#!/usr/bin/env node

/**
 * Module dependencies.
 */

try {
  var stylus = require('stylus');
} catch (err) {
  var stylus = require('../lib/stylus');
}

/**
 * Banner.
 */

var banner = '\n\
                                    \n\
             _         _            \n\
         ___| |_ _   _| |_   _ ___  \n\
        / __| __| | | | | | | / __| \n\
        \\__ \\ |_| |_| | | |_| \\__ \\ \n\
        |___/\\__|\\__, |_|\\__,_|___/ \n\
                 |___/              \n\
                                    \n\
';

/**
 * Steps.
 */

var steps = [];

/**
 * Clear the screen and move the cursor up.
 */

function clear() {
  console.log('\x1b[1J\x1b[H');
}

/**
 * Output "press enter" message.
 */

function enter() {
  process.stdout.write('\x1b[90mpress enter to continue:\x1b[0m ');
}

/**
 * Initialize a `Step` with the given data.
 *
 * @param {String} title
 * @param {String} desc
 * @param {String} src
 * @param {Function} fn
 */

function Step(title, desc, src, fn) {
  var self = this;
  this.n = steps.length;
  this.src = src;
  desc = desc.replace(/\_([^_]+)\_/g, '\x1b[33m$1\x1b[90m');
  
  this.next = function(){
    var step = steps[self.n + 1];
    if (step) {
      step.display();
    } else {
      console.log('     THE END\n');
      process.exit(0);
    }
  };
  
  this.display = function(retry){
    if (!retry) {
      console.log(' %d) \x1b[1m%s\x1b[0m\n', self.n, title);
      console.log(' \x1b[90m%s\x1b[0m', desc);
    }
    console.log('\n%s\n', src);
    console.log('\x1b[90m--------------------\x1b[0m \n');
    this.input();
  };
  
  this.input = function(){
    stdin.resume();
    var buf = '';
    stdin.on('data', function callback(chunk){
      if (0 == chunk.indexOf('quit')) process.exit(1);
      var dot = '.' == chunk[0] && '\n' == chunk[1]
        , equal = buf.trim() == self.src.trim();
      if (dot || equal) {
        stdin.pause();
        stdin.removeListener('data', callback);
        stylus.render(buf, { filename: 'stdin' }, function(err, css){
          if (err) {
            console.log('\n\x1b[31mError: ' + err.message + '\x1b[0m\n');
            self.display(true);
            return;
          }
          clear();
          console.log('\x1b[90m-------------------- stylus\x1b[0m \n');
          console.log(buf.replace(/^/gm, '  '));
          console.log('\x1b[90m-------------------- css\x1b[0m \n');
          console.log(css.replace(/^/gm, '  '));
          console.log();
          enter();
          stdin.resume();
          stdin.once('data', function(){
            clear();
            self.next();
          });
        });
        return;
      }
      buf += chunk;
    });
  };
}

/**
 * Step definitions.
 */

steps.push(new Step(
    'Selector Properties'
  , 'The Stylus grammar has indentation-based blocks,\n'
  + ' meaning one does not surround selector properties\n'
  + ' using braces _{_ _}_, but uses an indent of two \n'
  + ' spaces, or a single tab.\n'
  + '\n'
  + ' To get started, type the stylus you see below\n'
  + ' and then press return a few times or type _"."_ to render.'
  , 'body\n  color black'));

steps.push(new Step(
    'Multiple Selectors'
  , 'Blocks can be applied to several selectors at once\n'
  + ' by separating them via comma, or newline.\n'
  + '\n'
  + ' Both examples shown below are equivalent.'
  
  , 'a.button, input[type=button]\n'
  + '  border 1px solid #eee\n'
  + '  padding 5px\n\n'
  + 'a.button\n'
  + 'input[type=button]\n'
  + '  border 1px solid #eee\n'
  + '  padding 5px'
  ));

steps.push(new Step(
    'Nested Selectors'
  , 'Selectors may also be nested.\n'
  
  , 'ul\n'
  + '  li\n'
  + '    a\n'
  + '      color black\n'
  ));

steps.push(new Step(
    'Variables'
  , 'Stylus allows you to define variables by utilizing\n'
  + ' the _=_ operator, much like you would in any other language.\n'
  + '\n'
  + ' These variables may be assigned to _numbers_, _strings_, _booleans_,\n'
  + ' and virtually everything else you see in css.'
  
