package net.corda.core.internal.telemetry

import net.corda.core.CordaInternal
import net.corda.core.DeleteForDJVM
import net.corda.core.flows.FlowLogic
import net.corda.core.internal.uncheckedCast
import net.corda.core.node.ServiceHub
import net.corda.core.node.services.TelemetryService
import net.corda.core.serialization.CordaSerializable
import net.corda.core.serialization.SerializationFactory
import net.corda.core.serialization.SingletonSerializeAsToken
import net.corda.core.serialization.serialize
import net.corda.core.utilities.OpaqueBytes
import org.slf4j.Logger
import org.slf4j.LoggerFactory
import java.util.*

@CordaSerializable
interface TelemetryDataItem

@CordaSerializable
data class SerializedTelemetry(val serializedTelemetryData: Map<String, OpaqueBytes>)

enum class TelemetryStatusCode {
    /** The default status.  */
    UNSET,

    /**
     * The operation has been validated by an Application developers or Operator to have completed
     * successfully.
     */
    OK,

    /** The operation contains an error.  */
    ERROR
}

@DeleteForDJVM
@CordaSerializable
data class TelemetryId(private val telemetryService: TelemetryServiceImpl) {
    val id: UUID = UUID.randomUUID()

    fun setStatus(telemetryStatusCode: TelemetryStatusCode, message: String) {
        telemetryService.setStatus(this, telemetryStatusCode, message)
    }

    fun recordException(throwable: Throwable) {
        telemetryService.recordException( this, throwable)
    }

    fun close() {
        telemetryService.endSpan(this)
    }
}

@CordaSerializable
data class ComponentTelemetryIds(val componentTelemetryIds: Map<String, UUID>)



interface TelemetryEvent
@DeleteForDJVM
class StartSpanForFlowEvent(val name: String,
                            val attributes: Map<String, String>,
                            val telemetryId: UUID, val flowLogic: FlowLogic<*>?,
                            val telemetryDataItem: TelemetryDataItem?): TelemetryEvent
@DeleteForDJVM
class EndSpanForFlowEvent(val telemetryId: UUID): TelemetryEvent
@DeleteForDJVM
class StartSpanEvent(val name: String, val attributes: Map<String, String>, val telemetryId: UUID, val flowLogic: FlowLogic<*>?): TelemetryEvent
class EndSpanEvent(val telemetryId: UUID): TelemetryEvent
class SetStatusEvent(val telemetryId: UUID, val telemetryStatusCode: TelemetryStatusCode, val message: String): TelemetryEvent
class RecordExceptionEvent(val telemetryId: UUID, val throwable: Throwable): TelemetryEvent
class InitialiseTelemetryEvent: TelemetryEvent
class ShutdownTelemetryEvent: TelemetryEvent

interface TelemetryComponent {
    fun name(): String
    fun isEnabled(): Boolean
    fun onTelemetryEvent(event: TelemetryEvent)
    fun getCurrentTelemetryData(): TelemetryDataItem
    fun getCurrentTelemetryId(): UUID
    fun setCurrentTelemetryId(id: UUID)
    fun getCurrentSpanId(): String
    fun getCurrentTraceId(): String
    fun getCurrentBaggage(): Map<String, String>
    fun getTelemetryHandles(): List<Any>
}

interface TelemetryComponentId {
    fun name(): String
}

@Suppress("TooManyFunctions")
@DeleteForDJVM
class TelemetryServiceImpl : SingletonSerializeAsToken(), TelemetryService {

    companion object {
        private val log: Logger = LoggerFactory.getLogger(TelemetryServiceImpl::class.java)
    }

    fun getCurrentSpanId(telemetryComponentName: String): String? {
        return telemetryComponents[telemetryComponentName]?.getCurrentSpanId()
    }

    fun getCurrentTraceId(telemetryComponentName: String): String? {
        return telemetryComponents[telemetryComponentName]?.getCurrentTraceId()
    }

    fun getCurrentBaggage(telemetryComponentName: String): Map<String, String>? {
        return telemetryComponents[telemetryComponentName]?.getCurrentBaggage()
    }

    fun setStatus(telemetryId: TelemetryId, telemetryStatusCode: TelemetryStatusCode, message: String) {
        telemetryComponents.values.forEach {
            it.onTelemetryEvent(SetStatusEvent(telemetryId.id, telemetryStatusCode, message))
        }
    }

    fun recordException(telemetryId: TelemetryId, throwable: Throwable) {
        telemetryComponents.values.forEach {
            it.onTelemetryEvent(RecordExceptionEvent(telemetryId.id, throwable))
        }
    }

    @CordaInternal
    fun deserialize(data: OpaqueBytes): TelemetryDataItem {
        return SerializationFactory.defaultFactory.deserialize(data, TelemetryDataItem::class.java, SerializationFactory.defaultFactory.defaultContext)
    }

    private val telemetryComponents: MutableMap<String, TelemetryComponent> = mutableMapOf()

