import { logger } from "@coder/logger"
import * as express from "express"
import { WebsocketRequest } from "../../../typings/pluginapi"
import { logError } from "../../common/util"
import { toVsCodeArgs } from "../cli"
import { isDevMode } from "../constants"
import { authenticated, ensureAuthenticated, redirect, self } from "../http"
import { SocketProxyProvider } from "../socket"
import { loadAMDModule } from "../util"
import { Router as WsRouter } from "../wsRouter"
import { errorHandler } from "./errors"

export class CodeServerRouteWrapper {
  /** Assigned in `ensureCodeServerLoaded` */
  private _codeServerMain!: CodeServerLib.IServerAPI
  private _wsRouterWrapper = WsRouter()
  private _socketProxyProvider = new SocketProxyProvider()
  public router = express.Router()

  public get wsRouter() {
    return this._wsRouterWrapper.router
  }

  //#region Route Handlers

  private $root: express.Handler = async (req, res, next) => {
    const isAuthenticated = await authenticated(req)

    if (!isAuthenticated) {
      const to = self(req)
      return redirect(req, res, "login", {
        to: to !== "/" ? to : undefined,
      })
    }

    const { query } = await req.settings.read()
    if (query) {
      // Ew means the workspace was closed so clear the last folder/workspace.
      if (req.query.ew) {
        delete query.folder
        delete query.workspace
      }

      // Redirect to the last folder/workspace if nothing else is opened.
      if (
        !req.query.folder &&
        !req.query.workspace &&
        (query.folder || query.workspace) &&
        !req.args["ignore-last-opened"] // This flag disables this behavior.
      ) {
        const to = self(req)
        return redirect(req, res, to, {
          folder: query.folder,
          workspace: query.workspace,
        })
      }
    }

    // Store the query parameters so we can use them on the next load.  This
    // also allows users to create functionality around query parameters.
    await req.settings.write({ query: req.query })

    next()
  }

  private $proxyRequest: express.Handler = async (req, res, next) => {
    // We allow certain errors to propagate so that other routers may handle requests
    // outside VS Code
    const requestErrorHandler = (error: any) => {
      if (error instanceof Error && ["EntryNotFound", "FileNotFound", "HttpError"].includes(error.message)) {
        next()
      }
      errorHandler(error, req, res, next)
    }

    req.once("error", requestErrorHandler)

    this._codeServerMain.handleRequest(req, res)
  }

  private $proxyWebsocket = async (req: WebsocketRequest) => {
    const wrappedSocket = await this._socketProxyProvider.createProxy(req.ws)
    this._codeServerMain.handleUpgrade(req, wrappedSocket)

    req.ws.resume()
  }

  //#endregion

  /**
   * Fetches a code server instance asynchronously to avoid an initial memory overhead.
   */
  private ensureCodeServerLoaded: express.Handler = async (req, _res, next) => {
    if (this._codeServerMain) {
      // Already loaded...
      return next()
    }

    // Create the server...

    const { args } = req

    /**
     * @file ../../../vendor/modules/code-oss-dev/src/vs/server/main.js
     */
    const createVSServer = await loadAMDModule<CodeServerLib.CreateServer>(
      "vs/server/remoteExtensionHostAgent",
      "createServer",
    )

    try {
      this._codeServerMain = await createVSServer(null, {
        ...(await toVsCodeArgs(args)),
        // TODO: Make the browser helper script work.
        "without-browser-env-var": true,
      })
    } catch (error) {
      logError(logger, "CodeServerRouteWrapper", error)
      if (isDevMode) {
        return next(new Error((error instanceof Error ? error.message : error) + " (VS Code may still be compiling)"))
      }
      return next(error)
    }

    return next()
  }

  constructor() {
    this.router.get("/", this.ensureCodeServerLoaded, this.$root)
    this.router.all("*", ensureAuthenticated, this.ensureCodeServerLoaded, this.$proxyRequest)
    this._wsRouterWrapper.ws("/", ensureAuthenticated, this.ensureCodeServerLoaded, this.$proxyWebsocket)
  }

  dispose() {
    this._codeServerMain?.dispose()
    this._socketProxyProvider.stop()
  }
}