(function(){
	if(window.addEventListener){
		window.addEventListener('load', init, false)
	}else if(window.attachEvent){
		window.attachEvent('onload', init);
	}
})()

// 商品の価格
var prices = [
	[1680                  ], [1680                  ], [2205                  ], 
	[2940                  ], [2000, 4000, 5200      ], [2400, 4800, 7600      ], [ 800                  ],
	[ 380                  ], [2000, 4000, 5250      ], [2400, 4800, 7600      ], [ 800                  ],
	[2100                  ], [2100, 3885, 2940      ], [3150                  ], [6300                  ],
	[2100, 3150            ], [1470                  ], [1470                  ], [1470                  ],
	[1470                  ], [1470                  ], [1680                  ], [1575                  ],
	[2100                  ], [2100                  ], [2100                  ], [1470, 3150, 4515, 5775],
	[1470, 3150, 4515, 5775], [1470, 3150, 4515, 5775], [2100, 4410            ], [2940, 5670            ],
	[2100, 4410            ], [2940, 5670            ], [2100, 4410            ], [2940, 5670            ],
	[ 850                  ], [1000                  ], [1000                  ], [1890                  ],
	[2625                  ], [2940                  ], [3990                  ], [3150                  ],
	[5250                  ], [4725                  ], [5775                  ], [2520                  ],
	[2520                  ], [2520                  ], [3570                  ], [3570                  ],
	[3570                  ], [1890                  ],
	[3500                  ]
];

var maxCount = prices.length;
var items = [];
var sum = 0;

function init(){
	for(var i = 0; i < maxCount; i++){
		var a = { id:"item" + i, element:document.getElementById("buy" + (i + 1)), price:prices[i], selectedIndex:0, count:0 };
		items.push(a);
	}
}

function changeType(num, elem){
	items[num].selectedIndex = elem.options.selectedIndex;
	setSum(-1);
}

function setSum(itemNumber){
	sum = 0;
	
	if(itemNumber >= 0)
	items[itemNumber].count = items[itemNumber].element.value;
	
	for(var i = 0; i < items.length; i++){
		sum += items[i].price[items[i].selectedIndex] * items[i].count;
	}
	var p = document.getElementById('price');
	p.innerHTML = '合計金額　¥' + sum;
	console.log(sum);
}

function check(){
	if(sum == 0) {
		alert('どれか一つの商品を一つ以上選択してください。');
		return false;
	}else {
		return true;
	}
}