From 24f1c2d7b26b339ab8ed54798f1a2a8ff7256f3f Mon Sep 17 00:00:00 2001
From: Dimitris Papagiannis <d.papag.a@gmail.com>
Date: Wed, 29 Jan 2025 18:43:03 +0100
Subject: [PATCH] Paginate results

---
 static/pagination_helper.js        | 266 +++++++++++++++++++++++++++++
 templates/release_comparisons.html |  54 +++---
 2 files changed, 289 insertions(+), 31 deletions(-)
 create mode 100644 static/pagination_helper.js

diff --git a/static/pagination_helper.js b/static/pagination_helper.js
new file mode 100644
index 0000000..20b8d02
--- /dev/null
+++ b/static/pagination_helper.js
@@ -0,0 +1,266 @@
+
+function pagination_helper() {
+    let _current_page = 1;
+    let _data = {}
+    let _num_total_items = 1;
+    let _dom_element = '';  // The DOM element where the data will be put in
+    let _items_per_page = 1;
+    let _total_pages = 1;
+    let _item_creation_callback;
+    let _is_initialized = false;
+    const NUM_PAGES_SHOW_ELLIPSIS = 2
+
+
+    function _calculate_num_pages() {
+        _total_pages = Math.ceil(_num_total_items / _items_per_page);
+    }
+
+    /* Helper function for adding CSS classes to a paginato page button */
+    function _add_bootstrap_classes_to_page_li(el) {
+        el.classList.add('page-item')
+        el.firstChild.classList.add('page-link')
+        return el
+    }
+
+    /* Callback to run when clicking the next page button */
+    function _goto_next_page() {
+        if (_current_page + 1 > _total_pages) {
+            _current_page = _total_pages;
+        }
+        else {
+            _current_page += 1;
+        }
+        _goto_specific_page(_current_page)
+    }
+
+    /* Callback to run when clicking the previous page button */
+    function _goto_prev_page() {
+        if (_current_page - 1 < 1) {
+            _current_page = 1;
+        }
+        else {
+            _current_page -= 1;
+        }
+        _goto_specific_page(_current_page)
+    }
+
+    /* Callback to run when clicking on a page button */
+    function _goto_specific_page(page_num) {
+        if (page_num <= _total_pages && page_num >= 1) {
+            _current_page = page_num;
+            _clear_pagination_el()
+            _create_pages()
+            _clear_data()
+            _fill_data()
+        }
+    }
+
+    /*
+    Function that crates a paginator button for a single page.
+
+    content: can be either a DOM Element (in which case it is appended directly
+    into the button), or a text/number, in which case it replaces the innerHTML.
+
+    additional classes: a string of CSS classes to be added to the button (e.g., "class1 class2")
+
+    onclick: the function to run when the button is clicked. It will be passed the
+    DOM Element as an argument.
+
+    title: the string to display on button mouse hover.
+     */
+    function _create_page_el(content, additional_classes, onclick, title) {
+        let li = document.createElement('li')
+        if (additional_classes) {
+            li.classList.add(additional_classes)
+        }
+        if (title) {
+            li.setAttribute('title', title)
+        }
+        let a = document.createElement('a')
+        a.setAttribute.href = '#'
+        if (content instanceof Element) {
+            a.appendChild(content)
+        } else if (typeof content === 'string' || typeof content === 'number') {
+            a.innerHTML = content
+            if (!title) {
+                li.setAttribute('title', `Go to page ${content}`)
+            }
+        }
+        if (typeof onclick === 'function') {
+            li.onclick = onclick
+        }
+        li.appendChild(a)
+        return _add_bootstrap_classes_to_page_li(li)
+    }
+
+    function _create_first_page_el() {
+        let i = document.createElement('i')
+        i.classList.add('bi', 'bi-chevron-double-left')
+
+        return _create_page_el(i, _current_page === 1 ? "disabled" : "",
+            () => { _goto_specific_page(1) }, "First page")
+    }
+
+    function _create_previous_page_el() {
+        let i = document.createElement('i')
+        i.classList.add('bi', 'bi-chevron-left')
+        return _create_page_el(i, _current_page === 1 ? "disabled" : "",
+            _goto_prev_page, "Previous page")
+    }
+
+    function _create_last_page_el() {
+        let i = document.createElement('i')
+        i.classList.add('bi', 'bi-chevron-double-right')
+        return _create_page_el(i, (_current_page === _total_pages || _total_pages === 0) ?
+            "disabled" : "",
+            () => { _goto_specific_page(_total_pages) },
+            'Last page')
+    }
+
+    function _create_next_page_el() {
+        let i = document.createElement('i')
+        i.classList.add('bi', 'bi-chevron-right')
+        return _create_page_el(i, (_current_page === _total_pages || _total_pages === 0) ?
+            "disabled" : "",
+            _goto_next_page,
+            "Next page")
+    }
+
+    /* Create a single page button for a specific page */
+    function _create_page_number_el(page_num) {
+        return _create_page_el(
+            String(page_num),
+            _current_page === page_num ? "active" : "",
+            () => { _goto_specific_page(page_num) }
+        )
+    }
+
+    /* Get the DOM element id where page buttons will be added */
+    function _get_pagination_el_id() {
+        return `${_dom_element}_pagination`
+    }
+
+    /* Clear the pagination buttons completely */
+    function _clear_pagination_el() {
+        let pagination_el = document.getElementById(_get_pagination_el_id())
+        if (pagination_el) {
