'use strict';

const _ = require('lodash');

const handleFilterUrl = (originParam, newParam, delParam) => {
    let dest = '?';
    let tempOriginParam = {};

    delParam = delParam || {};

    tempOriginParam = Object.assign(tempOriginParam, originParam, newParam);
    delete tempOriginParam.uid;

    _.forEach(tempOriginParam, function(value, key) {
        if (!delParam[key] && value) {
            dest += `${key}=${value}&`;
        }
    });

    return _.trim(dest, '&');
};

exports.handlePagerData = (total, params) => {
    let result = {
        prePage: {
            url: ''
        },
        nextPage: {
            url: ''
        },
        pages: []
    };

    let currentPage = parseInt(_.get(params, 'page', 1), 10); // 当前页
    let perPageCount = parseInt(_.get(params, 'limit', 10), 10); // 每页商品数
    let totalPage = _.ceil(total / perPageCount); // 总页数

    result.count = total;
    result.curPage = currentPage;
    result.totalPages = totalPage;

    if (currentPage === 1) {
        // 当前页为 1，一定没有上一页
        delete result.prePage;
    } else {
        result.prePage.url = handleFilterUrl(params, {page: currentPage - 1});
    }

    if (currentPage === totalPage) {

        // 当前页为最后一页，一定没有下一页
        delete result.nextPage;
    } else {
        result.nextPage.url = handleFilterUrl(params, {page: currentPage + 1});
    }

    if (totalPage === 1) {
        return result;
    }

    // 页码临时数据
    let pages = [];

    if (currentPage > 2 && currentPage <= totalPage - 2) {
        for (let i = currentPage - 2; i <= ((currentPage + 2) > totalPage ? totalPage : (currentPage + 2)); i++) {
            pages.push({
                url: handleFilterUrl(params, {page: i}),
                num: i,
                cur: currentPage === i
            });
        }

        // 处理页码小于等于 2 的情况
    } else if (currentPage <= 2) {
        for (let i = 1; i <= (totalPage < 5 ? totalPage : 5); i++) {
            pages.push({
                url: handleFilterUrl(params, {page: i}),
                num: i,
                cur: currentPage === i
            });
        }
    } else if (currentPage > totalPage - 2) {
        for (let i = totalPage; i >= totalPage - 4; i--) {

            if (i > 0) {
                pages.push({
                    url: handleFilterUrl(params, {page: i}),
                    num: i,
                    cur: currentPage === i
                });
            }
        }
        pages = _.sortBy(pages, ['num']);
    }

    let prevPages = [];
    let nextPages = [];

    if (_.size(pages) === 5) {
        if (currentPage > 4) {
            prevPages.push({
                url: handleFilterUrl(params, {page: 1}),
                num: 1
            });
            prevPages.push({
                num: '...'
            });
        }
        if (currentPage < totalPage - 2 && totalPage > 5) {
            nextPages.push({
                num: '...'
            });
            nextPages.push({
                url: handleFilterUrl(params, {page: totalPage}),
                num: totalPage
            });
        }
    }

    result.pages = _.concat(prevPages, pages, nextPages);

    return result;

};