package org.openrs2.archive.cache

import io.netty.buffer.ByteBuf
import io.netty.buffer.ByteBufAllocator
import io.netty.buffer.ByteBufUtil
import io.netty.buffer.DefaultByteBufHolder
import org.openrs2.buffer.crc32
import org.openrs2.buffer.use
import org.openrs2.cache.Js5Archive
import org.openrs2.cache.Js5Compression
import org.openrs2.cache.Js5Index
import org.openrs2.cache.Store
import org.openrs2.cache.VersionTrailer
import org.openrs2.crypto.Whirlpool
import org.openrs2.db.Database
import java.io.IOException
import java.sql.Connection
import java.sql.Types
import javax.inject.Inject
import javax.inject.Singleton

@Singleton
public class CacheImporter @Inject constructor(
    private val database: Database,
    private val alloc: ByteBufAllocator
) {
    private abstract class Container(
        data: ByteBuf
    ) : DefaultByteBufHolder(data) {
        val bytes: ByteArray = ByteBufUtil.getBytes(data, data.readerIndex(), data.readableBytes(), false)
        val crc32 = data.crc32()
        val whirlpool = Whirlpool.whirlpool(bytes)
        abstract val encrypted: Boolean
    }

    private class Index(
        val archive: Int,
        val index: Js5Index,
        data: ByteBuf
    ) : Container(data) {
        override val encrypted: Boolean = false
    }

    private class Group(
        val archive: Int,
        val group: Int,
        data: ByteBuf,
        val version: Int,
        override val encrypted: Boolean
    ) : Container(data)

    public suspend fun import(store: Store) {
        database.execute { connection ->
            connection.prepareStatement(
                """
                LOCK TABLE containers IN EXCLUSIVE MODE
            """.trimIndent()
            ).use { stmt ->
                stmt.execute()
            }

            // create temporary tables
            connection.prepareStatement(
                """
                CREATE TEMPORARY TABLE tmp_containers (
                    index INTEGER NOT NULL,
                    crc32 INTEGER NOT NULL,
                    whirlpool BYTEA NOT NULL,
                    data BYTEA NOT NULL,
                    encrypted BOOLEAN NOT NULL
                ) ON COMMIT DROP
            """.trimIndent()
            ).use { stmt ->
                stmt.execute()
            }

            // import indexes
            val indexes = mutableListOf<Index>()
            try {
                for (archive in store.list(Js5Archive.ARCHIVESET)) {
                    indexes += readIndex(store, archive)
                }

                val cacheId = addCache(connection, indexes)

                for (index in indexes) {
                    addIndex(connection, cacheId, index)
                }
            } finally {
                indexes.forEach(Index::release)
            }

            // import groups
            val groups = mutableListOf<Group>()
            try {
                for (archive in store.list()) {
                    if (archive == Js5Archive.ARCHIVESET) {
                        continue
                    }

                    for (id in store.list(archive)) {
                        val group = readGroup(store, archive, id) ?: continue
                        groups += group

                        if (groups.size >= BATCH_SIZE) {
                            addGroups(connection, groups)

                            groups.forEach(Group::release)
                            groups.clear()
                        }
                    }
                }

                if (groups.isNotEmpty()) {
                    addGroups(connection, groups)
                }
            } finally {
                groups.forEach(Group::release)
            }
        }
    }

    private fun readGroup(store: Store, archive: Int, group: Int): Group? {
        try {
            store.read(archive, group).use { buf ->
                val version = VersionTrailer.strip(buf) ?: return null
                val encrypted = Js5Compression.isEncrypted(buf.slice())
                return Group(archive, group, buf.retain(), version, encrypted)
            }
        } catch (ex: IOException) {
            return null
        }
    }

    private fun addContainer(connection: Connection, container: Container): Long {
        return addContainers(connection, listOf(container)).single()
    }

    private fun addContainers(connection: Connection, containers: List<Container>): List<Long> {
        connection.prepareStatement(
            """
            TRUNCATE TABLE tmp_containers
        """.trimIndent()
        ).use { stmt ->
            stmt.execute()
        }

        connection.prepareStatement(
            """
            INSERT INTO tmp_containers (index, crc32, whirlpool, data, encrypted)
            VALUES (?, ?, ?, ?, ?)
        """.trimIndent()
        ).use { stmt ->
            for ((i, container) in containers.withIndex()) {
                stmt.setInt(1, i)
                stmt.setInt(2, container.crc32)
                stmt.setBytes(3, container.whirlpool)
                stmt.setBytes(4, container.bytes)
                stmt.setBoolean(5, container.encrypted)
                stmt.addBatch()
            }

            stmt.executeBatch()
        }

        connection.prepareStatement(
            """
            INSERT INTO containers (crc32, whirlpool, data, encrypted)
            SELECT t.crc32, t.whirlpool, t.data, t.encrypted
            FROM tmp_containers t
            LEFT JOIN containers c ON c.whirlpool = t.whirlpool
            WHERE c.whirlpool IS NULL
            ON CONFLICT DO NOTHING
        """.trimIndent()
        ).use { stmt ->
            stmt.execute()
        }

        val ids = mutableListOf<Long>()

