var master_ul
var second_ul_layer
var third_ul_layer

function navigation_init() {
    var nav_div = document.getElementById("leftnavi")
    var uls = nav_div.getElementsByTagName("ul")

    for(var i = 0; i < uls.length; i++) {
        if (uls[i].parentNode == nav_div) {
            master_ul = uls[i]
            break
        }
    }

    second_ul_layer = new Array()
    for(i = 0; i < uls.length; i++) {
        if(uls[i].parentNode == master_ul) {
            second_ul_layer.push(new Object())
            index = second_ul_layer.length - 1
            second_ul_layer[index] = uls[i]
        }
    }

    third_ul_layer = new Array()
    for(var l = 0; l < second_ul_layer.length; l++) {
        for(i = 0; i < uls.length; i++) {
            if(uls[i].parentNode == second_ul_layer[l]) {
                third_ul_layer.push(new Object())
                index = third_ul_layer.length - 1
                third_ul_layer[index]['object'] = new Object()
                third_ul_layer[index]['object'] = uls[i]
                third_ul_layer[index]['parent'] = new Object()
                third_ul_layer[index]['parent'] = second_ul_layer[l]
            }
        }
    }
    navigation_hide_all_second_layer()
}

function navigation_hide_all_second_layer() {
    for(var i = 0; i < second_ul_layer.length; i++) {
        layer = second_ul_layer[i]
        navigation_hide_all_third_layer(layer)
        layer.style.display = 'none'
    }
}

function navigation_hide_all_third_layer(second_layer) {
    for(var i = 0; i < third_ul_layer.length; i++) {
        if(third_ul_layer[i]['parent'] == second_layer) {
            third_ul_layer[i]['object'].style.display = 'none'
        }
    }
}

function navigation_open(category_li) {
    var sibling = category_li.nextSibling.nextSibling
    var open = (sibling.style.display == 'block') ? false : true;
    if(category_li.parentNode == master_ul) {
        navigation_hide_all_second_layer()
        if(open) {
            sibling.style.display = 'block'
        }
    }
    else {
        navigation_hide_all_third_layer(category_li.parentNode)
        if(open) {
            sibling.style.display = 'block'
        }
    }
}