ServletServer.kt

package com.hexagonkt.http.server.servlet

import com.hexagonkt.core.text.AnsiColor.BLUE
import com.hexagonkt.core.text.AnsiEffect.BOLD
import com.hexagonkt.core.text.AnsiColor.CYAN
import com.hexagonkt.core.text.AnsiColor.MAGENTA
import com.hexagonkt.core.text.Ansi.RESET
import com.hexagonkt.core.Jvm
import com.hexagonkt.core.text.prependIndent
import com.hexagonkt.core.require
import com.hexagonkt.core.logging.Logger
import com.hexagonkt.http.server.HttpServer
import com.hexagonkt.http.server.HttpServerSettings
import com.hexagonkt.http.handlers.HttpHandler
import com.hexagonkt.http.handlers.OnHandler
import jakarta.servlet.*
import java.lang.management.ManagementFactory
import java.util.*

/**
 * Adapter to run a router inside a Servlets container. It is not a standard engine as it is not
 * started/stopped (not passed to an [HttpServer]).
 */
abstract class ServletServer(
    private val handler: HttpHandler = OnHandler { this },
    private val settings: HttpServerSettings = HttpServerSettings(),
) : ServletContextListener {

    private companion object {
        val logger: Logger = Logger(ServletServer::class)
    }

    override fun contextInitialized(sce: ServletContextEvent) {
        val startTimestamp = System.nanoTime()

        val servletFilter = ServletFilter(handler)
        // Let's be a good JEE citizen
        val servletContext = sce.servletContext
        servletFilter.init(object : FilterConfig {
            val params = Hashtable<String, String>(1).apply { put("filterName", filterName) }
            override fun getFilterName(): String = ServletFilter::class.java.name
            override fun getServletContext(): ServletContext = servletContext
            override fun getInitParameter(name: String): String = params.require(name)
            override fun getInitParameterNames(): Enumeration<String> = params.keys()
        })
        val filter = servletContext.addFilter("filters", servletFilter)
        filter.addMappingForUrlPatterns(EnumSet.allOf(DispatcherType::class.java), true, "/*")

        logger.info { "Server started\n${createBanner(System.nanoTime() - startTimestamp)}" }
    }

    override fun contextDestroyed(sce: ServletContextEvent?) {
        logger.info { "Server context destroyed" }
    }

    private fun createBanner(startUpTimestamp: Long): String {

        val heap = ManagementFactory.getMemoryMXBean().heapMemoryUsage
        val jvmMemory = "%,d".format(heap.init / 1024)
        val usedMemory = "%,d".format(heap.used / 1024)
        val bootTime = "%01.3f".format(ManagementFactory.getRuntimeMXBean().uptime / 1e3)
        val startUpTime = "%,.0f".format(startUpTimestamp / 1e6)

        val serverAdapterValue = "$BOLD$CYAN${javaClass.simpleName}$RESET"

        val hostnameValue = "$BLUE${Jvm.hostName}$RESET"
        val cpuCountValue = "$BLUE${Jvm.cpuCount}$RESET"
        val jvmMemoryValue = "$BLUE$jvmMemory$RESET"

        val javaVersionValue = "$BOLD${BLUE}Java ${Jvm.version}$RESET [$BLUE${Jvm.name}$RESET]"

        val localeValue = "$BLUE${Jvm.localeCode}$RESET"
        val timezoneValue = "$BLUE${Jvm.timeZone.id}$RESET"
        val charsetValue = "$BLUE${Jvm.charset}$RESET"

        val bootTimeValue = "$BOLD$MAGENTA$bootTime s$RESET"
        val startUpTimeValue = "$BOLD$MAGENTA$startUpTime ms$RESET"
        val usedMemoryValue = "$BOLD$MAGENTA$usedMemory KB$RESET"

        val information = """

            Server Adapter: $serverAdapterValue

            🖥️️ Running in '$hostnameValue' with $cpuCountValue CPUs $jvmMemoryValue KB
            🛠 Using $javaVersionValue
            🌍 Locale: $localeValue Timezone: $timezoneValue Charset: $charsetValue

            ⏱ Started in $bootTimeValue (server: $startUpTimeValue) using $usedMemoryValue
            🚀 Served at a JEE Server

        """.trimIndent()

        val banner = (settings.banner?.let { "$it\n" } ?: HttpServer.banner) + information
        return banner.prependIndent()
    }
}