let querystring = require('querystring')
let stream_buffers = require('stream-buffers')
let XDate = require('xdate')

return async env => {
  if (env.request.method == 'POST') {
    let write_stream = new stream_buffers.WritableStreamBuffer()
    let data = new Promise(
      (resolve, reject) => {
        write_stream.
        on('finish', () => {resolve(write_stream.getContents())}).
        on('error', () => {reject()})
      }
    )
    env.request.pipe(write_stream)
    let query = querystring.parse((await data).toString())
    console.log('received feedback form:', JSON.stringify(query)) //query.page)

    // save the form contents in a dated logfile, so that we can
    // recover manually if the email doesn't send for some reason
    date = new XDate()
    query.date = date.toUTCString()

    await env.site.ensure_dir('/_logs')
    env.site.modify_json(
      `/_logs/feedback_${date.toUTCString('yyyyMMdd')}.json`,
      [],
      async result => {result.value.push(query)}
    )

    // send email (asynchronously)
    ;(await env.site.get_emailjs('/_config/email_feedback.json')).send(
      {
        text: query.message,
        from: 'Feedback form <feedback@ndcode.org>',
        to: 'Nick Downing <nick@ndcode.org>',
        subject: 'Page: ' + query.page
      },
      (err, message) => {
        if (err)
          console.error(err.stack || err.message)
        else
          console.log('sent feedback email:', query.page)
      }
    )
  }
  env.site.serve(env, 200, Buffer.from('Thanks!'), 'feedback_form.html.jst')
}