/**
 * Module dependencies.
 */

var fs = require('fs')
  , path = require('path')
  , join = path.join
  , debug = require('debug')('watch');

/**
 * Ignored directories.
 */

var ignore = ['node_modules', '.git'];

/**
 * Escape special characters in the given string of html.
 *
 * @param  {String} html
 * @return {String}
 * @api private
 */

exports.escape = function(html) {
  return String(html)
    .replace(/&/g, '&')
    .replace(/"/g, '"')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;');
};

/**
 * Array#forEach (<=IE8)
 *
 * @param {Array} array
 * @param {Function} fn
 * @param {Object} scope
 * @api private
 */

exports.forEach = function(arr, fn, scope) {
  for (var i = 0, l = arr.length; i < l; i++)
    fn.call(scope, arr[i], i);
};

/**
 * Array#indexOf (<=IE8)
 *
 * @parma {Array} arr
 * @param {Object} obj to find index of
 * @param {Number} start
 * @api private
 */

exports.indexOf = function (arr, obj, start) {
  for (var i = start || 0, l = arr.length; i < l; i++) {
    if (arr[i] === obj)
      return i;
  }
  return -1;
};

/**
 * Array#reduce (<=IE8)
 * 
 * @param {Array} array
 * @param {Function} fn
 * @param {Object} initial value
 * @param {Object} scope
 * @api private
 */

exports.reduce = function(arr, fn, val, scope) {
  var rval = val;

  for (var i = 0, l = arr.length; i < l; i++) {
    rval = fn.call(scope, rval, arr[i], i, arr);
  }

  return rval;
};

/**
 * Array#filter (<=IE8)
 *
 * @param {Array} array
 * @param {Function} fn
 * @param {Object} scope
 * @api private
 */

exports.filter = function(arr, fn, scope) {
  var ret = [];

  for (var i = 0, l = arr.length; i < l; i++) {
    var val = arr[i];
    if (fn.call(scope, val, i, arr))
      ret.push(val);
  }

  return ret;
};

/**
 * Object.keys (<=IE8)
 *
 * @param {Object} obj
 * @return {Array} keys
 * @api private
 */

exports.keys = Object.keys || function(obj) {
  var keys = []
    , has = Object.prototype.hasOwnProperty // for `window` on <=IE8

  for (var key in obj) {
    if (has.call(obj, key)) {
      keys.push(key);
    }
  }

  return keys;
};

/**
 * Watch the given `files` for changes
 * and invoke `fn(file)` on modification.
 *
 * @param {Array} files
 * @param {Function} fn
 * @api private
 */

exports.watch = function(files, fn){
  var options = { interval: 100 };
  files.forEach(function(file){
    debug('file %s', file);
    fs.watchFile(file, options, function(curr, prev){
      if (prev.mtime < curr.mtime) fn(file);
    });
  });
};

/**
 * Ignored files.
 */

function ignored(path){
  return !~ignore.indexOf(path);
}

/**
 * Lookup files in the given `dir`.
 *
 * @return {Array}
 * @api private
 */

exports.files = function(dir, ret){
  ret = ret || [];

  fs.readdirSync(dir)
  .filter(ignored)
  .forEach(function(path){
    path = join(dir, path);
    if (fs.statSync(path).isDirectory()) {
      exports.files(path, ret);
    } else if (path.match(/\.(js|coffee)$/)) {
      ret.push(path);
    }
  });

  return ret;
};

/**
 * Compute a slug from the given `str`.
 *
 * @param {String} str
 * @return {String}
 */

exports.slug = function(str){
  return str
    .toLowerCase()
    .replace(/ +/g, '-')
    .replace(/[^-\w]/g, '');
};