// JavaScript Document

// UTF-8
/**
 * scrollsmoothly.js
 * Copyright (c) 2008 KAZUMiX
 * http://d.hatena.ne.jp/KAZUMiX/
 * Licensed under the MIT License:
 * http://www.opensource.org/licenses/mit-license.php
 */

(function(){
    var easing = 0.25;
    var interval = 30;
    var d = document;
    var targetX = 0;
    var targetY = 0;
    var targetHash = '';
    var scrolling = false;
    var splitHref = location.href.split('#');
    var currentHref_WOHash = splitHref[0];
    var incomingHash = splitHref[1];
    var prevX = null;
    var prevY = null;

    // �h�L�������g�ǂݍ��݊�������init()����s����
    addEvent(window, 'load', init);

    // �h�L�������g�ǂݍ��݊������̏���
    function init(){
        // �y�[�W������N�ɃC�x���g��ݒ肷��
        setOnClickHandler();
        // �O������y�[�W������N�t���ŌĂяo���ꂽ�ꍇ
        if(incomingHash){
            if(window.attachEvent && !window.opera){
                // IE�̏ꍇ�͂�����Ƒ҂��Ă���X�N���[��
                setTimeout(function(){scrollTo(0,0);setScroll('#'+incomingHash);},50);
            }else{
                // IE�ȊO�͂��̂܂�GO
                scrollTo(0, 0);
                setScroll('#'+incomingHash);
            }
        }
    }

    // �C�x���g��lj�����֐�
    function addEvent(eventTarget, eventName, func){
        if(eventTarget.addEventListener){
            // ���_���u���E�U
            eventTarget.addEventListener(eventName, func, false);
        }else if(window.attachEvent){
            // IE
            eventTarget.attachEvent('on'+eventName, function(){func.apply(eventTarget);});
        }
    }
    
    function setOnClickHandler(){
        var links = d.links;
        for(var i=0; i<links.length; i++){
            // �y�[�W������N�Ȃ�X�N���[��������
            var link = links[i];
            var splitLinkHref = link.href.split('#');
            if(currentHref_WOHash == splitLinkHref[0] && d.getElementById(splitLinkHref[1])){
                addEvent(link, 'click', startScroll);
            }
        }
    }

    function startScroll(event){
        // �����N�̃f�t�H���g�����E��
        if(event){ // ���_���u���E�U
            event.preventDefault();
            //alert('modern');
        }else if(window.event){ // IE
            window.event.returnValue = false;
            //alert('ie');
        }
        // this�͌Ăяo�����ɂȂ��Ă�
        setScroll(this.hash);
    }

    function setScroll(hash){
        // �n�b�V������^�[�Q�b�g�v�f�̍��W��Q�b�g����
        var targetEle = d.getElementById(hash.substr(1));
        if(!targetEle)return;
        // �X�N���[������W��Z�b�g����
        var ele = targetEle
        var x = 0;
        var y = 0;
        while(ele){
            x += ele.offsetLeft;
            y += ele.offsetTop;
            ele = ele.offsetParent;
        }
        targetX = x;
        targetY = y;
        targetHash = hash;
        // �X�N���[����~���Ȃ�X�N���[���J�n
        if(!scrolling){
            scrolling = true;
            scroll();
        }
    }

    function scroll(){
        var currentX = d.documentElement.scrollLeft||d.body.scrollLeft;
        var currentY = d.documentElement.scrollTop||d.body.scrollTop;
        var vx = (targetX - currentX) * easing;
        var vy = (targetY - currentY) * easing;
        var nextX = currentX + vx;
        var nextY = currentY + vy;
        if((Math.abs(vx) < 1 && Math.abs(vy) < 1)
           || (prevX === currentX && prevY === currentY)){
            // �ڕW���W�t�߂ɓ��B���Ă�����I��
            scrollTo(targetX, targetY);
            scrolling = false;
            location.hash = targetHash;
            prevX = prevY = null;
            return;
        }else{
            // �J��Ԃ�
            scrollTo(parseInt(nextX), parseInt(nextY));
            prevX = currentX;
            prevY = currentY;
            var scope = this;
            setTimeout(function(){scroll.apply(scope)},interval);
        }
    }

}());