dshackle/src/main/kotlin/io/emeraldpay/dshackle/cache/Caches.kt

package io.emeraldpay.dshackle.cache

import com.fasterxml.jackson.databind.ObjectMapper
import io.emeraldpay.dshackle.data.BlockContainer
import io.emeraldpay.dshackle.data.BlockId
import io.emeraldpay.dshackle.data.TxContainer
import io.emeraldpay.dshackle.data.TxId
import io.emeraldpay.dshackle.reader.CompoundReader
import io.emeraldpay.dshackle.reader.Reader
import io.infinitape.etherjar.rpc.json.BlockJson
import io.infinitape.etherjar.rpc.json.TransactionJson
import org.slf4j.LoggerFactory
import reactor.core.publisher.Flux
import reactor.core.publisher.Mono

open class Caches(
        private val memBlocksByHash: BlocksMemCache,
        private val blocksByHeight: HeightCache,
        private val memTxsByHash: TxMemCache,
        private val redisBlocksByHash: BlocksRedisCache?,
        private val redisTxsByHash: TxRedisCache?,
        private val objectMapper: ObjectMapper
) {

    companion object {
        private val log = LoggerFactory.getLogger(Caches::class.java)

        @JvmStatic
        fun newBuilder(): Builder {
            return Builder()
        }

        @JvmStatic
        fun default(objectMapper: ObjectMapper): Caches {
            return newBuilder().setObjectMapper(objectMapper).build()
        }
    }

    private val blocksByHash: Reader<BlockId, BlockContainer>
    private val txsByHash: Reader<TxId, TxContainer>

    init {
        blocksByHash = if (redisBlocksByHash == null) {
            memBlocksByHash
        } else {
            CompoundReader(memBlocksByHash, redisBlocksByHash)
        }
        txsByHash = if (redisTxsByHash == null) {
            memTxsByHash
        } else {
            CompoundReader(memTxsByHash, redisTxsByHash)
        }
    }

    /**
     * Cache data that was just requested
     */
    fun cacheRequested(data: Any) {
        if (data is TxContainer) {
            cache(Tag.REQUESTED, data)
        } else if (data is BlockContainer) {
            cache(Tag.REQUESTED, data)
        }
    }

    fun cache(tag: Tag, tx: TxContainer) {
        //do not cache transactions that are not in a block yet
        if (tx.blockId == null) {
            return
        }
        memTxsByHash.add(tx)
        memBlocksByHash.get(tx.blockId)?.let { block ->
            redisTxsByHash?.add(tx, block)
        }
    }

    fun cache(tag: Tag, block: BlockContainer) {
        val job = ArrayList<Mono<Void>>()
        if (tag == Tag.LATEST) {
            //for LATEST data cache in memory, it will be short living so better to avoid Redis
            memBlocksByHash.add(block)
            val replaced = blocksByHeight.add(block)
            //evict cached transactions if an existing block was updated
            replaced?.let { replacedBlockHash ->
                var evicted = false
                redisBlocksByHash?.evict(replacedBlockHash)
                memBlocksByHash.get(replacedBlockHash)?.let { block ->
                    memTxsByHash.evict(block)
                    redisTxsByHash?.evict(block)
                    evicted = true
                }
                if (!evicted) {
                    memTxsByHash.evict(replacedBlockHash)
                }
            }
        } else if (tag == Tag.REQUESTED) {
            var blockOnlyContainer: BlockContainer? = null
            var jsonValue: BlockJson<*>? = null
            if (block.full) {
                jsonValue = objectMapper.readValue<BlockJson<*>>(block.json, BlockJson::class.java)
                //shouldn't cache block json with transactions, separate txes and blocks with refs
                val blockOnly = jsonValue.withoutTransactionDetails()
                blockOnlyContainer = BlockContainer.from(blockOnly, objectMapper)
            } else {
                blockOnlyContainer = block
            }
            memBlocksByHash.add(blockOnlyContainer)
            redisBlocksByHash?.add(blockOnlyContainer)?.let(job::add)

            // now cache only transactions
            jsonValue?.let { jsonValue ->
                val plainTransactions = jsonValue.transactions.filterIsInstance<TransactionJson>()
                if (plainTransactions.isNotEmpty()) {
                    val transactions = plainTransactions.map { tx ->
                        TxContainer.from(tx, objectMapper)
                    }
                    transactions.forEach {
                        cache(Tag.REQUESTED, it)
                    }
                    if (redisTxsByHash != null) {
                        job.add(Flux.fromIterable(transactions).flatMap { redisTxsByHash.add(it, block) }.then())
                    }
                }
            }
        }
        Flux.fromIterable(job).flatMap { it }.subscribe() //TODO move out to a caller
    }

    fun getBlocksByHash(): Reader<BlockId, BlockContainer> {
        return blocksByHash
    }

    fun getBlockHashByHeight(): Reader<Long, BlockId> {
        return blocksByHeight
    }

    fun getBlocksByHeight(): Reader<Long, BlockContainer> {
        return BlockByHeight(blocksByHeight, blocksByHash)
    }

    fun getTxByHash(): Reader<TxId, TxContainer> {
        return txsByHash
    }

    fun getFullBlocks(): Reader<BlockId, BlockContainer> {
        return EthereumBlocksWithTxCache(objectMapper, blocksByHash, txsByHash)
    }

    fun getFullBlocksByHeight(): Reader<Long, BlockContainer> {
        return BlockByHeight(blocksByHeight, EthereumBlocksWithTxCache(objectMapper, blocksByHash, txsByHash))
    }

    enum class Tag {
        /**
         * Latest data produced by blockchain
         */
        LATEST,

        /**
         * Data requested by client
         */
        REQUESTED
    }

    class Builder() {
        private var blocksByHash: BlocksMemCache? = null
        private var blocksByHeight: HeightCache? = null
        private var txsByHash: TxMemCache? = null
        private var redisBlocksByHash: BlocksRedisCache? = null
        private var redisTxsByHash: TxRedisCache? = null
        private var objectMapper: ObjectMapper? = null

        fun setBlockByHash(cache: BlocksMemCache): Builder {
            blocksByHash = cache
            return this
        }

        fun setBlockByHash(cache: BlocksRedisCache): Builder {
            redisBlocksByHash = cache
            return this
        }

        fun setBlockByHeight(cache: HeightCache): Builder {
            blocksByHeight = cache
            return this
        }

        fun setTxByHash(cache: TxMemCache): Builder {
            txsByHash = cache
            return this
        }

        fun setTxByHash(cache: TxRedisCache): Builder {
            redisTxsByHash = cache
            return this
        }

        fun setObjectMapper(value: ObjectMapper): Builder {
            objectMapper = value
            return this
        }

        fun build(): Caches {
            if (blocksByHash == null) {
                blocksByHash = BlocksMemCache()
            }
            if (blocksByHeight == null) {
                blocksByHeight = HeightCache()
            }
            if (txsByHash == null) {
                txsByHash = TxMemCache()
            }
            if (objectMapper == null) {
                throw IllegalStateException("ObjectMapper is not set")
            }
            return Caches(blocksByHash!!, blocksByHeight!!, txsByHash!!, redisBlocksByHash, redisTxsByHash, objectMapper!!)
        }
    }
}