        connection.prepareStatement(
            """
            SELECT c.id
            FROM tmp_containers t
            JOIN containers c ON c.whirlpool = t.whirlpool
            ORDER BY t.index ASC
        """.trimIndent()
        ).use { stmt ->
            stmt.executeQuery().use { rows ->
                while (rows.next()) {
                    ids += rows.getLong(1)
                }
            }
        }

        check(ids.size == containers.size)
        return ids
    }

    private fun addGroups(connection: Connection, groups: List<Group>) {
        val containerIds = addContainers(connection, groups)

        connection.prepareStatement(
            """
            INSERT INTO groups (archive_id, group_id, container_id, truncated_version)
            VALUES (?, ?, ?, ?)
            ON CONFLICT DO NOTHING
        """.trimIndent()
        ).use { stmt ->
            for ((i, group) in groups.withIndex()) {
                stmt.setInt(1, group.archive)
                stmt.setInt(2, group.group)
                stmt.setLong(3, containerIds[i])
                stmt.setInt(4, group.version)
                stmt.addBatch()
            }

            stmt.executeBatch()
        }
    }

    private fun readIndex(store: Store, archive: Int): Index {
        return store.read(Js5Archive.ARCHIVESET, archive).use { buf ->
            Js5Compression.uncompress(buf.slice()).use { uncompressed ->
                Index(archive, Js5Index.read(uncompressed), buf.retain())
            }
        }
    }

    private fun addCache(connection: Connection, indexes: List<Index>): Long {
        val len = indexes.size * (1 + Whirlpool.DIGESTBYTES)
        val whirlpool = alloc.buffer(len, len).use { buf ->
            for (index in indexes) {
                buf.writeByte(index.archive)
                buf.writeBytes(index.whirlpool)
            }

            Whirlpool.whirlpool(ByteBufUtil.getBytes(buf, 0, buf.readableBytes(), false))
        }

        connection.prepareStatement(
            """
            SELECT id
            FROM caches
            WHERE whirlpool = ?
        """.trimIndent()
        ).use { stmt ->
            stmt.setBytes(1, whirlpool)

            stmt.executeQuery().use { rows ->
                if (rows.next()) {
                    return rows.getLong(1)
                }
            }
        }

        connection.prepareStatement(
            """
            INSERT INTO caches (whirlpool)
            VALUES (?)
            ON CONFLICT DO NOTHING
            RETURNING id
        """.trimIndent()
        ).use { stmt ->
            stmt.setBytes(1, whirlpool)

            stmt.executeQuery().use { rows ->
                if (rows.next()) {
                    rows.getLong(1)
                }
            }
        }

        connection.prepareStatement(
            """
            SELECT id
            FROM caches
            WHERE whirlpool = ?
        """.trimIndent()
        ).use { stmt ->
            stmt.setBytes(1, whirlpool)

            stmt.executeQuery().use { rows ->
                check(rows.next())
                return rows.getLong(1)
            }
        }
    }

    // TODO(gpe): skip most of this function if we encounter a conflict?
    private fun addIndex(connection: Connection, cacheId: Long, index: Index) {
        val containerId = addContainer(connection, index)

        connection.prepareStatement(
            """
            INSERT INTO indexes (container_id, version)
            VALUES (?, ?)
            ON CONFLICT DO NOTHING
        """.trimIndent()
        ).use { stmt ->
            stmt.setLong(1, containerId)
            stmt.setInt(2, index.index.version)
            stmt.execute()
        }

        connection.prepareStatement(
            """
            INSERT INTO cache_indexes (cache_id, archive_id, container_id)
            VALUES (?, ?, ?)
            ON CONFLICT DO NOTHING
        """.trimIndent()
        ).use { stmt ->
            stmt.setLong(1, cacheId)
            stmt.setInt(2, index.archive)
            stmt.setLong(3, containerId)
            stmt.execute()
        }

        connection.prepareStatement(
            """
            INSERT INTO index_groups (container_id, group_id, crc32, whirlpool, version, name_hash)
            VALUES (?, ?, ?, ?, ?, ?)
            ON CONFLICT DO NOTHING
        """.trimIndent()
        ).use { stmt ->
            for (group in index.index) {
                stmt.setLong(1, containerId)
                stmt.setInt(2, group.id)
                stmt.setInt(3, group.checksum)
                stmt.setBytes(4, group.digest)
                stmt.setInt(5, group.version)

                if (index.index.hasNames) {
                    stmt.setInt(6, group.nameHash)
                } else {
                    stmt.setNull(6, Types.INTEGER)
                }

                stmt.addBatch()
            }

            stmt.executeBatch()
        }

        connection.prepareStatement(
            """
            INSERT INTO index_files (container_id, group_id, file_id, name_hash)
            VALUES (?, ?, ?, ?)
            ON CONFLICT DO NOTHING
        """.trimIndent()
        ).use { stmt ->
            for (group in index.index) {
                for (file in group) {
                    stmt.setLong(1, containerId)
                    stmt.setInt(2, group.id)
                    stmt.setInt(3, file.id)

                    if (index.index.hasNames) {
                        stmt.setInt(4, file.nameHash)
                    } else {
                        stmt.setNull(4, Types.INTEGER)
                    }

                    stmt.addBatch()
                }
            }

            stmt.executeBatch()
        }
    }

    private companion object {
        private val BATCH_SIZE = 1024
    }
}