screen-manager.js

'use strict';
var _ = require('lodash');
var util = require('./readline');
var cliWidth = require('cli-width');
var stripAnsi = require('strip-ansi');
var stringWidth = require('string-width');

function height(content) {
  return content.split('\n').length;
}

function lastLine(content) {
  return _.last(content.split('\n'));
}

var ScreenManager = module.exports = function (rl) {
  // These variables are keeping information to allow correct prompt re-rendering
  this.height = 0;
  this.extraLinesUnderPrompt = 0;

  this.rl = rl;
};

ScreenManager.prototype.render = function (content, bottomContent) {
  this.rl.output.unmute();
  this.clean(this.extraLinesUnderPrompt);

  /**
   * Write message to screen and setPrompt to control backspace
   */

  var promptLine = lastLine(content);
  var rawPromptLine = stripAnsi(promptLine);

  // Remove the rl.line from our prompt. We can't rely on the content of
  // rl.line (mainly because of the password prompt), so just rely on it's
  // length.
  var prompt = rawPromptLine;
  if (this.rl.line.length) {
    prompt = prompt.slice(0, -this.rl.line.length);
  }
  this.rl.setPrompt(prompt);

  // setPrompt will change cursor position, now we can get correct value
  var cursorPos = this.rl._getCursorPos();
  var width = this.normalizedCliWidth();

  content = forceLineReturn(content, width);
  if (bottomContent) {
    bottomContent = forceLineReturn(bottomContent, width);
  }
  // Manually insert an extra line if we're at the end of the line.
  // This prevent the cursor from appearing at the beginning of the
  // current line.
  if (rawPromptLine.length % width === 0) {
    content += '\n';
  }
  var fullContent = content + (bottomContent ? '\n' + bottomContent : '');
  this.rl.output.write(fullContent);

  /**
   * Re-adjust the cursor at the correct position.
   */

  // We need to consider parts of the prompt under the cursor as part of the bottom
  // content in order to correctly cleanup and re-render.
  var promptLineUpDiff = Math.floor(rawPromptLine.length / width) - cursorPos.rows;
  var bottomContentHeight = promptLineUpDiff + (bottomContent ? height(bottomContent) : 0);
  if (bottomContentHeight > 0) {
    util.up(this.rl, bottomContentHeight);
  }

  // Reset cursor at the beginning of the line
  util.left(this.rl, stringWidth(lastLine(fullContent)));

  // Adjust cursor on the right
  util.right(this.rl, cursorPos.cols);

  /**
   * Set up state for next re-rendering
   */
  this.extraLinesUnderPrompt = bottomContentHeight;
  this.height = height(fullContent);

  this.rl.output.mute();
};

ScreenManager.prototype.clean = function (extraLines) {
  if (extraLines > 0) {
    util.down(this.rl, extraLines);
  }
  util.clearLine(this.rl, this.height);
};

ScreenManager.prototype.done = function () {
  this.rl.setPrompt('');
  this.rl.output.unmute();
  this.rl.output.write('\n');
};

ScreenManager.prototype.releaseCursor = function () {
  if (this.extraLinesUnderPrompt > 0) {
    util.down(this.rl, this.extraLinesUnderPrompt);
  }
};

ScreenManager.prototype.normalizedCliWidth = function () {
  var width = cliWidth({
    defaultWidth: 80,
    output: this.rl.output
  });
  if (process.platform === 'win32') {
    return width - 1;
  }
  return width;
};

function breakLines(lines, width) {
  // Break lines who're longuer than the cli width so we can normalize the natural line
  // returns behavior accross terminals.
  var regex = new RegExp(
    '(?:(?:\\033[[0-9;]*m)*.?){1,' + width + '}',
    'g'
  );
  return lines.map(function (line) {
    var chunk = line.match(regex);
    // last match is always empty
    chunk.pop();
    return chunk || '';
  });
}

function forceLineReturn(content, width) {
  return _.flatten(breakLines(content.split('\n'), width)).join('\n');
}