/**
 * Copyright (c) 2020 EmeraldPay, Inc
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.emeraldpay.dshackle.upstream.bitcoin

import io.emeraldpay.dshackle.config.UpstreamsConfig
import io.emeraldpay.dshackle.reader.JsonRpcReader
import io.emeraldpay.dshackle.upstream.UpstreamAvailability
import io.emeraldpay.dshackle.upstream.rpcclient.JsonRpcRequest
import io.emeraldpay.dshackle.upstream.rpcclient.JsonRpcResponse
import org.slf4j.LoggerFactory
import org.springframework.scheduling.concurrent.CustomizableThreadFactory
import reactor.core.publisher.Flux
import reactor.core.publisher.Mono
import reactor.core.scheduler.Schedulers
import java.time.Duration
import java.util.concurrent.Executors

class BitcoinUpstreamValidator(
    private val api: JsonRpcReader,
    private val options: UpstreamsConfig.Options
) {

    companion object {
        private val log = LoggerFactory.getLogger(BitcoinUpstreamValidator::class.java)
        val scheduler =
            Schedulers.fromExecutor(Executors.newCachedThreadPool(CustomizableThreadFactory("bitcoin-validator")))
    }

    fun validate(): Mono<UpstreamAvailability> {
        return api.read(JsonRpcRequest("getconnectioncount", emptyList()))
            .flatMap(JsonRpcResponse::requireResult)
            .map { Integer.parseInt(String(it)) }
            .map { count ->
                val minPeers = options.minPeers ?: 1
                if (count < minPeers) {
                    UpstreamAvailability.IMMATURE
                } else {
                    UpstreamAvailability.OK
                }
            }
            .onErrorReturn(UpstreamAvailability.UNAVAILABLE)
    }

    fun start(): Flux<UpstreamAvailability> {
        return Flux.interval(Duration.ofSeconds(15))
            .subscribeOn(scheduler)
            .flatMap {
                validate()
            }
    }
}
