package sandbox

import jetbrains.exodus.io.Block
import jetbrains.exodus.io.DataReader
import jetbrains.exodus.io.FileDataReader
import jetbrains.exodus.io.RemoveBlockType
import jetbrains.exodus.log.Log
import jetbrains.exodus.log.LogUtil
import mu.KLogging
import software.amazon.awssdk.core.AwsRequestOverrideConfig
import software.amazon.awssdk.core.async.AsyncResponseHandler
import software.amazon.awssdk.services.s3.S3AsyncClient
import software.amazon.awssdk.services.s3.model.GetObjectRequest
import software.amazon.awssdk.services.s3.model.GetObjectResponse
import software.amazon.awssdk.services.s3.model.ListObjectsRequest
import software.amazon.awssdk.services.s3.model.S3Object
import java.util.concurrent.atomic.AtomicLong

class S3DataReader(val s3: S3AsyncClient, val bucketName: String, val requestOverrideConfig: AwsRequestOverrideConfig? = null) : DataReader {
    companion object : KLogging()

    val bytesRead = AtomicLong()

    private val blocks: Map<Long, S3Block> = s3.listObjects(ListObjectsRequest.builder()
            .requestOverrideConfig(requestOverrideConfig)
            .bucket(bucketName)
            .delimiter("/")
            //.prefix("My")
            .build()).get().contents().asSequence().filter {
        it.key().endsWith(".xd")
    }.map {
        S3Block(LogUtil.getAddress(it.key()), it)
    }.associateBy {
        it._address
    }

    @Suppress("UNCHECKED_CAST")
    override fun getBlocks(): Array<Block> {
        val files = blocks
        val size = files.size
        val result = arrayOfNulls<Block>(size)
        var i = 0
        blocks.forEach {
            result[i++] = it.value
        }
        FileDataReader.sortBlocks(result)
        return result as Array<Block>
    }

    override fun setLog(log: Log) {
    }

    override fun getLocation(): String = "s3:$bucketName"

    override fun removeBlock(blockAddress: Long, rbt: RemoveBlockType) {
        // TODO
    }

    override fun truncateBlock(blockAddress: Long, length: Long) {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }

    override fun close() {
        // TODO
    }

    override fun getBlock(address: Long): Block {
        logger.info { "Get block at ${LogUtil.getLogFilename(address)}" }
        return blocks[address]!!
    }

    override fun clear() {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }

    private inner class S3Block(val _address: Long, val s3Object: S3Object) : Block {
        override fun getAddress() = _address

        override fun setReadOnly(): Boolean {
            return true
        }

        override fun length(): Long = s3Object.size()

        override fun read(output: ByteArray, position: Long, count: Int): Int {
            if (count <= 0) {
                return 0
            }

            val range = "bytes=$position-${position + count - 1}"
            logger.debug { "Request range: $range" }
            val written = s3.getObject(
                    GetObjectRequest.builder().range(range)
                            .requestOverrideConfig(requestOverrideConfig).bucket(bucketName).key(s3Object.key()).build(),
                    ByteArrayAsyncResponseHandler(output)
            ).get()

            if (written < count) {
                logger.debug { "Read underflow: expected $count, got $written" }
            }

            bytesRead.addAndGet(written.toLong())

            return written
        }
    }
}