// ==UserScript==
// @name         京东单价助手
// @namespace    http://greasyfork.org/
// @version      1.0
// @description  京东商品列表页面的增强程序，增强了显示单价功能，帮助你在京东找到最便宜的商品
// @author       Yarmu
// @include      http*://search.jd.com/*
// @include      http*://list.jd.com/*
// @include      http*://item.jd.com/*
// @grant        none
// @supportURL     https://greasyfork.org/zh-CN/scripts/30522-%E4%BA%AC%E4%B8%9C%E5%8D%95%E4%BB%B7%E5%8A%A9%E6%89%8B
// @downloadURL none
// ==/UserScript==

(function() {
    setInterval(addPriceTipListener, 1000);
})();

function addPriceTipListener() {
    $('.p-price').each(function() {
        if (!$(this).attr('listening')) {
            $(this).attr('listening', '1');
            addPriceTip.call(this);
        }
    });
}

function addPriceTip() {
    $(this).unbind("DOMSubtreeModified");
    var price = parseFloat($(this).find('i').html());
    if (isNaN(price)) {
        price = parseFloat($(this).find('.price').html());
    }
    if (!isNaN(price)) {
        var title = null;
        var index = 0;
        $(this).parent().find('.p-scroll .ps-wrap .ps-main .ps-item a').each(function(idx) {
            if ($(this).attr('class') === 'curr' && $(this).attr('title')) {
                title = $(this).attr('title');
                index = idx;
                return false;
            }
        });
        var unit = getUnit(title, price);
        if (unit === null && index === 0) {
            title = $(this).parent().find('.p-name a em').text().trim();
            if (!title) {
                title = $('.sku-name').text().trim();
            }
            unit = getUnit(title, price);
        }
        if (unit !== null) {
            var htm = ' (' + toDecimal(unit.price) + '/' + unit.unit + ')';
            $(this).find('strong i').append(htm);
            $(this).find('.price').append(htm);
        }
    }
    $(this).bind("DOMSubtreeModified", addPriceTip);
}

function getUnit(title, price) {
    if (!title) return null;
    if (price <= 0) return null;
    var name = title.replace(/[(（][^)）]+[)）]/ig, '');
    var reg1 = /\b((\d+)\s*[包袋盒]?\s*[*x×]\s*)(\d+\.?\d*?)\s*(g|kg|ml|l|千克|克|毫升|升)\/?[个盒]?/ig;
    var reg2 = /\b(\d+\.?\d*?)\s*(g|kg|ml|l|千克|克|毫升|升)\/?[个盒]?(\s*[*x×]\s*(\d+))?/ig;
    var pCap = 3, pUnit = 4, pCount = 1;
    var reg = reg1;
    if (!reg.test(name)) {
        pCap = 1; pUnit = 2; pCount = 4;
        reg = reg2;
        if (!reg.test(name)) {
            name = title;
            pCap = 3; pUnit = 4; pCount = 1;
            reg = reg1;
            if (!reg.test(name)) {
                pCap = 1; pUnit = 2; pCount = 4;
                reg = reg2;
            }
        }
    }
    reg.lastIndex = 0;

    var match = null;
    var cap = 0;
    var un = '';
    var isOnlyOne = !/[+|＋|送]/i.test(name);
    while ((match = reg.exec(name))) {
        var capacity = parseFloat(match[pCap]);
        if (match.length > 4 && match[pCount]) {
            capacity *= parseInt(match[pCount]);
        }
        if (capacity <= 0) {
            continue;
        }
        var unit = match[pUnit].toLowerCase();

        if (unit === 'g' || unit === '克') {
            capacity /= 1000;
            unit = 'kg';
        } else if (unit === '千克') {
            unit = 'kg';
        } else if (unit === 'ml' || unit === '毫升') {
            capacity /= 1000;
            unit = 'L';
        } else if (unit === 'l' || unit === '升') {
            unit = 'L';
        }
        if (un === '' || un == unit) {
            un = unit;
            cap += capacity;
        }
        if (isOnlyOne) {
            break;
        }
    }

    if (cap > 0) return {
        capacity: cap,
        unit: un,
        price: parseFloat(price) / cap
    };
    else return null;
}

function toDecimal(x) {
    var f = parseFloat(x);
    if (isNaN(f)) {
        return;
    }
    f = Math.round(x * 100) / 100;
    return f;
}