    @CordaInternal
    fun initialiseTelemetry() {
        telemetryComponents.values.forEach {
            it.onTelemetryEvent(InitialiseTelemetryEvent())
        }
    }

    @CordaInternal
    fun shutdownTelemetry() {
        telemetryComponents.values.forEach {
            it.onTelemetryEvent(ShutdownTelemetryEvent())
        }
        telemetryComponents.clear()
    }

    @CordaInternal
    fun addTelemetryComponent(telemetryComponent: TelemetryComponent) {
        telemetryComponents[telemetryComponent.name()] = telemetryComponent
    }

    @CordaInternal
    fun startSpanForFlow(name: String, attributes: Map<String, String>, flowLogic: FlowLogic<*>? = null, remoteSerializedTelemetry: SerializedTelemetry? = null): TelemetryId {
        val telemetryId = TelemetryId(this)
        telemetryComponents.values.forEach {
            val bytes = remoteSerializedTelemetry?.serializedTelemetryData?.get(it.name())
            val telemetryDataItem = bytes?.let { deserialize(bytes) }
            it.onTelemetryEvent(StartSpanForFlowEvent(name, attributes, telemetryId.id, flowLogic, telemetryDataItem))
        }
        return telemetryId
    }

    @CordaInternal
    fun endSpanForFlow(telemetryId: TelemetryId) {
        telemetryComponents.values.forEach {
            it.onTelemetryEvent(EndSpanForFlowEvent(telemetryId.id))
        }
    }


    fun startSpan(name: String, attributes: Map<String, String> = emptyMap(), flowLogic: FlowLogic<*>? = null): TelemetryId {
        val telemetryId = TelemetryId(this)
        telemetryComponents.values.forEach {
            it.onTelemetryEvent(StartSpanEvent(name, attributes, telemetryId.id, flowLogic))
        }
        return telemetryId
    }

    fun endSpan(telemetryId: TelemetryId) {
        telemetryComponents.values.forEach {
            it.onTelemetryEvent(EndSpanEvent(telemetryId.id))
        }
    }

    @Suppress("TooGenericExceptionCaught")
    inline fun <R> span(name: String, attributes: Map<String, String> = emptyMap(), flowLogic: FlowLogic<*>? = null, block: () -> R): R {
        val telemetryId = startSpan(name, attributes, flowLogic)
        try {
            return block()
        }
        catch(ex: Throwable) {
            recordException(telemetryId, ex)
            setStatus(telemetryId, TelemetryStatusCode.ERROR, "Exception raised: ${ex.message}")
            throw ex
        }
        finally {
            endSpan(telemetryId)
        }
    }

    @CordaInternal
    @Suppress("LongParameterList", "TooGenericExceptionCaught")
    inline fun <R> spanForFlow(name: String, attributes: Map<String, String>, flowLogic: FlowLogic<*>? = null, remoteSerializedTelemetry: SerializedTelemetry? = null, block: () -> R): R {
        val telemetryId = startSpanForFlow(name, attributes, flowLogic, remoteSerializedTelemetry)
        try {
            return block()
        }
        catch(ex: Throwable) {
            recordException(telemetryId, ex)
            setStatus(telemetryId, TelemetryStatusCode.ERROR, "Exception raised: ${ex.message}")
            throw ex
        }
        finally {
            endSpanForFlow(telemetryId)
        }
    }

    @CordaInternal
    fun getCurrentTelemetryData(): SerializedTelemetry? {
        if (telemetryComponents.isEmpty()) {
            return null
        }
        val serializedTelemetryData = mutableMapOf<String, OpaqueBytes>()
        telemetryComponents.values.forEach {
            val currentTelemetryData = it.getCurrentTelemetryData()
            serializedTelemetryData[it.name()] = currentTelemetryData.serialize()
        }
        return SerializedTelemetry(serializedTelemetryData)
    }

    @CordaInternal
    fun getCurrentTelemetryIds(): ComponentTelemetryIds? {
        if (telemetryComponents.isEmpty()) {
            return null
        }
        val telemetryIds = mutableMapOf<String, UUID>()
        telemetryComponents.values.forEach {
            telemetryIds[it.name()] = it.getCurrentTelemetryId()
        }
        return ComponentTelemetryIds(telemetryIds)
    }

    @CordaInternal
    fun setCurrentTelemetryId(telemetryIds: ComponentTelemetryIds) {
        telemetryComponents.values.forEach {
            it.setCurrentTelemetryId(telemetryIds.componentTelemetryIds[it.name()]!!)
        }
    }
    
    private fun getTelemetryHandles(): List<Any> {
        return telemetryComponents.values.map { it.getTelemetryHandles() }.flatten()
    }

    override fun <T> getTelemetryHandle(telemetryClass: Class<T>): T? {
        getTelemetryHandles().forEach {
            if (telemetryClass.isInstance(it))
                @Suppress("UNCHECKED_CAST")
                return uncheckedCast(it as T)
        }
        return null
    }
}

val ServiceHub.telemetryServiceInternal
    get() = this.telemetryService as TelemetryServiceImpl
