/*****************************************************
 * Paginator Function                                *
 *****************************************************
 * config : {
 *     get_rows : function used to select rows to do pagination on
 *         If no function is provided, checks for a config.table element and looks for rows in there to page
 *
 *     box : Empty element that will have page buttons added to it
 *         If no config.box is provided, but a config.table is, then the page buttons will be added using the table
 *
 *     table : table element to be paginated
 *         not required if a get_rows function is provided
 *
 *     rows_per_page : number of rows to display per page
 *         default number is 10
 *
 *     page: page to display
 *         default page is 1
 *
 *     box_mode: "list", "buttons", or function. determines how the page number buttons are built.
 *         "list" builds the page index in list format and adds class "pagination" to the ul element. Meant for use with bootstrap
 *         "buttons" builds the page index out of buttons
 *         if this field is a function, it will be passed the config object as its only param and assumed to build the page index buttons
 *
 *     page_options: false or [{text: , value: }, ... ] used to set what the dropdown menu options are available, resets rows_per_page value
 *         false prevents the options from being displayed
 *         [{text: , value: }, ... ] allows you to customize what values can be chosen, a value of 0 will display all the table's rows.
 *         the default setup is
 *           [
 *               { value: 5,  text: '5'   },
 *               { value: 10, text: '10'  },
 *               { value: 20, text: '20'  },
 *               { value: 50, text: '50'  },
 *               { value: 100,text: '100' },
 *               { value: 0,  text: 'All' }
 *           ]
 *
 *     active_class: set the class for page buttons to have when active.
 *          defaults to "active"
 *
 *     disable: true or false, shows all rows of the table and hides pagination controlls if set to true.
 *
 *     tail_call: function to be called after paginator is done.
 *
 * }
 */
 function paginator(config) {
     // throw errors if insufficient parameters were given
     if (typeof config != "object")
         throw "Paginator was expecting a config object!";
     if (typeof config.get_rows != "function" && !(config.table instanceof Element))
         throw "Paginator was expecting a table or get_row function!";

     // get/set if things are disabled
     if (typeof config.disable == "undefined") {
         config.disable = false;
     }

     // get/make an element for storing the page numbers in
     var box;
     if (!(config.box instanceof Element)) {
         config.box = document.createElement("div");
     }
     box = config.box;

     // get/make function for getting table's rows
     if (typeof config.get_rows != "function") {
         config.get_rows = function () {
             var table = config.table;
             var tbody = table.getElementsByTagName("tbody")[0] || table;

             // get all the possible rows for paging
             // exclude any rows that are just headers or empty
             var children = tbody.children;
             var trs = [];
             for (var i = 0; i < children.length; i++) {
                 if (children[i].nodeType === 1 && children[i].nodeName === "TR") {
                     if (children[i].getElementsByTagName("td").length > 0) {
                         trs.push(children[i]);
                     }
                 }
             }

             return trs;
         }
     }
     var get_rows = config.get_rows;
     var trs = get_rows();

     // get/set rows per page
     if (typeof config.rows_per_page == "undefined") {
         var selects = box.getElementsByTagName("select");
         if (typeof selects != "undefined" && (selects.length > 0 && typeof selects[0].selectedIndex != "undefined")) {
             config.rows_per_page = selects[0].options[selects[0].selectedIndex].value;
         } else {
             config.rows_per_page = 10;
         }
     }
     var rows_per_page = config.rows_per_page;

     // get/set current page
     if (typeof config.page == "undefined") {
         config.page = 1;
     }
     var page = config.page;

     // get page count
     var pages = (rows_per_page > 0) ? Math.ceil(trs.length / rows_per_page) : 1;

     // check that page and page count are sensible values
     if (pages < 1) {
         pages = 1;
     }
     if (page > pages) {
         page = pages;
     }
     if (page < 1) {
         page = 1;
     }
     config.page = page;

     // hide rows not on current page and show the rows that are
     for (var i = 0; i < trs.length; i++) {
         if (typeof trs[i]["data-display"] == "undefined") {
             trs[i]["data-display"] = trs[i].style.display || "";
         }
         if (rows_per_page > 0) {
             if (i < page * rows_per_page && i >= (page - 1) * rows_per_page) {
                 trs[i].style.display = trs[i]["data-display"];
             } else {
                 // Only hide if pagination is not disabled
                 if (!config.disable) {
                     trs[i].style.display = "none";
                 } else {
                     trs[i].style.display = trs[i]["data-display"];
                 }
             }
         } else {
             trs[i].style.display = trs[i]["data-display"];
         }
     }

