Message Title

import ch.qos.logback.access.spi.IAccessEvent
import ch.qos.logback.classic.util.LogbackMDCAdapter
import com.fasterxml.jackson.core.JsonGenerator
import net.logstash.logback.composite.AbstractFieldJsonProvider
import net.logstash.logback.composite.FieldNamesAware
import net.logstash.logback.composite.JsonWritingUtils
import net.logstash.logback.fieldnames.LogstashAccessFieldNames
import org.slf4j.MDC
import java.io.IOException
import java.util.*

class AccessMdcProvider : AbstractFieldJsonProvider<IAccessEvent>(), FieldNamesAware<LogstashAccessFieldNames> {
    private var includeMdcKeyNames: MutableList<String> = ArrayList()
    private var excludeMdcKeyNames: MutableList<String> = ArrayList()

    override fun start() {
        if (!this.includeMdcKeyNames.isEmpty() && !this.excludeMdcKeyNames.isEmpty()) {
            addError("Both includeMdcKeyNames and excludeMdcKeyNames are not empty.  Only one is allowed to be not empty.")
        }
        super.start()
    }

    @Throws(IOException::class)
    override fun writeTo(generator: JsonGenerator, event: IAccessEvent) {
        val mdcProperties = getMDCPropertyMap().takeIf { it.isNotEmpty() }?.let { props ->
            if (!includeMdcKeyNames.isEmpty()) {
                props.toMutableMap().also { it.keys.retainAll(includeMdcKeyNames) }
            } else if (!excludeMdcKeyNames.isEmpty()) {
                props.toMutableMap().also { it.keys.removeAll(excludeMdcKeyNames) }
            } else
                props
        }

        mdcProperties?.also {
            if (fieldName != null) {
                generator.writeObjectFieldStart(fieldName)
            }
            JsonWritingUtils.writeMapEntries(generator, it)
            if (fieldName != null) {
                generator.writeEndObject()
            }
        }
    }

    private fun getMDCPropertyMap(): Map<String, String> {
        // populate mdcPropertyMap if null
        val mdcPropertyMap = MDC.getMDCAdapter().let { mdc->
            if (mdc is LogbackMDCAdapter)
                mdc.propertyMap
            else
                mdc.copyOfContextMap
        } ?: emptyMap<String, String>()
        return mdcPropertyMap
    }

    override fun setFieldNames(fieldNames: LogstashAccessFieldNames) {
        //fieldName = fieldNames.mdc
    }

    fun getIncludeMdcKeyNames(): List<String> {
        return Collections.unmodifiableList(includeMdcKeyNames)
    }

    fun addIncludeMdcKeyName(includedMdcKeyName: String) {
        this.includeMdcKeyNames.add(includedMdcKeyName)
    }

    fun setIncludeMdcKeyNames(includeMdcKeyNames: List<String>) {
        this.includeMdcKeyNames = ArrayList(includeMdcKeyNames)
    }

    fun getExcludeMdcKeyNames(): List<String> {
        return Collections.unmodifiableList(excludeMdcKeyNames)
    }

    fun addExcludeMdcKeyName(excludedMdcKeyName: String) {
        this.excludeMdcKeyNames.add(excludedMdcKeyName)
    }

    fun setExcludeMdcKeyNames(excludeMdcKeyNames: List<String>) {
        this.excludeMdcKeyNames = ArrayList(excludeMdcKeyNames)
    }
}