var TextFolder = Class.create();

TextFolder.prototype = {
    textBox:0,
    foldedText:0,
    expandedText:0,
    trigger:0,
    textStatus:0,
    initialize:function(textBoxId,triggerId,foldedStrLength){
        this.textBox = $(textBoxId);
        this.trigger = $(triggerId);

        this.expandedText = this.textBox.innerHTML;
        this.foldedText= this.expandedText.truncate(foldedStrLength);
        this.foldedText= this.foldedText.replace(/<br>/,"");

        if( this.expandedText.length >= foldedStrLength ){
            this.close();
            Event.observe(this.trigger,"click",this.switchStatus.bind(this));
        }
    },
    switchStatus:function(){
        if( this.textStatus == 0){
            this.open();
        }else{
            this.close();
        }
    },
    open:function(){
        this.textBox.innerHTML = this.expandedText;
        this.trigger.innerHTML = '<<たたむ';
        this.textStatus = 1;
    },
    close:function(){
        this.textBox.innerHTML = this.foldedText;
        this.trigger.innerHTML = '続きを表示>>';
        this.textStatus = 0;
    }
}