import {Inject, Singleton} from '../di'
import {ErrorWithContext} 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 {RequestLocalStorage} from '../http/RequestLocalStorage'
import {Bus} from '../support/bus'

/**
 * 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!: Bus

    @Inject()
    protected readonly requestLocalStorage!: RequestLocalStorage

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

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

            this.server.listen(port, () => {
                this.logging.success(`Server listening on port ${port}.`)
                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 getServer(): Server {
        if ( !this.server ) {
            throw new ErrorWithContext('Unable to access server: it has not yet been created')
        }

        return this.server
    }

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

            await this.requestLocalStorage.run(extolloReq, async () => {
                this.logging.info(`${extolloReq.method} ${extolloReq.path}`)

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

                    await error(new ErrorWithContext('Unknown error occurred.', { e }))
                }

                if ( extolloReq.response.canSend() ) {
                    await extolloReq.response.send()
                }
            }).finally(() => {
                this.logging.verbose('Destroying request container...')
                extolloReq.destroy()
            })
        }
    }
}