var Postcode = function(url, address, postcode, onSetted) {
  this.url = url;
  this.address = address;
  this.postcode = postcode;
  this.onSetted = function(self, value){};
  if (typeof onSetted == 'function') {
    this.onSetted = onSetted;
  }
};
Postcode.prototype.init = function() {
  var _self = this;
  
  this.address.live('keyup', function() {
    if (this.value.length <= 3) return;
    
    var _trimPostcode = function(postcode) {
      if (typeof postcode == 'undefined') return '';
      return postcode.trim().split('-').join('');
    };
    var _isSetPostcode = function(postcode) {
      return (_trimPostcode(postcode).length == 7);  
    };

    if (_isSetPostcode(_self.postcode.val())) return;
    
    $.ajax(_self.url, {
      type: 'post',
      data: {
        address : this.value
      },
      cache: false,
      success: function(data) {
        if (data.length != 7) return;
        
        data_trimmed = _trimPostcode(_self.postcode.val());
        if (data_trimmed == data) return;
        if (_isSetPostcode(data_trimmed)) return;
  
        postcode = data.substr(0, 3) + '-' + data.substr(3, 4);
        _self.postcode.val(postcode);
        
        if (typeof _self.onSetted == 'function') {
          _self.onSetted(_self, postcode);
        }
      }
    })
  });
};