     // page button maker functions
     config.active_class = config.active_class || "active";
     if (typeof config.box_mode != "function" && config.box_mode != "list" && config.box_mode != "buttons") {
         config.box_mode = "button";
     }
     if (typeof config.box_mode == "function") {
         config.box_mode(config);
     } else {
         var make_button;
         if (config.box_mode == "list") {
             make_button = function (symbol, index, config, disabled, active) {
                 var li = document.createElement("li");
                 var a = document.createElement("a");
                 a.className = 'page-link';
                 a.href = "#";
                 a.innerHTML = symbol;
                 a.addEventListener("click", function (event) {
                     event.preventDefault();
                     this.parentNode.click();
                     return false;
                 }, false);
                 li.appendChild(a);

                 var classes = [];
                 if (disabled) {
                     classes.push("page-item");
                     classes.push("disabled");
                 } else if (active) {
                     classes.push("page-item");
                     classes.push(config.active_class);
                 } else {
                     classes.push("page-item");
                 }
                 li.className = classes.join(" ");
                 li.addEventListener("click", function () {
                     if (this.className.split(" ").indexOf("disabled") == -1) {
                         config.page = index;
                         paginator(config);
                     }
                 }, false);
                 return li;
             }
         } else {
             make_button = function (symbol, index, config, disabled, active) {
                 var button = document.createElement("button");
                 button.innerHTML = symbol;
                 button.addEventListener("click", function (event) {
                     event.preventDefault();
                     if (this.disabled != true) {
                         config.page = index;
                         paginator(config);
                     }
                     return false;
                 }, false);
                 if (disabled) {
                     button.disabled = true;
                 }
                 if (active) {
                     button.className = config.active_class;
                 }
                 return button;
             }
         }

         // make page button collection
         var page_box = document.createElement(config.box_mode == "list" ? "ul" : "div");
         if (config.box_mode == "list") {
             page_box.className = "pagination";
         }

         var left = make_button("&laquo;", (page > 1 ? page - 1 : 1), config, (page == 1), false);
         page_box.appendChild(left);

         // 添加处理 page_range 参数的逻辑
         var page_range = config.page_range || 5;
         var start_page = Math.max(1, page - Math.floor(page_range / 2));
         var end_page = Math.min(start_page + page_range - 1, pages);
         if (end_page - start_page + 1 < page_range) {
             start_page = Math.max(1, end_page - page_range + 1);
         }

         for (var i = start_page; i <= end_page; i++) {
             var li = make_button(i, i, config, false, (page == i));
             page_box.appendChild(li);
         }

         var right = make_button("&raquo;", (pages > page ? page + 1 : page), config, (page == pages), false);
         page_box.appendChild(right);

         if (box.childNodes.length) {
             while (box.childNodes.length > 1) {
                 box.removeChild(box.childNodes[0]);
             }
             box.replaceChild(page_box, box.childNodes[0]);
         } else {
             box.appendChild(page_box);
         }
     }

     // make rows per page selector
     if (!(typeof config.page_options == "boolean" && !config.page_options)) {
         if (typeof config.page_options == "undefined") {
             config.page_options = [
                 { value: 5, text: '5' },
                 { value: 10, text: '10' },
                 { value: 20, text: '20' },
                 { value: 50, text: '50' },
                 { value: 100, text: '100' },
                 { value: 0, text: 'All' }
             ];
         }
         var options = config.page_options;
         var select = document.createElement("select");
         for (var i = 0; i < options.length; i++) {
             var o = document.createElement("option");
             o.value = options[i].value;
             o.text = options[i].text;
             select.appendChild(o);
         }
         select.value = rows_per_page;
         select.addEventListener("change", function () {
             config.rows_per_page = this.value;
             paginator(config);
         }, false);
         box.appendChild(select);
     }

     // hide pagination if disabled
     if (config.disable) {
         if (typeof box["data-display"] == "undefined") {
             box["data-display"] = box.style.display || "";
         }
         box.style.display = "none";
     } else {
         if (box.style.display == "none") {
             box.style.display = box["data-display"] || "";
         }
     }

     // run tail function
     if (typeof config.tail_call == "function") {
         config.tail_call(config);
     }

     return box;
 }