Application and Lifecycle Management

/**
 * Main application instance extending ApplicationCallPipeline
 */
class Application : ApplicationCallPipeline(), CoroutineScope {
    /** Application environment containing configuration and logging */
    val environment: ApplicationEnvironment
    /** Attributes for storing application-scoped data */
    val attributes: Attributes
    /** Event monitor for application lifecycle events */
    val monitor: Events
    /** Coroutine context for application scope */
    override val coroutineContext: CoroutineContext
    
    /** Get installed plugin instance by plugin key */
    fun <TPlugin : Any> plugin(plugin: Plugin<*, *, TPlugin>): TPlugin
    /** Get installed plugin instance or null if not installed */
    fun <TPlugin : Any> pluginOrNull(plugin: Plugin<*, *, TPlugin>): TPlugin?
    /** Access application configuration */
    val config: ApplicationConfig get() = environment.config
    /** Access application logger */
    val log: Logger get() = environment.log

    /** Property access to configuration with serialization */
    inline fun <reified T> property(path: String): T
    /** Safe property access that returns null if not found */
    inline fun <reified T> propertyOrNull(path: String): T?
}

/**
 * Server configuration containing modules and settings
 */
class ServerConfig {
    /** List of application modules to install */
    val modules: List<suspend Application.() -> Unit>
    /** Paths to watch for application reload */
    val watchPaths: List<String>
    /** Application's root path (prefix) */
    val rootPath: String
    /** Development mode flag */
    val developmentMode: Boolean
    /** Application environment */
    val environment: ApplicationEnvironment
}

/**
 * Builder for creating ServerConfig instances
 */
class ServerConfigBuilder(val environment: ApplicationEnvironment) {
    /** List of application modules */
    val modules: MutableList<suspend Application.() -> Unit>
    /** Paths to watch for application reload */
    var watchPaths: List<String>
    /** Application's root path (prefix) */
    var rootPath: String
    /** Development mode flag */
    var developmentMode: Boolean
    
    /** Add a module to the server configuration */
    fun module(module: suspend Application.() -> Unit)
    /** Build the final ServerConfig */
    fun build(): ServerConfig
}

/**
 * Create a server configuration
 */
fun serverConfig(
    environment: ApplicationEnvironment,
    configure: ServerConfigBuilder.() -> Unit = {}
): ServerConfig

/**
 * Application environment providing access to configuration, classloader, and logging
 */
interface ApplicationEnvironment {
    /** Application configuration */
    val config: ApplicationConfig
    /** Application logger */
    val log: Logger
    /** Event monitor for lifecycle events */
    val monitor: Events
    /** Whether application is running in development mode */
    val developmentMode: Boolean
    /** Root path for the application */
    val rootPath: String
    /** Class loader for the application */
    val classLoader: ClassLoader
}

/**
 * Represents a single HTTP request-response cycle
 */
interface ApplicationCall {
    /** The application instance handling this call */
    val application: Application
    /** The HTTP request */
    val request: ApplicationRequest
    /** The HTTP response */
    val response: ApplicationResponse
    /** URL and form parameters */
    val parameters: Parameters
    /** Call-scoped attributes for storing data */
    val attributes: Attributes
}

/** Access application from within a call context */
suspend fun ApplicationCall.application(): Application = application

/**
 * Property to access the application from within a call
 */
val ApplicationCall.application: Application

/**
 * Main pipeline for processing application calls
 */
open class ApplicationCallPipeline : Pipeline<Unit, ApplicationCall> {
    companion object {
        /** Setup phase for call processing */
        val Setup: PipelinePhase = PipelinePhase("Setup")
        /** Monitoring phase for call processing */
        val Monitoring: PipelinePhase = PipelinePhase("Monitoring")
        /** Plugins phase for call processing */
        val Plugins: PipelinePhase = PipelinePhase("Plugins")
        /** Call processing phase */
        val Call: PipelinePhase = PipelinePhase("Call")
        /** Fallback phase for unhandled calls */
        val Fallback: PipelinePhase = PipelinePhase("Fallback")
    }
    
    /** Install a plugin into this pipeline */
    fun <TConfiguration : Any, TPlugin : Any> install(
        plugin: BaseApplicationPlugin<*, TConfiguration, TPlugin>,
        configure: TConfiguration.() -> Unit = {}
    ): TPlugin
    
    /** Get installed plugin instance */
    fun <TPlugin : Any> plugin(plugin: Plugin<*, *, TPlugin>): TPlugin
    
