import http from 'http'
import { resolve, join } from 'path'
import { parse } from 'url'
import send from 'send'
import Router from './router'
import { render, renderJSON, errorToJSON } from './render'
import HotReloader from './hot-reloader'
import { resolveFromList } from './resolve'

export default class Server {
  constructor ({ dir = '.', dev = false, hotReload = false }) {
    this.dir = resolve(dir)
    this.dev = dev
    this.hotReloader = hotReload ? new HotReloader(this.dir) : null
    this.router = new Router()

    this.http = http.createServer((req, res) => {
      this.run(req, res)
      .catch((err) => {
        console.error(err)
        res.status(500)
        res.end('error')
      })
    })

    this.defineRoutes()
  }

  async start (port) {
    if (this.hotReloader) {
      await this.hotReloader.start()
    }

    await new Promise((resolve, reject) => {
      this.http.listen(port, (err) => {
        if (err) return reject(err)
        resolve()
      })
    })
  }

  defineRoutes () {
    this.router.get('/_next/:path+', async (req, res, params) => {
      const p = join(__dirname, '..', 'client', ...(params.path || []))
      await this.serveStatic(req, res, p)
    })

    this.router.get('/static/:path+', async (req, res, params) => {
      const p = join(this.dir, 'static', ...(params.path || []))
      await this.serveStatic(req, res, p)
    })

    this.router.get('/:path+.json', async (req, res) => {
      await this.renderJSON(req, res)
    })

    this.router.get('/:path*', async (req, res) => {
      await this.render(req, res)
    })
  }

  async run (req, res) {
    const fn = this.router.match(req, res)
    if (fn) {
      await fn()
    } else {
      await this.render404(req, res)
    }
  }

  async render (req, res) {
    const { dir, dev } = this
    const ctx = { req, res }
    const opts = { dir, dev }

    let html

    const err = this.getCompilationError(req.url)
    if (err) {
      res.statusCode = 500
      html = await render('/_error-debug', { ...ctx, err }, opts)
    } else {
      try {
        html = await render(req.url, ctx, opts)
      } catch (err) {
        if (err.code === 'ENOENT') {
          res.statusCode = 404
        } else {
          console.error(err)
          res.statusCode = 500
        }
        html = await render('/_error', { ...ctx, err }, opts)
      }
    }

    sendHTML(res, html)
  }

  async renderJSON (req, res) {
    const { dir } = this
    const opts = { dir }

    let json

    const err = this.getCompilationError(req.url)
    if (err) {
      res.statusCode = 500
      json = await renderJSON('/_error-debug.json', opts)
      json = { ...json, err: errorToJSON(err) }
    } else {
      try {
        json = await renderJSON(req.url, opts)
      } catch (err) {
        if (err.code === 'ENOENT') {
          res.statusCode = 404
        } else {
          console.error(err)
          res.statusCode = 500
        }
        json = await renderJSON('/_error.json', opts)
      }
    }

    const data = JSON.stringify(json)
    res.setHeader('Content-Type', 'application/json')
    res.setHeader('Content-Length', Buffer.byteLength(data))
    res.end(data)
  }

  async render404 (req, res) {
    const { dir, dev } = this

    res.statusCode = 404
    const html = await render('/_error', { req, res }, { dir, dev })
    sendHTML(res, html)
  }

  serveStatic (req, res, path) {
    return new Promise((resolve, reject) => {
      send(req, path)
      .on('error', (err) => {
        if (err.code === 'ENOENT') {
          this.render404(req, res).then(resolve, reject)
        } else {
          reject(err)
        }
      })
      .pipe(res)
      .on('finish', resolve)
    })
  }

  getCompilationError (url) {
    if (!this.hotReloader) return

    const errors = this.hotReloader.getCompilationErrors()
    if (!errors.size) return

    const p = parse(url || '/').pathname.replace(/\.json$/, '')
    const id = join(this.dir, '.next', 'bundles', 'pages', p)
    const path = resolveFromList(id, errors.keys())
    if (path) return errors.get(path)[0]
  }
}

function sendHTML (res, html) {
  res.setHeader('Content-Type', 'text/html')
  res.setHeader('Content-Length', Buffer.byteLength(html))
  res.end(html)
}