/*
 * Copyright (C) Contributors to the Suwayomi project
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

package suwayomi.tachidesk.graphql.queries

import com.expediagroup.graphql.server.extensions.getValueFromDataLoader
import graphql.schema.DataFetchingEnvironment
import org.jetbrains.exposed.sql.Column
import org.jetbrains.exposed.sql.Op
import org.jetbrains.exposed.sql.SortOrder
import org.jetbrains.exposed.sql.SqlExpressionBuilder.greater
import org.jetbrains.exposed.sql.SqlExpressionBuilder.less
import org.jetbrains.exposed.sql.andWhere
import org.jetbrains.exposed.sql.selectAll
import org.jetbrains.exposed.sql.transactions.transaction
import suwayomi.tachidesk.global.model.table.GlobalMetaTable
import suwayomi.tachidesk.graphql.queries.filter.Filter
import suwayomi.tachidesk.graphql.queries.filter.HasGetOp
import suwayomi.tachidesk.graphql.queries.filter.OpAnd
import suwayomi.tachidesk.graphql.queries.filter.StringFilter
import suwayomi.tachidesk.graphql.queries.filter.andFilterWithCompareString
import suwayomi.tachidesk.graphql.queries.filter.applyOps
import suwayomi.tachidesk.graphql.server.primitives.Cursor
import suwayomi.tachidesk.graphql.server.primitives.OrderBy
import suwayomi.tachidesk.graphql.server.primitives.PageInfo
import suwayomi.tachidesk.graphql.server.primitives.QueryResults
import suwayomi.tachidesk.graphql.server.primitives.greaterNotUnique
import suwayomi.tachidesk.graphql.server.primitives.lessNotUnique
import suwayomi.tachidesk.graphql.server.primitives.maybeSwap
import suwayomi.tachidesk.graphql.types.GlobalMetaNodeList
import suwayomi.tachidesk.graphql.types.GlobalMetaType
import java.util.concurrent.CompletableFuture

class MetaQuery {
    fun meta(dataFetchingEnvironment: DataFetchingEnvironment, key: String): CompletableFuture<GlobalMetaType?> {
        return dataFetchingEnvironment.getValueFromDataLoader<String, GlobalMetaType?>("GlobalMetaDataLoader", key)
    }

    enum class MetaOrderBy(override val column: Column<out Comparable<*>>) : OrderBy<GlobalMetaType> {
        KEY(GlobalMetaTable.key),
        VALUE(GlobalMetaTable.value);

        override fun greater(cursor: Cursor): Op<Boolean> {
            return when (this) {
                KEY -> GlobalMetaTable.key greater cursor.value
                VALUE -> greaterNotUnique(GlobalMetaTable.value, GlobalMetaTable.key, cursor, String::toString)
            }
        }

        override fun less(cursor: Cursor): Op<Boolean> {
            return when (this) {
                KEY -> GlobalMetaTable.key less cursor.value
                VALUE -> lessNotUnique(GlobalMetaTable.value, GlobalMetaTable.key, cursor, String::toString)
            }
        }

        override fun asCursor(type: GlobalMetaType): Cursor {
            val value = when (this) {
                KEY -> type.key
                VALUE -> type.key + "\\-" + type.value
            }
            return Cursor(value)
        }
    }

    data class MetaCondition(
        val key: String? = null,
        val value: String? = null
    ) : HasGetOp {
        override fun getOp(): Op<Boolean>? {
            val opAnd = OpAnd()
            opAnd.eq(key, GlobalMetaTable.key)
            opAnd.eq(value, GlobalMetaTable.value)

            return opAnd.op
        }
    }

    data class MetaFilter(
        val key: StringFilter? = null,
        val value: StringFilter? = null,
        override val and: List<MetaFilter>? = null,
        override val or: List<MetaFilter>? = null,
        override val not: MetaFilter? = null
    ) : Filter<MetaFilter> {
        override fun getOpList(): List<Op<Boolean>> {
            return listOfNotNull(
                andFilterWithCompareString(GlobalMetaTable.key, key),
                andFilterWithCompareString(GlobalMetaTable.value, value)
            )
        }
    }

    fun metas(
        condition: MetaCondition? = null,
        filter: MetaFilter? = null,
        orderBy: MetaOrderBy? = null,
        orderByType: SortOrder? = null,
        before: Cursor? = null,
        after: Cursor? = null,
        first: Int? = null,
        last: Int? = null,
        offset: Int? = null
    ): GlobalMetaNodeList {
        val queryResults = transaction {
            val res = GlobalMetaTable.selectAll()

            res.applyOps(condition, filter)

            if (orderBy != null || (last != null || before != null)) {
                val orderByColumn = orderBy?.column ?: GlobalMetaTable.key
                val orderType = orderByType.maybeSwap(last ?: before)

                if (orderBy == MetaOrderBy.KEY || orderBy == null) {
                    res.orderBy(orderByColumn to orderType)
                } else {
                    res.orderBy(
                        orderByColumn to orderType,
                        GlobalMetaTable.key to SortOrder.ASC
                    )
                }
            }

            val total = res.count()
            val firstResult = res.firstOrNull()?.get(GlobalMetaTable.key)
            val lastResult = res.lastOrNull()?.get(GlobalMetaTable.key)

            if (after != null) {
                res.andWhere {
                    (orderBy ?: MetaOrderBy.KEY).greater(after)
                }
            } else if (before != null) {
                res.andWhere {
                    (orderBy ?: MetaOrderBy.KEY).less(before)
                }
            }

            if (first != null) {
                res.limit(first, offset?.toLong() ?: 0)
            } else if (last != null) {
                res.limit(last)
            }

            QueryResults(total, firstResult, lastResult, res.toList())
        }

        val getAsCursor: (GlobalMetaType) -> Cursor = (orderBy ?: MetaOrderBy.KEY)::asCursor

        val resultsAsType = queryResults.results.map { GlobalMetaType(it) }

        return GlobalMetaNodeList(
            resultsAsType,
            if (resultsAsType.isEmpty()) {
                emptyList()
            } else {
                listOfNotNull(
                    resultsAsType.firstOrNull()?.let {
                        GlobalMetaNodeList.MetaEdge(
                            getAsCursor(it),
                            it
                        )
                    },
                    resultsAsType.lastOrNull()?.let {
                        GlobalMetaNodeList.MetaEdge(
                            getAsCursor(it),
                            it
                        )
                    }
                )
            },
            pageInfo = PageInfo(
                hasNextPage = queryResults.lastKey != resultsAsType.lastOrNull()?.key,
                hasPreviousPage = queryResults.firstKey != resultsAsType.firstOrNull()?.key,
                startCursor = resultsAsType.firstOrNull()?.let { getAsCursor(it) },
                endCursor = resultsAsType.lastOrNull()?.let { getAsCursor(it) }
            ),
            totalCount = queryResults.total.toInt()
        )
    }
}