/* eslint-disable import/first */
import {IncomingMessage, ServerResponse} from 'http'
import { resolve, join, sep } from 'path'
import { parse as parseUrl, UrlWithParsedQuery } from 'url'
import { parse as parseQs, ParsedUrlQuery } from 'querystring'
import fs from 'fs'
import {renderToHTML} from './render'
import {sendHTML} from './send-html'
import {serveStatic} from './serve-static'
import Router, {route, Route} from './router'
import { isInternalUrl, isBlockedPage } from './utils'
import loadConfig from 'next-server/next-config'
import {PHASE_PRODUCTION_SERVER, BUILD_ID_FILE, CLIENT_STATIC_FILES_PATH, CLIENT_STATIC_FILES_RUNTIME} from 'next-server/constants'
import * as envConfig from '../lib/runtime-config'
import {loadComponents} from './load-components'

type NextConfig = any

type ServerConstructor = {
  dir?: string,
  staticMarkup?: boolean,
  quiet?: boolean,
  conf?: NextConfig,
}

export default class Server {
  dir: string
  quiet: boolean
  nextConfig: NextConfig
  distDir: string
  buildId: string
  renderOpts: {
    ampEnabled: boolean,
    staticMarkup: boolean,
    buildId: string,
    generateEtags: boolean,
    runtimeConfig?: {[key: string]: any},
    assetPrefix?: string,
  }
  router: Router

  public constructor({ dir = '.', staticMarkup = false, quiet = false, conf = null }: ServerConstructor = {}) {
    this.dir = resolve(dir)
    this.quiet = quiet
    const phase = this.currentPhase()
    this.nextConfig = loadConfig(phase, this.dir, conf)
    this.distDir = join(this.dir, this.nextConfig.distDir)

    // Only serverRuntimeConfig needs the default
    // publicRuntimeConfig gets it's default in client/index.js
    const {serverRuntimeConfig = {}, publicRuntimeConfig, assetPrefix, generateEtags, target} = this.nextConfig

    if (process.env.NODE_ENV === 'production' && target !== 'server') throw new Error('Cannot start server when target is not server. https://err.sh/zeit/next.js/next-start-serverless')

    this.buildId = this.readBuildId()
    this.renderOpts = {
      ampEnabled: this.nextConfig.experimental.amp,
      staticMarkup,
      buildId: this.buildId,
      generateEtags,
    }

    // Only the `publicRuntimeConfig` key is exposed to the client side
    // It'll be rendered as part of __NEXT_DATA__ on the client side
    if (publicRuntimeConfig) {
      this.renderOpts.runtimeConfig = publicRuntimeConfig
    }

    // Initialize next/config with the environment configuration
    envConfig.setConfig({
      serverRuntimeConfig,
      publicRuntimeConfig,
    })

    const routes = this.generateRoutes()
    this.router = new Router(routes)
    this.setAssetPrefix(assetPrefix)
  }

  private currentPhase(): string {
    return PHASE_PRODUCTION_SERVER
  }

  private logError(...args: any): void {
    if (this.quiet) return
    // tslint:disable-next-line
    console.error(...args)
  }

  private handleRequest(req: IncomingMessage, res: ServerResponse, parsedUrl?: UrlWithParsedQuery): Promise<void> {
    // Parse url if parsedUrl not provided
    if (!parsedUrl || typeof parsedUrl !== 'object') {
      const url: any = req.url
      parsedUrl = parseUrl(url, true)
    }

    // Parse the querystring ourselves if the user doesn't handle querystring parsing
    if (typeof parsedUrl.query === 'string') {
      parsedUrl.query = parseQs(parsedUrl.query)
    }

    res.statusCode = 200
    return this.run(req, res, parsedUrl)
      .catch((err) => {
        this.logError(err)
        res.statusCode = 500
        res.end('Internal Server Error')
      })
  }

  public getRequestHandler() {
    return this.handleRequest.bind(this)
  }

  public setAssetPrefix(prefix?: string) {
    this.renderOpts.assetPrefix = prefix ? prefix.replace(/\/$/, '') : ''
  }