+            pagination_el.innerHTML = ''
+        }
+    }
+
+    /*
+    Create the pagination element under the same parent as the
+    _dom_element passed at initialization.
+    */
+    function _create_pagination_el() {
+        let base_el = document.getElementById(_dom_element).parentElement;
+        let pagination_el = document.createElement('nav');
+        let ul_el = document.createElement('ul');
+        ul_el.classList.add('pagination', 'mt-2')
+        ul_el.setAttribute('id', _get_pagination_el_id())
+        pagination_el.appendChild(ul_el)
+        base_el.appendChild(pagination_el);
+    }
+
+    /*
+        Create the page links inside the pagination DOM element.
+    */
+    function _create_pages() {
+        let pagination_el = document.getElementById(_get_pagination_el_id())
+        pagination_el.appendChild(_create_first_page_el())
+        pagination_el.appendChild(_create_previous_page_el())
+        if (_total_pages < 3) {
+            for (i = 1; i <= _total_pages; i++) {
+                pagination_el.appendChild(_create_page_number_el(i))
+            }
+        }
+        else {
+            if (_current_page - 1 <= NUM_PAGES_SHOW_ELLIPSIS) {
+                for (let i = 1; i <= _current_page - 1; i++) {
+                    pagination_el.appendChild(_create_page_number_el(i))
+                }
+            }
+            else {
+                pagination_el.appendChild(_create_page_el('...', 'disabled'))
+                pagination_el.appendChild(_create_page_number_el(_current_page - 1))
+            }
+
+            pagination_el.appendChild(_create_page_number_el(_current_page))
+
+            if (_total_pages - _current_page <= NUM_PAGES_SHOW_ELLIPSIS) {
+                for (let i = _current_page + 1; i <= _total_pages; i++) {
+                    pagination_el.appendChild(_create_page_number_el(i))
+                }
+            }
+            else {
+                pagination_el.appendChild(_create_page_number_el(_current_page + 1))
+                pagination_el.appendChild(_create_page_el('...', 'disabled'))
+
+            }
+        }
+        pagination_el.appendChild(_create_next_page_el())
+        pagination_el.appendChild(_create_last_page_el())
+    }
+
+    // Create a single li element for a single comparison report.
+    function _create_result_list_element(data) {
+        let li = document.createElement("li");
+
+        if (typeof _item_creation_callback === 'function') {
+            li = _item_creation_callback(li, data)
+        }
+        return li;
+    }
+
+    function _clear_data() {
+        let data_el = document.getElementById(_dom_element)
+        data_el.innerHTML = ''
+    }
+    function _fill_data() {
+        let data_el = document.getElementById(_dom_element)
+        let index_start = (_current_page - 1) * _items_per_page
+        let page_data = _data.slice(index_start, index_start + _items_per_page)
+        page_data.forEach(element => {
+            data_el.appendChild(_create_result_list_element(element))
+        });
+    }
+    function _paginate(data, dom_element, item_creation_callback, items_per_page) {
+        if (typeof data !== 'object' || !data.hasOwnProperty('length')) {
+            throw Error(`data passed should be array-like, cannot initialize pagination`)
+        }
+        _data = data;
+        _num_total_items = data.length;
+        if (typeof dom_element !== 'string' || !document.getElementById(dom_element)) {
+            throw Error(`Could not find DOM element "${dom_element}" to attach pagination to`)
+        }
+        _dom_element = dom_element;
+
+        _items_per_page = Number(items_per_page)
+        if (isNaN(_items_per_page)) {
+            throw Error(`items_per_page should be a number, received ${typeof items_per_page}: ${items_per_page}`)
+        }
+
+        if (typeof item_creation_callback === 'function') {
+            _item_creation_callback = item_creation_callback
+        }
+        _calculate_num_pages()
+        _clear_pagination_el()
+        _create_pagination_el()
+        _create_pages()
+        _clear_data()
+        _fill_data()
+    }
+    /* "Public" methods are returned as an object with functions */
+    return {
+        paginate: (data, dom_element, item_creation_callback, items_per_page = _items_per_page) => {
+            _paginate(data, dom_element, item_creation_callback, items_per_page)
+            _is_initialized = true
+        },
+        data: (data) => {
+            if (!_is_initialized) {
+                throw Error(`Paginator has not been initialized!`)
+            }
+            _paginate(data, _dom_element, _item_creation_callback, _items_per_page)
+        }
+    }
+};
\ No newline at end of file
diff --git a/templates/release_comparisons.html b/templates/release_comparisons.html
index 951d5f9..ae92eaa 100644
--- a/templates/release_comparisons.html
+++ b/templates/release_comparisons.html
@@ -1,5 +1,5 @@
 {% extends "base.html" %} {% block head %}
-<script src="{{ url_for('static', filename='index_utils.js') }}"></script>
+<script src="{{ url_for('static', filename='pagination_helper.js') }}"></script>
 <title>DQM CMSSW Release comparison results browser</title>
 {% endblock %} {% block content %}
 <div class="row mt-5">
@@ -27,10 +27,7 @@ <h2>Click an item from the list on the left.</h2>
 <script>
   const TIMEZONE = "{{ TIMEZONE }}";
   const PREFIX = "{{ PREFIX }}";
-
-  function initialize_results_list() {
-    document.getElementById("results-list").innerHTML = "";
-  }
+  const MAX_RESULTS_PER_PAGE = 10;
 
