module.exports = CreateTorrentPage

var h = require('virtual-dom/h')
var hyperx = require('hyperx')
var hx = hyperx(h)

var createTorrent = require('create-torrent')
var path = require('path')
var prettyBytes = require('prettier-bytes')

var {dispatch} = require('../lib/dispatcher')

function CreateTorrentPage (state) {
  var info = state.location.current()

  // First, extract the base folder that the files are all in
  var files = info.files
  var pathPrefix = info.folderPath
  if (!pathPrefix) {
    if (files.length > 0) {
      pathPrefix = files.map((x) => x.path).reduce(findCommonPrefix)
      if (!pathPrefix.endsWith('/') && !pathPrefix.endsWith('\\')) {
        pathPrefix = path.dirname(pathPrefix)
      }
    } else {
      pathPrefix = files[0]
    }
  }

  // Sanity check: show the number of files and total size
  var numFiles = files.length
  var totalBytes = files
    .map((f) => f.length)
    .reduce((a, b) => a + b, 0)
  var torrentInfo = `${numFiles} files, ${prettyBytes(totalBytes)}`

  // Then, use the name of the base folder (or sole file, for a single file torrent)
  // as the default name. Show all files relative to the base folder.
  var defaultName = path.basename(pathPrefix)
  var basePath = path.dirname(pathPrefix)
  var maxFileElems = 100
  var fileElems = files.slice(0, maxFileElems).map(function (file) {
    var relativePath = files.length === 0 ? file.name : path.relative(pathPrefix, file.path)
    return hx`<div>${relativePath}</div>`
  })
  if (files.length > maxFileElems) {
    fileElems.push(hx`<div>+ ${maxFileElems - files.length} more</div>`)
  }
  var trackers = createTorrent.announceList.join('\n')
  var collapsedClass = info.showAdvanced ? 'expanded' : 'collapsed'

  return hx`
    <div class='create-torrent-page'>
      <h2>Create torrent ${defaultName}</h2>
      <p class="torrent-info">
        ${torrentInfo}
      </p>
      <p class='torrent-attribute'>
        <label>Path:</label>
        <div class='torrent-attribute'>${pathPrefix}</div>
      </p>
      <div class='expand-collapse ${collapsedClass}' onclick=${handleToggleShowAdvanced}>
        ${info.showAdvanced ? 'Basic' : 'Advanced'}
      </div>
      <div class="create-torrent-advanced ${collapsedClass}">
        <p class='torrent-attribute'>
          <label>Comment:</label>
          <textarea class='torrent-attribute torrent-comment'></textarea>
        </p>
        <p class='torrent-attribute'>
          <label>Trackers:</label>
          <textarea class='torrent-attribute torrent-trackers'>${trackers}</textarea>
        </p>
        <p class='torrent-attribute'>
          <label>Private:</label>
          <input type='checkbox' class='torrent-is-private' value='torrent-is-private'>
        </p>
        <p class='torrent-attribute'>
          <label>Files:</label>
          <div>${fileElems}</div>
        </p>
      </div>
      <p class="float-right">
        <button class='button-flat light' onclick=${handleCancel}>Cancel</button>
        <button class='button-raised' onclick=${handleOK}>Create Torrent</button>
      </p>
    </div>
  `

  function handleOK () {
    var announceList = document.querySelector('.torrent-trackers').value
      .split('\n')
      .map((s) => s.trim())
      .filter((s) => s !== '')
    var isPrivate = document.querySelector('.torrent-is-private').checked
    var comment = document.querySelector('.torrent-comment').value.trim()
    var options = {
      // We can't let the user choose their own name if we want WebTorrent
      // to use the files in place rather than creating a new folder.
      // If we ever want to add support for that:
      // name: document.querySelector('.torrent-name').value
      name: defaultName,
      path: basePath,
      files: files,
      announce: announceList,
      private: isPrivate,
      comment: comment
    }
    dispatch('createTorrent', options)
    dispatch('backToList')
  }

  function handleCancel () {
    dispatch('backToList')
  }

  function handleToggleShowAdvanced () {
    // TODO: what's the clean way to handle this?
    // Should every button on every screen have its own dispatch()?
    info.showAdvanced = !info.showAdvanced
    dispatch('update')
  }
}

// Finds the longest common prefix
function findCommonPrefix (a, b) {
  for (var i = 0; i < a.length && i < b.length; i++) {
    if (a.charCodeAt(i) !== b.charCodeAt(i)) break
  }
  if (i === a.length) return a
  if (i === b.length) return b
  return a.substring(0, i)
}