworkValidationInfo()
    }

    private suspend fun doUpsertOpdsFeed(
        opdsFeed: OpdsFeed,
        dataLoadMetaInfo: DataLoadMetaInfo,
    ) {
        val feedEntities = opdsFeed.asEntities(
            dataLoadMetaInfo =  dataLoadMetaInfo,
            json = json,
            primaryKeyGenerator = primaryKeyGenerator,
            uidNumberMapper = uidNumberMapper,
        )
        val feedUrl = opdsFeed.requireSelfUrl()

        val hasMetaData = feedEntities.feedMetaData.any {
            it.ofmeOfeUid == feedEntities.opdsFeed.ofeUid
        }

        if(!hasMetaData) {
            throw IllegalStateException("WTF: feedEntities has no metadata for opdsfeed")
        }

        val feedUid = uidNumberMapper(feedUrl.toString())
        schoolDb.getOpdsFeedEntityDao().deleteByFeedUid(feedUid)
        schoolDb.getOpdsFeedMetadataEntityDao().deleteByFeedUid(feedUid)
        schoolDb.getLangMapEntityDao().deleteAllByFeedUid(feedUid)
        schoolDb.getReadiumLinkEntityDao().deleteAllByFeedUid(feedUid)
        schoolDb.getOpdsPublicationEntityDao().deleteAllByFeedUid(feedUid)
        schoolDb.getOpdsGroupEntityDao().deleteByFeedUid(feedUid)

        schoolDb.getOpdsFeedEntityDao().insertList(
            listOf(feedEntities.opdsFeed.copy(ofeStored = Clock.System.now()))
        )
        schoolDb.getOpdsFeedMetadataEntityDao().insertList(feedEntities.feedMetaData)
        schoolDb.getLangMapEntityDao().insertAsync(feedEntities.langMapEntities)
        schoolDb.getReadiumLinkEntityDao().insertList(feedEntities.linkEntities)
        schoolDb.getOpdsPublicationEntityDao().insertList(feedEntities.publications)
        schoolDb.getOpdsGroupEntityDao().insertList(feedEntities.groups)
    }

    override suspend fun store(list: List<OpdsFeed>) {
        //TODO: throw illegal argument exception if anything on list is not for this school url
        //TODO: run permission check to see if user is allowed to save/write this feed
        schoolDb.useWriterConnection { con ->
            con.withTransaction(Transactor.SQLiteTransactionType.IMMEDIATE) {
                list.forEach { feed ->
                    doUpsertOpdsFeed(
                        opdsFeed = feed,
                        dataLoadMetaInfo = feed.dataLoadMetaInfoForPlaylist()
                    )
                }
            }
        }
    }

    override suspend fun updateLocal(
        url: Url,
        dataLoadResult: DataReadyState<OpdsFeed>,
    ) {
        schoolDb.useWriterConnection { con ->
            con.withTransaction(Transactor.SQLiteTransactionType.IMMEDIATE) {
                val opdsFeedEntity = schoolDb.getOpdsFeedEntityDao().findByUrlHash(
                    uidNumberMapper(url.toString())
                )
                val dbLastModified = opdsFeedEntity?.ofeLastModified ?: EPOCH
                val isMoreRecent = dataLoadResult.data.metadata.modified?.let {
                    it > dbLastModified
                } ?: true

                if(isMoreRecent) {
                    doUpsertOpdsFeed(
                        opdsFeed = dataLoadResult.data,
                        dataLoadMetaInfo = dataLoadResult.metaInfo,
                    )
                }
            }
        }
    }

}