From c2727e6fc82c4d3deca9611a824fd161722f2a6b Mon Sep 17 00:00:00 2001
From: Edward Betts <edward@4angle.com>
Date: Sun, 29 Sep 2019 20:19:40 +0100
Subject: [PATCH] Add pager to browse page.

---
 app.py                   | 18 ++++++++++-----
 depicts/pager.py         | 47 ++++++++++++++++++++++++++++++++++++++++
 depicts/utils.py         |  5 ++++-
 templates/find_more.html |  7 ++----
 templates/macro.html     | 29 +++++++++++++++++++++++++
 5 files changed, 95 insertions(+), 11 deletions(-)
 create mode 100644 depicts/pager.py
 create mode 100644 templates/macro.html

diff --git a/app.py b/app.py
index fb729d5..67be47b 100755
--- a/app.py
+++ b/app.py
@@ -4,6 +4,7 @@ from flask import Flask, render_template, url_for, redirect, request, g, jsonify
 from depicts import (utils, wdqs, commons, mediawiki, painting, saam, database,
                      dia, rijksmuseum, npg, museodelprado, barnesfoundation,
                      wd_catalog)
+from depicts.pager import Pagination, init_pager
 from depicts.model import DepictsItem, DepictsItemAltLabel, Edit, PaintingItem
 from requests_oauthlib import OAuth1Session
 from urllib.parse import urlencode
@@ -24,6 +25,7 @@ user_agent = 'Mozilla/5.0 (X11; Linux i586; rv:32.0) Gecko/20160101 Firefox/32.0
 app = Flask(__name__)
 app.config.from_object('config.default')
 database.init_db(app.config['DB_URL'])
+init_pager(app)
 
 find_more_props = {
     'P135': 'movement',
@@ -664,20 +666,24 @@ def browse_page():
     page_size = 45
 
     item_map = wdqs.build_browse_item_map(bindings)
-    items = []
+
+    all_items = []
     for item in item_map.values():
         if len(item['image_filename']) != 1:
             continue
         item['image_filename'] = item['image_filename'][0]
-        items.append(item)
-        if len(items) >= page_size:
-            break
+        all_items.append(item)
+
+    page = utils.get_int_arg('page') or 1
+    pager = Pagination(page, page_size, len(all_items))
+
+    items = pager.slice(all_items)
 
     filenames = [cur['image_filename'] for cur in items]
 
     thumbwidth = app.config['THUMBWIDTH']
 
-    filename = f'cache/{flat}_{page_size}_images.json'
+    filename = f'cache/{flat}_{page}_{page_size}_images.json'
     if os.path.exists(filename):
         detail = json.load(open(filename))
     else:
@@ -694,6 +700,8 @@ def browse_page():
                            facets=facets,
                            prop_labels=find_more_props,
                            label=title,
+                           pager=pager,
+                           page=page,
                            labels=find_more_props,
                            bindings=bindings,
                            total=len(bindings),
diff --git a/depicts/pager.py b/depicts/pager.py
new file mode 100644
index 0000000..16846ed
--- /dev/null
+++ b/depicts/pager.py
@@ -0,0 +1,47 @@
+from math import ceil
+from flask import request, url_for
+
+class Pagination(object):
+    def __init__(self, page, per_page, total_count):
+        self.page = page
+        self.per_page = per_page
+        self.total_count = total_count
+
+    @property
+    def pages(self):
+        return int(ceil(self.total_count / float(self.per_page)))
+
+    @property
+    def has_prev(self):
+        return self.page > 1
+
+    @property
+    def has_next(self):
+        return self.page < self.pages
+
+    def slice(self, items):
+        first = ((self.page - 1) * self.per_page)
+        last = self.page * self.per_page
+        return items[first:last]
+
+    def iter_pages(self, left_edge=2, left_current=6,
+                   right_current=6, right_edge=2):
+        last = 0
+        for num in range(1, self.pages + 1):
+            if num <= left_edge or \
+               (num > self.page - left_current - 1 and \
+                num < self.page + right_current) or \
+               num > self.pages - right_edge:
+                if last + 1 != num:
+                    yield None
+                yield num
+                last = num
+
+def url_for_other_page(page):
+    args = request.view_args.copy()
+    args.update(request.args)
+    args['page'] = page
+    return url_for(request.endpoint, **args)
+
+def init_pager(app):
+    app.jinja_env.globals['url_for_other_page'] = url_for_other_page
diff --git a/depicts/utils.py b/depicts/utils.py
index 5b8d4b9..132386f 100644
--- a/depicts/utils.py
+++ b/depicts/utils.py
@@ -1,3 +1,4 @@
+from flask import request
 from itertools import islice
 import urllib.parse
 import inflect
@@ -70,4 +71,6 @@ def wiki_url(title, site, ns=None):
 
     return f'https://{host}/wiki/' + url_ns + urllib.parse.quote(title.replace(' ', '_'))
 
-
+def get_int_arg(name):
+    if name in request.args and request.args[name].isdigit():
+        return int(request.args[name])
diff --git a/templates/find_more.html b/templates/find_more.html
index ea99304..5d9fc42 100644
--- a/templates/find_more.html
+++ b/templates/find_more.html
@@ -1,3 +1,4 @@
+{% from "macro.html" import render_pagination %}
 {% extends "base.html" %}
 
 {% block title %}{{ label }}{% endblock %}
@@ -51,11 +52,7 @@
   {% endfor %}
 </div>
 
-{#
-  {% for item in items %}
-  <pre>{{ item | pprint }}</pre>
-  {% endfor %}
-#}
+{{ render_pagination(pager) }}
 
 </div>
 {% endblock %}
diff --git a/templates/macro.html b/templates/macro.html
new file mode 100644
index 0000000..faf8686
--- /dev/null
+++ b/templates/macro.html
@@ -0,0 +1,29 @@
+{% macro render_pagination(pagination) %}
+{% if pagination.pages > 1 %}
+<nav aria-label="Page navigation example">
+  <ul class="pagination">
+  {% if pagination.has_prev %}
+		<li class="page-item"><a class="page-link" href="{{ url_for_other_page(pagination.page - 1) }}">&laquo; Previous</a></li>
+  {% endif %}
+  {%- for page in pagination.iter_pages() %}
+    {% if page %}
+      {% if page != pagination.page %}
+		<li class="page-item"><a class="page-link" href="{{ url_for_other_page(page) }}">{{ page }}</a></li>
+      {% else %}
+        <li class="page-item active"><a class="page-link" href="{{ url_for_other_page(page) }}">{{ page }} <span class="sr-only">(current)</span></a></li>
+      {% endif %}
+    {% else %}
+      <li><span class="ellipsis">…</span></li>
+    {% endif %}
+  {%- endfor %}
+  {% if pagination.has_next %}
+    <li class="page-item">
+      <a class="page-link" href="{{ url_for_other_page(pagination.page + 1) }}" aria-label="Next">
+        <span aria-hidden="true">Next &raquo;</span>
+      </a>
+    </li>
+  {% endif %}
+  </ul>
+</nav>
+{% endif %}
+{% endmacro %}