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package org.apache.james.rate.limiter.memory

import java.time.Duration

import com.google.inject.AbstractModule
import es.moki.ratelimitj.core.limiter.request.{RequestLimitRule, RequestRateLimiter}
import es.moki.ratelimitj.inmemory.request.InMemorySlidingWindowRequestRateLimiter
import org.apache.james.rate.limiter.api.Increment.Increment
import org.apache.james.rate.limiter.api.{AcceptableRate, RateExceeded, RateLimiter, RateLimiterFactory, RateLimitingKey, RateLimitingResult, Rule, Rules}
import org.reactivestreams.Publisher
import reactor.core.scala.publisher.SMono

import scala.jdk.CollectionConverters._

class MemoryRateLimiterModule() extends AbstractModule {
  override def configure(): Unit =
    bind(classOf[RateLimiterFactory])
      .to(classOf[MemoryRateLimiterFactory])
}

class MemoryRateLimiterFactory() extends RateLimiterFactory {
  override def withSpecification(rules: Rules, precision: Option[Duration]): RateLimiter =
    MemoryRateLimiter(new InMemorySlidingWindowRequestRateLimiter(rules.rules
      .map(convert)
      .map(withPrecision(_, precision))
      .toSet.asJava))

  private def withPrecision(rule: RequestLimitRule, precision: Option[Duration]): RequestLimitRule =
    precision.map(rule.withPrecision).getOrElse(rule)

  private def convert(rule: Rule): RequestLimitRule = RequestLimitRule.of(rule.duration, rule.quantity.value)
}

case class MemoryRateLimiter(limiter: RequestRateLimiter) extends RateLimiter {
  override def rateLimit(key: RateLimitingKey, increaseQuantity: Increment): Publisher[RateLimitingResult] =
    if (limiter.overLimitWhenIncremented(key.asString(), increaseQuantity.value)) {
      SMono.just(RateExceeded)
    } else {
      SMono.just(AcceptableRate)
    }
}