    /** Get installed plugin instance or null if not installed */
    fun <TPlugin : Any> pluginOrNull(plugin: Plugin<*, *, TPlugin>): TPlugin?
}

/**
 * Pipeline for processing incoming content
 */
class ApplicationReceivePipeline : Pipeline<ApplicationReceiveRequest, ApplicationCall> {
    companion object {
        /** Before transformation phase */
        val Before: PipelinePhase = PipelinePhase("Before")
        /** Transformation phase */
        val Transform: PipelinePhase = PipelinePhase("Transform")
        /** After transformation phase */
        val After: PipelinePhase = PipelinePhase("After")
    }
}

/**
 * Pipeline for processing outgoing content
 */
class ApplicationSendPipeline : Pipeline<Any, ApplicationCall> {
    companion object {
        /** Before transformation phase */
        val Before: PipelinePhase = PipelinePhase("Before")
        /** Transform phase */
        val Transform: PipelinePhase = PipelinePhase("Transform")
        /** Render phase */
        val Render: PipelinePhase = PipelinePhase("Render")
        /** Content encoding phase */
        val ContentEncoding: PipelinePhase = PipelinePhase("ContentEncoding")
        /** Transfer encoding phase */ 
        val TransferEncoding: PipelinePhase = PipelinePhase("TransferEncoding")
        /** After phase */
        val After: PipelinePhase = PipelinePhase("After")
    }
}

/**
 * Pipeline for processing call responses
 */
class ApplicationResponsePipeline : Pipeline<Any, ApplicationCall> {
    companion object {
        /** Transform phase */
        val Transform: PipelinePhase = PipelinePhase("Transform")
        /** Render phase */
        val Render: PipelinePhase = PipelinePhase("Render")
        /** Content encoding phase */
        val ContentEncoding: PipelinePhase = PipelinePhase("ContentEncoding")
        /** After phase */
        val After: PipelinePhase = PipelinePhase("After")
    }
}

/**
 * Pipeline context for interceptors
 */
interface PipelineContext<TSubject : Any, TContext : Any> {
    /** Current pipeline subject */
    val subject: TSubject
    /** Pipeline execution context */
    val context: TContext
    /** Proceed to next interceptor */
    suspend fun proceed(): TSubject
    /** Proceed with modified subject */
    suspend fun proceedWith(subject: TSubject): TSubject
    /** Finish pipeline execution */
    fun finish()
}

/**
 * Type alias for pipeline interceptor function
 */
typealias PipelineInterceptor<TSubject, TContext> = 
    suspend PipelineContext<TSubject, TContext>.(TSubject) -> Unit

/**
 * Hook definition for event-driven extensions
 */
class Hook<T : Function<Unit>> {
    /** Install hook handler */
    fun install(handler: T)
    /** Uninstall hook handler */
    fun uninstall(handler: T)
}

/**
 * Application call hooks for lifecycle events
 */
object ApplicationCallHooks {
    /** Called when application call starts */
    val CallStart: Hook<(ApplicationCall) -> Unit>
    /** Called when application call completes */
    val CallFinished: Hook<(ApplicationCall) -> Unit>
    /** Called when application call fails */
    val CallFailed: Hook<(ApplicationCall, Throwable) -> Unit>
}

/** Install hook handler */
fun <T : Function<Unit>> Application.hook(hook: Hook<T>, handler: T)

/**
 * Application module function type for configuration
 */
typealias ApplicationModule = Application.() -> Unit

/**
 * Configure application with module function
 */
fun Application.module(body: Application.() -> Unit) = body()

import io.ktor.server.application.*
import io.ktor.server.response.*
import io.ktor.server.routing.*

// Basic application module
fun Application.myModule() {
    routing {
        get("/health") {
            call.respondText("OK")
        }
    }
}

// Access application properties
fun Application.configExample() {
    val dbUrl = config.property("database.url").getString()
    val isDev = environment.developmentMode
    
    log.info("Starting application in ${if (isDev) "development" else "production"} mode")
    log.info("Database URL: $dbUrl")
}

// Hook installation
fun Application.hookExample() {
    hook(ApplicationCallHooks.CallStart) { call ->
        log.info("Processing ${call.request.httpMethod.value} ${call.request.uri}")
    }
    
    hook(ApplicationCallHooks.CallFinished) { call ->
        log.info("Completed ${call.request.uri} with status ${call.response.status()}")
    }
}