import {Inject, Singleton} from '../di'
import {HTTPStatus, universalPath, UniversalPath, withTimeout} from '../util'
import {Unit} from '../lifecycle/Unit'
import {createServer, IncomingMessage, RequestListener, Server, ServerResponse} from 'http'
import {Logging} from './Logging'
import {Request} from '../http/lifecycle/Request'
import {HTTPKernel} from '../http/kernel/HTTPKernel'
import {PoweredByHeaderInjectionHTTPModule} from '../http/kernel/module/PoweredByHeaderInjectionHTTPModule'
import {SetSessionCookieHTTPModule} from '../http/kernel/module/SetSessionCookieHTTPModule'
import {InjectSessionHTTPModule} from '../http/kernel/module/InjectSessionHTTPModule'
import {PersistSessionHTTPModule} from '../http/kernel/module/PersistSessionHTTPModule'
import {MountActivatedRouteHTTPModule} from '../http/kernel/module/MountActivatedRouteHTTPModule'
import {ExecuteResolvedRouteHandlerHTTPModule} from '../http/kernel/module/ExecuteResolvedRouteHandlerHTTPModule'
import {error} from '../http/response/ErrorResponseFactory'
import {ExecuteResolvedRoutePreflightHTTPModule} from '../http/kernel/module/ExecuteResolvedRoutePreflightHTTPModule'
import {ExecuteResolvedRoutePostflightHTTPModule} from '../http/kernel/module/ExecuteResolvedRoutePostflightHTTPModule'
import {ParseIncomingBodyHTTPModule} from '../http/kernel/module/ParseIncomingBodyHTTPModule'
import {Config} from './Config'
import {InjectRequestEventBusHTTPModule} from '../http/kernel/module/InjectRequestEventBusHTTPModule'
import {Routing} from './Routing'
import {Route} from '../http/routing/Route'
import {staticServer} from '../http/servers/static'
import {EventBus} from '../event/EventBus'
import {PackageDiscovered} from '../support/PackageDiscovered'

/**
 * Application unit that starts the HTTP/S server, creates Request and Response objects
 * for it, and handles those requests using the HTTPKernel.
 */
@Singleton()
export class HTTPServer extends Unit {
    @Inject()
    protected readonly logging!: Logging

    @Inject()
    protected readonly config!: Config

    @Inject()
    protected readonly kernel!: HTTPKernel

    @Inject()
    protected readonly routing!: Routing

    @Inject()
    protected readonly bus!: EventBus

    /** The underlying native Node.js server. */
    protected server?: Server

    /**
     * Register an asset directory for the given package.
     * This creates a static server route for the package with the
     * configured vendor prefix.
     * @param packageName
     * @param basePath
     */
    public async registerVendorAssets(packageName: string, basePath: UniversalPath): Promise<void> {
        if ( this.config.get('server.builtIns.vendor.enabled', true) ) {
            this.logging.debug(`Registering vendor assets route for package ${packageName} on ${basePath}...`)
            await this.routing.registerRoutes(() => {
                const prefix = this.config.get('server.builtIns.vendor.prefix', '/vendor')
                Route.group(prefix, () => {
                    Route.group(packageName, () => {
                        Route.get('/**', staticServer({
                            basePath,
                            directoryListing: false,
                        }))
                    })
                })
            })
        }
    }

    public async up(): Promise<void> {
        const port = this.config.get('server.port', 8000)

        // TODO register these by config
        PoweredByHeaderInjectionHTTPModule.register(this.kernel)
        SetSessionCookieHTTPModule.register(this.kernel)
        InjectSessionHTTPModule.register(this.kernel)
        PersistSessionHTTPModule.register(this.kernel)
        MountActivatedRouteHTTPModule.register(this.kernel)
        ExecuteResolvedRouteHandlerHTTPModule.register(this.kernel)
        ExecuteResolvedRoutePreflightHTTPModule.register(this.kernel)
        ExecuteResolvedRoutePostflightHTTPModule.register(this.kernel)
        ParseIncomingBodyHTTPModule.register(this.kernel)
        InjectRequestEventBusHTTPModule.register(this.kernel)

        await this.registerBuiltIns()

        await new Promise<void>(res => {
            this.server = createServer(this.handler)

            this.server.listen(port, () => {
                this.logging.success(`Server listening on port ${port}. Press ^C to stop.`)
            })

            process.on('SIGINT', res)
        })
    }

    public async down(): Promise<void> {
        if ( this.server ) {
            this.server.close(err => {
                if ( err ) {
                    this.logging.error(`Error encountered while closing HTTP server: ${err.message}`)
                    this.logging.debug(err)
                }
            })
        }
    }

    public get handler(): RequestListener {
        const timeout = this.config.get('server.timeout', 10000)

        return async (request: IncomingMessage, response: ServerResponse) => {
            const extolloReq = new Request(request, response)

            withTimeout(timeout, extolloReq.response.sent$.toPromise())
                .onTime(() => {
                    this.logging.verbose(`Request lifecycle finished on time. (Path: ${extolloReq.path})`)
                })
                .late(() => {
                    if ( !extolloReq.bypassTimeout ) {
                        this.logging.warn(`Request lifecycle finished late, so an error response was returned! (Path: ${extolloReq.path})`)
                    }
                })
                .timeout(() => {
                    if ( extolloReq.bypassTimeout ) {
                        this.logging.info(`Request lifecycle has timed out, but bypassRequest was set. (Path: ${extolloReq.path})`)
                        return
                    }

                    this.logging.error(`Request lifecycle has timed out. Will send error response instead. (Path: ${extolloReq.path})`)
                    extolloReq.response.setStatus(HTTPStatus.REQUEST_TIMEOUT)
                    extolloReq.response.body = 'Sorry, your request timed out.'
                    extolloReq.response.send()
                })
                .run()
                .catch(e => this.logging.error(e))

            try {
                await this.kernel.handle(extolloReq)
            } catch (e) {
                await error(e).write(extolloReq)
            }

            await extolloReq.response.send()
        }
    }

    /** Register built-in servers and routes. */
    protected async registerBuiltIns(): Promise<void> {
        const extolloAssets = universalPath(__dirname, '..', 'resources', 'assets')
        await this.registerVendorAssets('@extollo/lib', extolloAssets)

        this.bus.subscribe(PackageDiscovered, async (event: PackageDiscovered) => {
            if ( event.packageConfig?.extollo?.assets?.discover && event.packageConfig.name ) {
                this.logging.debug(`Registering vendor assets for discovered package: ${event.packageConfig.name}`)
                const basePath = event.packageConfig?.extollo?.assets?.basePath
                if ( basePath && Array.isArray(basePath) ) {
                    const assetPath = event.packageJson.concat('..', ...basePath)
                    await this.registerVendorAssets(event.packageConfig.name, assetPath)
                }
            }
        })

        if ( this.config.get('server.builtIns.assets.enabled', true) ) {
            const prefix = this.config.get('server.builtIns.assets.prefix', '/assets')
            this.logging.debug(`Registering built-in assets server with prefix: ${prefix}`)
            await this.routing.registerRoutes(() => {
                Route.group(prefix, () => {
                    Route.get('/**', staticServer({
                        directoryListing: false,
                        basePath: ['resources', 'assets'],
                    }))
                })
            })
        }
    }
}