  // Backwards compatibility
  public async prepare(): Promise<void> {}

  // Backwards compatibility
  private async close(): Promise<void> {}

  private setImmutableAssetCacheControl(res: ServerResponse) {
    res.setHeader('Cache-Control', 'public, max-age=31536000, immutable')
  }

  private generateRoutes(): Route[] {
    const routes: Route[] = [
      {
        match: route('/_next/static/:path*'),
        fn: async (req, res, params, parsedUrl) => {
          // The commons folder holds commonschunk files
          // The chunks folder holds dynamic entries
          // The buildId folder holds pages and potentially other assets. As buildId changes per build it can be long-term cached.
          if (params.path[0] === CLIENT_STATIC_FILES_RUNTIME || params.path[0] === 'chunks' || params.path[0] === this.buildId) {
            this.setImmutableAssetCacheControl(res)
          }
          const p = join(this.distDir, CLIENT_STATIC_FILES_PATH, ...(params.path || []))
          await this.serveStatic(req, res, p, parsedUrl)
        },
      },
      {
        match: route('/_next/:path*'),
        // This path is needed because `render()` does a check for `/_next` and the calls the routing again
        fn: async (req, res, _params, parsedUrl) => {
          await this.render404(req, res, parsedUrl)
        },
      },
      {
        // It's very important to keep this route's param optional.
        // (but it should support as many params as needed, separated by '/')
        // Otherwise this will lead to a pretty simple DOS attack.
        // See more: https://github.com/zeit/next.js/issues/2617
        match: route('/static/:path*'),
        fn: async (req, res, params, parsedUrl) => {
          const p = join(this.dir, 'static', ...(params.path || []))
          await this.serveStatic(req, res, p, parsedUrl)
        },
      },
    ]

    if (this.nextConfig.useFileSystemPublicRoutes) {
      if (this.nextConfig.experimental.amp) {
        // It's very important to keep this route's param optional.
        // (but it should support as many params as needed, separated by '/')
        // Otherwise this will lead to a pretty simple DOS attack.
        // See more: https://github.com/zeit/next.js/issues/2617
        routes.push({
          match: route('/:path*/amp'),
          fn: async (req, res, params, parsedUrl) => {
            let pathname
            if (!params.path) {
              pathname = '/'
            } else {
              pathname = '/' + params.path.join('/')
            }
            const { query } = parsedUrl
            if (!pathname) {
              throw new Error('pathname is undefined')
            }
            await this.renderToAMP(req, res, pathname, query, parsedUrl)
          },
        })
      }

      // It's very important to keep this route's param optional.
      // (but it should support as many params as needed, separated by '/')
      // Otherwise this will lead to a pretty simple DOS attack.
      // See more: https://github.com/zeit/next.js/issues/2617
      routes.push({
        match: route('/:path*'),
        fn: async (req, res, _params, parsedUrl) => {
          const { pathname, query } = parsedUrl
          if (!pathname) {
            throw new Error('pathname is undefined')
          }
          await this.render(req, res, pathname, query, parsedUrl)
        },
      })
    }

    return routes
  }

  private async run(req: IncomingMessage, res: ServerResponse, parsedUrl: UrlWithParsedQuery) {
    try {
      const fn = this.router.match(req, res, parsedUrl)
      if (fn) {
        await fn()
        return
      }
    } catch (err) {
      if (err.code === 'DECODE_FAILED') {
        res.statusCode = 400
        return this.renderError(null, req, res, '/_error', {})
      }
      throw err
    }

    if (req.method === 'GET' || req.method === 'HEAD') {
      await this.render404(req, res, parsedUrl)
    } else {
      res.statusCode = 501
      res.end('Not Implemented')
    }
  }

  private async sendHTML(req: IncomingMessage, res: ServerResponse, html: string) {
    const {generateEtags} = this.renderOpts
    return sendHTML(req, res, html, {generateEtags})
  }

  public async render(req: IncomingMessage, res: ServerResponse, pathname: string, query: ParsedUrlQuery = {}, parsedUrl?: UrlWithParsedQuery): Promise<void> {
    const url: any = req.url
    if (isInternalUrl(url)) {
      return this.handleRequest(req, res, parsedUrl)
    }

    if (isBlockedPage(pathname)) {
      return this.render404(req, res, parsedUrl)
    }

    const html = await this.renderToHTML(req, res, pathname, query)
    // Request was ended by the user
    if (html === null) {
      return
    }

    if (this.nextConfig.poweredByHeader) {
      res.setHeader('X-Powered-By', 'Next.js ' + process.env.NEXT_VERSION)
    }
    return this.sendHTML(req, res, html)
  }

