kanye.js

'use strict';

var sektor = require('sektor');
var crossvent = require('crossvent');
var rspaces = /\s+/g;
var keymap = {
  13: 'enter',
  27: 'esc',
  32: 'space'
};
var handlers = {};

crossvent.add(window, 'keydown', keydown);

function clear (context) {
  if (context) {
    if (context in handlers) {
      handlers[context] = {};
    }
  } else {
    handlers = {};
  }
}

function switchboard (then, combo, options, fn) {
  if (fn === void 0) {
    fn = options;
    options = {};
  }

  var context = options.context || 'defaults';

  if (!fn) {
    return;
  }

  if (handlers[context] === void 0) {
    handlers[context] = {};
  }

  combo.toLowerCase().split(rspaces).forEach(item);

  function item (keys) {
    var c = keys.trim();
    if (c.length === 0) {
      return;
    }
    then(handlers[context], c, options, fn);
  }
}

function on (combo, options, fn) {
  switchboard(add, combo, options, fn);

  function add (area, key, options, fn) {
    var handler = {
      handle: fn,
      filter: options.filter
    };
    if (area[key]) {
      area[key].push(handler);
    } else {
      area[key] = [handler];
    }
  }
}

function off (combo, options, fn) {
  switchboard(rm, combo, options, fn);

  function rm (area, key, options, fn) {
    if (area[key]) {
      area[key] = area[key].filter(matching);
    }

    function matching (handler) {
      return handler.handle === fn && handler.filter === options.filter;
    }
  }
}

function getKeyCode (e) {
  return e.which || e.keyCode || e.charCode;
}

function keydown (e) {
  var code = getKeyCode(e);
  var key = keymap[code] || String.fromCharCode(code);
  if (key) {
    handle(key, e);
  }
}

function parseKeyCombo (key, e) {
  var combo = [key];
  if (e.shiftKey) {
    combo.unshift('shift');
  }
  if (e.altKey) {
    combo.unshift('alt');
  }
  if (e.ctrlKey ^ e.metaKey) {
    combo.unshift('cmd');
  }
  return combo.join('+').toLowerCase();
}

function handle (key, e) {
  var combo = parseKeyCombo(key, e);
  var context;
  for (context in handlers) {
    if (handlers[context][combo]) {
      handlers[context][combo].forEach(exec);
    }
  }

  function filtered (handler) {
    var filter = handler.filter;
    if (!filter) {
      return;
    }

    var el = e.target;
    var selector = typeof filter === 'string';
    if (selector) {
      return sektor.matchesSelector(el, filter) === false;
    }
    while (el.parentElement && el !== filter) {
      el = el.parentElement;
    }
    return el !== filter;
  }

  function exec (handler) {
    if (filtered(handler)) {
      return;
    }
    handler.handle(e);
  }
}

module.exports = {
  on: on,
  off: off,
  clear: clear,
  handlers: handlers
};