/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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
 *
 *      https://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 org.apache.nlpcraft.probe.mgrs.dialogflow

import io.opencensus.trace.Span
import org.apache.nlpcraft.common.ascii.NCAsciiTable
import org.apache.nlpcraft.common.{NCService, _}
import org.apache.nlpcraft.model.intent.solver.NCIntentSolverResult
import org.apache.nlpcraft.model.{NCCompany, NCContext, NCDialogFlowItem, NCIntentMatch, NCResult, NCToken, NCUser, NCVariant}
import org.apache.nlpcraft.probe.mgrs.model.NCModelManager

import java.text.DateFormat
import java.util
import java.util.{Date, Optional}
import scala.collection._

/**
 * Dialog flow manager.
 */
object NCDialogFlowManager extends NCService {
    /**
      *
      * @param usrId
      * @param mdlId
      */
    case class Key(
        usrId: Long,
        mdlId: String
    )

    private final val flow = mutable.HashMap.empty[Key, mutable.ArrayBuffer[NCDialogFlowItem]]

    @volatile private var gc: Thread = _

    /**
     *
     * @param parent Optional parent span.
     * @return
     */
    override def start(parent: Span = null): NCService = startScopedSpan("start", parent) { _ =>
        ackStarting()

        gc = U.mkThread("dialog-flow-manager-gc") { t =>
            while (!t.isInterrupted)
                try
                    flow.synchronized {
                        val sleepTime = clearForTimeout() - U.now()

                        if (sleepTime > 0)
                            flow.wait(sleepTime)
                    }
                catch {
                    case _: InterruptedException => // No-op.
                    case e: Throwable => U.prettyError(logger, s"Unexpected error for thread: ${t.getName}", e)
                }
        }

        gc.start()

        ackStarted()
    }

    /**
     *
     * @param parent Optional parent span.
     */
    override def stop(parent: Span = null): Unit = startScopedSpan("stop", parent) { _ =>
        ackStopping()

        U.stopThread(gc)

        gc = null

        flow.clear()

        ackStopped()
    }

    /**
     * Adds matched (winning) intent to the dialog flow.
     *
     * @param intentMatch
     * @param res Intent match result.
     * @param cbRes Intent callback result.
     * @param ctx Original query context.
     * @param parent
     */
    def addMatchedIntent(intentMatch: NCIntentMatch, res: NCIntentSolverResult, cbRes: NCResult, ctx: NCContext, parent: Span = null): Unit = {
        val usrId = ctx.getRequest.getUser.getId
        val srvReqId = ctx.getRequest.getServerRequestId
        val mdlId = ctx.getModel.getId
        val intentId = res.intentId
        
        startScopedSpan(
            "addMatchedIntent",
            parent,
            "usrId" -> usrId,
            "mdlId" -> mdlId,
            "srvReqId" -> srvReqId,
            "intentId" -> intentId) { _ =>
            flow.synchronized {
                val req = ctx.getRequest
                
                val key = Key(usrId, mdlId)
                val item: NCDialogFlowItem = new NCDialogFlowItem {
                    override val getIntentId: String = intentId
                    override val getIntentTokens: util.List[util.List[NCToken]] = intentMatch.getIntentTokens
                    override def getTermTokens(idx: Int): util.List[NCToken] = intentMatch.getTermTokens(idx)
                    override def getTermTokens(termId: String): util.List[NCToken] = intentMatch.getTermTokens(termId)
                    override val getVariant: NCVariant = intentMatch.getVariant
                    override val getUser: NCUser = req.getUser
                    override val getCompany: NCCompany = req.getCompany
                    override val getServerRequestId: String = req.getServerRequestId
                    override val getNormalizedText: String = req.getNormalizedText
                    override val getReceiveTimestamp: Long = req.getReceiveTimestamp
                    override val getRemoteAddress: Optional[String] = req.getRemoteAddress
                    override val getClientAgent: Optional[String] = req.getClientAgent
                    override val getRequestData: util.Map[String, AnyRef] = req.getRequestData
                    override lazy val getMetadata: util.Map[String, AnyRef] = new util.HashMap[String, Object]
                    override def getResult: NCResult = cbRes
                }
                
                flow.getOrElseUpdate(key, mutable.ArrayBuffer.empty[NCDialogFlowItem]).append(item)
                flow.notifyAll()
            }

            logger.trace(s"Added matched intent to dialog flow [" +
                s"mdlId=$mdlId, " +
                s"intentId=$intentId, " +
                s"userId=$usrId" +
                s"srvReqId=${m(srvReqId)}" +
            s"]")
        }
    }