  public async renderToAMP(req: IncomingMessage, res: ServerResponse, pathname: string, query: ParsedUrlQuery = {}, parsedUrl?: UrlWithParsedQuery): Promise<void> {
    if (!this.nextConfig.experimental.amp) {
      throw new Error('"experimental.amp" is not enabled in "next.config.js"')
    }
    const url: any = req.url
    if (isInternalUrl(url)) {
      return this.handleRequest(req, res, parsedUrl)
    }

    if (isBlockedPage(pathname)) {
      return this.render404(req, res, parsedUrl)
    }

    const html = await this.renderToAMPHTML(req, res, pathname, query)
    // Request was ended by the user
    if (html === null) {
      return
    }

    if (this.nextConfig.poweredByHeader) {
      res.setHeader('X-Powered-By', 'Next.js ' + process.env.NEXT_VERSION)
    }
    return this.sendHTML(req, res, html)
  }

  private async renderToHTMLWithComponents(req: IncomingMessage, res: ServerResponse, pathname: string, query: ParsedUrlQuery = {}, opts: any) {
    const result = await loadComponents(this.distDir, this.buildId, pathname)
    return renderToHTML(req, res, pathname, query, {...result, ...opts})
  }

  public async renderToAMPHTML(req: IncomingMessage, res: ServerResponse, pathname: string, query: ParsedUrlQuery = {}): Promise<string|null> {
    if (!this.nextConfig.experimental.amp) {
      throw new Error('"experimental.amp" is not enabled in "next.config.js"')
    }
    return this.renderToHTML(req, res, pathname, query, {amphtml: true})
  }

  public async renderToHTML(req: IncomingMessage, res: ServerResponse, pathname: string, query: ParsedUrlQuery = {}, {amphtml}: {amphtml?: boolean} = {}): Promise<string|null> {
    try {
      // To make sure the try/catch is executed
      const html = await this.renderToHTMLWithComponents(req, res, pathname, query, {...this.renderOpts, amphtml})
      return html
    } catch (err) {
      if (err.code === 'ENOENT') {
        res.statusCode = 404
        return this.renderErrorToHTML(null, req, res, pathname, query)
      } else {
        this.logError(err)
        res.statusCode = 500
        return this.renderErrorToHTML(err, req, res, pathname, query)
      }
    }
  }

  public async renderError(err: Error|null, req: IncomingMessage, res: ServerResponse, pathname: string, query: ParsedUrlQuery = {}): Promise<void> {
    res.setHeader('Cache-Control', 'no-cache, no-store, max-age=0, must-revalidate')
    const html = await this.renderErrorToHTML(err, req, res, pathname, query)
    if (html === null) {
      return
    }
    return this.sendHTML(req, res, html)
  }

  public async renderErrorToHTML(err: Error|null, req: IncomingMessage, res: ServerResponse, _pathname: string, query: ParsedUrlQuery = {}) {
    return this.renderToHTMLWithComponents(req, res, '/_error', query, {...this.renderOpts, err})
  }

  public async render404(req: IncomingMessage, res: ServerResponse, parsedUrl?: UrlWithParsedQuery): Promise<void> {
    const url: any = req.url
    const { pathname, query } = parsedUrl ? parsedUrl : parseUrl(url, true)
    if (!pathname) {
      throw new Error('pathname is undefined')
    }
    res.statusCode = 404
    return this.renderError(null, req, res, pathname, query)
  }

  public async serveStatic(req: IncomingMessage, res: ServerResponse, path: string, parsedUrl?: UrlWithParsedQuery): Promise<void> {
    if (!this.isServeableUrl(path)) {
      return this.render404(req, res, parsedUrl)
    }

    try {
      await serveStatic(req, res, path)
    } catch (err) {
      if (err.code === 'ENOENT' || err.statusCode === 404) {
        this.render404(req, res, parsedUrl)
      } else {
        throw err
      }
    }
  }

  private isServeableUrl(path: string): boolean {
    const resolved = resolve(path)
    if (
      resolved.indexOf(join(this.distDir) + sep) !== 0 &&
      resolved.indexOf(join(this.dir, 'static') + sep) !== 0
    ) {
      // Seems like the user is trying to traverse the filesystem.
      return false
    }

    return true
  }

  private readBuildId(): string {
    const buildIdFile = join(this.distDir, BUILD_ID_FILE)
    try {
      return fs.readFileSync(buildIdFile, 'utf8').trim()
    } catch (err) {
      if (!fs.existsSync(buildIdFile)) {
        throw new Error(`Could not find a valid build in the '${this.distDir}' directory! Try building your app with 'next build' before starting the server.`)
      }

      throw err
    }
  }
}