   // Remove the bootstrap 'active' class from all items
   // in the available reports list.
@@ -57,28 +54,6 @@ <h2>Click an item from the list on the left.</h2>
     set_comparison_frame_contents(id);
   }
 
-  // Create a single li element for a single comparison report.
-  function create_result_list_element(data) {
-    let li = document.createElement("li");
-    li.classList.add("list-group-item", "list-group-item-action");
-    li.onclick = onclick_specific_comparison;
-    li.innerHTML = `${data.base_cmssw_version} (${data.base_prs}) vs ${data.comp_cmssw_version} (${data.comp_prs})`;
-    li.setAttribute("id", data.id);
-    li.setAttribute("title", `Comparison ran at ${data.comparison_ran_at}`);
-    return li;
-  }
-
-  // Given the list of available comparison reports, populate
-  // the results list.
-  function update_available_results_list(data) {
-    let results_list = document.getElementById("results-list");
-    data.forEach((element) => {
-      console.log(element);
-      let li = create_result_list_element(element);
-      results_list.append(li);
-    });
-  }
-
   // Fetch the list of the available comparison reports from the API.
   // Return the json response as a Promise.
   function get_available_comparisons() {
@@ -89,10 +64,27 @@ <h2>Click an item from the list on the left.</h2>
 
   // Attach to the load event of the window.
   addEventListener("load", (event) => {
-    initialize_results_list();
-    get_available_comparisons().then((data) =>
-      update_available_results_list(data)
-    );
+    let pagination = pagination_helper();
+    get_available_comparisons().then((data) => {
+      pagination.paginate(
+        data /* data paginate */,
+        "results-list" /* DOM element to attach to */,
+        /* On result creation callback. Gets the DOM element created (li)
+        and the data corresponding as arg, must return it. */
+        (li, data) => {
+          li.setAttribute("id", data.id);
+          li.setAttribute(
+            "title",
+            `Comparison ran at ${data.comparison_ran_at}`
+          );
+          li.innerHTML = `${data.base_cmssw_version} (${data.base_prs}) vs ${data.comp_cmssw_version} (${data.comp_prs})`;
+          li.classList.add("list-group-item", "list-group-item-action");
+          li.onclick = onclick_specific_comparison;
+          return li;
+        },
+        MAX_RESULTS_PER_PAGE /* Items per page to show */
+      );
+    });
   });
 </script>
 {% endblock %}