/**
 * # Terminal Riot Tag
 *
 * Provides a pretend commandline interface, capable of displaying output from a
 * "shell" JavaScript class. Multiple terminal tags can be used on a page, using
 * the same shell class or different ones - each terminal will work
 * independently.
 *
 * ## Defaults
 *
 * The default prompt is `'$ '`.
 * The default welcome message is empty.
 * The default shell performs no actions: pressing enter will simply move the
 * cursor to the next prompt line.
 *
 * ## Usage
 *
 *     <terminal shell='myshellclass' welcome='text' prompt='text'></terminal>
 *
 *     <script src='riot+compiler.min.js'></script>
 *     <script src='he.js'></script>
 *     <script src='myshell.js'></script>
 *     <script src='terminal.tag' type='riot/tag'></script>
 *     <script>riot.mount('terminal')</script>
 *
 * ## Dependencies
 *
 * - riot.js (http://riotjs.com/)
 * - he.js (https://github.com/mathiasbynens/he) for HTML Entity conversion.
 *
 * ## Making A Shell Class
 *
 * A shell class must be defined before the tag is mounted. Shells can keep
 * prompt and welcome message settings, and should listen to the `'cmd_entered'`
 * event to process input from the `commandline` tag.
 *
 * Here is the structure of a minimal shell that does nothing:
 *
 *     // Contents of myshell.js
 *     function myshellclass(events) {
 *        this.prompt = ''
 *        this.welcome = ''
 *        events.on('cmd_entered', function(input) {
 *          // Do nothing
 *        })
 *     }
 *
 * The shell can trigger events available on the `display` and `commandline`
 * tags to make things happen:
 *
 *     events.trigger('disp_add', text)   // Append `text` to the display
 *     events.trigger('disp_set', text)   // Display only `text`
 *     events.trigger('disp_clear')       // Clear the display
 *     events.trigger('disp_hide')        // Save the display, then clear it
 *     events.trigger('disp_restore')     // Restore the saved display
 *     events.trigger('prompt_set', text) // Change the command prompt to `text`
 *     events.trigger('prompt_hide')      // Hide the command prompt
 *     events.trigger('prompt_show')      // Show the command prompt, if hidden
 *
 */
<terminal>
  <display welcome={ welcome } events={ this } />
  <commandline prompt={ prompt } events={ this } />

  /**
   * Create a new shell with the class name given to the terminal tag.
   * The terminal tag object passes events between the shell and the other tags.
   */
  var shell = window[opts.shell] ? new window[opts.shell](this) : {}
  this.welcome = shell.welcome || opts.welcome
  this.prompt = shell.prompt || opts.prompt
</terminal>

<display>
  <div each={ output }>
    <raw content={ content } />
  </div>

  var ev = opts.events
  var self = this
  this.output = []

  this.on('mount', function() {
    this.add(opts.welcome)
  })

  ev.on('disp_add', function(text) {
    self.add(text)
  })

  ev.on('disp_set', function(text) {
    if (text) {
      self.clear()
      self.add(text)
    }
  })

  ev.on('disp_clear', function() {
    self.clear()
  })

  ev.on('disp_hide', function() {
    self.saved = self.output.splice(0, self.output.length)
    self.clear()
  })

  ev.on('disp_restore', function() {
    if (self.saved.length > 0) {
      self.clear()
      self.output = self.saved.splice(0, self.saved.length)
      self.update()
    }
  })

  add(text) {
    if (text) {
      text = this.preserveWhiteSpace(text)
      this.output.push({ 'content': text })
      this.update()
    }
  }

  clear() {
    this.output.length = 0
    this.update()
  }

  preserveWhiteSpace(text) {
    text = text.replace(/\r\n|\r|\n/g, '<br />')
    // Search for tags or whitespace. Escape whitespace, leave tags.
    text = text.replace(/<[^<]+>|( )/g, function(match, group1) {
      if (group1 == " ") { return '&nbsp;' }
      return match
    })
    return text
  }
</display>

<commandline>
  <form autocomplete='off' onsubmit={ process }>
    <raw name='lhs' content={ prompt } show={ visible } /><input type='text' name='command' />
  </form>

  <style>
    input[name='command'] {
      background: transparent;
      border: none; outline: none;
      padding: 0; margin: 0;
      width: 90%;
    }
  </style>

  var ev = opts.events
  var self = this
  this.prompt = opts.prompt || '$ '
  this.visible = true

  this.on('mount', function() {
    document.getElementsByName('command')[0].focus()
  })

  ev.on('prompt_set', function(value) {
    self.prompt = value
    // `write()` is called to actually update the `raw` tag's html.
    self.tags.lhs.write(value)
  })

  ev.on('prompt_hide', function() {
    self.update({ visible: false })
  })

  ev.on('prompt_show', function() {
    self.update({ visible: true })
  })

  process() {
    var prompt = this.visible ? this.prompt : ''
    var command = he.encode(this.command.value)
    this.command.value = ''
    ev.trigger('disp_add', prompt + command + '\n')
    ev.trigger('cmd_entered', command)
  }
</commandline>

<raw>
  <span></span>

  // Initialise HTML from tag options and expose `write()` for updating.
  write(text) {
    this.root.innerHTML = text
  }
  this.write(opts.content)
</raw>