slid.js

#!/usr/bin/env node
/*jshint node:true*/

// Let's show some slides

var fs = require('fs');
var exec= require('child_process').exec;
var keypress = require('keypress');
var async = require('async');
var marked = require('marked');
var markdown = require('./ansi-markdown');

var express = require('express');
var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);


// Load slides from the provided argument
// Error handling is for people who make errors
// A line consisting of exactly four dashes separates slides
// A line consisting of exactly two slashes separates slide content
var rawSlides = fs.readFileSync(process.argv[2], { encoding: 'UTF-8' })
    .split(/\n----\n/)
    .reduce(function(collectedSlides, str) {
      str = str.trim();
      str.split('\n--\n').reduce(function(a, b) {
        var currentSlide = stripExecCode(a) + '\n' + b;
        collectedSlides.push(currentSlide);
        return currentSlide;
      }, '');
      return collectedSlides;
    }, []);

async.map(rawSlides, function(rawSlide, callback) {
  markdown.render(rawSlide, function(data, codeToRun) {
    callback(null, [data, codeToRun]);
  });
}, function(err, slides) {
  // Guess what this function does (read the function name for a hint)
  function clearScreen() {
    process.stdout.write('\u001B[2J\u001B[0;0f');
  }

  // Keep track of where we are in the slide deck
  var currentSlide = 0;

  // Render a slide with a specific number
  function renderSlide(n) {
    if (slides[n]) {
      var slide = slides[n][0];
      var code = slides[n][1];
      clearScreen();
      process.stdout.write(slide);
      code.forEach(function(c) {
        exec(c);
      });
    }
  }

  // Show next slide
  function next() {
    if (currentSlide < slides.length - 1) {
      currentSlide++;
      renderSlide(currentSlide);
      sendSlide();
    }
  }

  // Show previous slide
  function prev() {
    if (currentSlide > 0) {
      currentSlide = currentSlide - 1;
      renderSlide(currentSlide);
      sendSlide();
    }
  }

  // Make process.stdin respond to keyboard events
  keypress(process.stdin);

  // Space or right arrow advances, left arrow goes back, ctrl+c or q quits
  process.stdin.on('keypress', function (ch, key) {
    if (key.name === 'space' || key.name === 'right') {
      next();
    } else if (key.name === 'left') {
      prev();
    } else if ((key.ctrl && key.name === 'c') || key.name === 'q') {
      clearScreen();
      process.stdin.pause();
      process.exit();
    }
  });


  // Start http server
  var presenterDisplayRenderer = new marked.Renderer();
  var notes = '';
  presenterDisplayRenderer.blockquote = function(text) {
    notes += '<p>' + text.replace(/\n/g, '<br>') + '</p>';
    return '';
  };

  marked.setOptions({
    renderer: presenterDisplayRenderer
  });

  app.get('/', function(req, res) {
    res.sendFile(__dirname + '/index.html');
  });
  app.use(express.static('.'));

  function sendSlide() {
    var current = 'Last slide!';
    var next = 'Last slide!';
    notes = '';
    var curNotes = '';
    if (rawSlides[currentSlide]) {
      current = marked(rawSlides[currentSlide].replace(/(\n)?~/mg, '$1'));
    }
    curNotes = notes;
    notes = '';
    if (rawSlides[currentSlide + 1]) {
      next = marked(rawSlides[currentSlide + 1].replace(/(\n)?~/mg, '$1'));
    }
    io.emit('slide', {
      num: currentSlide + 1,
      total: slides.length,
      current: current,
      next: next,
      notes: curNotes,
      nextNotes: notes
    });
  }

  io.on('connection', function(socket) {
    sendSlide(socket);
    socket.on('next', next);
    socket.on('prev', prev);
  });

  http.listen(3000, function() {

  });

  if (process.argv[3]) {
    var num = parseInt(process.argv[3], 10);
    if (num < 0) {
      num = slides.length + num;
    } else if (num != 0) {
      num = num -1;
    }
    if (slides[num]) {
      currentSlide = num;
    }
  }
  // Let's go
  renderSlide(currentSlide);

  process.stdin.setRawMode(true);
  process.stdin.resume();
});

function stripExecCode(str) {
  return str.replace(/^ *(`{3,}|~{3,}) *(\S+)? *\n([\s\S]+?)\s*\1 *(?:\n+|$)/m, function(match, _, lang) {
    if (lang === '#!') {
      return '';
    } else {
      return match;
    }
  });
}