  , 'size = 14px\n\n'
  + 'body\n'
  + '  font size Arial, sans-serif'
  ));

steps.push(new Step(
    'Conditional Assignment'
  , 'The conditional assignment operator _?=_ may be used to\n'
  + ' define a variable only when previously undefined.'
  
  , 'size = 14px\n\n'
  + 'body\n'
  + '  size ?= 22px\n'
  + '  font size Arial, sans-serif'
  ));

steps.push(new Step(
    'Arithmetic'
  , 'A variety of binary arithmetic operators are supported\n'
  + ' as well as unary operators such as _-_, _+_, and _~_.'
  
  , 'size = 14px\n'
  + 'large-size = size * 2\n'
  + '\n'
  + 'body\n'
  + '  font large-size\n'
  + '\n'
  + 'p\n'
  + '  margin-left -(size - 2)'
  ));

steps.push(new Step(
    'Coercion'
  , 'Arithmetic operations coerce the right-hand operand when\n'
  + ' applicable, for example converting _2s_ in _1000ms + 2s_\n'
  + ' into _2000ms_ before evaluating the expression.\n'
  + '\n'
  + ' Examples:\n'
  + '    _15px_ - _5_\n'
  + '    _#000_ + _#eee_\n'
  + '    _#fff_ - rgba(_0_,_0_,_0_,_.5_)\n'
  + '    _#fff_ / _2_\n'
  + '    _5in_ - _3cm_\n'
  
  , 'duration = 2s\n\n'
  + '.fade\n'
  + '  -webkit-transition opacity duration - 1500ms linear'
  ));

steps.push(new Step(
    'Functions'
  , 'Stylus functions may act as mixins or have a return value.\n'
  + 'For example here we use the unit() built-in function to.\n'
  + 'forcing both unit\'s type to _px_, and then add them.\n'
  + '\n'
  + 'Note that we may also use the _return_ keyword, however it\n'
  + 'is optional in most cases.'
  
  , 'add(a, b)\n'
  + '  a = unit(a, "px")\n'
  + '  b = unit(b, "px")\n'
  + '  a + b\n'
  + '\n'
  + 'body\n'
  + '  padding add(5px, 10px)\n'
  + '  margin add(5, 10)'
  ));

steps.push(new Step(
    'Mixins'
  , 'Mixins are defined in the same manner as functions\n'
  + 'with return values, however they "mix in" their properties\n'
  + 'and selectors into the caller.\n'
  + '\n'
  + 'Mixin parens are optional in most cases, so we may apply\n'
  + 'the transparently.'
  
  , 'border-radius(n)\n'
  + '  -webkit-border-radius n\n'
  + '  -moz-border-radius n\n'
  + '  border-radius n\n'
  + '\n'
  + 'body\n'
  + '  border-radius(5px)\n'
  + '\n'
  + 'form input\n'
  + '  border-radius 5px'
  ));

/**
 * Start tutorial.
 */

clear();
console.log('\x1b[1m' + banner + '\x1b[0m');
console.log('\n Welcome to the stylus interactive tutorial.\n');
console.log('  - To quit at any time type \x1b[1mquit\x1b[0m.');
console.log('  - To force rendering type "." and press enter,');
console.log('    however source will be automatically rendered');
console.log('    when it matches the step\'s source.');
console.log();
enter();

var stdin = process.openStdin();
stdin.setEncoding('utf8');

stdin.once = function(event, fn){
  this.on(event, function callback(chunk){
    stdin.removeListener(event, callback);
    fn(chunk);
  });
};

stdin.once('data', function(chunk){
  stdin.pause();
  clear();
  steps[0].display();
});