better links for search result pagination

closes #69

app/assets/stylesheets/application.css

@@ -591,18 +591,22 @@ div.page_link_buttons {
 	font-weight: bold;
 	margin-top: 2em;
 }
-div.page_link_buttons a {
+div.page_link_buttons a,
-	color: #666;
+div.page_link_buttons span {
 	border: 1px solid #d0d0d0;
 	background-color: #f3f3f3;
+	color: #666;
 	padding: 0.25em 0.5em;
 	font-weight: bold;
 	text-decoration: none;
 	margin-left: 0.5em;
 }
-div.page_link_buttons a.cur {
+div.page_link_buttons a.cur,
+div.page_link_buttons span {
 	background-color: transparent;
 	border-color: transparent;
+	margin-left: 0.25em;
+	padding-right: 0.25em;
 }
 
 

app/helpers/application_helper.rb

@@ -1,4 +1,6 @@
 module ApplicationHelper
+  MAX_PAGES = 15
+
   def errors_for(object, message=nil)
     html = ""
     unless object.errors.blank?
@@ -22,4 +24,40 @@ module ApplicationHelper
 
     raw(label_tag(nil, ago, :title => time.strftime("%F %T %z")))
   end
+
+  def page_numbers_for_pagination(max, cur)
+    if max <= MAX_PAGES
+      return (1 .. max).to_a
+    end
+
+    pages = (cur - (MAX_PAGES / 2) + 1 .. cur + (MAX_PAGES / 2) - 1).to_a
+
+    while pages[0] < 1
+      pages.push (pages.last + 1)
+      pages.shift
+    end
+
+    while pages.last > max
+      if pages[0] > 1
+        pages.unshift (pages[0] - 1)
+      end
+      pages.pop
+    end
+
+    if pages[0] != 1
+      if pages[0] != 2
+        pages.unshift "..."
+      end
+      pages.unshift 1
+    end
+
+    if pages.last != max
+      if pages.last != max - 1
+        pages.push "..."
+      end
+      pages.push max
+    end
+
+    pages
+  end
 end

app/views/search/index.html.erb

@@ -72,10 +72,14 @@
     <div class="page_link_buttons">
       Page:
 
-      <% 1.upto(@search.page_count) do |p| %>
+      <% page_numbers_for_pagination(@search.page_count, @search.page).each do |p| %>
-        <a href="/search?<%= raw(@search.to_url_params) %>&amp;page=<%= p
+        <% if p.is_a?(Integer) %>
-          %>" class="<%= @search.page == p ? "cur" : "" %>"><%= p
+          <a href="/search?<%= raw(@search.to_url_params) %>&amp;page=<%= p
-          %></a>
+            %>" class="<%= @search.page == p ? "cur" : "" %>"><%= p
+            %></a>
+        <% else %>
+          <span>...</span>
+        <% end %>
       <% end %>
     </div>
   <% end %>

spec/helpers/application_helper_spec.rb

@@ -0,0 +1,22 @@
+require "spec_helper"
+
+describe ApplicationHelper do
+  describe "#page_numbers_for_pagination" do
+    it "returns the right number of pages" do
+      helper.page_numbers_for_pagination(10, 1).should ==
+        [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]
+
+      helper.page_numbers_for_pagination(20, 1).should ==
+        [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, "...", 20 ]
+
+      helper.page_numbers_for_pagination(25, 1).should ==
+        [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, "...", 25 ]
+
+      helper.page_numbers_for_pagination(25, 10).should ==
+        [ 1, "...", 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, "...", 25 ]
+
+      helper.page_numbers_for_pagination(25, 20).should ==
+        [ 1, "...", 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 ]
+    end
+  end
+end