    /**
      * Gets sequence of dialog flow items sorted from oldest to newest (i.e. dialog flow) for given user and model IDs.
      *
      * @param usrId User ID.
      * @param mdlId Model ID.
      * @param parent Optional parent span.
      * @return Dialog flow.
      */
    def getDialogFlow(usrId: Long, mdlId: String, parent: Span = null): Seq[NCDialogFlowItem] =
        startScopedSpan("getDialogFlow", parent, "usrId" -> usrId, "mdlId" -> mdlId) { _ =>
            flow.synchronized {
                flow.getOrElseUpdate(Key(usrId, mdlId), mutable.ArrayBuffer.empty[NCDialogFlowItem])
            }
        }

    /**
     * Prints out ASCII table for current dialog flow.
     *
     * @param usrId User ID.
     * @param mdlId Model ID.
     * @param parent Optional parent span.
     */
    def ack(usrId: Long, mdlId: String, parent: Span = null): Unit = {
        startScopedSpan("ack", parent, "usrId" -> usrId, "mdlId" -> mdlId) { _ =>
            val curFlow = flow.synchronized {
                flow.getOrElseUpdate(Key(usrId, mdlId), mutable.ArrayBuffer.empty[NCDialogFlowItem])
            }

            val tbl = NCAsciiTable(
                "",
                "Intent ID",
                "Sever Request ID",
                "Text",
                "Received"
            )

            var i = 1

            curFlow.foreach(x => {
                tbl += (
                    i,
                    x.getIntentId,
                    m(x.getServerRequestId),
                    x.getNormalizedText,
                    DateFormat.getDateTimeInstance.format(new Date(x.getReceiveTimestamp))
                )

                i += 1
            })

            logger.info(s"Current dialog flow (oldest first) for [" +
                s"mdlId=$mdlId, " +
                s"usrId=$usrId" +
            s"]:\n${tbl.toString()}")
        }
    }

    /**
     *  Gets next clearing time.
     */
    private def clearForTimeout(): Long =
        startScopedSpan("clearForTimeout") { _ =>
            require(Thread.holdsLock(flow))

            val now = U.now()
            val delKeys = mutable.HashSet.empty[Key]
            val timeouts = mutable.HashMap.empty[String, Long]

            for ((key, values) <- flow)
                NCModelManager.getModelOpt(key.mdlId) match {
                    case Some(mdl) =>
                        val ms = now - mdl.model.getConversationTimeout

                        values --= values.filter(_.getReceiveTimestamp < ms)

                        timeouts += mdl.model.getId -> mdl.model.getConversationTimeout

                        // https://github.com/scala/bug/issues/10151
                        // Scala bug workaround.
                        ()

                    case None => delKeys += key
                }

            delKeys ++= flow.filter(_._2.isEmpty).keySet

            flow --= delKeys

            val times = (for ((key, values) <- flow) yield values.map(v => v.getReceiveTimestamp + timeouts(key.mdlId))).flatten

            if (times.nonEmpty)
                times.min
            else
                Long.MaxValue
        }
    
    /**
     * Clears dialog history for given user and model IDs.
     *
     * @param usrId User ID.
     * @param mdlId Model ID.
     * @param parent Parent span, if any.
     */
    def clear(usrId: Long, mdlId: String, parent: Span = null): Unit =
        startScopedSpan("clear", parent, "usrId" -> usrId, "mdlId" -> mdlId) { _ =>
            flow.synchronized {
                flow -= Key(usrId, mdlId)

                flow.notifyAll()
            }

            logger.trace(s"Dialog flow history is cleared [" +
                s"usrId=$usrId, " +
                s"mdlId=$mdlId" +
            s"]")
        }
    
    /**
     * Clears dialog history for given user, model IDs and predicate.
     *
     * @param usrId User ID.
     * @param mdlId Model ID.
     * @param pred Intent ID predicate.
     * @param parent Parent span, if any.
     */
    def clearForPredicate(usrId: Long, mdlId: String, pred: String => Boolean, parent: Span = null): Unit =
        startScopedSpan("clearForPredicate", parent, "usrId" -> usrId, "mdlId" -> mdlId) { _ =>
            val key = Key(usrId, mdlId)

            flow.synchronized {
                flow(key) = flow(key).filterNot(v => pred(v.getIntentId))

                flow.notifyAll()
            }

            logger.trace(s"Dialog flow history is cleared [" +
                s"usrId=$usrId, " +
                s"mdlId=$mdlId" +
            s"]")
        }
}